inode.c 138.3 KB
Newer Older
1
/*
2
 *  linux/fs/ext4/inode.c
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Goal-directed block allocation by Stephen Tweedie
 *	(sct@redhat.com), 1993, 1998
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 *	(jj@sunsite.ms.mff.cuni.cz)
 *
22
 *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
23 24 25 26 27
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/time.h>
28
#include <linux/jbd2.h>
29 30 31 32 33 34
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
35
#include <linux/pagevec.h>
36 37 38
#include <linux/mpage.h>
#include <linux/uio.h>
#include <linux/bio.h>
39
#include "ext4_jbd2.h"
40 41
#include "xattr.h"
#include "acl.h"
42
#include "ext4_extents.h"
43

44 45
#define MPAGE_DA_EXTENT_TAIL 0x01

46 47 48 49 50 51 52
static inline int ext4_begin_ordered_truncate(struct inode *inode,
					      loff_t new_size)
{
	return jbd2_journal_begin_ordered_truncate(&EXT4_I(inode)->jinode,
						   new_size);
}

53 54
static void ext4_invalidatepage(struct page *page, unsigned long offset);

55 56 57
/*
 * Test whether an inode is a fast symlink.
 */
58
static int ext4_inode_is_fast_symlink(struct inode *inode)
59
{
60
	int ea_blocks = EXT4_I(inode)->i_file_acl ?
61 62 63 64 65 66
		(inode->i_sb->s_blocksize >> 9) : 0;

	return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
}

/*
67
 * The ext4 forget function must perform a revoke if we are freeing data
68 69 70 71 72 73 74
 * which has been journaled.  Metadata (eg. indirect blocks) must be
 * revoked in all cases.
 *
 * "bh" may be NULL: a metadata block may have been freed from memory
 * but there may still be a record of it in the journal, and that record
 * still needs to be revoked.
 */
75 76
int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
			struct buffer_head *bh, ext4_fsblk_t blocknr)
77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93
{
	int err;

	might_sleep();

	BUFFER_TRACE(bh, "enter");

	jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "
		  "data mode %lx\n",
		  bh, is_metadata, inode->i_mode,
		  test_opt(inode->i_sb, DATA_FLAGS));

	/* Never use the revoke function if we are doing full data
	 * journaling: there is no need to, and a V1 superblock won't
	 * support it.  Otherwise, only skip the revoke on un-journaled
	 * data blocks. */

94 95
	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
	    (!is_metadata && !ext4_should_journal_data(inode))) {
96
		if (bh) {
97
			BUFFER_TRACE(bh, "call jbd2_journal_forget");
98
			return ext4_journal_forget(handle, bh);
99 100 101 102 103 104 105
		}
		return 0;
	}

	/*
	 * data!=journal && (is_metadata || should_journal_data(inode))
	 */
106 107
	BUFFER_TRACE(bh, "call ext4_journal_revoke");
	err = ext4_journal_revoke(handle, blocknr, bh);
108
	if (err)
109
		ext4_abort(inode->i_sb, __func__,
110 111 112 113 114 115 116 117 118 119 120
			   "error %d when attempting revoke", err);
	BUFFER_TRACE(bh, "exit");
	return err;
}

/*
 * Work out how many blocks we need to proceed with the next chunk of a
 * truncate transaction.
 */
static unsigned long blocks_for_truncate(struct inode *inode)
{
A
Aneesh Kumar K.V 已提交
121
	ext4_lblk_t needed;
122 123 124 125 126 127

	needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);

	/* Give ourselves just enough room to cope with inodes in which
	 * i_blocks is corrupt: we've seen disk corruptions in the past
	 * which resulted in random data in an inode which looked enough
128
	 * like a regular file for ext4 to try to delete it.  Things
129 130 131 132 133 134 135
	 * will go a bit crazy if that happens, but at least we should
	 * try not to panic the whole kernel. */
	if (needed < 2)
		needed = 2;

	/* But we need to bound the transaction so we don't overflow the
	 * journal. */
136 137
	if (needed > EXT4_MAX_TRANS_DATA)
		needed = EXT4_MAX_TRANS_DATA;
138

139
	return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155
}

/*
 * Truncate transactions can be complex and absolutely huge.  So we need to
 * be able to restart the transaction at a conventient checkpoint to make
 * sure we don't overflow the journal.
 *
 * start_transaction gets us a new handle for a truncate transaction,
 * and extend_transaction tries to extend the existing one a bit.  If
 * extend fails, we need to propagate the failure up and restart the
 * transaction in the top-level truncate loop. --sct
 */
static handle_t *start_transaction(struct inode *inode)
{
	handle_t *result;

156
	result = ext4_journal_start(inode, blocks_for_truncate(inode));
157 158 159
	if (!IS_ERR(result))
		return result;

160
	ext4_std_error(inode->i_sb, PTR_ERR(result));
161 162 163 164 165 166 167 168 169 170 171
	return result;
}

/*
 * Try to extend this transaction for the purposes of truncation.
 *
 * Returns 0 if we managed to create more room.  If we can't create more
 * room, and the transaction must be restarted we return 1.
 */
static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
{
172
	if (handle->h_buffer_credits > EXT4_RESERVE_TRANS_BLOCKS)
173
		return 0;
174
	if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
175 176 177 178 179 180 181 182 183
		return 0;
	return 1;
}

/*
 * Restart the transaction associated with *handle.  This does a commit,
 * so before we call here everything must be consistently dirtied against
 * this transaction.
 */
184
static int ext4_journal_test_restart(handle_t *handle, struct inode *inode)
185 186
{
	jbd_debug(2, "restarting handle %p\n", handle);
187
	return ext4_journal_restart(handle, blocks_for_truncate(inode));
188 189 190 191 192
}

/*
 * Called at the last iput() if i_nlink is zero.
 */
193
void ext4_delete_inode(struct inode *inode)
194 195
{
	handle_t *handle;
196
	int err;
197

198 199
	if (ext4_should_order_data(inode))
		ext4_begin_ordered_truncate(inode, 0);
200 201 202 203 204
	truncate_inode_pages(&inode->i_data, 0);

	if (is_bad_inode(inode))
		goto no_delete;

205
	handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
206
	if (IS_ERR(handle)) {
207
		ext4_std_error(inode->i_sb, PTR_ERR(handle));
208 209 210 211 212
		/*
		 * If we're going to skip the normal cleanup, we still need to
		 * make sure that the in-core orphan linked list is properly
		 * cleaned up.
		 */
213
		ext4_orphan_del(NULL, inode);
214 215 216 217 218 219
		goto no_delete;
	}

	if (IS_SYNC(inode))
		handle->h_sync = 1;
	inode->i_size = 0;
220 221 222 223 224 225
	err = ext4_mark_inode_dirty(handle, inode);
	if (err) {
		ext4_warning(inode->i_sb, __func__,
			     "couldn't mark inode dirty (err %d)", err);
		goto stop_handle;
	}
226
	if (inode->i_blocks)
227
		ext4_truncate(inode);
228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247

	/*
	 * ext4_ext_truncate() doesn't reserve any slop when it
	 * restarts journal transactions; therefore there may not be
	 * enough credits left in the handle to remove the inode from
	 * the orphan list and set the dtime field.
	 */
	if (handle->h_buffer_credits < 3) {
		err = ext4_journal_extend(handle, 3);
		if (err > 0)
			err = ext4_journal_restart(handle, 3);
		if (err != 0) {
			ext4_warning(inode->i_sb, __func__,
				     "couldn't extend journal (err %d)", err);
		stop_handle:
			ext4_journal_stop(handle);
			goto no_delete;
		}
	}

248
	/*
249
	 * Kill off the orphan record which ext4_truncate created.
250
	 * AKPM: I think this can be inside the above `if'.
251
	 * Note that ext4_orphan_del() has to be able to cope with the
252
	 * deletion of a non-existent orphan - this is because we don't
253
	 * know if ext4_truncate() actually created an orphan record.
254 255
	 * (Well, we could do this if we need to, but heck - it works)
	 */
256 257
	ext4_orphan_del(handle, inode);
	EXT4_I(inode)->i_dtime	= get_seconds();
258 259 260 261 262 263 264 265

	/*
	 * One subtle ordering requirement: if anything has gone wrong
	 * (transaction abort, IO errors, whatever), then we can still
	 * do these next steps (the fs will already have been marked as
	 * having errors), but we can't free the inode if the mark_dirty
	 * fails.
	 */
266
	if (ext4_mark_inode_dirty(handle, inode))
267 268 269
		/* If that failed, just do the required in-core inode clear. */
		clear_inode(inode);
	else
270 271
		ext4_free_inode(handle, inode);
	ext4_journal_stop(handle);
272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289
	return;
no_delete:
	clear_inode(inode);	/* We must guarantee clearing of inode... */
}

typedef struct {
	__le32	*p;
	__le32	key;
	struct buffer_head *bh;
} Indirect;

static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
{
	p->key = *(p->p = v);
	p->bh = bh;
}

/**
290
 *	ext4_block_to_path - parse the block number into array of offsets
291 292 293
 *	@inode: inode in question (we are only interested in its superblock)
 *	@i_block: block number to be parsed
 *	@offsets: array to store the offsets in
D
Dave Kleikamp 已提交
294 295
 *	@boundary: set this non-zero if the referred-to block is likely to be
 *	       followed (on disk) by an indirect block.
296
 *
297
 *	To store the locations of file's data ext4 uses a data structure common
298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319
 *	for UNIX filesystems - tree of pointers anchored in the inode, with
 *	data blocks at leaves and indirect blocks in intermediate nodes.
 *	This function translates the block number into path in that tree -
 *	return value is the path length and @offsets[n] is the offset of
 *	pointer to (n+1)th node in the nth one. If @block is out of range
 *	(negative or too large) warning is printed and zero returned.
 *
 *	Note: function doesn't find node addresses, so no IO is needed. All
 *	we need to know is the capacity of indirect blocks (taken from the
 *	inode->i_sb).
 */

/*
 * Portability note: the last comparison (check that we fit into triple
 * indirect block) is spelled differently, because otherwise on an
 * architecture with 32-bit longs and 8Kb pages we might get into trouble
 * if our filesystem had 8Kb blocks. We might use long long, but that would
 * kill us on x86. Oh, well, at least the sign propagation does not matter -
 * i_block would have to be negative in the very beginning, so we would not
 * get there at all.
 */

320
static int ext4_block_to_path(struct inode *inode,
A
Aneesh Kumar K.V 已提交
321 322
			ext4_lblk_t i_block,
			ext4_lblk_t offsets[4], int *boundary)
323
{
324 325 326
	int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
	int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
	const long direct_blocks = EXT4_NDIR_BLOCKS,
327 328 329 330 331 332
		indirect_blocks = ptrs,
		double_blocks = (1 << (ptrs_bits * 2));
	int n = 0;
	int final = 0;

	if (i_block < 0) {
333
		ext4_warning(inode->i_sb, "ext4_block_to_path", "block < 0");
334 335 336
	} else if (i_block < direct_blocks) {
		offsets[n++] = i_block;
		final = direct_blocks;
337
	} else if ((i_block -= direct_blocks) < indirect_blocks) {
338
		offsets[n++] = EXT4_IND_BLOCK;
339 340 341
		offsets[n++] = i_block;
		final = ptrs;
	} else if ((i_block -= indirect_blocks) < double_blocks) {
342
		offsets[n++] = EXT4_DIND_BLOCK;
343 344 345 346
		offsets[n++] = i_block >> ptrs_bits;
		offsets[n++] = i_block & (ptrs - 1);
		final = ptrs;
	} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
347
		offsets[n++] = EXT4_TIND_BLOCK;
348 349 350 351 352
		offsets[n++] = i_block >> (ptrs_bits * 2);
		offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
		offsets[n++] = i_block & (ptrs - 1);
		final = ptrs;
	} else {
353
		ext4_warning(inode->i_sb, "ext4_block_to_path",
354
				"block %lu > max",
355 356
				i_block + direct_blocks +
				indirect_blocks + double_blocks);
357 358 359 360 361 362 363
	}
	if (boundary)
		*boundary = final - 1 - (i_block & (ptrs - 1));
	return n;
}

/**
364
 *	ext4_get_branch - read the chain of indirect blocks leading to data
365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388
 *	@inode: inode in question
 *	@depth: depth of the chain (1 - direct pointer, etc.)
 *	@offsets: offsets of pointers in inode/indirect blocks
 *	@chain: place to store the result
 *	@err: here we store the error value
 *
 *	Function fills the array of triples <key, p, bh> and returns %NULL
 *	if everything went OK or the pointer to the last filled triple
 *	(incomplete one) otherwise. Upon the return chain[i].key contains
 *	the number of (i+1)-th block in the chain (as it is stored in memory,
 *	i.e. little-endian 32-bit), chain[i].p contains the address of that
 *	number (it points into struct inode for i==0 and into the bh->b_data
 *	for i>0) and chain[i].bh points to the buffer_head of i-th indirect
 *	block for i>0 and NULL for i==0. In other words, it holds the block
 *	numbers of the chain, addresses they were taken from (and where we can
 *	verify that chain did not change) and buffer_heads hosting these
 *	numbers.
 *
 *	Function stops when it stumbles upon zero pointer (absent block)
 *		(pointer to last triple returned, *@err == 0)
 *	or when it gets an IO error reading an indirect block
 *		(ditto, *@err == -EIO)
 *	or when it reads all @depth-1 indirect blocks successfully and finds
 *	the whole chain, all way to the data (returns %NULL, *err == 0).
389 390
 *
 *      Need to be called with
391
 *      down_read(&EXT4_I(inode)->i_data_sem)
392
 */
A
Aneesh Kumar K.V 已提交
393 394
static Indirect *ext4_get_branch(struct inode *inode, int depth,
				 ext4_lblk_t  *offsets,
395 396 397 398 399 400 401 402
				 Indirect chain[4], int *err)
{
	struct super_block *sb = inode->i_sb;
	Indirect *p = chain;
	struct buffer_head *bh;

	*err = 0;
	/* i_data is not going away, no lock needed */
403
	add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
404 405 406 407 408 409
	if (!p->key)
		goto no_block;
	while (--depth) {
		bh = sb_bread(sb, le32_to_cpu(p->key));
		if (!bh)
			goto failure;
410
		add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
411 412 413 414 415 416 417 418 419 420 421 422 423
		/* Reader: end */
		if (!p->key)
			goto no_block;
	}
	return NULL;

failure:
	*err = -EIO;
no_block:
	return p;
}

/**
424
 *	ext4_find_near - find a place for allocation with sufficient locality
425 426 427
 *	@inode: owner
 *	@ind: descriptor of indirect block.
 *
428
 *	This function returns the preferred place for block allocation.
429 430 431 432 433 434 435 436 437 438 439 440 441 442
 *	It is used when heuristic for sequential allocation fails.
 *	Rules are:
 *	  + if there is a block to the left of our position - allocate near it.
 *	  + if pointer will live in indirect block - allocate near that block.
 *	  + if pointer will live in inode - allocate in the same
 *	    cylinder group.
 *
 * In the latter case we colour the starting block by the callers PID to
 * prevent it from clashing with concurrent allocations for a different inode
 * in the same block group.   The PID is used here so that functionally related
 * files will be close-by on-disk.
 *
 *	Caller must make sure that @ind is valid and will stay that way.
 */
443
static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
444
{
445
	struct ext4_inode_info *ei = EXT4_I(inode);
446
	__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
447
	__le32 *p;
448
	ext4_fsblk_t bg_start;
449
	ext4_fsblk_t last_block;
450
	ext4_grpblk_t colour;
451 452 453 454 455 456 457 458 459 460 461 462 463 464 465

	/* Try to find previous block */
	for (p = ind->p - 1; p >= start; p--) {
		if (*p)
			return le32_to_cpu(*p);
	}

	/* No such thing, so let's try location of indirect block */
	if (ind->bh)
		return ind->bh->b_blocknr;

	/*
	 * It is going to be referred to from the inode itself? OK, just put it
	 * into the same cylinder group then.
	 */
466
	bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group);
467 468 469 470
	last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;

	if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
		colour = (current->pid % 16) *
471
			(EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
472 473
	else
		colour = (current->pid % 16) * ((last_block - bg_start) / 16);
474 475 476 477
	return bg_start + colour;
}

/**
478
 *	ext4_find_goal - find a preferred place for allocation.
479 480 481 482
 *	@inode: owner
 *	@block:  block we want
 *	@partial: pointer to the last triple within a chain
 *
483
 *	Normally this function find the preferred place for block allocation,
484
 *	returns it.
485
 */
A
Aneesh Kumar K.V 已提交
486
static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
487
		Indirect *partial)
488
{
489
	struct ext4_block_alloc_info *block_i;
490

491
	block_i =  EXT4_I(inode)->i_block_alloc_info;
492 493 494 495 496 497 498 499 500 501

	/*
	 * try the heuristic for sequential allocation,
	 * failing that at least try to get decent locality.
	 */
	if (block_i && (block == block_i->last_alloc_logical_block + 1)
		&& (block_i->last_alloc_physical_block != 0)) {
		return block_i->last_alloc_physical_block + 1;
	}

502
	return ext4_find_near(inode, partial);
503 504 505
}

/**
506
 *	ext4_blks_to_allocate: Look up the block map and count the number
507 508 509 510 511 512 513 514 515 516
 *	of direct blocks need to be allocated for the given branch.
 *
 *	@branch: chain of indirect blocks
 *	@k: number of blocks need for indirect blocks
 *	@blks: number of data blocks to be mapped.
 *	@blocks_to_boundary:  the offset in the indirect block
 *
 *	return the total number of blocks to be allocate, including the
 *	direct and indirect blocks.
 */
517
static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned long blks,
518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543
		int blocks_to_boundary)
{
	unsigned long count = 0;

	/*
	 * Simple case, [t,d]Indirect block(s) has not allocated yet
	 * then it's clear blocks on that path have not allocated
	 */
	if (k > 0) {
		/* right now we don't handle cross boundary allocation */
		if (blks < blocks_to_boundary + 1)
			count += blks;
		else
			count += blocks_to_boundary + 1;
		return count;
	}

	count++;
	while (count < blks && count <= blocks_to_boundary &&
		le32_to_cpu(*(branch[0].p + count)) == 0) {
		count++;
	}
	return count;
}

/**
544
 *	ext4_alloc_blocks: multiple allocate blocks needed for a branch
545 546 547 548 549 550 551 552
 *	@indirect_blks: the number of blocks need to allocate for indirect
 *			blocks
 *
 *	@new_blocks: on return it will store the new block numbers for
 *	the indirect blocks(if needed) and the first direct block,
 *	@blks:	on return it will store the total number of allocated
 *		direct blocks
 */
553
static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
554 555 556
				ext4_lblk_t iblock, ext4_fsblk_t goal,
				int indirect_blks, int blks,
				ext4_fsblk_t new_blocks[4], int *err)
557 558
{
	int target, i;
559
	unsigned long count = 0, blk_allocated = 0;
560
	int index = 0;
561
	ext4_fsblk_t current_block = 0;
562 563 564 565 566 567 568 569 570 571
	int ret = 0;

	/*
	 * Here we try to allocate the requested multiple blocks at once,
	 * on a best-effort basis.
	 * To build a branch, we should allocate blocks for
	 * the indirect blocks(if not allocated yet), and at least
	 * the first direct block of this branch.  That's the
	 * minimum number of blocks need to allocate(required)
	 */
572 573 574
	/* first we try to allocate the indirect blocks */
	target = indirect_blks;
	while (target > 0) {
575 576
		count = target;
		/* allocating blocks for indirect blocks and direct blocks */
577 578
		current_block = ext4_new_meta_blocks(handle, inode,
							goal, &count, err);
579 580 581 582 583 584 585 586 587
		if (*err)
			goto failed_out;

		target -= count;
		/* allocate blocks for indirect blocks */
		while (index < indirect_blks && count) {
			new_blocks[index++] = current_block++;
			count--;
		}
588 589 590 591 592 593 594 595 596
		if (count > 0) {
			/*
			 * save the new block number
			 * for the first direct block
			 */
			new_blocks[index] = current_block;
			printk(KERN_INFO "%s returned more blocks than "
						"requested\n", __func__);
			WARN_ON(1);
597
			break;
598
		}
599 600
	}

601 602 603 604 605 606
	target = blks - count ;
	blk_allocated = count;
	if (!target)
		goto allocated;
	/* Now allocate data blocks */
	count = target;
A
Aneesh Kumar K.V 已提交
607
	/* allocating blocks for data blocks */
608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627
	current_block = ext4_new_blocks(handle, inode, iblock,
						goal, &count, err);
	if (*err && (target == blks)) {
		/*
		 * if the allocation failed and we didn't allocate
		 * any blocks before
		 */
		goto failed_out;
	}
	if (!*err) {
		if (target == blks) {
		/*
		 * save the new block number
		 * for the first direct block
		 */
			new_blocks[index] = current_block;
		}
		blk_allocated += count;
	}
allocated:
628
	/* total number of blocks allocated for direct blocks */
629
	ret = blk_allocated;
630 631 632
	*err = 0;
	return ret;
failed_out:
633
	for (i = 0; i < index; i++)
634
		ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
635 636 637 638
	return ret;
}

