inode.c 95.8 KB
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/*
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 *  linux/fs/ext4/inode.c
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 *
 * 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
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 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/time.h>
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#include <linux/ext4_jbd2.h>
#include <linux/jbd2.h>
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#include <linux/smp_lock.h>
#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>
#include <linux/mpage.h>
#include <linux/uio.h>
#include <linux/bio.h>
#include "xattr.h"
#include "acl.h"

/*
 * Test whether an inode is a fast symlink.
 */
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static int ext4_inode_is_fast_symlink(struct inode *inode)
47
{
48
	int ea_blocks = EXT4_I(inode)->i_file_acl ?
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		(inode->i_sb->s_blocksize >> 9) : 0;

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

/*
55
 * The ext4 forget function must perform a revoke if we are freeing data
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 * 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.
 */
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int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
			struct buffer_head *bh, ext4_fsblk_t blocknr)
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{
	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. */

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	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
	    (!is_metadata && !ext4_should_journal_data(inode))) {
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		if (bh) {
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			BUFFER_TRACE(bh, "call jbd2_journal_forget");
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			return ext4_journal_forget(handle, bh);
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		}
		return 0;
	}

	/*
	 * data!=journal && (is_metadata || should_journal_data(inode))
	 */
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	BUFFER_TRACE(bh, "call ext4_journal_revoke");
	err = ext4_journal_revoke(handle, blocknr, bh);
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	if (err)
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		ext4_abort(inode->i_sb, __FUNCTION__,
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			   "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)
{
	unsigned long needed;

	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
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	 * like a regular file for ext4 to try to delete it.  Things
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	 * 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. */
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	if (needed > EXT4_MAX_TRANS_DATA)
		needed = EXT4_MAX_TRANS_DATA;
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	return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
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}

/*
 * 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;

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	result = ext4_journal_start(inode, blocks_for_truncate(inode));
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	if (!IS_ERR(result))
		return result;

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	ext4_std_error(inode->i_sb, PTR_ERR(result));
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	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)
{
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	if (handle->h_buffer_credits > EXT4_RESERVE_TRANS_BLOCKS)
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		return 0;
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	if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
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		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.
 */
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static int ext4_journal_test_restart(handle_t *handle, struct inode *inode)
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{
	jbd_debug(2, "restarting handle %p\n", handle);
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	return ext4_journal_restart(handle, blocks_for_truncate(inode));
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}

/*
 * Called at the last iput() if i_nlink is zero.
 */
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void ext4_delete_inode (struct inode * inode)
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{
	handle_t *handle;

	truncate_inode_pages(&inode->i_data, 0);

	if (is_bad_inode(inode))
		goto no_delete;

	handle = start_transaction(inode);
	if (IS_ERR(handle)) {
		/*
		 * 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.
		 */
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		ext4_orphan_del(NULL, inode);
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		goto no_delete;
	}

	if (IS_SYNC(inode))
		handle->h_sync = 1;
	inode->i_size = 0;
	if (inode->i_blocks)
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		ext4_truncate(inode);
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	/*
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	 * Kill off the orphan record which ext4_truncate created.
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	 * AKPM: I think this can be inside the above `if'.
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	 * Note that ext4_orphan_del() has to be able to cope with the
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	 * deletion of a non-existent orphan - this is because we don't
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	 * know if ext4_truncate() actually created an orphan record.
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	 * (Well, we could do this if we need to, but heck - it works)
	 */
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	ext4_orphan_del(handle, inode);
	EXT4_I(inode)->i_dtime	= get_seconds();
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	/*
	 * 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.
	 */
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	if (ext4_mark_inode_dirty(handle, inode))
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		/* If that failed, just do the required in-core inode clear. */
		clear_inode(inode);
	else
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		ext4_free_inode(handle, inode);
	ext4_journal_stop(handle);
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	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;
}

static int verify_chain(Indirect *from, Indirect *to)
{
	while (from <= to && from->key == *from->p)
		from++;
	return (from > to);
}

/**
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 *	ext4_block_to_path - parse the block number into array of offsets
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 *	@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
 *      @boundary: set this non-zero if the referred-to block is likely to be
 *             followed (on disk) by an indirect block.
 *
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 *	To store the locations of file's data ext4 uses a data structure common
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 *	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.
 */