/**
639
 *	ext4_alloc_branch - allocate and set up a chain of blocks.
640 641 642 643 644 645 646 647 648 649
 *	@inode: owner
 *	@indirect_blks: number of allocated indirect blocks
 *	@blks: number of allocated direct blocks
 *	@offsets: offsets (in the blocks) to store the pointers to next.
 *	@branch: place to store the chain in.
 *
 *	This function allocates blocks, zeroes out all but the last one,
 *	links them into chain and (if we are synchronous) writes them to disk.
 *	In other words, it prepares a branch that can be spliced onto the
 *	inode. It stores the information about that chain in the branch[], in
650
 *	the same format as ext4_get_branch() would do. We are calling it after
651 652
 *	we had read the existing part of chain and partial points to the last
 *	triple of that (one with zero ->key). Upon the exit we have the same
653
 *	picture as after the successful ext4_get_block(), except that in one
654 655 656 657 658 659
 *	place chain is disconnected - *branch->p is still zero (we did not
 *	set the last link), but branch->key contains the number that should
 *	be placed into *branch->p to fill that gap.
 *
 *	If allocation fails we free all blocks we've allocated (and forget
 *	their buffer_heads) and return the error value the from failed
660
 *	ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
661 662
 *	as described above and return 0.
 */
663
static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
664 665 666
				ext4_lblk_t iblock, int indirect_blks,
				int *blks, ext4_fsblk_t goal,
				ext4_lblk_t *offsets, Indirect *branch)
667 668 669 670 671 672
{
	int blocksize = inode->i_sb->s_blocksize;
	int i, n = 0;
	int err = 0;
	struct buffer_head *bh;
	int num;
673 674
	ext4_fsblk_t new_blocks[4];
	ext4_fsblk_t current_block;
675

676
	num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694
				*blks, new_blocks, &err);
	if (err)
		return err;

	branch[0].key = cpu_to_le32(new_blocks[0]);
	/*
	 * metadata blocks and data blocks are allocated.
	 */
	for (n = 1; n <= indirect_blks;  n++) {
		/*
		 * Get buffer_head for parent block, zero it out
		 * and set the pointer to new one, then send
		 * parent to disk.
		 */
		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
		branch[n].bh = bh;
		lock_buffer(bh);
		BUFFER_TRACE(bh, "call get_create_access");
695
		err = ext4_journal_get_create_access(handle, bh);
696 697 698 699 700 701 702 703 704 705
		if (err) {
			unlock_buffer(bh);
			brelse(bh);
			goto failed;
		}

		memset(bh->b_data, 0, blocksize);
		branch[n].p = (__le32 *) bh->b_data + offsets[n];
		branch[n].key = cpu_to_le32(new_blocks[n]);
		*branch[n].p = branch[n].key;
706
		if (n == indirect_blks) {
707 708 709 710 711 712 713 714 715 716 717 718 719
			current_block = new_blocks[n];
			/*
			 * End of chain, update the last new metablock of
			 * the chain to point to the new allocated
			 * data blocks numbers
			 */
			for (i=1; i < num; i++)
				*(branch[n].p + i) = cpu_to_le32(++current_block);
		}
		BUFFER_TRACE(bh, "marking uptodate");
		set_buffer_uptodate(bh);
		unlock_buffer(bh);

720 721
		BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
		err = ext4_journal_dirty_metadata(handle, bh);
722 723 724 725 726 727 728 729
		if (err)
			goto failed;
	}
	*blks = num;
	return err;
failed:
	/* Allocation failed, free what we already allocated */
	for (i = 1; i <= n ; i++) {
730
		BUFFER_TRACE(branch[i].bh, "call jbd2_journal_forget");
731
		ext4_journal_forget(handle, branch[i].bh);
732
	}
733
	for (i = 0; i < indirect_blks; i++)
734
		ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
735

736
	ext4_free_blocks(handle, inode, new_blocks[i], num, 0);
737 738 739 740 741

	return err;
}

/**
742
 * ext4_splice_branch - splice the allocated branch onto inode.
743 744 745
 * @inode: owner
 * @block: (logical) number of block we are adding
 * @chain: chain of indirect blocks (with a missing link - see
746
 *	ext4_alloc_branch)
747 748 749 750 751 752 753 754
 * @where: location of missing link
 * @num:   number of indirect blocks we are adding
 * @blks:  number of direct blocks we are adding
 *
 * This function fills the missing link and does all housekeeping needed in
 * inode (->i_blocks, etc.). In case of success we end up with the full
 * chain to new block and return 0.
 */
755
static int ext4_splice_branch(handle_t *handle, struct inode *inode,
A
Aneesh Kumar K.V 已提交
756
			ext4_lblk_t block, Indirect *where, int num, int blks)
757 758 759
{
	int i;
	int err = 0;
760 761
	struct ext4_block_alloc_info *block_i;
	ext4_fsblk_t current_block;
762

763
	block_i = EXT4_I(inode)->i_block_alloc_info;
764 765 766 767 768 769 770
	/*
	 * If we're splicing into a [td]indirect block (as opposed to the
	 * inode) then we need to get write access to the [td]indirect block
	 * before the splice.
	 */
	if (where->bh) {
		BUFFER_TRACE(where->bh, "get_write_access");
771
		err = ext4_journal_get_write_access(handle, where->bh);
772 773 774 775 776 777 778 779 780 781 782 783 784 785
		if (err)
			goto err_out;
	}
	/* That's it */

	*where->p = where->key;

	/*
	 * Update the host buffer_head or inode to point to more just allocated
	 * direct blocks blocks
	 */
	if (num == 0 && blks > 1) {
		current_block = le32_to_cpu(where->key) + 1;
		for (i = 1; i < blks; i++)
786
			*(where->p + i) = cpu_to_le32(current_block++);
787 788 789 790 791 792 793 794 795 796 797 798 799 800 801
	}

	/*
	 * update the most recently allocated logical & physical block
	 * in i_block_alloc_info, to assist find the proper goal block for next
	 * allocation
	 */
	if (block_i) {
		block_i->last_alloc_logical_block = block + blks - 1;
		block_i->last_alloc_physical_block =
				le32_to_cpu(where[num].key) + blks - 1;
	}

	/* We are done with atomic stuff, now do the rest of housekeeping */

K
Kalpak Shah 已提交
802
	inode->i_ctime = ext4_current_time(inode);
803
	ext4_mark_inode_dirty(handle, inode);
804 805 806 807 808 809 810 811 812

	/* had we spliced it onto indirect block? */
	if (where->bh) {
		/*
		 * If we spliced it onto an indirect block, we haven't
		 * altered the inode.  Note however that if it is being spliced
		 * onto an indirect block at the very end of the file (the
		 * file is growing) then we *will* alter the inode to reflect
		 * the new i_size.  But that is not done here - it is done in
813
		 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
814 815
		 */
		jbd_debug(5, "splicing indirect only\n");
816 817
		BUFFER_TRACE(where->bh, "call ext4_journal_dirty_metadata");
		err = ext4_journal_dirty_metadata(handle, where->bh);
818 819 820 821 822 823 824 825 826 827 828 829 830
		if (err)
			goto err_out;
	} else {
		/*
		 * OK, we spliced it into the inode itself on a direct block.
		 * Inode was dirtied above.
		 */
		jbd_debug(5, "splicing direct\n");
	}
	return err;

err_out:
	for (i = 1; i <= num; i++) {
831
		BUFFER_TRACE(where[i].bh, "call jbd2_journal_forget");
832
		ext4_journal_forget(handle, where[i].bh);
833 834
		ext4_free_blocks(handle, inode,
					le32_to_cpu(where[i-1].key), 1, 0);
835
	}
836
	ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks, 0);
837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857

	return err;
}

/*
 * Allocation strategy is simple: if we have to allocate something, we will
 * have to go the whole way to leaf. So let's do it before attaching anything
 * to tree, set linkage between the newborn blocks, write them if sync is
 * required, recheck the path, free and repeat if check fails, otherwise
 * set the last missing link (that will protect us from any truncate-generated
 * removals - all blocks on the path are immune now) and possibly force the
 * write on the parent block.
 * That has a nice additional property: no special recovery from the failed
 * allocations is needed - we simply release blocks and do not touch anything
 * reachable from inode.
 *
 * `handle' can be NULL if create == 0.
 *
 * return > 0, # of blocks mapped or allocated.
 * return = 0, if plain lookup failed.
 * return < 0, error case.
858 859 860
 *
 *
 * Need to be called with
861 862
 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
 * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
863
 */
864
int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
A
Aneesh Kumar K.V 已提交
865
		ext4_lblk_t iblock, unsigned long maxblocks,
866 867 868 869
		struct buffer_head *bh_result,
		int create, int extend_disksize)
{
	int err = -EIO;
A
Aneesh Kumar K.V 已提交
870
	ext4_lblk_t offsets[4];
871 872
	Indirect chain[4];
	Indirect *partial;
873
	ext4_fsblk_t goal;
874 875 876
	int indirect_blks;
	int blocks_to_boundary = 0;
	int depth;
877
	struct ext4_inode_info *ei = EXT4_I(inode);
878
	int count = 0;
879
	ext4_fsblk_t first_block = 0;
880
	loff_t disksize;
881 882


A
Alex Tomas 已提交
883
	J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
884
	J_ASSERT(handle != NULL || create == 0);
A
Aneesh Kumar K.V 已提交
885 886
	depth = ext4_block_to_path(inode, iblock, offsets,
					&blocks_to_boundary);
887 888 889 890

	if (depth == 0)
		goto out;

891
	partial = ext4_get_branch(inode, depth, offsets, chain, &err);
892 893 894 895 896 897 898 899

	/* Simplest case - block found, no allocation needed */
	if (!partial) {
		first_block = le32_to_cpu(chain[depth - 1].key);
		clear_buffer_new(bh_result);
		count++;
		/*map more blocks*/
		while (count < maxblocks && count <= blocks_to_boundary) {
900
			ext4_fsblk_t blk;
901 902 903 904 905 906 907 908

			blk = le32_to_cpu(*(chain[depth-1].p + count));

			if (blk == first_block + count)
				count++;
			else
				break;
		}
909
		goto got_it;
910 911 912 913 914 915 916 917 918 919 920
	}

	/* Next simple case - plain lookup or failed read of indirect block */
	if (!create || err == -EIO)
		goto cleanup;

	/*
	 * Okay, we need to do block allocation.  Lazily initialize the block
	 * allocation info here if necessary
	*/
	if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
921
		ext4_init_block_alloc_info(inode);
922

923
	goal = ext4_find_goal(inode, iblock, partial);
924 925 926 927 928 929 930 931

	/* the number of blocks need to allocate for [d,t]indirect blocks */
	indirect_blks = (chain + depth) - partial - 1;

	/*
	 * Next look up the indirect map to count the totoal number of
	 * direct blocks to allocate for this branch.
	 */
932
	count = ext4_blks_to_allocate(partial, indirect_blks,
933 934
					maxblocks, blocks_to_boundary);
	/*
935
	 * Block out ext4_truncate while we alter the tree
936
	 */
937 938 939
	err = ext4_alloc_branch(handle, inode, iblock, indirect_blks,
					&count, goal,
					offsets + (partial - chain), partial);
940 941

	/*
942
	 * The ext4_splice_branch call will free and forget any buffers
943 944 945 946 947 948
	 * on the new chain if there is a failure, but that risks using
	 * up transaction credits, especially for bitmaps where the
	 * credits cannot be returned.  Can we handle this somehow?  We
	 * may need to return -EAGAIN upwards in the worst case.  --sct
	 */
	if (!err)
949
		err = ext4_splice_branch(handle, inode, iblock,
950 951
					partial, indirect_blks, count);
	/*
952
	 * i_disksize growing is protected by i_data_sem.  Don't forget to
953
	 * protect it if you're about to implement concurrent
954
	 * ext4_get_block() -bzzz
955
	*/
956 957 958 959 960 961 962
	if (!err && extend_disksize) {
		disksize = ((loff_t) iblock + count) << inode->i_blkbits;
		if (disksize > i_size_read(inode))
			disksize = i_size_read(inode);
		if (disksize > ei->i_disksize)
			ei->i_disksize = disksize;
	}
963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984
	if (err)
		goto cleanup;

	set_buffer_new(bh_result);
got_it:
	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
	if (count > blocks_to_boundary)
		set_buffer_boundary(bh_result);
	err = count;
	/* Clean up and exit */
	partial = chain + depth - 1;	/* the whole chain */
cleanup:
	while (partial > chain) {
		BUFFER_TRACE(partial->bh, "call brelse");
		brelse(partial->bh);
		partial--;
	}
	BUFFER_TRACE(bh_result, "returned");
out:
	return err;
}

985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009
/*
 * Calculate the number of metadata blocks need to reserve
 * to allocate @blocks for non extent file based file
 */
static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
{
	int icap = EXT4_ADDR_PER_BLOCK(inode->i_sb);
	int ind_blks, dind_blks, tind_blks;

	/* number of new indirect blocks needed */
	ind_blks = (blocks + icap - 1) / icap;

	dind_blks = (ind_blks + icap - 1) / icap;

	tind_blks = 1;

	return ind_blks + dind_blks + tind_blks;
}

/*
 * Calculate the number of metadata blocks need to reserve
 * to allocate given number of blocks
 */
static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
{
1010 1011 1012
	if (!blocks)
		return 0;

1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048
	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
		return ext4_ext_calc_metadata_amount(inode, blocks);

	return ext4_indirect_calc_metadata_amount(inode, blocks);
}

static void ext4_da_update_reserve_space(struct inode *inode, int used)
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	int total, mdb, mdb_free;

	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
	/* recalculate the number of metablocks still need to be reserved */
	total = EXT4_I(inode)->i_reserved_data_blocks - used;
	mdb = ext4_calc_metadata_amount(inode, total);

	/* figure out how many metablocks to release */
	BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
	mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;

	/* Account for allocated meta_blocks */
	mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;

	/* update fs free blocks counter for truncate case */
	percpu_counter_add(&sbi->s_freeblocks_counter, mdb_free);

	/* update per-inode reservations */
	BUG_ON(used  > EXT4_I(inode)->i_reserved_data_blocks);
	EXT4_I(inode)->i_reserved_data_blocks -= used;

	BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
	EXT4_I(inode)->i_reserved_meta_blocks = mdb;
	EXT4_I(inode)->i_allocated_meta_blocks = 0;
	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
}

1049
/*
1050 1051
 * The ext4_get_blocks_wrap() function try to look up the requested blocks,
 * and returns if the blocks are already mapped.
1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070
 *
 * Otherwise it takes the write lock of the i_data_sem and allocate blocks
 * and store the allocated blocks in the result buffer head and mark it
 * mapped.
 *
 * If file type is extents based, it will call ext4_ext_get_blocks(),
 * Otherwise, call with ext4_get_blocks_handle() to handle indirect mapping
 * based files
 *
 * On success, it returns the number of blocks being mapped or allocate.
 * if create==0 and the blocks are pre-allocated and uninitialized block,
 * the result buffer head is unmapped. If the create ==1, it will make sure
 * the buffer head is mapped.
 *
 * It returns 0 if plain look up failed (blocks have not been allocated), in
 * that casem, buffer head is unmapped
 *
 * It returns the error in case of allocation failure.
 */
1071 1072
int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
			unsigned long max_blocks, struct buffer_head *bh,
1073
			int create, int extend_disksize, int flag)
1074 1075
{
	int retval;
1076 1077 1078

	clear_buffer_mapped(bh);

1079 1080 1081 1082 1083 1084 1085 1086
	/*
	 * Try to see if we can get  the block without requesting
	 * for new file system block.
	 */
	down_read((&EXT4_I(inode)->i_data_sem));
	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
		retval =  ext4_ext_get_blocks(handle, inode, block, max_blocks,
				bh, 0, 0);
1087
	} else {
1088 1089
		retval = ext4_get_blocks_handle(handle,
				inode, block, max_blocks, bh, 0, 0);
1090
	}
1091
	up_read((&EXT4_I(inode)->i_data_sem));
1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104

	/* If it is only a block(s) look up */
	if (!create)
		return retval;

	/*
	 * Returns if the blocks have already allocated
	 *
	 * Note that if blocks have been preallocated
	 * ext4_ext_get_block() returns th create = 0
	 * with buffer head unmapped.
	 */
	if (retval > 0 && buffer_mapped(bh))
1105 1106 1107
		return retval;

	/*
1108 1109 1110 1111
	 * New blocks allocate and/or writing to uninitialized extent
	 * will possibly result in updating i_data, so we take
	 * the write lock of i_data_sem, and call get_blocks()
	 * with create == 1 flag.
1112 1113
	 */
	down_write((&EXT4_I(inode)->i_data_sem));
1114 1115 1116 1117 1118 1119 1120 1121 1122

	/*
	 * if the caller is from delayed allocation writeout path
	 * we have already reserved fs blocks for allocation
	 * let the underlying get_block() function know to
	 * avoid double accounting
	 */
	if (flag)
		EXT4_I(inode)->i_delalloc_reserved_flag = 1;
1123 1124 1125 1126
	/*
	 * We need to check for EXT4 here because migrate
	 * could have changed the inode type in between
	 */
1127 1128 1129 1130 1131 1132
	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
		retval =  ext4_ext_get_blocks(handle, inode, block, max_blocks,
				bh, create, extend_disksize);
	} else {
		retval = ext4_get_blocks_handle(handle, inode, block,
				max_blocks, bh, create, extend_disksize);
1133 1134 1135 1136 1137 1138 1139 1140 1141 1142

		if (retval > 0 && buffer_new(bh)) {
			/*
			 * We allocated new blocks which will result in
			 * i_data's format changing.  Force the migrate
			 * to fail by clearing migrate flags
			 */
			EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags &
							~EXT4_EXT_MIGRATE;
		}
1143
	}
1144 1145 1146 1147 1148 1149 1150 1151 1152

	if (flag) {
		EXT4_I(inode)->i_delalloc_reserved_flag = 0;
		/*
		 * Update reserved blocks/metadata blocks
		 * after successful block allocation
		 * which were deferred till now
		 */
		if ((retval > 0) && buffer_delay(bh))
1153
			ext4_da_update_reserve_space(inode, retval);
1154 1155
	}

1156
	up_write((&EXT4_I(inode)->i_data_sem));
1157 1158 1159
	return retval;
}

1160 1161 1162
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096

1163
static int ext4_get_block(struct inode *inode, sector_t iblock,
1164 1165
			struct buffer_head *bh_result, int create)
{
1166
	handle_t *handle = ext4_journal_current_handle();
J
Jan Kara 已提交
1167
	int ret = 0, started = 0;
1168
	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
1169
	int dio_credits;
1170

J
Jan Kara 已提交
1171 1172 1173 1174
	if (create && !handle) {
		/* Direct IO write... */
		if (max_blocks > DIO_MAX_BLOCKS)
			max_blocks = DIO_MAX_BLOCKS;
1175 1176
		dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
		handle = ext4_journal_start(inode, dio_credits);
J
Jan Kara 已提交
1177
		if (IS_ERR(handle)) {
1178
			ret = PTR_ERR(handle);
J
Jan Kara 已提交
1179
			goto out;
1180
		}
J
Jan Kara 已提交
1181
		started = 1;
1182 1183
	}

J
Jan Kara 已提交
1184
	ret = ext4_get_blocks_wrap(handle, inode, iblock,
1185
					max_blocks, bh_result, create, 0, 0);
J
Jan Kara 已提交
1186 1187 1188
	if (ret > 0) {
		bh_result->b_size = (ret << inode->i_blkbits);
		ret = 0;
1189
	}
J
Jan Kara 已提交
1190 1191 1192
	if (started)
		ext4_journal_stop(handle);
out:
1193 1194 1195 1196 1197 1198
	return ret;
}

/*
 * `handle' can be NULL if create is zero
 */
1199
struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
A
Aneesh Kumar K.V 已提交
1200
				ext4_lblk_t block, int create, int *errp)
1201 1202 1203 1204 1205 1206 1207 1208 1209
{
	struct buffer_head dummy;
	int fatal = 0, err;

	J_ASSERT(handle != NULL || create == 0);

	dummy.b_state = 0;
	dummy.b_blocknr = -1000;
	buffer_trace_init(&dummy.b_history);
A
Alex Tomas 已提交
1210
	err = ext4_get_blocks_wrap(handle, inode, block, 1,
1211
					&dummy, create, 1, 0);
1212
	/*
1213
	 * ext4_get_blocks_handle() returns number of blocks
1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230
	 * mapped. 0 in case of a HOLE.
	 */
	if (err > 0) {
		if (err > 1)
			WARN_ON(1);
		err = 0;
	}
	*errp = err;
	if (!err && buffer_mapped(&dummy)) {
		struct buffer_head *bh;
		bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
		if (!bh) {
			*errp = -EIO;
			goto err;
		}
		if (buffer_new(&dummy)) {
			J_ASSERT(create != 0);
A
Aneesh Kumar K.V 已提交
1231
			J_ASSERT(handle != NULL);
1232 1233 1234 1235 1236

			/*
			 * Now that we do not always journal data, we should
			 * keep in mind whether this should always journal the
			 * new buffer as metadata.  For now, regular file
1237
			 * writes use ext4_get_block instead, so it's not a
1238 1239 1240 1241
			 * problem.
			 */
			lock_buffer(bh);
			BUFFER_TRACE(bh, "call get_create_access");
1242
			fatal = ext4_journal_get_create_access(handle, bh);
1243
			if (!fatal && !buffer_uptodate(bh)) {
1244
				memset(bh->b_data, 0, inode->i_sb->s_blocksize);
1245 1246 1247
				set_buffer_uptodate(bh);
			}
			unlock_buffer(bh);
1248 1249
			BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
			err = ext4_journal_dirty_metadata(handle, bh);
1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265
			if (!fatal)
				fatal = err;
		} else {
			BUFFER_TRACE(bh, "not a new buffer");
		}
		if (fatal) {
			*errp = fatal;
			brelse(bh);
			bh = NULL;
		}
		return bh;
	}
err:
	return NULL;
}

1266
struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
A
Aneesh Kumar K.V 已提交
1267
			       ext4_lblk_t block, int create, int *err)
1268
{
1269
	struct buffer_head *bh;
1270

1271
	bh = ext4_getblk(handle, inode, block, create, err);
1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284
	if (!bh)
		return bh;
	if (buffer_uptodate(bh))
		return bh;
	ll_rw_block(READ_META, 1, &bh);
	wait_on_buffer(bh);
	if (buffer_uptodate(bh))
		return bh;
	put_bh(bh);
	*err = -EIO;
	return NULL;
}

1285 1286 1287 1288 1289 1290 1291
static int walk_page_buffers(handle_t *handle,
			     struct buffer_head *head,
			     unsigned from,
			     unsigned to,
			     int *partial,
			     int (*fn)(handle_t *handle,
				       struct buffer_head *bh))
1292 1293 1294 1295 1296 1297 1298
{
	struct buffer_head *bh;
	unsigned block_start, block_end;
	unsigned blocksize = head->b_size;
	int err, ret = 0;
	struct buffer_head *next;

1299 1300 1301
	for (bh = head, block_start = 0;
	     ret == 0 && (bh != head || !block_start);
	     block_start = block_end, bh = next)
1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319
	{
		next = bh->b_this_page;
		block_end = block_start + blocksize;
		if (block_end <= from || block_start >= to) {
			if (partial && !buffer_uptodate(bh))
				*partial = 1;
			continue;
		}
		err = (*fn)(handle, bh);
		if (!ret)
			ret = err;
	}
	return ret;
}

/*
 * To preserve ordering, it is essential that the hole instantiation and
 * the data write be encapsulated in a single transaction.  We cannot
1320
 * close off a transaction and start a new one between the ext4_get_block()
1321
 * and the commit_write().  So doing the jbd2_journal_start at the start of
1322 1323
 * prepare_write() is the right place.
 *
1324 1325
 * Also, this function can nest inside ext4_writepage() ->
 * block_write_full_page(). In that case, we *know* that ext4_writepage()
1326 1327 1328 1329
 * has generated enough buffer credits to do the whole page.  So we won't
 * block on the journal in that case, which is good, because the caller may
 * be PF_MEMALLOC.
 *
1330
 * By accident, ext4 can be reentered when a transaction is open via
1331 1332 1333 1334 1335 1336
 * quota file writes.  If we were to commit the transaction while thus
 * reentered, there can be a deadlock - we would be holding a quota
 * lock, and the commit would never complete if another thread had a
 * transaction open and was blocking on the quota lock - a ranking
 * violation.
 *
1337
 * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1338 1339 1340 1341 1342 1343 1344 1345 1346
 * will _not_ run commit under these circumstances because handle->h_ref
 * is elevated.  We'll still have enough credits for the tiny quotafile
 * write.
 */
static int do_journal_get_write_access(handle_t *handle,
					struct buffer_head *bh)
{
	if (!buffer_mapped(bh) || buffer_freed(bh))
		return 0;
1347
	return ext4_journal_get_write_access(handle, bh);
1348 1349
}

N
Nick Piggin 已提交
1350 1351 1352
static int ext4_write_begin(struct file *file, struct address_space *mapping,
				loff_t pos, unsigned len, unsigned flags,
				struct page **pagep, void **fsdata)
1353
{
1354
	struct inode *inode = mapping->host;
1355
	int ret, needed_blocks = ext4_writepage_trans_blocks(inode);
1356 1357
	handle_t *handle;
	int retries = 0;
1358
	struct page *page;
N
Nick Piggin 已提交
1359
 	pgoff_t index;
1360
	unsigned from, to;
N
Nick Piggin 已提交
1361 1362

 	index = pos >> PAGE_CACHE_SHIFT;
1363 1364
	from = pos & (PAGE_CACHE_SIZE - 1);
	to = from + len;
1365 1366

retry:
1367 1368 1369 1370
	handle = ext4_journal_start(inode, needed_blocks);
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto out;
1371
	}
1372

1373 1374 1375 1376 1377 1378 1379 1380
	page = __grab_cache_page(mapping, index);
	if (!page) {
		ext4_journal_stop(handle);
		ret = -ENOMEM;
		goto out;
	}
	*pagep = page;

N
Nick Piggin 已提交
1381 1382 1383 1384
	ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
							ext4_get_block);

	if (!ret && ext4_should_journal_data(inode)) {
1385 1386 1387
		ret = walk_page_buffers(handle, page_buffers(page),
				from, to, NULL, do_journal_get_write_access);
	}
N
Nick Piggin 已提交
1388 1389

	if (ret) {
1390
		unlock_page(page);
1391
		ext4_journal_stop(handle);
1392
		page_cache_release(page);
N
Nick Piggin 已提交
1393 1394
	}

1395
	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1396
		goto retry;
1397
out:
1398 1399 1400
	return ret;
}

N
Nick Piggin 已提交
1401 1402
/* For write_end() in data=journal mode */
static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1403 1404 1405 1406
{
	if (!buffer_mapped(bh) || buffer_freed(bh))
		return 0;
	set_buffer_uptodate(bh);
1407
	return ext4_journal_dirty_metadata(handle, bh);
1408 1409 1410 1411 1412 1413
}

/*
 * We need to pick up the new inode size which generic_commit_write gave us
 * `file' can be NULL - eg, when called from page_symlink().
 *
1414
 * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1415 1416
 * buffers are managed internally.
 */
N
Nick Piggin 已提交
1417 1418 1419 1420
static int ext4_ordered_write_end(struct file *file,
				struct address_space *mapping,
				loff_t pos, unsigned len, unsigned copied,
				struct page *page, void *fsdata)
1421
{
1422
	handle_t *handle = ext4_journal_current_handle();
1423
	struct inode *inode = mapping->host;
1424 1425
	int ret = 0, ret2;

1426
	ret = ext4_jbd2_file_inode(handle, inode);
1427 1428 1429

	if (ret == 0) {
		/*
N
Nick Piggin 已提交
1430
		 * generic_write_end() will run mark_inode_dirty() if i_size
1431 1432 1433 1434 1435
		 * changes.  So let's piggyback the i_disksize mark_inode_dirty
		 * into that.
		 */
		loff_t new_i_size;

N
Nick Piggin 已提交
1436
		new_i_size = pos + copied;
1437 1438
		if (new_i_size > EXT4_I(inode)->i_disksize)
			EXT4_I(inode)->i_disksize = new_i_size;
1439
		ret2 = generic_write_end(file, mapping, pos, len, copied,
N
Nick Piggin 已提交
1440
							page, fsdata);
1441 1442 1443
		copied = ret2;
		if (ret2 < 0)
			ret = ret2;
1444
	}
1445
	ret2 = ext4_journal_stop(handle);
1446 1447
	if (!ret)
		ret = ret2;
N
Nick Piggin 已提交
1448 1449

	return ret ? ret : copied;
1450 1451
}

N
Nick Piggin 已提交
1452 1453 1454 1455
static int ext4_writeback_write_end(struct file *file,
				struct address_space *mapping,
				loff_t pos, unsigned len, unsigned copied,
				struct page *page, void *fsdata)
1456
{
1457
	handle_t *handle = ext4_journal_current_handle();
1458
	struct inode *inode = mapping->host;
1459 1460 1461
	int ret = 0, ret2;
	loff_t new_i_size;

N
Nick Piggin 已提交
1462
	new_i_size = pos + copied;
1463 1464
	if (new_i_size > EXT4_I(inode)->i_disksize)
		EXT4_I(inode)->i_disksize = new_i_size;
1465

1466
	ret2 = generic_write_end(file, mapping, pos, len, copied,
N
Nick Piggin 已提交
1467
							page, fsdata);
1468 1469 1470
	copied = ret2;
	if (ret2 < 0)
		ret = ret2;
1471

1472
	ret2 = ext4_journal_stop(handle);
1473 1474
	if (!ret)
		ret = ret2;
N
Nick Piggin 已提交
1475 1476

	return ret ? ret : copied;
1477 1478
}

N
Nick Piggin 已提交
1479 1480 1481 1482
static int ext4_journalled_write_end(struct file *file,
				struct address_space *mapping,
				loff_t pos, unsigned len, unsigned copied,
				struct page *page, void *fsdata)
1483
{
1484
	handle_t *handle = ext4_journal_current_handle();
N
Nick Piggin 已提交
1485
	struct inode *inode = mapping->host;
1486 1487
	int ret = 0, ret2;
	int partial = 0;
N
Nick Piggin 已提交
1488
	unsigned from, to;
1489

N
Nick Piggin 已提交
1490 1491 1492 1493 1494 1495 1496 1497
	from = pos & (PAGE_CACHE_SIZE - 1);
	to = from + len;

	if (copied < len) {
		if (!PageUptodate(page))
			copied = 0;
		page_zero_new_buffers(page, from+copied, to);
	}
1498 1499

	ret = walk_page_buffers(handle, page_buffers(page), from,
N
Nick Piggin 已提交
1500
				to, &partial, write_end_fn);
1501 1502
	if (!partial)
		SetPageUptodate(page);
N
Nick Piggin 已提交
1503 1504
	if (pos+copied > inode->i_size)
		i_size_write(inode, pos+copied);
1505 1506 1507 1508
	EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
	if (inode->i_size > EXT4_I(inode)->i_disksize) {
		EXT4_I(inode)->i_disksize = inode->i_size;
		ret2 = ext4_mark_inode_dirty(handle, inode);
1509 1510 1511
		if (!ret)
			ret = ret2;
	}
N
Nick Piggin 已提交
1512

1513
	unlock_page(page);
1514
	ret2 = ext4_journal_stop(handle);
1515 1516
	if (!ret)
		ret = ret2;
N
Nick Piggin 已提交
1517 1518 1519
	page_cache_release(page);

	return ret ? ret : copied;
1520
}
1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553

static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
{
       struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
       unsigned long md_needed, mdblocks, total = 0;

	/*
	 * recalculate the amount of metadata blocks to reserve
	 * in order to allocate nrblocks
	 * worse case is one extent per block
	 */
	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
	total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks;
	mdblocks = ext4_calc_metadata_amount(inode, total);
	BUG_ON(mdblocks < EXT4_I(inode)->i_reserved_meta_blocks);

	md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
	total = md_needed + nrblocks;

	if (ext4_has_free_blocks(sbi, total) < total) {
		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
		return -ENOSPC;
	}
	/* reduce fs free blocks counter */
	percpu_counter_sub(&sbi->s_freeblocks_counter, total);

	EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
	EXT4_I(inode)->i_reserved_meta_blocks = mdblocks;

	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
	return 0;       /* success */
}

1554
static void ext4_da_release_space(struct inode *inode, int to_free)
1555 1556 1557 1558
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	int total, mdb, mdb_free, release;

1559 1560 1561
	if (!to_free)
		return;		/* Nothing to release, exit */

1562
	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577

	if (!EXT4_I(inode)->i_reserved_data_blocks) {
		/*
		 * if there is no reserved blocks, but we try to free some
		 * then the counter is messed up somewhere.
		 * but since this function is called from invalidate
		 * page, it's harmless to return without any action
		 */
		printk(KERN_INFO "ext4 delalloc try to release %d reserved "
			    "blocks for inode %lu, but there is no reserved "
			    "data blocks\n", to_free, inode->i_ino);
		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
		return;
	}

1578
	/* recalculate the number of metablocks still need to be reserved */
1579
	total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591
	mdb = ext4_calc_metadata_amount(inode, total);

	/* figure out how many metablocks to release */
	BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
	mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;

	release = to_free + mdb_free;

	/* update fs free blocks counter for truncate case */
	percpu_counter_add(&sbi->s_freeblocks_counter, release);

	/* update per-inode reservations */
1592 1593
	BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks);
	EXT4_I(inode)->i_reserved_data_blocks -= to_free;
1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617

	BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
	EXT4_I(inode)->i_reserved_meta_blocks = mdb;
	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
}

static void ext4_da_page_release_reservation(struct page *page,
						unsigned long offset)
{
	int to_release = 0;
	struct buffer_head *head, *bh;
	unsigned int curr_off = 0;

	head = page_buffers(page);
	bh = head;
	do {
		unsigned int next_off = curr_off + bh->b_size;

		if ((offset <= curr_off) && (buffer_delay(bh))) {
			to_release++;
			clear_buffer_delay(bh);
		}
		curr_off = next_off;
	} while ((bh = bh->b_this_page) != head);
1618
	ext4_da_release_space(page->mapping->host, to_release);
1619
}
1620

1621 1622 1623 1624 1625 1626 1627 1628 1629 1630
/*
 * Delayed allocation stuff
 */

struct mpage_da_data {
	struct inode *inode;
	struct buffer_head lbh;			/* extent of blocks */
	unsigned long first_page, next_page;	/* extent of pages */
	get_block_t *get_block;
	struct writeback_control *wbc;
1631 1632
	int io_done;
	long pages_written;
1633 1634 1635 1636
};

/*
 * mpage_da_submit_io - walks through extent of pages and try to write
1637
 * them with writepage() call back
1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673
 *
 * @mpd->inode: inode
 * @mpd->first_page: first page of the extent
 * @mpd->next_page: page after the last page of the extent
 * @mpd->get_block: the filesystem's block mapper function
 *
 * By the time mpage_da_submit_io() is called we expect all blocks
 * to be allocated. this may be wrong if allocation failed.
 *
 * As pages are already locked by write_cache_pages(), we can't use it
 */
static int mpage_da_submit_io(struct mpage_da_data *mpd)
{
	struct address_space *mapping = mpd->inode->i_mapping;
	int ret = 0, err, nr_pages, i;
	unsigned long index, end;
	struct pagevec pvec;

	BUG_ON(mpd->next_page <= mpd->first_page);
	pagevec_init(&pvec, 0);
	index = mpd->first_page;
	end = mpd->next_page - 1;

	while (index <= end) {
		/* XXX: optimize tail */
		nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
		if (nr_pages == 0)
			break;
		for (i = 0; i < nr_pages; i++) {
			struct page *page = pvec.pages[i];

			index = page->index;
			if (index > end)
				break;
			index++;

1674 1675 1676
			err = mapping->a_ops->writepage(page, mpd->wbc);
			if (!err)
				mpd->pages_written++;
1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708
			/*
			 * In error case, we have to continue because
			 * remaining pages are still locked
			 * XXX: unlock and re-dirty them?
			 */
			if (ret == 0)
				ret = err;
		}
		pagevec_release(&pvec);
	}
	return ret;
}

/*
 * mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
 *
 * @mpd->inode - inode to walk through
 * @exbh->b_blocknr - first block on a disk
 * @exbh->b_size - amount of space in bytes
 * @logical - first logical block to start assignment with
 *
 * the function goes through all passed space and put actual disk
 * block numbers into buffer heads, dropping BH_Delay
 */
static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
				 struct buffer_head *exbh)
{
	struct inode *inode = mpd->inode;
	struct address_space *mapping = inode->i_mapping;
	int blocks = exbh->b_size >> inode->i_blkbits;
	sector_t pblock = exbh->b_blocknr, cur_logical;
	struct buffer_head *head, *bh;
1709
	pgoff_t index, end;
1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751
	struct pagevec pvec;
	int nr_pages, i;

	index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
	end = (logical + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
	cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);

	pagevec_init(&pvec, 0);

	while (index <= end) {
		/* XXX: optimize tail */
		nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
		if (nr_pages == 0)
			break;
		for (i = 0; i < nr_pages; i++) {
			struct page *page = pvec.pages[i];

			index = page->index;
			if (index > end)
				break;
			index++;

			BUG_ON(!PageLocked(page));
			BUG_ON(PageWriteback(page));
			BUG_ON(!page_has_buffers(page));

			bh = page_buffers(page);
			head = bh;

			/* skip blocks out of the range */
			do {
				if (cur_logical >= logical)
					break;
				cur_logical++;
			} while ((bh = bh->b_this_page) != head);

			do {
				if (cur_logical >= logical + blocks)
					break;
				if (buffer_delay(bh)) {
					bh->b_blocknr = pblock;
					clear_buffer_delay(bh);
1752 1753 1754 1755 1756 1757 1758
					bh->b_bdev = inode->i_sb->s_bdev;
				} else if (buffer_unwritten(bh)) {
					bh->b_blocknr = pblock;
					clear_buffer_unwritten(bh);
					set_buffer_mapped(bh);
					set_buffer_new(bh);
					bh->b_bdev = inode->i_sb->s_bdev;
1759
				} else if (buffer_mapped(bh))
1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796
					BUG_ON(bh->b_blocknr != pblock);

				cur_logical++;
				pblock++;
			} while ((bh = bh->b_this_page) != head);
		}
		pagevec_release(&pvec);
	}
}


/*
 * __unmap_underlying_blocks - just a helper function to unmap
 * set of blocks described by @bh
 */
static inline void __unmap_underlying_blocks(struct inode *inode,
					     struct buffer_head *bh)
{
	struct block_device *bdev = inode->i_sb->s_bdev;
	int blocks, i;

	blocks = bh->b_size >> inode->i_blkbits;
	for (i = 0; i < blocks; i++)
		unmap_underlying_metadata(bdev, bh->b_blocknr + i);
}

/*
 * mpage_da_map_blocks - go through given space
 *
 * @mpd->lbh - bh describing space
 * @mpd->get_block - the filesystem's block mapper function
 *
 * The function skips space we know is already mapped to disk blocks.
 *
 */
static void mpage_da_map_blocks(struct mpage_da_data *mpd)
{
1797
	int err = 0;
1798 1799 1800 1801 1802 1803 1804 1805 1806 1807
	struct buffer_head *lbh = &mpd->lbh;
	sector_t next = lbh->b_blocknr;
	struct buffer_head new;

	/*
	 * We consider only non-mapped and non-allocated blocks
	 */
	if (buffer_mapped(lbh) && !buffer_delay(lbh))
		return;

1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821
	new.b_state = lbh->b_state;
	new.b_blocknr = 0;
	new.b_size = lbh->b_size;

	/*
	 * If we didn't accumulate anything
	 * to write simply return
	 */
	if (!new.b_size)
		return;
	err = mpd->get_block(mpd->inode, next, &new, 1);
	if (err)
		return;
	BUG_ON(new.b_size == 0);
1822

1823 1824
	if (buffer_new(&new))
		__unmap_underlying_blocks(mpd->inode, &new);
1825

1826 1827 1828 1829 1830 1831
	/*
	 * If blocks are delayed marked, we need to
	 * put actual blocknr and drop delayed bit
	 */
	if (buffer_delay(lbh) || buffer_unwritten(lbh))
		mpage_put_bnr_to_bhs(mpd, next, &new);
1832

1833
	return;
1834 1835
}

1836 1837
#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
		(1 << BH_Delay) | (1 << BH_Unwritten))
1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851

/*
 * mpage_add_bh_to_extent - try to add one more block to extent of blocks
 *
 * @mpd->lbh - extent of blocks
 * @logical - logical number of the block in the file
 * @bh - bh of the block (used to access block's state)
 *
 * the function is used to collect contig. blocks in same state
 */
static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
				   sector_t logical, struct buffer_head *bh)
{
	sector_t next;
1852 1853 1854
	size_t b_size = bh->b_size;
	struct buffer_head *lbh = &mpd->lbh;
	int nrblocks = lbh->b_size >> mpd->inode->i_blkbits;
1855

1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877
	/* check if thereserved journal credits might overflow */
	if (!(EXT4_I(mpd->inode)->i_flags & EXT4_EXTENTS_FL)) {
		if (nrblocks >= EXT4_MAX_TRANS_DATA) {
			/*
			 * With non-extent format we are limited by the journal
			 * credit available.  Total credit needed to insert
			 * nrblocks contiguous blocks is dependent on the
			 * nrblocks.  So limit nrblocks.
			 */
			goto flush_it;
		} else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
				EXT4_MAX_TRANS_DATA) {
			/*
			 * Adding the new buffer_head would make it cross the
			 * allowed limit for which we have journal credit
			 * reserved. So limit the new bh->b_size
			 */
			b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
						mpd->inode->i_blkbits;
			/* we will do mpage_da_submit_io in the next loop */
		}
	}
1878 1879 1880 1881 1882
	/*
	 * First block in the extent
	 */
	if (lbh->b_size == 0) {
		lbh->b_blocknr = logical;
1883
		lbh->b_size = b_size;
1884 1885 1886 1887
		lbh->b_state = bh->b_state & BH_FLAGS;
		return;
	}

1888
	next = lbh->b_blocknr + nrblocks;
1889 1890 1891 1892
	/*
	 * Can we merge the block to our big extent?
	 */
	if (logical == next && (bh->b_state & BH_FLAGS) == lbh->b_state) {
1893
		lbh->b_size += b_size;
1894 1895 1896
		return;
	}

1897
flush_it:
1898 1899 1900 1901 1902
	/*
	 * We couldn't merge the block to our extent, so we
	 * need to flush current  extent and start new one
	 */
	mpage_da_map_blocks(mpd);
1903 1904 1905
	mpage_da_submit_io(mpd);
	mpd->io_done = 1;
	return;
1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924
}

/*
 * __mpage_da_writepage - finds extent of pages and blocks
 *
 * @page: page to consider
 * @wbc: not used, we just follow rules
 * @data: context
 *
 * The function finds extents of pages and scan them for all blocks.
 */
static int __mpage_da_writepage(struct page *page,
				struct writeback_control *wbc, void *data)
{
	struct mpage_da_data *mpd = data;
	struct inode *inode = mpd->inode;
	struct buffer_head *bh, *head, fake;
	sector_t logical;

1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935
	if (mpd->io_done) {
		/*
		 * Rest of the page in the page_vec
		 * redirty then and skip then. We will
		 * try to to write them again after
		 * starting a new transaction
		 */
		redirty_page_for_writepage(wbc, page);
		unlock_page(page);
		return MPAGE_DA_EXTENT_TAIL;
	}
1936 1937 1938 1939 1940 1941
	/*
	 * Can we merge this page to current extent?
	 */
	if (mpd->next_page != page->index) {
		/*
		 * Nope, we can't. So, we map non-allocated blocks
1942
		 * and start IO on them using writepage()
1943 1944 1945 1946
		 */
		if (mpd->next_page != mpd->first_page) {
			mpage_da_map_blocks(mpd);
			mpage_da_submit_io(mpd);
1947 1948 1949 1950 1951 1952 1953
			/*
			 * skip rest of the page in the page_vec
			 */
			mpd->io_done = 1;
			redirty_page_for_writepage(wbc, page);
			unlock_page(page);
			return MPAGE_DA_EXTENT_TAIL;
1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983
		}

		/*
		 * Start next extent of pages ...
		 */
		mpd->first_page = page->index;

		/*
		 * ... and blocks
		 */
		mpd->lbh.b_size = 0;
		mpd->lbh.b_state = 0;
		mpd->lbh.b_blocknr = 0;
	}

	mpd->next_page = page->index + 1;
	logical = (sector_t) page->index <<
		  (PAGE_CACHE_SHIFT - inode->i_blkbits);

	if (!page_has_buffers(page)) {
		/*
		 * There is no attached buffer heads yet (mmap?)
		 * we treat the page asfull of dirty blocks
		 */
		bh = &fake;
		bh->b_size = PAGE_CACHE_SIZE;
		bh->b_state = 0;
		set_buffer_dirty(bh);
		set_buffer_uptodate(bh);
		mpage_add_bh_to_extent(mpd, logical, bh);
1984 1985
		if (mpd->io_done)
			return MPAGE_DA_EXTENT_TAIL;
1986 1987 1988 1989 1990 1991 1992 1993
	} else {
		/*
		 * Page with regular buffer heads, just add all dirty ones
		 */
		head = page_buffers(page);
		bh = head;
		do {
			BUG_ON(buffer_locked(bh));
1994 1995
			if (buffer_dirty(bh) &&
				(!buffer_mapped(bh) || buffer_delay(bh))) {
1996
				mpage_add_bh_to_extent(mpd, logical, bh);
1997 1998 1999
				if (mpd->io_done)
					return MPAGE_DA_EXTENT_TAIL;
			}
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023
			logical++;
		} while ((bh = bh->b_this_page) != head);
	}

	return 0;
}

/*
 * mpage_da_writepages - walk the list of dirty pages of the given
 * address space, allocates non-allocated blocks, maps newly-allocated
 * blocks to existing bhs and issue IO them
 *
 * @mapping: address space structure to write
 * @wbc: subtract the number of written pages from *@wbc->nr_to_write
 * @get_block: the filesystem's block mapper function.
 *
 * This is a library function, which implements the writepages()
 * address_space_operation.
 */
static int mpage_da_writepages(struct address_space *mapping,
			       struct writeback_control *wbc,
			       get_block_t get_block)
{
	struct mpage_da_data mpd;
2024
	long to_write;
2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037
	int ret;

	if (!get_block)
		return generic_writepages(mapping, wbc);

	mpd.wbc = wbc;
	mpd.inode = mapping->host;
	mpd.lbh.b_size = 0;
	mpd.lbh.b_state = 0;
	mpd.lbh.b_blocknr = 0;
	mpd.first_page = 0;
	mpd.next_page = 0;
	mpd.get_block = get_block;
2038 2039 2040 2041
	mpd.io_done = 0;
	mpd.pages_written = 0;

	to_write = wbc->nr_to_write;
2042 2043 2044 2045 2046 2047

	ret = write_cache_pages(mapping, wbc, __mpage_da_writepage, &mpd);

	/*
	 * Handle last extent of pages
	 */
2048
	if (!mpd.io_done && mpd.next_page != mpd.first_page) {
2049 2050 2051 2052
		mpage_da_map_blocks(&mpd);
		mpage_da_submit_io(&mpd);
	}

2053
	wbc->nr_to_write = to_write - mpd.pages_written;
2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073
	return ret;
}

/*
 * this is a special callback for ->write_begin() only
 * it's intention is to return mapped block or reserve space
 */
static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
				  struct buffer_head *bh_result, int create)
{
	int ret = 0;

	BUG_ON(create == 0);
	BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);

	/*
	 * first, we need to know whether the block is allocated already
	 * preallocated blocks are unmapped but should treated
	 * the same as allocated blocks.
	 */
2074 2075 2076
	ret = ext4_get_blocks_wrap(NULL, inode, iblock, 1,  bh_result, 0, 0, 0);
	if ((ret == 0) && !buffer_delay(bh_result)) {
		/* the block isn't (pre)allocated yet, let's reserve space */
2077 2078 2079 2080
		/*
		 * XXX: __block_prepare_write() unmaps passed block,
		 * is it OK?
		 */
2081 2082 2083 2084 2085
		ret = ext4_da_reserve_space(inode, 1);
		if (ret)
			/* not enough space to reserve */
			return ret;

2086 2087 2088 2089 2090 2091 2092 2093 2094 2095
		map_bh(bh_result, inode->i_sb, 0);
		set_buffer_new(bh_result);
		set_buffer_delay(bh_result);
	} else if (ret > 0) {
		bh_result->b_size = (ret << inode->i_blkbits);
		ret = 0;
	}

	return ret;
}
2096
#define		EXT4_DELALLOC_RSVED	1
2097 2098 2099
static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
				   struct buffer_head *bh_result, int create)
{
2100
	int ret;
2101 2102 2103 2104
	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
	loff_t disksize = EXT4_I(inode)->i_disksize;
	handle_t *handle = NULL;

2105
	handle = ext4_journal_current_handle();
2106 2107 2108 2109 2110 2111
	if (!handle) {
		ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
				   bh_result, 0, 0, 0);
		BUG_ON(!ret);
	} else {
		ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
2112
				   bh_result, create, 0, EXT4_DELALLOC_RSVED);
2113 2114
	}

2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135
	if (ret > 0) {
		bh_result->b_size = (ret << inode->i_blkbits);

		/*
		 * Update on-disk size along with block allocation
		 * we don't use 'extend_disksize' as size may change
		 * within already allocated block -bzzz
		 */
		disksize = ((loff_t) iblock + ret) << inode->i_blkbits;
		if (disksize > i_size_read(inode))
			disksize = i_size_read(inode);
		if (disksize > EXT4_I(inode)->i_disksize) {
			/*
			 * XXX: replace with spinlock if seen contended -bzzz
			 */
			down_write(&EXT4_I(inode)->i_data_sem);
			if (disksize > EXT4_I(inode)->i_disksize)
				EXT4_I(inode)->i_disksize = disksize;
			up_write(&EXT4_I(inode)->i_data_sem);

			if (EXT4_I(inode)->i_disksize == disksize) {
2136 2137
				ret = ext4_mark_inode_dirty(handle, inode);
				return ret;
2138 2139 2140 2141 2142 2143
			}
		}
		ret = 0;
	}
	return ret;
}
2144 2145 2146

static int ext4_bh_unmapped_or_delay(handle_t *handle, struct buffer_head *bh)
{
2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170
	/*
	 * unmapped buffer is possible for holes.
	 * delay buffer is possible with delayed allocation
	 */
	return ((!buffer_mapped(bh) || buffer_delay(bh)) && buffer_dirty(bh));
}

static int ext4_normal_get_block_write(struct inode *inode, sector_t iblock,
				   struct buffer_head *bh_result, int create)
{
	int ret = 0;
	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;

	/*
	 * we don't want to do block allocation in writepage
	 * so call get_block_wrap with create = 0
	 */
	ret = ext4_get_blocks_wrap(NULL, inode, iblock, max_blocks,
				   bh_result, 0, 0, 0);
	if (ret > 0) {
		bh_result->b_size = (ret << inode->i_blkbits);
		ret = 0;
	}
	return ret;
2171 2172 2173
}

/*
2174 2175 2176 2177
 * get called vi ext4_da_writepages after taking page lock (have journal handle)
 * get called via journal_submit_inode_data_buffers (no journal handle)
 * get called via shrink_page_list via pdflush (no journal handle)
 * or grab_page_cache when doing write_begin (have journal handle)
2178
 */
2179 2180 2181 2182
static int ext4_da_writepage(struct page *page,
				struct writeback_control *wbc)
{
	int ret = 0;
2183 2184 2185 2186 2187
	loff_t size;
	unsigned long len;
	struct buffer_head *page_bufs;
	struct inode *inode = page->mapping->host;

2188 2189 2190 2191 2192
	size = i_size_read(inode);
	if (page->index == size >> PAGE_CACHE_SHIFT)
		len = size & ~PAGE_CACHE_MASK;
	else
		len = PAGE_CACHE_SIZE;
2193

2194
	if (page_has_buffers(page)) {
2195
		page_bufs = page_buffers(page);
2196 2197
		if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
					ext4_bh_unmapped_or_delay)) {
2198
			/*
2199 2200
			 * We don't want to do  block allocation
			 * So redirty the page and return
2201 2202 2203
			 * We may reach here when we do a journal commit
			 * via journal_submit_inode_data_buffers.
			 * If we don't have mapping block we just ignore
2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239
			 * them. We can also reach here via shrink_page_list
			 */
			redirty_page_for_writepage(wbc, page);
			unlock_page(page);
			return 0;
		}
	} else {
		/*
		 * The test for page_has_buffers() is subtle:
		 * We know the page is dirty but it lost buffers. That means
		 * that at some moment in time after write_begin()/write_end()
		 * has been called all buffers have been clean and thus they
		 * must have been written at least once. So they are all
		 * mapped and we can happily proceed with mapping them
		 * and writing the page.
		 *
		 * Try to initialize the buffer_heads and check whether
		 * all are mapped and non delay. We don't want to
		 * do block allocation here.
		 */
		ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
						ext4_normal_get_block_write);
		if (!ret) {
			page_bufs = page_buffers(page);
			/* check whether all are mapped and non delay */
			if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
						ext4_bh_unmapped_or_delay)) {
				redirty_page_for_writepage(wbc, page);
				unlock_page(page);
				return 0;
			}
		} else {
			/*
			 * We can't do block allocation here
			 * so just redity the page and unlock
			 * and return
2240 2241 2242 2243 2244
			 */
			redirty_page_for_writepage(wbc, page);
			unlock_page(page);
			return 0;
		}
2245 2246 2247
	}

	if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
2248
		ret = nobh_writepage(page, ext4_normal_get_block_write, wbc);
2249
	else
2250 2251 2252
		ret = block_write_full_page(page,
						ext4_normal_get_block_write,
						wbc);
2253 2254 2255 2256

	return ret;
}

2257
/*
2258 2259 2260 2261 2262
 * This is called via ext4_da_writepages() to
 * calulate the total number of credits to reserve to fit
 * a single extent allocation into a single transaction,
 * ext4_da_writpeages() will loop calling this before
 * the block allocation.
2263
 */
2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280

static int ext4_da_writepages_trans_blocks(struct inode *inode)
{
	int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;

	/*
	 * With non-extent format the journal credit needed to
	 * insert nrblocks contiguous block is dependent on
	 * number of contiguous block. So we will limit
	 * number of contiguous block to a sane value
	 */
	if (!(inode->i_flags & EXT4_EXTENTS_FL) &&
	    (max_blocks > EXT4_MAX_TRANS_DATA))
		max_blocks = EXT4_MAX_TRANS_DATA;

	return ext4_chunk_trans_blocks(inode, max_blocks);
}
2281

2282
static int ext4_da_writepages(struct address_space *mapping,
2283
			      struct writeback_control *wbc)
2284
{
2285 2286
	handle_t *handle = NULL;
	loff_t range_start = 0;
2287 2288 2289 2290
	struct inode *inode = mapping->host;
	int needed_blocks, ret = 0, nr_to_writebump = 0;
	long to_write, pages_skipped = 0;
	struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2291 2292 2293 2294 2295 2296

	/*
	 * No pages to write? This is mainly a kludge to avoid starting
	 * a transaction for special inodes like journal inode on last iput()
	 * because that could violate lock ordering on umount
	 */
2297
	if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2298
		return 0;
2299 2300 2301 2302 2303 2304 2305 2306 2307 2308
	/*
	 * Make sure nr_to_write is >= sbi->s_mb_stream_request
	 * This make sure small files blocks are allocated in
	 * single attempt. This ensure that small files
	 * get less fragmented.
	 */
	if (wbc->nr_to_write < sbi->s_mb_stream_request) {
		nr_to_writebump = sbi->s_mb_stream_request - wbc->nr_to_write;
		wbc->nr_to_write = sbi->s_mb_stream_request;
	}
2309

2310
	if (!wbc->range_cyclic)
2311 2312 2313 2314 2315 2316
		/*
		 * If range_cyclic is not set force range_cont
		 * and save the old writeback_index
		 */
		wbc->range_cont = 1;

2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330
	range_start =  wbc->range_start;
	pages_skipped = wbc->pages_skipped;

restart_loop:
	to_write = wbc->nr_to_write;
	while (!ret && to_write > 0) {

		/*
		 * we  insert one extent at a time. So we need
		 * credit needed for single extent allocation.
		 * journalled mode is currently not supported
		 * by delalloc
		 */
		BUG_ON(ext4_should_journal_data(inode));
2331
		needed_blocks = ext4_da_writepages_trans_blocks(inode);
2332

2333 2334 2335 2336
		/* start a new transaction*/
		handle = ext4_journal_start(inode, needed_blocks);
		if (IS_ERR(handle)) {
			ret = PTR_ERR(handle);
2337 2338 2339 2340
			printk(KERN_EMERG "%s: jbd2_start: "
			       "%ld pages, ino %lu; err %d\n", __func__,
				wbc->nr_to_write, inode->i_ino, ret);
			dump_stack();
2341 2342
			goto out_writepages;
		}
2343 2344 2345
		if (ext4_should_order_data(inode)) {
			/*
			 * With ordered mode we need to add
2346
			 * the inode to the journal handl
2347 2348 2349 2350 2351 2352 2353 2354
			 * when we do block allocation.
			 */
			ret = ext4_jbd2_file_inode(handle, inode);
			if (ret) {
				ext4_journal_stop(handle);
				goto out_writepages;
			}
		}
2355 2356 2357

		to_write -= wbc->nr_to_write;
		ret = mpage_da_writepages(mapping, wbc,
2358
					  ext4_da_get_block_write);
2359
		ext4_journal_stop(handle);
2360 2361 2362 2363 2364 2365 2366 2367
		if (ret == MPAGE_DA_EXTENT_TAIL) {
			/*
			 * got one extent now try with
			 * rest of the pages
			 */
			to_write += wbc->nr_to_write;
			ret = 0;
		} else if (wbc->nr_to_write) {
2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378
			/*
			 * There is no more writeout needed
			 * or we requested for a noblocking writeout
			 * and we found the device congested
			 */
			to_write += wbc->nr_to_write;
			break;
		}
		wbc->nr_to_write = to_write;
	}

2379 2380 2381 2382 2383 2384 2385 2386 2387
	if (wbc->range_cont && (pages_skipped != wbc->pages_skipped)) {
		/* We skipped pages in this loop */
		wbc->range_start = range_start;
		wbc->nr_to_write = to_write +
				wbc->pages_skipped - pages_skipped;
		wbc->pages_skipped = pages_skipped;
		goto restart_loop;
	}

2388
out_writepages:
2389
	wbc->nr_to_write = to_write - nr_to_writebump;
2390
	wbc->range_start = range_start;
2391
	return ret;
2392 2393 2394 2395 2396 2397
}

static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
				loff_t pos, unsigned len, unsigned flags,
				struct page **pagep, void **fsdata)
{
2398
	int ret, retries = 0;
2399 2400 2401 2402 2403 2404 2405 2406 2407 2408
	struct page *page;
	pgoff_t index;
	unsigned from, to;
	struct inode *inode = mapping->host;
	handle_t *handle;

	index = pos >> PAGE_CACHE_SHIFT;
	from = pos & (PAGE_CACHE_SIZE - 1);
	to = from + len;

2409
retry:
2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422
	/*
	 * With delayed allocation, we don't log the i_disksize update
	 * if there is delayed block allocation. But we still need
	 * to journalling the i_disksize update if writes to the end
	 * of file which has an already mapped buffer.
	 */
	handle = ext4_journal_start(inode, 1);
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto out;
	}

	page = __grab_cache_page(mapping, index);
2423 2424 2425 2426 2427
	if (!page) {
		ext4_journal_stop(handle);
		ret = -ENOMEM;
		goto out;
	}
2428 2429 2430 2431 2432 2433 2434 2435 2436 2437
	*pagep = page;

	ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
							ext4_da_get_block_prep);
	if (ret < 0) {
		unlock_page(page);
		ext4_journal_stop(handle);
		page_cache_release(page);
	}

2438 2439
	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
		goto retry;
2440 2441 2442 2443
out:
	return ret;
}

2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458
/*
 * Check if we should update i_disksize
 * when write to the end of file but not require block allocation
 */
static int ext4_da_should_update_i_disksize(struct page *page,
					 unsigned long offset)
{
	struct buffer_head *bh;
	struct inode *inode = page->mapping->host;
	unsigned int idx;
	int i;

	bh = page_buffers(page);
	idx = offset >> inode->i_blkbits;

2459
	for (i = 0; i < idx; i++)
2460 2461 2462 2463 2464 2465 2466
		bh = bh->b_this_page;

	if (!buffer_mapped(bh) || (buffer_delay(bh)))
		return 0;
	return 1;
}

2467 2468 2469 2470 2471 2472 2473 2474 2475
static int ext4_da_write_end(struct file *file,
				struct address_space *mapping,
				loff_t pos, unsigned len, unsigned copied,
				struct page *page, void *fsdata)
{
	struct inode *inode = mapping->host;
	int ret = 0, ret2;
	handle_t *handle = ext4_journal_current_handle();
	loff_t new_i_size;
2476 2477 2478
	unsigned long start, end;

	start = pos & (PAGE_CACHE_SIZE - 1);
2479
	end = start + copied - 1;
2480 2481 2482 2483 2484 2485 2486 2487

	/*
	 * generic_write_end() will run mark_inode_dirty() if i_size
	 * changes.  So let's piggyback the i_disksize mark_inode_dirty
	 * into that.
	 */

	new_i_size = pos + copied;
2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498
	if (new_i_size > EXT4_I(inode)->i_disksize) {
		if (ext4_da_should_update_i_disksize(page, end)) {
			down_write(&EXT4_I(inode)->i_data_sem);
			if (new_i_size > EXT4_I(inode)->i_disksize) {
				/*
				 * Updating i_disksize when extending file
				 * without needing block allocation
				 */
				if (ext4_should_order_data(inode))
					ret = ext4_jbd2_file_inode(handle,
								   inode);
2499

2500 2501 2502
				EXT4_I(inode)->i_disksize = new_i_size;
			}
			up_write(&EXT4_I(inode)->i_data_sem);
2503
		}
2504
	}
2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525
	ret2 = generic_write_end(file, mapping, pos, len, copied,
							page, fsdata);
	copied = ret2;
	if (ret2 < 0)
		ret = ret2;
	ret2 = ext4_journal_stop(handle);
	if (!ret)
		ret = ret2;

	return ret ? ret : copied;
}

static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
{
	/*
	 * Drop reserved blocks
	 */
	BUG_ON(!PageLocked(page));
	if (!page_has_buffers(page))
		goto out;

2526
	ext4_da_page_release_reservation(page, offset);
2527 2528 2529 2530 2531 2532 2533 2534

out:
	ext4_invalidatepage(page, offset);

	return;
}


2535 2536 2537 2538 2539
/*
 * bmap() is special.  It gets used by applications such as lilo and by
 * the swapper to find the on-disk block of a specific piece of data.
 *
 * Naturally, this is dangerous if the block concerned is still in the
2540
 * journal.  If somebody makes a swapfile on an ext4 data-journaling
2541 2542 2543 2544 2545 2546 2547 2548
 * filesystem and enables swap, then they may get a nasty shock when the
 * data getting swapped to that swapfile suddenly gets overwritten by
 * the original zero's written out previously to the journal and
 * awaiting writeback in the kernel's buffer cache.
 *
 * So, if we see any bmap calls here on a modified, data-journaled file,
 * take extra steps to flush any blocks which might be in the cache.
 */
2549
static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
2550 2551 2552 2553 2554
{
	struct inode *inode = mapping->host;
	journal_t *journal;
	int err;

2555 2556 2557 2558 2559 2560 2561 2562 2563 2564
	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
			test_opt(inode->i_sb, DELALLOC)) {
		/*
		 * With delalloc we want to sync the file
		 * so that we can make sure we allocate
		 * blocks for file
		 */
		filemap_write_and_wait(mapping);
	}

2565
	if (EXT4_I(inode)->i_state & EXT4_STATE_JDATA) {
2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576
		/*
		 * This is a REALLY heavyweight approach, but the use of
		 * bmap on dirty files is expected to be extremely rare:
		 * only if we run lilo or swapon on a freshly made file
		 * do we expect this to happen.
		 *
		 * (bmap requires CAP_SYS_RAWIO so this does not
		 * represent an unprivileged user DOS attack --- we'd be
		 * in trouble if mortal users could trigger this path at
		 * will.)
		 *
2577
		 * NB. EXT4_STATE_JDATA is not set on files other than
2578 2579 2580 2581 2582 2583
		 * regular files.  If somebody wants to bmap a directory
		 * or symlink and gets confused because the buffer
		 * hasn't yet been flushed to disk, they deserve
		 * everything they get.
		 */

2584 2585
		EXT4_I(inode)->i_state &= ~EXT4_STATE_JDATA;
		journal = EXT4_JOURNAL(inode);
2586 2587 2588
		jbd2_journal_lock_updates(journal);
		err = jbd2_journal_flush(journal);
		jbd2_journal_unlock_updates(journal);
2589 2590 2591 2592 2593

		if (err)
			return 0;
	}

2594
	return generic_block_bmap(mapping, block, ext4_get_block);
2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609
}

static int bget_one(handle_t *handle, struct buffer_head *bh)
{
	get_bh(bh);
	return 0;
}

static int bput_one(handle_t *handle, struct buffer_head *bh)
{
	put_bh(bh);
	return 0;
}

/*
2610 2611 2612 2613 2614 2615 2616 2617
 * Note that we don't need to start a transaction unless we're journaling data
 * because we should have holes filled from ext4_page_mkwrite(). We even don't
 * need to file the inode to the transaction's list in ordered mode because if
 * we are writing back data added by write(), the inode is already there and if
 * we are writing back data modified via mmap(), noone guarantees in which
 * transaction the data will hit the disk. In case we are journaling data, we
 * cannot start transaction directly because transaction start ranks above page
 * lock so we have to do some magic.
2618
 *
2619
 * In all journaling modes block_write_full_page() will start the I/O.
2620 2621 2622
 *
 * Problem:
 *
2623 2624
 *	ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
 *		ext4_writepage()
2625 2626 2627
 *
 * Similar for:
 *
2628
 *	ext4_file_write() -> generic_file_write() -> __alloc_pages() -> ...
2629
 *
2630
 * Same applies to ext4_get_block().  We will deadlock on various things like
2631
 * lock_journal and i_data_sem
2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661
 *
 * Setting PF_MEMALLOC here doesn't work - too many internal memory
 * allocations fail.
 *
 * 16May01: If we're reentered then journal_current_handle() will be
 *	    non-zero. We simply *return*.
 *
 * 1 July 2001: @@@ FIXME:
 *   In journalled data mode, a data buffer may be metadata against the
 *   current transaction.  But the same file is part of a shared mapping
 *   and someone does a writepage() on it.
 *
 *   We will move the buffer onto the async_data list, but *after* it has
 *   been dirtied. So there's a small window where we have dirty data on
 *   BJ_Metadata.
 *
 *   Note that this only applies to the last partial page in the file.  The
 *   bit which block_write_full_page() uses prepare/commit for.  (That's
 *   broken code anyway: it's wrong for msync()).
 *
 *   It's a rare case: affects the final partial page, for journalled data
 *   where the file is subject to bith write() and writepage() in the same
 *   transction.  To fix it we'll need a custom block_write_full_page().
 *   We'll probably need that anyway for journalling writepage() output.
 *
 * We don't honour synchronous mounts for writepage().  That would be
 * disastrous.  Any write() or metadata operation will sync the fs for
 * us.
 *
 */
2662
static int __ext4_normal_writepage(struct page *page,
2663 2664 2665 2666 2667
				struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;

	if (test_opt(inode->i_sb, NOBH))
2668 2669
		return nobh_writepage(page,
					ext4_normal_get_block_write, wbc);
2670
	else
2671 2672 2673
		return block_write_full_page(page,
						ext4_normal_get_block_write,
						wbc);
2674 2675
}

2676
static int ext4_normal_writepage(struct page *page,
2677 2678 2679
				struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
2680 2681 2682 2683 2684 2685 2686 2687
	loff_t size = i_size_read(inode);
	loff_t len;

	J_ASSERT(PageLocked(page));
	if (page->index == size >> PAGE_CACHE_SHIFT)
		len = size & ~PAGE_CACHE_MASK;
	else
		len = PAGE_CACHE_SIZE;
2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701

	if (page_has_buffers(page)) {
		/* if page has buffers it should all be mapped
		 * and allocated. If there are not buffers attached
		 * to the page we know the page is dirty but it lost
		 * buffers. That means that at some moment in time
		 * after write_begin() / write_end() has been called
		 * all buffers have been clean and thus they must have been
		 * written at least once. So they are all mapped and we can
		 * happily proceed with mapping them and writing the page.
		 */
		BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
					ext4_bh_unmapped_or_delay));
	}
2702 2703

	if (!ext4_journal_current_handle())
2704
		return __ext4_normal_writepage(page, wbc);
2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716

	redirty_page_for_writepage(wbc, page);
	unlock_page(page);
	return 0;
}

static int __ext4_journalled_writepage(struct page *page,
				struct writeback_control *wbc)
{
	struct address_space *mapping = page->mapping;
	struct inode *inode = mapping->host;
	struct buffer_head *page_bufs;
2717 2718 2719 2720
	handle_t *handle = NULL;
	int ret = 0;
	int err;

2721 2722
	ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
					ext4_normal_get_block_write);
2723 2724 2725 2726 2727 2728 2729 2730 2731
	if (ret != 0)
		goto out_unlock;

	page_bufs = page_buffers(page);
	walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE, NULL,
								bget_one);
	/* As soon as we unlock the page, it can go away, but we have
	 * references to buffers so we are safe */
	unlock_page(page);
2732

2733
	handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
2734 2735
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
2736
		goto out;
2737 2738
	}

2739 2740
	ret = walk_page_buffers(handle, page_bufs, 0,
			PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
2741

2742 2743 2744 2745
	err = walk_page_buffers(handle, page_bufs, 0,
				PAGE_CACHE_SIZE, NULL, write_end_fn);
	if (ret == 0)
		ret = err;
2746
	err = ext4_journal_stop(handle);
2747 2748 2749
	if (!ret)
		ret = err;

2750 2751 2752 2753 2754 2755
	walk_page_buffers(handle, page_bufs, 0,
				PAGE_CACHE_SIZE, NULL, bput_one);
	EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
	goto out;

out_unlock:
2756
	unlock_page(page);
2757
out:
2758 2759 2760
	return ret;
}

2761
static int ext4_journalled_writepage(struct page *page,
2762 2763 2764
				struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
2765 2766
	loff_t size = i_size_read(inode);
	loff_t len;
2767

2768 2769 2770 2771 2772
	J_ASSERT(PageLocked(page));
	if (page->index == size >> PAGE_CACHE_SHIFT)
		len = size & ~PAGE_CACHE_MASK;
	else
		len = PAGE_CACHE_SIZE;
2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786

	if (page_has_buffers(page)) {
		/* if page has buffers it should all be mapped
		 * and allocated. If there are not buffers attached
		 * to the page we know the page is dirty but it lost
		 * buffers. That means that at some moment in time
		 * after write_begin() / write_end() has been called
		 * all buffers have been clean and thus they must have been
		 * written at least once. So they are all mapped and we can
		 * happily proceed with mapping them and writing the page.
		 */
		BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
					ext4_bh_unmapped_or_delay));
	}
2787

2788
	if (ext4_journal_current_handle())
2789 2790
		goto no_write;

2791
	if (PageChecked(page)) {
2792 2793 2794 2795 2796
		/*
		 * It's mmapped pagecache.  Add buffers and journal it.  There
		 * doesn't seem much point in redirtying the page here.
		 */
		ClearPageChecked(page);
2797
		return __ext4_journalled_writepage(page, wbc);
2798 2799 2800 2801 2802 2803
	} else {
		/*
		 * It may be a page full of checkpoint-mode buffers.  We don't
		 * really know unless we go poke around in the buffer_heads.
		 * But block_write_full_page will do the right thing.
		 */
2804 2805 2806
		return block_write_full_page(page,
						ext4_normal_get_block_write,
						wbc);
2807 2808 2809 2810
	}
no_write:
	redirty_page_for_writepage(wbc, page);
	unlock_page(page);
2811
	return 0;
2812 2813
}

2814
static int ext4_readpage(struct file *file, struct page *page)
2815
{
2816
	return mpage_readpage(page, ext4_get_block);
2817 2818 2819
}

static int
2820
ext4_readpages(struct file *file, struct address_space *mapping,
2821 2822
		struct list_head *pages, unsigned nr_pages)
{
2823
	return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
2824 2825
}

2826
static void ext4_invalidatepage(struct page *page, unsigned long offset)
2827
{
2828
	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2829 2830 2831 2832 2833 2834 2835

	/*
	 * If it's a full truncate we just forget about the pending dirtying
	 */
	if (offset == 0)
		ClearPageChecked(page);

2836
	jbd2_journal_invalidatepage(journal, page, offset);
2837 2838
}

2839
static int ext4_releasepage(struct page *page, gfp_t wait)
2840
{
2841
	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2842 2843 2844 2845

	WARN_ON(PageChecked(page));
	if (!page_has_buffers(page))
		return 0;
2846
	return jbd2_journal_try_to_free_buffers(journal, page, wait);
2847 2848 2849 2850 2851 2852 2853 2854
}

/*
 * If the O_DIRECT write will extend the file then add this inode to the
 * orphan list.  So recovery will truncate it back to the original size
 * if the machine crashes during the write.
 *
 * If the O_DIRECT write is intantiating holes inside i_size and the machine
J
Jan Kara 已提交
2855 2856
 * crashes then stale disk data _may_ be exposed inside the file. But current
 * VFS code falls back into buffered path in that case so we are safe.
2857
 */
2858
static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
2859 2860 2861 2862 2863
			const struct iovec *iov, loff_t offset,
			unsigned long nr_segs)
{
	struct file *file = iocb->ki_filp;
	struct inode *inode = file->f_mapping->host;
2864
	struct ext4_inode_info *ei = EXT4_I(inode);
J
Jan Kara 已提交
2865
	handle_t *handle;
2866 2867 2868 2869 2870 2871 2872 2873
	ssize_t ret;
	int orphan = 0;
	size_t count = iov_length(iov, nr_segs);

	if (rw == WRITE) {
		loff_t final_size = offset + count;

		if (final_size > inode->i_size) {
J
Jan Kara 已提交
2874 2875 2876 2877 2878 2879
			/* Credits for sb + inode write */
			handle = ext4_journal_start(inode, 2);
			if (IS_ERR(handle)) {
				ret = PTR_ERR(handle);
				goto out;
			}
2880
			ret = ext4_orphan_add(handle, inode);
J
Jan Kara 已提交
2881 2882 2883 2884
			if (ret) {
				ext4_journal_stop(handle);
				goto out;
			}
2885 2886
			orphan = 1;
			ei->i_disksize = inode->i_size;
J
Jan Kara 已提交
2887
			ext4_journal_stop(handle);
2888 2889 2890 2891 2892
		}
	}

	ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
				 offset, nr_segs,
2893
				 ext4_get_block, NULL);
2894

J
Jan Kara 已提交
2895
	if (orphan) {
2896 2897
		int err;

J
Jan Kara 已提交
2898 2899 2900 2901 2902 2903 2904 2905 2906 2907
		/* Credits for sb + inode write */
		handle = ext4_journal_start(inode, 2);
		if (IS_ERR(handle)) {
			/* This is really bad luck. We've written the data
			 * but cannot extend i_size. Bail out and pretend
			 * the write failed... */
			ret = PTR_ERR(handle);
			goto out;
		}
		if (inode->i_nlink)
2908
			ext4_orphan_del(handle, inode);
J
Jan Kara 已提交
2909
		if (ret > 0) {
2910 2911 2912 2913 2914 2915 2916 2917
			loff_t end = offset + ret;
			if (end > inode->i_size) {
				ei->i_disksize = end;
				i_size_write(inode, end);
				/*
				 * We're going to return a positive `ret'
				 * here due to non-zero-length I/O, so there's
				 * no way of reporting error returns from
2918
				 * ext4_mark_inode_dirty() to userspace.  So
2919 2920
				 * ignore it.
				 */
2921
				ext4_mark_inode_dirty(handle, inode);
2922 2923
			}
		}
2924
		err = ext4_journal_stop(handle);
2925 2926 2927 2928 2929 2930 2931 2932
		if (ret == 0)
			ret = err;
	}
out:
	return ret;
}

/*
2933
 * Pages can be marked dirty completely asynchronously from ext4's journalling
2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944
 * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
 * much here because ->set_page_dirty is called under VFS locks.  The page is
 * not necessarily locked.
 *
 * We cannot just dirty the page and leave attached buffers clean, because the
 * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
 * or jbddirty because all the journalling code will explode.
 *
 * So what we do is to mark the page "pending dirty" and next time writepage
 * is called, propagate that into the buffers appropriately.
 */
2945
static int ext4_journalled_set_page_dirty(struct page *page)
2946 2947 2948 2949 2950
{
	SetPageChecked(page);
	return __set_page_dirty_nobuffers(page);
}

2951
static const struct address_space_operations ext4_ordered_aops = {
2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963
	.readpage		= ext4_readpage,
	.readpages		= ext4_readpages,
	.writepage		= ext4_normal_writepage,
	.sync_page		= block_sync_page,
	.write_begin		= ext4_write_begin,
	.write_end		= ext4_ordered_write_end,
	.bmap			= ext4_bmap,
	.invalidatepage		= ext4_invalidatepage,
	.releasepage		= ext4_releasepage,
	.direct_IO		= ext4_direct_IO,
	.migratepage		= buffer_migrate_page,
	.is_partially_uptodate  = block_is_partially_uptodate,
2964 2965
};

2966
static const struct address_space_operations ext4_writeback_aops = {
2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978
	.readpage		= ext4_readpage,
	.readpages		= ext4_readpages,
	.writepage		= ext4_normal_writepage,
	.sync_page		= block_sync_page,
	.write_begin		= ext4_write_begin,
	.write_end		= ext4_writeback_write_end,
	.bmap			= ext4_bmap,
	.invalidatepage		= ext4_invalidatepage,
	.releasepage		= ext4_releasepage,
	.direct_IO		= ext4_direct_IO,
	.migratepage		= buffer_migrate_page,
	.is_partially_uptodate  = block_is_partially_uptodate,
2979 2980
};

2981
static const struct address_space_operations ext4_journalled_aops = {
2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992
	.readpage		= ext4_readpage,
	.readpages		= ext4_readpages,
	.writepage		= ext4_journalled_writepage,
	.sync_page		= block_sync_page,
	.write_begin		= ext4_write_begin,
	.write_end		= ext4_journalled_write_end,
	.set_page_dirty		= ext4_journalled_set_page_dirty,
	.bmap			= ext4_bmap,
	.invalidatepage		= ext4_invalidatepage,
	.releasepage		= ext4_releasepage,
	.is_partially_uptodate  = block_is_partially_uptodate,
2993 2994
};

2995
static const struct address_space_operations ext4_da_aops = {
2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008
	.readpage		= ext4_readpage,
	.readpages		= ext4_readpages,
	.writepage		= ext4_da_writepage,
	.writepages		= ext4_da_writepages,
	.sync_page		= block_sync_page,
	.write_begin		= ext4_da_write_begin,
	.write_end		= ext4_da_write_end,
	.bmap			= ext4_bmap,
	.invalidatepage		= ext4_da_invalidatepage,
	.releasepage		= ext4_releasepage,
	.direct_IO		= ext4_direct_IO,
	.migratepage		= buffer_migrate_page,
	.is_partially_uptodate  = block_is_partially_uptodate,
3009 3010
};

3011
void ext4_set_aops(struct inode *inode)
3012
{
3013 3014 3015 3016
	if (ext4_should_order_data(inode) &&
		test_opt(inode->i_sb, DELALLOC))
		inode->i_mapping->a_ops = &ext4_da_aops;
	else if (ext4_should_order_data(inode))
3017
		inode->i_mapping->a_ops = &ext4_ordered_aops;
3018 3019 3020
	else if (ext4_should_writeback_data(inode) &&
		 test_opt(inode->i_sb, DELALLOC))
		inode->i_mapping->a_ops = &ext4_da_aops;
3021 3022
	else if (ext4_should_writeback_data(inode))
		inode->i_mapping->a_ops = &ext4_writeback_aops;
3023
	else
3024
		inode->i_mapping->a_ops = &ext4_journalled_aops;
3025 3026 3027
}

/*
3028
 * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
3029 3030 3031 3032
 * up to the end of the block which corresponds to `from'.
 * This required during truncate. We need to physically zero the tail end
 * of that block so it doesn't yield old data if the file is later grown.
 */
3033
int ext4_block_truncate_page(handle_t *handle,
3034 3035
		struct address_space *mapping, loff_t from)
{
3036
	ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
3037
	unsigned offset = from & (PAGE_CACHE_SIZE-1);
A
Aneesh Kumar K.V 已提交
3038 3039
	unsigned blocksize, length, pos;
	ext4_lblk_t iblock;
3040 3041
	struct inode *inode = mapping->host;
	struct buffer_head *bh;
3042
	struct page *page;
3043 3044
	int err = 0;

3045 3046 3047 3048
	page = grab_cache_page(mapping, from >> PAGE_CACHE_SHIFT);
	if (!page)
		return -EINVAL;

3049 3050 3051 3052 3053 3054 3055 3056 3057
	blocksize = inode->i_sb->s_blocksize;
	length = blocksize - (offset & (blocksize - 1));
	iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);

	/*
	 * For "nobh" option,  we can only work if we don't need to
	 * read-in the page - otherwise we create buffers to do the IO.
	 */
	if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
3058
	     ext4_should_writeback_data(inode) && PageUptodate(page)) {
3059
		zero_user(page, offset, length);
3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083
		set_page_dirty(page);
		goto unlock;
	}

	if (!page_has_buffers(page))
		create_empty_buffers(page, blocksize, 0);

	/* Find the buffer that contains "offset" */
	bh = page_buffers(page);
	pos = blocksize;
	while (offset >= pos) {
		bh = bh->b_this_page;
		iblock++;
		pos += blocksize;
	}

	err = 0;
	if (buffer_freed(bh)) {
		BUFFER_TRACE(bh, "freed: skip");
		goto unlock;
	}

	if (!buffer_mapped(bh)) {
		BUFFER_TRACE(bh, "unmapped");
3084
		ext4_get_block(inode, iblock, bh, 0);
3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104
		/* unmapped? It's a hole - nothing to do */
		if (!buffer_mapped(bh)) {
			BUFFER_TRACE(bh, "still unmapped");
			goto unlock;
		}
	}

	/* Ok, it's mapped. Make sure it's up-to-date */
	if (PageUptodate(page))
		set_buffer_uptodate(bh);

	if (!buffer_uptodate(bh)) {
		err = -EIO;
		ll_rw_block(READ, 1, &bh);
		wait_on_buffer(bh);
		/* Uhhuh. Read error. Complain and punt. */
		if (!buffer_uptodate(bh))
			goto unlock;
	}

3105
	if (ext4_should_journal_data(inode)) {
3106
		BUFFER_TRACE(bh, "get write access");
3107
		err = ext4_journal_get_write_access(handle, bh);
3108 3109 3110 3111
		if (err)
			goto unlock;
	}

3112
	zero_user(page, offset, length);
3113 3114 3115 3116

	BUFFER_TRACE(bh, "zeroed end of block");

	err = 0;
3117 3118
	if (ext4_should_journal_data(inode)) {
		err = ext4_journal_dirty_metadata(handle, bh);
3119
	} else {
3120
		if (ext4_should_order_data(inode))
3121
			err = ext4_jbd2_file_inode(handle, inode);
3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144
		mark_buffer_dirty(bh);
	}

unlock:
	unlock_page(page);
	page_cache_release(page);
	return err;
}

/*
 * Probably it should be a library function... search for first non-zero word
 * or memcmp with zero_page, whatever is better for particular architecture.
 * Linus?
 */
static inline int all_zeroes(__le32 *p, __le32 *q)
{
	while (p < q)
		if (*p++)
			return 0;
	return 1;
}

/**
3145
 *	ext4_find_shared - find the indirect blocks for partial truncation.
3146 3147
 *	@inode:	  inode in question
 *	@depth:	  depth of the affected branch
3148
 *	@offsets: offsets of pointers in that branch (see ext4_block_to_path)
3149 3150 3151
 *	@chain:	  place to store the pointers to partial indirect blocks
 *	@top:	  place to the (detached) top of branch
 *
3152
 *	This is a helper function used by ext4_truncate().
3153 3154 3155 3156 3157 3158 3159
 *
 *	When we do truncate() we may have to clean the ends of several
 *	indirect blocks but leave the blocks themselves alive. Block is
 *	partially truncated if some data below the new i_size is refered
 *	from it (and it is on the path to the first completely truncated
 *	data block, indeed).  We have to free the top of that path along
 *	with everything to the right of the path. Since no allocation
3160
 *	past the truncation point is possible until ext4_truncate()
3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178
 *	finishes, we may safely do the latter, but top of branch may
 *	require special attention - pageout below the truncation point
 *	might try to populate it.
 *
 *	We atomically detach the top of branch from the tree, store the
 *	block number of its root in *@top, pointers to buffer_heads of
 *	partially truncated blocks - in @chain[].bh and pointers to
 *	their last elements that should not be removed - in
 *	@chain[].p. Return value is the pointer to last filled element
 *	of @chain.
 *
 *	The work left to caller to do the actual freeing of subtrees:
 *		a) free the subtree starting from *@top
 *		b) free the subtrees whose roots are stored in
 *			(@chain[i].p+1 .. end of @chain[i].bh->b_data)
 *		c) free the subtrees growing from the inode past the @chain[0].
 *			(no partially truncated stuff there).  */

3179
static Indirect *ext4_find_shared(struct inode *inode, int depth,
A
Aneesh Kumar K.V 已提交
3180
			ext4_lblk_t offsets[4], Indirect chain[4], __le32 *top)
3181 3182 3183 3184 3185 3186 3187 3188
{
	Indirect *partial, *p;
	int k, err;

	*top = 0;
	/* Make k index the deepest non-null offest + 1 */
	for (k = depth; k > 1 && !offsets[k-1]; k--)
		;
3189
	partial = ext4_get_branch(inode, k, offsets, chain, &err);
3190 3191 3192 3193 3194 3195 3196 3197 3198 3199
	/* Writer: pointers */
	if (!partial)
		partial = chain + k-1;
	/*
	 * If the branch acquired continuation since we've looked at it -
	 * fine, it should all survive and (new) top doesn't belong to us.
	 */
	if (!partial->key && *partial->p)
		/* Writer: end */
		goto no_top;
3200
	for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211
		;
	/*
	 * OK, we've found the last block that must survive. The rest of our
	 * branch should be detached before unlocking. However, if that rest
	 * of branch is all ours and does not grow immediately from the inode
	 * it's easier to cheat and just decrement partial->p.
	 */
	if (p == chain + k - 1 && p > chain) {
		p->p--;
	} else {
		*top = *p->p;
3212
		/* Nope, don't do this in ext4.  Must leave the tree intact */
3213 3214 3215 3216 3217 3218
#if 0
		*p->p = 0;
#endif
	}
	/* Writer: end */

3219
	while (partial > p) {
3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234
		brelse(partial->bh);
		partial--;
	}
no_top:
	return partial;
}

/*
 * Zero a number of block pointers in either an inode or an indirect block.
 * If we restart the transaction we must again get write access to the
 * indirect block for further modification.
 *
 * We release `count' blocks on disk, but (last - first) may be greater
 * than `count' because there can be holes in there.
 */
3235 3236
static void ext4_clear_blocks(handle_t *handle, struct inode *inode,
		struct buffer_head *bh, ext4_fsblk_t block_to_free,
3237 3238 3239 3240 3241
		unsigned long count, __le32 *first, __le32 *last)
{
	__le32 *p;
	if (try_to_extend_transaction(handle, inode)) {
		if (bh) {
3242 3243
			BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
			ext4_journal_dirty_metadata(handle, bh);
3244
		}
3245 3246
		ext4_mark_inode_dirty(handle, inode);
		ext4_journal_test_restart(handle, inode);
3247 3248
		if (bh) {
			BUFFER_TRACE(bh, "retaking write access");
3249
			ext4_journal_get_write_access(handle, bh);
3250 3251 3252 3253 3254
		}
	}

	/*
	 * Any buffers which are on the journal will be in memory. We find
3255
	 * them on the hash table so jbd2_journal_revoke() will run jbd2_journal_forget()
3256
	 * on them.  We've already detached each block from the file, so
3257
	 * bforget() in jbd2_journal_forget() should be safe.
3258
	 *
3259
	 * AKPM: turn on bforget in jbd2_journal_forget()!!!
3260 3261 3262 3263
	 */
	for (p = first; p < last; p++) {
		u32 nr = le32_to_cpu(*p);
		if (nr) {
A
Aneesh Kumar K.V 已提交
3264
			struct buffer_head *tbh;
3265 3266

			*p = 0;
A
Aneesh Kumar K.V 已提交
3267 3268
			tbh = sb_find_get_block(inode->i_sb, nr);
			ext4_forget(handle, 0, inode, tbh, nr);
3269 3270 3271
		}
	}

3272
	ext4_free_blocks(handle, inode, block_to_free, count, 0);
3273 3274 3275
}

/**
3276
 * ext4_free_data - free a list of data blocks
3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293
 * @handle:	handle for this transaction
 * @inode:	inode we are dealing with
 * @this_bh:	indirect buffer_head which contains *@first and *@last
 * @first:	array of block numbers
 * @last:	points immediately past the end of array
 *
 * We are freeing all blocks refered from that array (numbers are stored as
 * little-endian 32-bit) and updating @inode->i_blocks appropriately.
 *
 * We accumulate contiguous runs of blocks to free.  Conveniently, if these
 * blocks are contiguous then releasing them at one time will only affect one
 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
 * actually use a lot of journal space.
 *
 * @this_bh will be %NULL if @first and @last point into the inode's direct
 * block pointers.
 */
3294
static void ext4_free_data(handle_t *handle, struct inode *inode,
3295 3296 3297
			   struct buffer_head *this_bh,
			   __le32 *first, __le32 *last)
{
3298
	ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
3299 3300 3301 3302
	unsigned long count = 0;	    /* Number of blocks in the run */
	__le32 *block_to_free_p = NULL;	    /* Pointer into inode/ind
					       corresponding to
					       block_to_free */
3303
	ext4_fsblk_t nr;		    /* Current block # */
3304 3305 3306 3307 3308 3309
	__le32 *p;			    /* Pointer into inode/ind
					       for current block */
	int err;

	if (this_bh) {				/* For indirect block */
		BUFFER_TRACE(this_bh, "get_write_access");
3310
		err = ext4_journal_get_write_access(handle, this_bh);
3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327
		/* Important: if we can't update the indirect pointers
		 * to the blocks, we can't free them. */
		if (err)
			return;
	}

	for (p = first; p < last; p++) {
		nr = le32_to_cpu(*p);
		if (nr) {
			/* accumulate blocks to free if they're contiguous */
			if (count == 0) {
				block_to_free = nr;
				block_to_free_p = p;
				count = 1;
			} else if (nr == block_to_free + count) {
				count++;
			} else {
3328
				ext4_clear_blocks(handle, inode, this_bh,
3329 3330 3331 3332 3333 3334 3335 3336 3337 3338
						  block_to_free,
						  count, block_to_free_p, p);
				block_to_free = nr;
				block_to_free_p = p;
				count = 1;
			}
		}
	}

	if (count > 0)
3339
		ext4_clear_blocks(handle, inode, this_bh, block_to_free,
3340 3341 3342
				  count, block_to_free_p, p);

	if (this_bh) {
3343
		BUFFER_TRACE(this_bh, "call ext4_journal_dirty_metadata");
3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358

		/*
		 * The buffer head should have an attached journal head at this
		 * point. However, if the data is corrupted and an indirect
		 * block pointed to itself, it would have been detached when
		 * the block was cleared. Check for this instead of OOPSing.
		 */
		if (bh2jh(this_bh))
			ext4_journal_dirty_metadata(handle, this_bh);
		else
			ext4_error(inode->i_sb, __func__,
				   "circular indirect block detected, "
				   "inode=%lu, block=%llu",
				   inode->i_ino,
				   (unsigned long long) this_bh->b_blocknr);
3359 3360 3361 3362
	}
}

/**
3363
 *	ext4_free_branches - free an array of branches
3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374
 *	@handle: JBD handle for this transaction
 *	@inode:	inode we are dealing with
 *	@parent_bh: the buffer_head which contains *@first and *@last
 *	@first:	array of block numbers
 *	@last:	pointer immediately past the end of array
 *	@depth:	depth of the branches to free
 *
 *	We are freeing all blocks refered from these branches (numbers are
 *	stored as little-endian 32-bit) and updating @inode->i_blocks
 *	appropriately.
 */
3375
static void ext4_free_branches(handle_t *handle, struct inode *inode,
3376 3377 3378
			       struct buffer_head *parent_bh,
			       __le32 *first, __le32 *last, int depth)
{
3379
	ext4_fsblk_t nr;
3380 3381 3382 3383 3384 3385 3386
	__le32 *p;

	if (is_handle_aborted(handle))
		return;

	if (depth--) {
		struct buffer_head *bh;
3387
		int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401
		p = last;
		while (--p >= first) {
			nr = le32_to_cpu(*p);
			if (!nr)
				continue;		/* A hole */

			/* Go read the buffer for the next level down */
			bh = sb_bread(inode->i_sb, nr);

			/*
			 * A read failure? Report error and clear slot
			 * (should be rare).
			 */
			if (!bh) {
3402
				ext4_error(inode->i_sb, "ext4_free_branches",
3403
					   "Read failure, inode=%lu, block=%llu",
3404 3405 3406 3407 3408 3409
					   inode->i_ino, nr);
				continue;
			}

			/* This zaps the entire block.  Bottom up. */
			BUFFER_TRACE(bh, "free child branches");
3410
			ext4_free_branches(handle, inode, bh,
3411 3412 3413
					(__le32 *) bh->b_data,
					(__le32 *) bh->b_data + addr_per_block,
					depth);
3414 3415 3416 3417 3418

			/*
			 * We've probably journalled the indirect block several
			 * times during the truncate.  But it's no longer
			 * needed and we now drop it from the transaction via
3419
			 * jbd2_journal_revoke().
3420 3421 3422
			 *
			 * That's easy if it's exclusively part of this
			 * transaction.  But if it's part of the committing
3423
			 * transaction then jbd2_journal_forget() will simply
3424
			 * brelse() it.  That means that if the underlying
3425
			 * block is reallocated in ext4_get_block(),
3426 3427 3428 3429 3430 3431 3432 3433
			 * unmap_underlying_metadata() will find this block
			 * and will try to get rid of it.  damn, damn.
			 *
			 * If this block has already been committed to the
			 * journal, a revoke record will be written.  And
			 * revoke records must be emitted *before* clearing
			 * this block's bit in the bitmaps.
			 */
3434
			ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453 3454

			/*
			 * Everything below this this pointer has been
			 * released.  Now let this top-of-subtree go.
			 *
			 * We want the freeing of this indirect block to be
			 * atomic in the journal with the updating of the
			 * bitmap block which owns it.  So make some room in
			 * the journal.
			 *
			 * We zero the parent pointer *after* freeing its
			 * pointee in the bitmaps, so if extend_transaction()
			 * for some reason fails to put the bitmap changes and
			 * the release into the same transaction, recovery
			 * will merely complain about releasing a free block,
			 * rather than leaking blocks.
			 */
			if (is_handle_aborted(handle))
				return;
			if (try_to_extend_transaction(handle, inode)) {
3455 3456
				ext4_mark_inode_dirty(handle, inode);
				ext4_journal_test_restart(handle, inode);
3457 3458
			}

3459
			ext4_free_blocks(handle, inode, nr, 1, 1);
3460 3461 3462 3463 3464 3465 3466

			if (parent_bh) {
				/*
				 * The block which we have just freed is
				 * pointed to by an indirect block: journal it
				 */
				BUFFER_TRACE(parent_bh, "get_write_access");
3467
				if (!ext4_journal_get_write_access(handle,
3468 3469 3470
								   parent_bh)){
					*p = 0;
					BUFFER_TRACE(parent_bh,
3471 3472
					"call ext4_journal_dirty_metadata");
					ext4_journal_dirty_metadata(handle,
3473 3474 3475 3476 3477 3478 3479
								    parent_bh);
				}
			}
		}
	} else {
		/* We have reached the bottom of the tree. */
		BUFFER_TRACE(parent_bh, "free data blocks");
3480
		ext4_free_data(handle, inode, parent_bh, first, last);
3481 3482 3483
	}
}

3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496
int ext4_can_truncate(struct inode *inode)
{
	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
		return 0;
	if (S_ISREG(inode->i_mode))
		return 1;
	if (S_ISDIR(inode->i_mode))
		return 1;
	if (S_ISLNK(inode->i_mode))
		return !ext4_inode_is_fast_symlink(inode);
	return 0;
}

3497
/*
3498
 * ext4_truncate()
3499
 *
3500 3501
 * We block out ext4_get_block() block instantiations across the entire
 * transaction, and VFS/VM ensures that ext4_truncate() cannot run
3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513 3514 3515 3516 3517
 * simultaneously on behalf of the same inode.
 *
 * As we work through the truncate and commmit bits of it to the journal there
 * is one core, guiding principle: the file's tree must always be consistent on
 * disk.  We must be able to restart the truncate after a crash.
 *
 * The file's tree may be transiently inconsistent in memory (although it
 * probably isn't), but whenever we close off and commit a journal transaction,
 * the contents of (the filesystem + the journal) must be consistent and
 * restartable.  It's pretty simple, really: bottom up, right to left (although
 * left-to-right works OK too).
 *
 * Note that at recovery time, journal replay occurs *before* the restart of
 * truncate against the orphan inode list.
 *
 * The committed inode has the new, desired i_size (which is the same as
3518
 * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
3519
 * that this inode's truncate did not complete and it will again call
3520 3521
 * ext4_truncate() to have another go.  So there will be instantiated blocks
 * to the right of the truncation point in a crashed ext4 filesystem.  But
3522
 * that's fine - as long as they are linked from the inode, the post-crash
3523
 * ext4_truncate() run will find them and release them.
3524
 */
3525
void ext4_truncate(struct inode *inode)
3526 3527
{
	handle_t *handle;
3528
	struct ext4_inode_info *ei = EXT4_I(inode);
3529
	__le32 *i_data = ei->i_data;
3530
	int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
3531
	struct address_space *mapping = inode->i_mapping;
A
Aneesh Kumar K.V 已提交
3532
	ext4_lblk_t offsets[4];
3533 3534 3535 3536
	Indirect chain[4];
	Indirect *partial;
	__le32 nr = 0;
	int n;
A
Aneesh Kumar K.V 已提交
3537
	ext4_lblk_t last_block;
3538 3539
	unsigned blocksize = inode->i_sb->s_blocksize;

3540
	if (!ext4_can_truncate(inode))
3541 3542
		return;

A
Aneesh Kumar K.V 已提交
3543
	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
3544
		ext4_ext_truncate(inode);
A
Aneesh Kumar K.V 已提交
3545 3546
		return;
	}
A
Alex Tomas 已提交
3547

3548
	handle = start_transaction(inode);
3549
	if (IS_ERR(handle))
3550 3551 3552
		return;		/* AKPM: return what? */

	last_block = (inode->i_size + blocksize-1)
3553
					>> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
3554

3555 3556 3557
	if (inode->i_size & (blocksize - 1))
		if (ext4_block_truncate_page(handle, mapping, inode->i_size))
			goto out_stop;
3558

3559
	n = ext4_block_to_path(inode, last_block, offsets, NULL);
3560 3561 3562 3563 3564 3565 3566 3567 3568 3569 3570 3571
	if (n == 0)
		goto out_stop;	/* error */

	/*
	 * OK.  This truncate is going to happen.  We add the inode to the
	 * orphan list, so that if this truncate spans multiple transactions,
	 * and we crash, we will resume the truncate when the filesystem
	 * recovers.  It also marks the inode dirty, to catch the new size.
	 *
	 * Implication: the file must always be in a sane, consistent
	 * truncatable state while each transaction commits.
	 */
3572
	if (ext4_orphan_add(handle, inode))
3573 3574
		goto out_stop;

3575 3576 3577 3578 3579
	/*
	 * From here we block out all ext4_get_block() callers who want to
	 * modify the block allocation tree.
	 */
	down_write(&ei->i_data_sem);
3580 3581 3582

	ext4_discard_reservation(inode);

3583 3584 3585 3586 3587
	/*
	 * The orphan list entry will now protect us from any crash which
	 * occurs before the truncate completes, so it is now safe to propagate
	 * the new, shorter inode size (held for now in i_size) into the
	 * on-disk inode. We do this via i_disksize, which is the value which
3588
	 * ext4 *really* writes onto the disk inode.
3589 3590 3591 3592
	 */
	ei->i_disksize = inode->i_size;

	if (n == 1) {		/* direct blocks */
3593 3594
		ext4_free_data(handle, inode, NULL, i_data+offsets[0],
			       i_data + EXT4_NDIR_BLOCKS);
3595 3596 3597
		goto do_indirects;
	}

3598
	partial = ext4_find_shared(inode, n, offsets, chain, &nr);
3599 3600 3601 3602
	/* Kill the top of shared branch (not detached) */
	if (nr) {
		if (partial == chain) {
			/* Shared branch grows from the inode */
3603
			ext4_free_branches(handle, inode, NULL,
3604 3605 3606 3607 3608 3609 3610 3611 3612
					   &nr, &nr+1, (chain+n-1) - partial);
			*partial->p = 0;
			/*
			 * We mark the inode dirty prior to restart,
			 * and prior to stop.  No need for it here.
			 */
		} else {
			/* Shared branch grows from an indirect block */
			BUFFER_TRACE(partial->bh, "get_write_access");
3613
			ext4_free_branches(handle, inode, partial->bh,
3614 3615 3616 3617 3618 3619
					partial->p,
					partial->p+1, (chain+n-1) - partial);
		}
	}
	/* Clear the ends of indirect blocks on the shared branch */
	while (partial > chain) {
3620
		ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
3621 3622 3623 3624 3625 3626 3627 3628 3629 3630
				   (__le32*)partial->bh->b_data+addr_per_block,
				   (chain+n-1) - partial);
		BUFFER_TRACE(partial->bh, "call brelse");
		brelse (partial->bh);
		partial--;
	}
do_indirects:
	/* Kill the remaining (whole) subtrees */
	switch (offsets[0]) {
	default:
3631
		nr = i_data[EXT4_IND_BLOCK];
3632
		if (nr) {
3633 3634
			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
			i_data[EXT4_IND_BLOCK] = 0;
3635
		}
3636 3637
	case EXT4_IND_BLOCK:
		nr = i_data[EXT4_DIND_BLOCK];
3638
		if (nr) {
3639 3640
			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
			i_data[EXT4_DIND_BLOCK] = 0;
3641
		}
3642 3643
	case EXT4_DIND_BLOCK:
		nr = i_data[EXT4_TIND_BLOCK];
3644
		if (nr) {
3645 3646
			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
			i_data[EXT4_TIND_BLOCK] = 0;
3647
		}
3648
	case EXT4_TIND_BLOCK:
3649 3650 3651
		;
	}

3652
	up_write(&ei->i_data_sem);
K
Kalpak Shah 已提交
3653
	inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
3654
	ext4_mark_inode_dirty(handle, inode);
3655 3656 3657 3658 3659 3660 3661 3662 3663 3664 3665 3666

	/*
	 * In a multi-transaction truncate, we only make the final transaction
	 * synchronous
	 */
	if (IS_SYNC(inode))
		handle->h_sync = 1;
out_stop:
	/*
	 * If this was a simple ftruncate(), and the file will remain alive
	 * then we need to clear up the orphan record which we created above.
	 * However, if this was a real unlink then we were called by
3667
	 * ext4_delete_inode(), and we allow that function to clean up the
3668 3669 3670
	 * orphan info for us.
	 */
	if (inode->i_nlink)
3671
		ext4_orphan_del(handle, inode);
3672

3673
	ext4_journal_stop(handle);
3674 3675
}

3676 3677
static ext4_fsblk_t ext4_get_inode_block(struct super_block *sb,
		unsigned long ino, struct ext4_iloc *iloc)
3678
{
3679
	ext4_group_t block_group;
3680
	unsigned long offset;
3681
	ext4_fsblk_t block;
A
Akinobu Mita 已提交
3682
	struct ext4_group_desc *gdp;
3683

3684
	if (!ext4_valid_inum(sb, ino)) {
3685 3686 3687 3688 3689 3690 3691 3692
		/*
		 * This error is already checked for in namei.c unless we are
		 * looking at an NFS filehandle, in which case no error
		 * report is needed
		 */
		return 0;
	}

3693
	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
A
Akinobu Mita 已提交
3694 3695
	gdp = ext4_get_group_desc(sb, block_group, NULL);
	if (!gdp)
3696 3697 3698 3699 3700
		return 0;

	/*
	 * Figure out the offset within the block group inode table
	 */
3701 3702
	offset = ((ino - 1) % EXT4_INODES_PER_GROUP(sb)) *
		EXT4_INODE_SIZE(sb);
3703 3704
	block = ext4_inode_table(sb, gdp) +
		(offset >> EXT4_BLOCK_SIZE_BITS(sb));
3705 3706

	iloc->block_group = block_group;
3707
	iloc->offset = offset & (EXT4_BLOCK_SIZE(sb) - 1);
3708 3709 3710 3711
	return block;
}

/*
3712
 * ext4_get_inode_loc returns with an extra refcount against the inode's
3713 3714 3715 3716
 * underlying buffer_head on success. If 'in_mem' is true, we have all
 * data in memory that is needed to recreate the on-disk version of this
 * inode.
 */
3717 3718
static int __ext4_get_inode_loc(struct inode *inode,
				struct ext4_iloc *iloc, int in_mem)
3719
{
3720
	ext4_fsblk_t block;
3721 3722
	struct buffer_head *bh;

3723
	block = ext4_get_inode_block(inode->i_sb, inode->i_ino, iloc);
3724 3725 3726 3727 3728
	if (!block)
		return -EIO;

	bh = sb_getblk(inode->i_sb, block);
	if (!bh) {
3729
		ext4_error (inode->i_sb, "ext4_get_inode_loc",
3730
				"unable to read inode block - "
3731
				"inode=%lu, block=%llu",
3732 3733 3734 3735 3736
				 inode->i_ino, block);
		return -EIO;
	}
	if (!buffer_uptodate(bh)) {
		lock_buffer(bh);
3737 3738 3739 3740 3741 3742 3743 3744 3745 3746

		/*
		 * If the buffer has the write error flag, we have failed
		 * to write out another inode in the same block.  In this
		 * case, we don't have to read the block because we may
		 * read the old inode data successfully.
		 */
		if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
			set_buffer_uptodate(bh);

3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759
		if (buffer_uptodate(bh)) {
			/* someone brought it uptodate while we waited */
			unlock_buffer(bh);
			goto has_buffer;
		}

		/*
		 * If we have all information of the inode in memory and this
		 * is the only valid inode in the block, we need not read the
		 * block.
		 */
		if (in_mem) {
			struct buffer_head *bitmap_bh;
3760
			struct ext4_group_desc *desc;
3761 3762
			int inodes_per_buffer;
			int inode_offset, i;
3763
			ext4_group_t block_group;
3764 3765 3766
			int start;

			block_group = (inode->i_ino - 1) /
3767
					EXT4_INODES_PER_GROUP(inode->i_sb);
3768
			inodes_per_buffer = bh->b_size /
3769
				EXT4_INODE_SIZE(inode->i_sb);
3770
			inode_offset = ((inode->i_ino - 1) %
3771
					EXT4_INODES_PER_GROUP(inode->i_sb));
3772 3773 3774
			start = inode_offset & ~(inodes_per_buffer - 1);

			/* Is the inode bitmap in cache? */
3775
			desc = ext4_get_group_desc(inode->i_sb,
3776 3777 3778 3779 3780
						block_group, NULL);
			if (!desc)
				goto make_io;

			bitmap_bh = sb_getblk(inode->i_sb,
3781
				ext4_inode_bitmap(inode->i_sb, desc));
3782 3783 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796
			if (!bitmap_bh)
				goto make_io;

			/*
			 * If the inode bitmap isn't in cache then the
			 * optimisation may end up performing two reads instead
			 * of one, so skip it.
			 */
			if (!buffer_uptodate(bitmap_bh)) {
				brelse(bitmap_bh);
				goto make_io;
			}
			for (i = start; i < start + inodes_per_buffer; i++) {
				if (i == inode_offset)
					continue;
3797
				if (ext4_test_bit(i, bitmap_bh->b_data))
3798 3799 3800 3801 3802 3803 3804 3805 3806 3807 3808 3809 3810 3811 3812 3813 3814 3815 3816 3817 3818 3819 3820
					break;
			}
			brelse(bitmap_bh);
			if (i == start + inodes_per_buffer) {
				/* all other inodes are free, so skip I/O */
				memset(bh->b_data, 0, bh->b_size);
				set_buffer_uptodate(bh);
				unlock_buffer(bh);
				goto has_buffer;
			}
		}

make_io:
		/*
		 * There are other valid inodes in the buffer, this inode
		 * has in-inode xattrs, or we don't have this inode in memory.
		 * Read the block from disk.
		 */
		get_bh(bh);
		bh->b_end_io = end_buffer_read_sync;
		submit_bh(READ_META, bh);
		wait_on_buffer(bh);
		if (!buffer_uptodate(bh)) {
3821
			ext4_error(inode->i_sb, "ext4_get_inode_loc",
3822
					"unable to read inode block - "
3823
					"inode=%lu, block=%llu",
3824 3825 3826 3827 3828 3829 3830 3831 3832 3833
					inode->i_ino, block);
			brelse(bh);
			return -EIO;
		}
	}
has_buffer:
	iloc->bh = bh;
	return 0;
}

3834
int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
3835 3836
{
	/* We have all inode data except xattrs in memory here. */
3837 3838
	return __ext4_get_inode_loc(inode, iloc,
		!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR));
3839 3840
}

3841
void ext4_set_inode_flags(struct inode *inode)
3842
{
3843
	unsigned int flags = EXT4_I(inode)->i_flags;
3844 3845

	inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
3846
	if (flags & EXT4_SYNC_FL)
3847
		inode->i_flags |= S_SYNC;
3848
	if (flags & EXT4_APPEND_FL)
3849
		inode->i_flags |= S_APPEND;
3850
	if (flags & EXT4_IMMUTABLE_FL)
3851
		inode->i_flags |= S_IMMUTABLE;
3852
	if (flags & EXT4_NOATIME_FL)
3853
		inode->i_flags |= S_NOATIME;
3854
	if (flags & EXT4_DIRSYNC_FL)
3855 3856 3857
		inode->i_flags |= S_DIRSYNC;
}

3858 3859 3860 3861 3862 3863 3864 3865 3866 3867 3868 3869 3870 3871 3872 3873 3874 3875
/* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
void ext4_get_inode_flags(struct ext4_inode_info *ei)
{
	unsigned int flags = ei->vfs_inode.i_flags;

	ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
			EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL);
	if (flags & S_SYNC)
		ei->i_flags |= EXT4_SYNC_FL;
	if (flags & S_APPEND)
		ei->i_flags |= EXT4_APPEND_FL;
	if (flags & S_IMMUTABLE)
		ei->i_flags |= EXT4_IMMUTABLE_FL;
	if (flags & S_NOATIME)
		ei->i_flags |= EXT4_NOATIME_FL;
	if (flags & S_DIRSYNC)
		ei->i_flags |= EXT4_DIRSYNC_FL;
}
3876 3877 3878 3879
static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
					struct ext4_inode_info *ei)
{
	blkcnt_t i_blocks ;
A
Aneesh Kumar K.V 已提交
3880 3881
	struct inode *inode = &(ei->vfs_inode);
	struct super_block *sb = inode->i_sb;
3882 3883 3884 3885 3886 3887

	if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
				EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
		/* we are using combined 48 bit field */
		i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
					le32_to_cpu(raw_inode->i_blocks_lo);
A
Aneesh Kumar K.V 已提交
3888 3889 3890 3891 3892 3893
		if (ei->i_flags & EXT4_HUGE_FILE_FL) {
			/* i_blocks represent file system block size */
			return i_blocks  << (inode->i_blkbits - 9);
		} else {
			return i_blocks;
		}
3894 3895 3896 3897
	} else {
		return le32_to_cpu(raw_inode->i_blocks_lo);
	}
}
3898

3899
struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
3900
{
3901 3902
	struct ext4_iloc iloc;
	struct ext4_inode *raw_inode;
3903
	struct ext4_inode_info *ei;
3904
	struct buffer_head *bh;
3905 3906
	struct inode *inode;
	long ret;
3907 3908
	int block;

3909 3910 3911 3912 3913 3914 3915
	inode = iget_locked(sb, ino);
	if (!inode)
		return ERR_PTR(-ENOMEM);
	if (!(inode->i_state & I_NEW))
		return inode;

	ei = EXT4_I(inode);
3916 3917 3918
#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
	ei->i_acl = EXT4_ACL_NOT_CACHED;
	ei->i_default_acl = EXT4_ACL_NOT_CACHED;
3919 3920 3921
#endif
	ei->i_block_alloc_info = NULL;

3922 3923
	ret = __ext4_get_inode_loc(inode, &iloc, 0);
	if (ret < 0)
3924 3925
		goto bad_inode;
	bh = iloc.bh;
3926
	raw_inode = ext4_raw_inode(&iloc);
3927 3928 3929
	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
	inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
	inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
3930
	if (!(test_opt(inode->i_sb, NO_UID32))) {
3931 3932 3933 3934 3935 3936 3937 3938 3939 3940 3941 3942 3943 3944 3945
		inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
		inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
	}
	inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);

	ei->i_state = 0;
	ei->i_dir_start_lookup = 0;
	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
	/* We now have enough fields to check if the inode was active or not.
	 * This is needed because nfsd might try to access dead inodes
	 * the test is that same one that e2fsck uses
	 * NeilBrown 1999oct15
	 */
	if (inode->i_nlink == 0) {
		if (inode->i_mode == 0 ||
3946
		    !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
3947
			/* this inode is deleted */
3948
			brelse(bh);
3949
			ret = -ESTALE;
3950 3951 3952 3953 3954 3955 3956 3957
			goto bad_inode;
		}
		/* The only unlinked inodes we let through here have
		 * valid i_mode and are being read by the orphan
		 * recovery code: that's fine, we're about to complete
		 * the process of deleting those. */
	}
	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
3958
	inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
3959
	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
3960
	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
3961
	    cpu_to_le32(EXT4_OS_HURD)) {
B
Badari Pulavarty 已提交
3962 3963
		ei->i_file_acl |=
			((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
3964
	}
3965
	inode->i_size = ext4_isize(raw_inode);
3966 3967 3968 3969 3970 3971 3972
	ei->i_disksize = inode->i_size;
	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
	ei->i_block_group = iloc.block_group;
	/*
	 * NOTE! The in-memory inode i_data array is in little-endian order
	 * even on big-endian machines: we do NOT byteswap the block numbers!
	 */
3973
	for (block = 0; block < EXT4_N_BLOCKS; block++)
3974 3975 3976
		ei->i_data[block] = raw_inode->i_block[block];
	INIT_LIST_HEAD(&ei->i_orphan);

3977
	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
3978
		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
3979
		if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
3980
		    EXT4_INODE_SIZE(inode->i_sb)) {
3981
			brelse(bh);
3982
			ret = -EIO;
3983
			goto bad_inode;
3984
		}
3985 3986
		if (ei->i_extra_isize == 0) {
			/* The extra space is currently unused. Use it. */
3987 3988
			ei->i_extra_isize = sizeof(struct ext4_inode) -
					    EXT4_GOOD_OLD_INODE_SIZE;
3989 3990
		} else {
			__le32 *magic = (void *)raw_inode +
3991
					EXT4_GOOD_OLD_INODE_SIZE +
3992
					ei->i_extra_isize;
3993 3994
			if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
				 ei->i_state |= EXT4_STATE_XATTR;
3995 3996 3997 3998
		}
	} else
		ei->i_extra_isize = 0;

K
Kalpak Shah 已提交
3999 4000 4001 4002 4003
	EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
	EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
	EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
	EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);

4004 4005 4006 4007 4008 4009 4010
	inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
		if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
			inode->i_version |=
			(__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
	}

4011
	if (S_ISREG(inode->i_mode)) {
4012 4013 4014
		inode->i_op = &ext4_file_inode_operations;
		inode->i_fop = &ext4_file_operations;
		ext4_set_aops(inode);
4015
	} else if (S_ISDIR(inode->i_mode)) {
4016 4017
		inode->i_op = &ext4_dir_inode_operations;
		inode->i_fop = &ext4_dir_operations;
4018
	} else if (S_ISLNK(inode->i_mode)) {
4019 4020
		if (ext4_inode_is_fast_symlink(inode))
			inode->i_op = &ext4_fast_symlink_inode_operations;
4021
		else {
4022 4023
			inode->i_op = &ext4_symlink_inode_operations;
			ext4_set_aops(inode);
4024 4025
		}
	} else {
4026
		inode->i_op = &ext4_special_inode_operations;
4027 4028 4029 4030 4031 4032 4033
		if (raw_inode->i_block[0])
			init_special_inode(inode, inode->i_mode,
			   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
		else
			init_special_inode(inode, inode->i_mode,
			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
	}
4034
	brelse(iloc.bh);
4035
	ext4_set_inode_flags(inode);
4036 4037
	unlock_new_inode(inode);
	return inode;
4038 4039

bad_inode:
4040 4041
	iget_failed(inode);
	return ERR_PTR(ret);
4042 4043
}

4044 4045 4046 4047 4048 4049 4050 4051 4052 4053 4054 4055 4056 4057
static int ext4_inode_blocks_set(handle_t *handle,
				struct ext4_inode *raw_inode,
				struct ext4_inode_info *ei)
{
	struct inode *inode = &(ei->vfs_inode);
	u64 i_blocks = inode->i_blocks;
	struct super_block *sb = inode->i_sb;
	int err = 0;

	if (i_blocks <= ~0U) {
		/*
		 * i_blocks can be represnted in a 32 bit variable
		 * as multiple of 512 bytes
		 */
A
Aneesh Kumar K.V 已提交
4058
		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4059
		raw_inode->i_blocks_high = 0;
A
Aneesh Kumar K.V 已提交
4060
		ei->i_flags &= ~EXT4_HUGE_FILE_FL;
4061 4062 4063 4064 4065 4066 4067 4068 4069 4070
	} else if (i_blocks <= 0xffffffffffffULL) {
		/*
		 * i_blocks can be represented in a 48 bit variable
		 * as multiple of 512 bytes
		 */
		err = ext4_update_rocompat_feature(handle, sb,
					    EXT4_FEATURE_RO_COMPAT_HUGE_FILE);
		if (err)
			goto  err_out;
		/* i_block is stored in the split  48 bit fields */
A
Aneesh Kumar K.V 已提交
4071
		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4072
		raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
A
Aneesh Kumar K.V 已提交
4073
		ei->i_flags &= ~EXT4_HUGE_FILE_FL;
4074
	} else {
A
Aneesh Kumar K.V 已提交
4075 4076 4077 4078 4079 4080 4081 4082 4083 4084 4085 4086 4087
		/*
		 * i_blocks should be represented in a 48 bit variable
		 * as multiple of  file system block size
		 */
		err = ext4_update_rocompat_feature(handle, sb,
					    EXT4_FEATURE_RO_COMPAT_HUGE_FILE);
		if (err)
			goto  err_out;
		ei->i_flags |= EXT4_HUGE_FILE_FL;
		/* i_block is stored in file system block size */
		i_blocks = i_blocks >> (inode->i_blkbits - 9);
		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
		raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4088 4089 4090 4091 4092
	}
err_out:
	return err;
}

4093 4094 4095 4096 4097 4098 4099
/*
 * Post the struct inode info into an on-disk inode location in the
 * buffer-cache.  This gobbles the caller's reference to the
 * buffer_head in the inode location struct.
 *
 * The caller must have write access to iloc->bh.
 */
4100
static int ext4_do_update_inode(handle_t *handle,
4101
				struct inode *inode,
4102
				struct ext4_iloc *iloc)
4103
{
4104 4105
	struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
	struct ext4_inode_info *ei = EXT4_I(inode);
4106 4107 4108 4109 4110
	struct buffer_head *bh = iloc->bh;
	int err = 0, rc, block;

	/* For fields not not tracking in the in-memory inode,
	 * initialise them to zero for new inodes. */
4111 4112
	if (ei->i_state & EXT4_STATE_NEW)
		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
4113

4114
	ext4_get_inode_flags(ei);
4115
	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
4116
	if (!(test_opt(inode->i_sb, NO_UID32))) {
4117 4118 4119 4120 4121 4122
		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
/*
 * Fix up interoperability with old kernels. Otherwise, old inodes get
 * re-used with the upper 16 bits of the uid/gid intact
 */
4123
		if (!ei->i_dtime) {
4124 4125 4126 4127 4128 4129 4130 4131 4132 4133 4134 4135 4136 4137 4138 4139 4140
			raw_inode->i_uid_high =
				cpu_to_le16(high_16_bits(inode->i_uid));
			raw_inode->i_gid_high =
				cpu_to_le16(high_16_bits(inode->i_gid));
		} else {
			raw_inode->i_uid_high = 0;
			raw_inode->i_gid_high = 0;
		}
	} else {
		raw_inode->i_uid_low =
			cpu_to_le16(fs_high2lowuid(inode->i_uid));
		raw_inode->i_gid_low =
			cpu_to_le16(fs_high2lowgid(inode->i_gid));
		raw_inode->i_uid_high = 0;
		raw_inode->i_gid_high = 0;
	}
	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
K
Kalpak Shah 已提交
4141 4142 4143 4144 4145 4146

	EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
	EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
	EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
	EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);

4147 4148
	if (ext4_inode_blocks_set(handle, raw_inode, ei))
		goto out_brelse;
4149
	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
4150 4151
	/* clear the migrate flag in the raw_inode */
	raw_inode->i_flags = cpu_to_le32(ei->i_flags & ~EXT4_EXT_MIGRATE);
4152 4153
	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
	    cpu_to_le32(EXT4_OS_HURD))
B
Badari Pulavarty 已提交
4154 4155
		raw_inode->i_file_acl_high =
			cpu_to_le16(ei->i_file_acl >> 32);
4156
	raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
4157 4158 4159 4160 4161 4162 4163 4164 4165 4166 4167 4168 4169 4170 4171 4172
	ext4_isize_set(raw_inode, ei->i_disksize);
	if (ei->i_disksize > 0x7fffffffULL) {
		struct super_block *sb = inode->i_sb;
		if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
				EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
				EXT4_SB(sb)->s_es->s_rev_level ==
				cpu_to_le32(EXT4_GOOD_OLD_REV)) {
			/* If this is the first large file
			 * created, add a flag to the superblock.
			 */
			err = ext4_journal_get_write_access(handle,
					EXT4_SB(sb)->s_sbh);
			if (err)
				goto out_brelse;
			ext4_update_dynamic_rev(sb);
			EXT4_SET_RO_COMPAT_FEATURE(sb,
4173
					EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
4174 4175 4176 4177
			sb->s_dirt = 1;
			handle->h_sync = 1;
			err = ext4_journal_dirty_metadata(handle,
					EXT4_SB(sb)->s_sbh);
4178 4179 4180 4181 4182 4183 4184 4185 4186 4187 4188 4189 4190 4191
		}
	}
	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
		if (old_valid_dev(inode->i_rdev)) {
			raw_inode->i_block[0] =
				cpu_to_le32(old_encode_dev(inode->i_rdev));
			raw_inode->i_block[1] = 0;
		} else {
			raw_inode->i_block[0] = 0;
			raw_inode->i_block[1] =
				cpu_to_le32(new_encode_dev(inode->i_rdev));
			raw_inode->i_block[2] = 0;
		}
4192
	} else for (block = 0; block < EXT4_N_BLOCKS; block++)
4193 4194
		raw_inode->i_block[block] = ei->i_data[block];

4195 4196 4197 4198 4199
	raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
	if (ei->i_extra_isize) {
		if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
			raw_inode->i_version_hi =
			cpu_to_le32(inode->i_version >> 32);
4200
		raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
4201 4202
	}

4203

4204 4205
	BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
	rc = ext4_journal_dirty_metadata(handle, bh);
4206 4207
	if (!err)
		err = rc;
4208
	ei->i_state &= ~EXT4_STATE_NEW;
4209 4210

out_brelse:
4211
	brelse(bh);
4212
	ext4_std_error(inode->i_sb, err);
4213 4214 4215 4216
	return err;
}

/*
4217
 * ext4_write_inode()
4218 4219 4220 4221 4222 4223 4224 4225 4226 4227 4228 4229 4230 4231 4232 4233
 *
 * We are called from a few places:
 *
 * - Within generic_file_write() for O_SYNC files.
 *   Here, there will be no transaction running. We wait for any running
 *   trasnaction to commit.
 *
 * - Within sys_sync(), kupdate and such.
 *   We wait on commit, if tol to.
 *
 * - Within prune_icache() (PF_MEMALLOC == true)
 *   Here we simply return.  We can't afford to block kswapd on the
 *   journal commit.
 *
 * In all cases it is actually safe for us to return without doing anything,
 * because the inode has been copied into a raw inode buffer in
4234
 * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
4235 4236 4237 4238 4239 4240 4241 4242 4243 4244 4245 4246 4247 4248 4249 4250
 * knfsd.
 *
 * Note that we are absolutely dependent upon all inode dirtiers doing the
 * right thing: they *must* call mark_inode_dirty() after dirtying info in
 * which we are interested.
 *
 * It would be a bug for them to not do this.  The code:
 *
 *	mark_inode_dirty(inode)
 *	stuff();
 *	inode->i_size = expr;
 *
 * is in error because a kswapd-driven write_inode() could occur while
 * `stuff()' is running, and the new i_size will be lost.  Plus the inode
 * will no longer be on the superblock's dirty inode list.
 */
4251
int ext4_write_inode(struct inode *inode, int wait)
4252 4253 4254 4255
{
	if (current->flags & PF_MEMALLOC)
		return 0;

4256
	if (ext4_journal_current_handle()) {
M
Mingming Cao 已提交
4257
		jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
4258 4259 4260 4261 4262 4263 4264
		dump_stack();
		return -EIO;
	}

	if (!wait)
		return 0;

4265
	return ext4_force_commit(inode->i_sb);
4266 4267 4268
}

/*
4269
 * ext4_setattr()
4270 4271 4272 4273 4274 4275 4276 4277 4278 4279 4280 4281 4282
 *
 * Called from notify_change.
 *
 * We want to trap VFS attempts to truncate the file as soon as
 * possible.  In particular, we want to make sure that when the VFS
 * shrinks i_size, we put the inode on the orphan list and modify
 * i_disksize immediately, so that during the subsequent flushing of
 * dirty pages and freeing of disk blocks, we can guarantee that any
 * commit will leave the blocks being flushed in an unused state on
 * disk.  (On recovery, the inode will get truncated and the blocks will
 * be freed, so we have a strong guarantee that no future commit will
 * leave these blocks visible to the user.)
 *
4283 4284 4285 4286 4287 4288 4289 4290
 * Another thing we have to assure is that if we are in ordered mode
 * and inode is still attached to the committing transaction, we must
 * we start writeout of all the dirty pages which are being truncated.
 * This way we are sure that all the data written in the previous
 * transaction are already on disk (truncate waits for pages under
 * writeback).
 *
 * Called with inode->i_mutex down.
4291
 */
4292
int ext4_setattr(struct dentry *dentry, struct iattr *attr)
4293 4294 4295 4296 4297 4298 4299 4300 4301 4302 4303 4304 4305 4306 4307
{
	struct inode *inode = dentry->d_inode;
	int error, rc = 0;
	const unsigned int ia_valid = attr->ia_valid;

	error = inode_change_ok(inode, attr);
	if (error)
		return error;

	if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
		(ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
		handle_t *handle;

		/* (user+group)*(old+new) structure, inode write (sb,
		 * inode block, ? - but truncate inode update has it) */
4308 4309
		handle = ext4_journal_start(inode, 2*(EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)+
					EXT4_QUOTA_DEL_BLOCKS(inode->i_sb))+3);
4310 4311 4312 4313 4314 4315
		if (IS_ERR(handle)) {
			error = PTR_ERR(handle);
			goto err_out;
		}
		error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
		if (error) {
4316
			ext4_journal_stop(handle);
4317 4318 4319 4320 4321 4322 4323 4324
			return error;
		}
		/* Update corresponding info in inode so that everything is in
		 * one transaction */
		if (attr->ia_valid & ATTR_UID)
			inode->i_uid = attr->ia_uid;
		if (attr->ia_valid & ATTR_GID)
			inode->i_gid = attr->ia_gid;
4325 4326
		error = ext4_mark_inode_dirty(handle, inode);
		ext4_journal_stop(handle);
4327 4328
	}

4329 4330 4331 4332 4333 4334 4335 4336 4337 4338 4339
	if (attr->ia_valid & ATTR_SIZE) {
		if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
			struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

			if (attr->ia_size > sbi->s_bitmap_maxbytes) {
				error = -EFBIG;
				goto err_out;
			}
		}
	}

4340 4341 4342 4343
	if (S_ISREG(inode->i_mode) &&
	    attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
		handle_t *handle;

4344
		handle = ext4_journal_start(inode, 3);
4345 4346 4347 4348 4349
		if (IS_ERR(handle)) {
			error = PTR_ERR(handle);
			goto err_out;
		}

4350 4351 4352
		error = ext4_orphan_add(handle, inode);
		EXT4_I(inode)->i_disksize = attr->ia_size;
		rc = ext4_mark_inode_dirty(handle, inode);
4353 4354
		if (!error)
			error = rc;
4355
		ext4_journal_stop(handle);
4356 4357 4358 4359 4360 4361 4362 4363 4364 4365 4366 4367 4368 4369 4370 4371

		if (ext4_should_order_data(inode)) {
			error = ext4_begin_ordered_truncate(inode,
							    attr->ia_size);
			if (error) {
				/* Do as much error cleanup as possible */
				handle = ext4_journal_start(inode, 3);
				if (IS_ERR(handle)) {
					ext4_orphan_del(NULL, inode);
					goto err_out;
				}
				ext4_orphan_del(handle, inode);
				ext4_journal_stop(handle);
				goto err_out;
			}
		}
4372 4373 4374 4375
	}

	rc = inode_setattr(inode, attr);

4376
	/* If inode_setattr's call to ext4_truncate failed to get a
4377 4378 4379
	 * transaction handle at all, we need to clean up the in-core
	 * orphan list manually. */
	if (inode->i_nlink)
4380
		ext4_orphan_del(NULL, inode);
4381 4382

	if (!rc && (ia_valid & ATTR_MODE))
4383
		rc = ext4_acl_chmod(inode);
4384 4385

err_out:
4386
	ext4_std_error(inode->i_sb, error);
4387 4388 4389 4390 4391
	if (!error)
		error = rc;
	return error;
}

4392 4393 4394 4395 4396 4397 4398 4399 4400 4401 4402 4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415 4416 4417
int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
		 struct kstat *stat)
{
	struct inode *inode;
	unsigned long delalloc_blocks;

	inode = dentry->d_inode;
	generic_fillattr(inode, stat);

	/*
	 * We can't update i_blocks if the block allocation is delayed
	 * otherwise in the case of system crash before the real block
	 * allocation is done, we will have i_blocks inconsistent with
	 * on-disk file blocks.
	 * We always keep i_blocks updated together with real
	 * allocation. But to not confuse with user, stat
	 * will return the blocks that include the delayed allocation
	 * blocks for this file.
	 */
	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
	delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks;
	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);

	stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9;
	return 0;
}
4418

4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433 4434 4435 4436 4437 4438 4439 4440 4441 4442 4443 4444 4445 4446 4447 4448 4449
static int ext4_indirect_trans_blocks(struct inode *inode, int nrblocks,
				      int chunk)
{
	int indirects;

	/* if nrblocks are contiguous */
	if (chunk) {
		/*
		 * With N contiguous data blocks, it need at most
		 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks
		 * 2 dindirect blocks
		 * 1 tindirect block
		 */
		indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb);
		return indirects + 3;
	}
	/*
	 * if nrblocks are not contiguous, worse case, each block touch
	 * a indirect block, and each indirect block touch a double indirect
	 * block, plus a triple indirect block
	 */
	indirects = nrblocks * 2 + 1;
	return indirects;
}

static int ext4_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
{
	if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
		return ext4_indirect_trans_blocks(inode, nrblocks, 0);
	return ext4_ext_index_trans_blocks(inode, nrblocks, 0);
}
4450
/*
4451 4452 4453
 * Account for index blocks, block groups bitmaps and block group
 * descriptor blocks if modify datablocks and index blocks
 * worse case, the indexs blocks spread over different block groups
4454
 *
4455 4456 4457
 * If datablocks are discontiguous, they are possible to spread over
 * different block groups too. If they are contiugous, with flexbg,
 * they could still across block group boundary.
4458
 *
4459 4460 4461 4462 4463 4464 4465 4466 4467 4468 4469 4470 4471 4472 4473 4474 4475 4476 4477 4478 4479 4480 4481 4482 4483 4484 4485 4486 4487 4488 4489 4490 4491 4492 4493 4494 4495 4496 4497 4498 4499 4500 4501 4502 4503 4504 4505
 * Also account for superblock, inode, quota and xattr blocks
 */
int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
{
	int groups, gdpblocks;
	int idxblocks;
	int ret = 0;

	/*
	 * How many index blocks need to touch to modify nrblocks?
	 * The "Chunk" flag indicating whether the nrblocks is
	 * physically contiguous on disk
	 *
	 * For Direct IO and fallocate, they calls get_block to allocate
	 * one single extent at a time, so they could set the "Chunk" flag
	 */
	idxblocks = ext4_index_trans_blocks(inode, nrblocks, chunk);

	ret = idxblocks;

	/*
	 * Now let's see how many group bitmaps and group descriptors need
	 * to account
	 */
	groups = idxblocks;
	if (chunk)
		groups += 1;
	else
		groups += nrblocks;

	gdpblocks = groups;
	if (groups > EXT4_SB(inode->i_sb)->s_groups_count)
		groups = EXT4_SB(inode->i_sb)->s_groups_count;
	if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
		gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;

	/* bitmaps and block group descriptor blocks */
	ret += groups + gdpblocks;

	/* Blocks for super block, inode, quota and xattr blocks */
	ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);

	return ret;
}

/*
 * Calulate the total number of credits to reserve to fit
4506 4507
 * the modification of a single pages into a single transaction,
 * which may include multiple chunks of block allocations.
4508
 *
4509
 * This could be called via ext4_write_begin()
4510
 *
4511
 * We need to consider the worse case, when
4512
 * one new block per extent.
4513
 */
A
Alex Tomas 已提交
4514
int ext4_writepage_trans_blocks(struct inode *inode)
4515
{
4516
	int bpp = ext4_journal_blocks_per_page(inode);
4517 4518
	int ret;

4519
	ret = ext4_meta_trans_blocks(inode, bpp, 0);
A
Alex Tomas 已提交
4520

4521
	/* Account for data blocks for journalled mode */
4522
	if (ext4_should_journal_data(inode))
4523
		ret += bpp;
4524 4525
	return ret;
}
4526 4527 4528 4529 4530 4531 4532 4533 4534 4535 4536 4537 4538 4539 4540

/*
 * Calculate the journal credits for a chunk of data modification.
 *
 * This is called from DIO, fallocate or whoever calling
 * ext4_get_blocks_wrap() to map/allocate a chunk of contigous disk blocks.
 *
 * journal buffers for data blocks are not included here, as DIO
 * and fallocate do no need to journal data buffers.
 */
int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
{
	return ext4_meta_trans_blocks(inode, nrblocks, 1);
}

4541
/*
4542
 * The caller must have previously called ext4_reserve_inode_write().
4543 4544
 * Give this, we know that the caller already has write access to iloc->bh.
 */
4545 4546
int ext4_mark_iloc_dirty(handle_t *handle,
		struct inode *inode, struct ext4_iloc *iloc)
4547 4548 4549
{
	int err = 0;

4550 4551 4552
	if (test_opt(inode->i_sb, I_VERSION))
		inode_inc_iversion(inode);

4553 4554 4555
	/* the do_update_inode consumes one bh->b_count */
	get_bh(iloc->bh);

4556
	/* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
4557
	err = ext4_do_update_inode(handle, inode, iloc);
4558 4559 4560 4561 4562 4563 4564 4565 4566 4567
	put_bh(iloc->bh);
	return err;
}

/*
 * On success, We end up with an outstanding reference count against
 * iloc->bh.  This _must_ be cleaned up later.
 */

int
4568 4569
ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
			 struct ext4_iloc *iloc)
4570 4571 4572
{
	int err = 0;
	if (handle) {
4573
		err = ext4_get_inode_loc(inode, iloc);
4574 4575
		if (!err) {
			BUFFER_TRACE(iloc->bh, "get_write_access");
4576
			err = ext4_journal_get_write_access(handle, iloc->bh);
4577 4578 4579 4580 4581 4582
			if (err) {
				brelse(iloc->bh);
				iloc->bh = NULL;
			}
		}
	}
4583
	ext4_std_error(inode->i_sb, err);
4584 4585 4586
	return err;
}

4587 4588 4589 4590
/*
 * Expand an inode by new_extra_isize bytes.
 * Returns 0 on success or negative error number on failure.
 */
A
Aneesh Kumar K.V 已提交
4591 4592 4593 4594
static int ext4_expand_extra_isize(struct inode *inode,
				   unsigned int new_extra_isize,
				   struct ext4_iloc iloc,
				   handle_t *handle)
4595 4596 4597 4598 4599 4600 4601 4602 4603 4604 4605 4606 4607 4608 4609 4610 4611 4612 4613 4614 4615 4616 4617 4618 4619 4620 4621
{
	struct ext4_inode *raw_inode;
	struct ext4_xattr_ibody_header *header;
	struct ext4_xattr_entry *entry;

	if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
		return 0;

	raw_inode = ext4_raw_inode(&iloc);

	header = IHDR(inode, raw_inode);
	entry = IFIRST(header);

	/* No extended attributes present */
	if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR) ||
		header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
		memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
			new_extra_isize);
		EXT4_I(inode)->i_extra_isize = new_extra_isize;
		return 0;
	}

	/* try to expand with EAs present */
	return ext4_expand_extra_isize_ea(inode, new_extra_isize,
					  raw_inode, handle);
}

4622 4623 4624 4625 4626 4627 4628 4629 4630 4631 4632 4633 4634 4635 4636 4637 4638 4639 4640 4641 4642
/*
 * What we do here is to mark the in-core inode as clean with respect to inode
 * dirtiness (it may still be data-dirty).
 * This means that the in-core inode may be reaped by prune_icache
 * without having to perform any I/O.  This is a very good thing,
 * because *any* task may call prune_icache - even ones which
 * have a transaction open against a different journal.
 *
 * Is this cheating?  Not really.  Sure, we haven't written the
 * inode out, but prune_icache isn't a user-visible syncing function.
 * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
 * we start and wait on commits.
 *
 * Is this efficient/effective?  Well, we're being nice to the system
 * by cleaning up our inodes proactively so they can be reaped
 * without I/O.  But we are potentially leaving up to five seconds'
 * worth of inodes floating about which prune_icache wants us to
 * write out.  One way to fix that would be to get prune_icache()
 * to do a write_super() to free up some memory.  It has the desired
 * effect.
 */
4643
int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
4644
{
4645
	struct ext4_iloc iloc;
4646 4647 4648
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	static unsigned int mnt_count;
	int err, ret;
4649 4650

	might_sleep();
4651
	err = ext4_reserve_inode_write(handle, inode, &iloc);
4652 4653 4654 4655 4656 4657 4658 4659 4660 4661 4662 4663 4664 4665 4666 4667
	if (EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
	    !(EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND)) {
		/*
		 * We need extra buffer credits since we may write into EA block
		 * with this same handle. If journal_extend fails, then it will
		 * only result in a minor loss of functionality for that inode.
		 * If this is felt to be critical, then e2fsck should be run to
		 * force a large enough s_min_extra_isize.
		 */
		if ((jbd2_journal_extend(handle,
			     EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) {
			ret = ext4_expand_extra_isize(inode,
						      sbi->s_want_extra_isize,
						      iloc, handle);
			if (ret) {
				EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND;
A
Aneesh Kumar K.V 已提交
4668 4669
				if (mnt_count !=
					le16_to_cpu(sbi->s_es->s_mnt_count)) {
4670
					ext4_warning(inode->i_sb, __func__,
4671 4672 4673
					"Unable to expand inode %lu. Delete"
					" some EAs or run e2fsck.",
					inode->i_ino);
A
Aneesh Kumar K.V 已提交
4674 4675
					mnt_count =
					  le16_to_cpu(sbi->s_es->s_mnt_count);
4676 4677 4678 4679
				}
			}
		}
	}
4680
	if (!err)
4681
		err = ext4_mark_iloc_dirty(handle, inode, &iloc);
4682 4683 4684 4685
	return err;
}

/*
4686
 * ext4_dirty_inode() is called from __mark_inode_dirty()
4687 4688 4689 4690 4691 4692 4693 4694 4695 4696 4697 4698
 *
 * We're really interested in the case where a file is being extended.
 * i_size has been changed by generic_commit_write() and we thus need
 * to include the updated inode in the current transaction.
 *
 * Also, DQUOT_ALLOC_SPACE() will always dirty the inode when blocks
 * are allocated to the file.
 *
 * If the inode is marked synchronous, we don't honour that here - doing
 * so would cause a commit on atime updates, which we don't bother doing.
 * We handle synchronous inodes at the highest possible level.
 */
4699
void ext4_dirty_inode(struct inode *inode)
4700
{
4701
	handle_t *current_handle = ext4_journal_current_handle();
4702 4703
	handle_t *handle;

4704
	handle = ext4_journal_start(inode, 2);
4705 4706 4707 4708 4709 4710
	if (IS_ERR(handle))
		goto out;
	if (current_handle &&
		current_handle->h_transaction != handle->h_transaction) {
		/* This task has a transaction open against a different fs */
		printk(KERN_EMERG "%s: transactions do not match!\n",
4711
		       __func__);
4712 4713 4714
	} else {
		jbd_debug(5, "marking dirty.  outer handle=%p\n",
				current_handle);
4715
		ext4_mark_inode_dirty(handle, inode);
4716
	}
4717
	ext4_journal_stop(handle);
4718 4719 4720 4721 4722 4723 4724 4725
out:
	return;
}

#if 0
/*
 * Bind an inode's backing buffer_head into this transaction, to prevent
 * it from being flushed to disk early.  Unlike
4726
 * ext4_reserve_inode_write, this leaves behind no bh reference and
4727 4728 4729
 * returns no iloc structure, so the caller needs to repeat the iloc
 * lookup to mark the inode dirty later.
 */
4730
static int ext4_pin_inode(handle_t *handle, struct inode *inode)
4731
{
4732
	struct ext4_iloc iloc;
4733 4734 4735

	int err = 0;
	if (handle) {
4736
		err = ext4_get_inode_loc(inode, &iloc);
4737 4738
		if (!err) {
			BUFFER_TRACE(iloc.bh, "get_write_access");
4739
			err = jbd2_journal_get_write_access(handle, iloc.bh);
4740
			if (!err)
4741
				err = ext4_journal_dirty_metadata(handle,
4742 4743 4744 4745
								  iloc.bh);
			brelse(iloc.bh);
		}
	}
4746
	ext4_std_error(inode->i_sb, err);
4747 4748 4749 4750
	return err;
}
#endif

4751
int ext4_change_inode_journal_flag(struct inode *inode, int val)
4752 4753 4754 4755 4756 4757 4758 4759 4760 4761 4762 4763 4764 4765 4766
{
	journal_t *journal;
	handle_t *handle;
	int err;

	/*
	 * We have to be very careful here: changing a data block's
	 * journaling status dynamically is dangerous.  If we write a
	 * data block to the journal, change the status and then delete
	 * that block, we risk forgetting to revoke the old log record
	 * from the journal and so a subsequent replay can corrupt data.
	 * So, first we make sure that the journal is empty and that
	 * nobody is changing anything.
	 */

4767
	journal = EXT4_JOURNAL(inode);
4768
	if (is_journal_aborted(journal))
4769 4770
		return -EROFS;

4771 4772
	jbd2_journal_lock_updates(journal);
	jbd2_journal_flush(journal);
4773 4774 4775 4776 4777 4778 4779 4780 4781 4782

	/*
	 * OK, there are no updates running now, and all cached data is
	 * synced to disk.  We are now in a completely consistent state
	 * which doesn't have anything in the journal, and we know that
	 * no filesystem updates are running, so it is safe to modify
	 * the inode's in-core data-journaling state flag now.
	 */

	if (val)
4783
		EXT4_I(inode)->i_flags |= EXT4_JOURNAL_DATA_FL;
4784
	else
4785 4786
		EXT4_I(inode)->i_flags &= ~EXT4_JOURNAL_DATA_FL;
	ext4_set_aops(inode);
4787

4788
	jbd2_journal_unlock_updates(journal);
4789 4790 4791

	/* Finally we can mark the inode as dirty. */

4792
	handle = ext4_journal_start(inode, 1);
4793 4794 4795
	if (IS_ERR(handle))
		return PTR_ERR(handle);

4796
	err = ext4_mark_inode_dirty(handle, inode);
4797
	handle->h_sync = 1;
4798 4799
	ext4_journal_stop(handle);
	ext4_std_error(inode->i_sb, err);
4800 4801 4802

	return err;
}
4803 4804 4805 4806 4807 4808 4809 4810 4811 4812 4813 4814 4815 4816 4817 4818 4819 4820 4821 4822 4823 4824 4825 4826 4827 4828 4829 4830 4831 4832 4833 4834 4835 4836 4837 4838 4839 4840 4841 4842 4843 4844 4845 4846 4847 4848 4849 4850 4851 4852 4853 4854 4855 4856 4857 4858 4859 4860 4861 4862 4863

static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
{
	return !buffer_mapped(bh);
}

int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
{
	loff_t size;
	unsigned long len;
	int ret = -EINVAL;
	struct file *file = vma->vm_file;
	struct inode *inode = file->f_path.dentry->d_inode;
	struct address_space *mapping = inode->i_mapping;

	/*
	 * Get i_alloc_sem to stop truncates messing with the inode. We cannot
	 * get i_mutex because we are already holding mmap_sem.
	 */
	down_read(&inode->i_alloc_sem);
	size = i_size_read(inode);
	if (page->mapping != mapping || size <= page_offset(page)
	    || !PageUptodate(page)) {
		/* page got truncated from under us? */
		goto out_unlock;
	}
	ret = 0;
	if (PageMappedToDisk(page))
		goto out_unlock;

	if (page->index == size >> PAGE_CACHE_SHIFT)
		len = size & ~PAGE_CACHE_MASK;
	else
		len = PAGE_CACHE_SIZE;

	if (page_has_buffers(page)) {
		/* return if we have all the buffers mapped */
		if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
				       ext4_bh_unmapped))
			goto out_unlock;
	}
	/*
	 * OK, we need to fill the hole... Do write_begin write_end
	 * to do block allocation/reservation.We are not holding
	 * inode.i__mutex here. That allow * parallel write_begin,
	 * write_end call. lock_page prevent this from happening
	 * on the same page though
	 */
	ret = mapping->a_ops->write_begin(file, mapping, page_offset(page),
			len, AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	if (ret < 0)
		goto out_unlock;
	ret = mapping->a_ops->write_end(file, mapping, page_offset(page),
			len, len, page, NULL);
	if (ret < 0)
		goto out_unlock;
	ret = 0;
out_unlock:
	up_read(&inode->i_alloc_sem);
	return ret;
}