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static int ext4_block_to_path(struct inode *inode,
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			long i_block, int offsets[4], int *boundary)
{
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	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,
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		indirect_blocks = ptrs,
		double_blocks = (1 << (ptrs_bits * 2));
	int n = 0;
	int final = 0;

	if (i_block < 0) {
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		ext4_warning (inode->i_sb, "ext4_block_to_path", "block < 0");
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	} else if (i_block < direct_blocks) {
		offsets[n++] = i_block;
		final = direct_blocks;
	} else if ( (i_block -= direct_blocks) < indirect_blocks) {
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		offsets[n++] = EXT4_IND_BLOCK;
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		offsets[n++] = i_block;
		final = ptrs;
	} else if ((i_block -= indirect_blocks) < double_blocks) {
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		offsets[n++] = EXT4_DIND_BLOCK;
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		offsets[n++] = i_block >> ptrs_bits;
		offsets[n++] = i_block & (ptrs - 1);
		final = ptrs;
	} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
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		offsets[n++] = EXT4_TIND_BLOCK;
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		offsets[n++] = i_block >> (ptrs_bits * 2);
		offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
		offsets[n++] = i_block & (ptrs - 1);
		final = ptrs;
	} else {
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		ext4_warning(inode->i_sb, "ext4_block_to_path", "block > big");
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	}
	if (boundary)
		*boundary = final - 1 - (i_block & (ptrs - 1));
	return n;
}

/**
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 *	ext4_get_branch - read the chain of indirect blocks leading to data
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 *	@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 notices that chain had been changed while it was reading
 *		(ditto, *@err == -EAGAIN)
 *	or when it reads all @depth-1 indirect blocks successfully and finds
 *	the whole chain, all way to the data (returns %NULL, *err == 0).
 */
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static Indirect *ext4_get_branch(struct inode *inode, int depth, int *offsets,
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				 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 */
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	add_chain (chain, NULL, EXT4_I(inode)->i_data + *offsets);
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	if (!p->key)
		goto no_block;
	while (--depth) {
		bh = sb_bread(sb, le32_to_cpu(p->key));
		if (!bh)
			goto failure;
		/* Reader: pointers */
		if (!verify_chain(chain, p))
			goto changed;
		add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
		/* Reader: end */
		if (!p->key)
			goto no_block;
	}
	return NULL;

changed:
	brelse(bh);
	*err = -EAGAIN;
	goto no_block;
failure:
	*err = -EIO;
no_block:
	return p;
}

/**
390
 *	ext4_find_near - find a place for allocation with sufficient locality
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 *	@inode: owner
 *	@ind: descriptor of indirect block.
 *
 *	This function returns the prefered place for block allocation.
 *	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.
 */
409
static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
410
{
411
	struct ext4_inode_info *ei = EXT4_I(inode);
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	__le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data;
	__le32 *p;
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	ext4_fsblk_t bg_start;
	ext4_grpblk_t colour;
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	/* 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.
	 */
431
	bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group);
432
	colour = (current->pid % 16) *
433
			(EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
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	return bg_start + colour;
}

/**
438
 *	ext4_find_goal - find a prefered place for allocation.
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 *	@inode: owner
 *	@block:  block we want
 *	@chain:  chain of indirect blocks
 *	@partial: pointer to the last triple within a chain
 *	@goal:	place to store the result.
 *
 *	Normally this function find the prefered place for block allocation,
 *	stores it in *@goal and returns zero.
 */

449
static ext4_fsblk_t ext4_find_goal(struct inode *inode, long block,
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		Indirect chain[4], Indirect *partial)
{
452
	struct ext4_block_alloc_info *block_i;
453

454
	block_i =  EXT4_I(inode)->i_block_alloc_info;
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	/*
	 * 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;
	}

465
	return ext4_find_near(inode, partial);
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}

/**
469
 *	ext4_blks_to_allocate: Look up the block map and count the number
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 *	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.
 */
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static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned long blks,
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		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;
}

/**
507
 *	ext4_alloc_blocks: multiple allocate blocks needed for a branch
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 *	@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
 */
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static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
			ext4_fsblk_t goal, int indirect_blks, int blks,
			ext4_fsblk_t new_blocks[4], int *err)
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{
	int target, i;
	unsigned long count = 0;
	int index = 0;
523
	ext4_fsblk_t current_block = 0;
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	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)
	 */
	target = blks + indirect_blks;

	while (1) {
		count = target;
		/* allocating blocks for indirect blocks and direct blocks */
539
		current_block = ext4_new_blocks(handle,inode,goal,&count,err);
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		if (*err)
			goto failed_out;

		target -= count;
		/* allocate blocks for indirect blocks */
		while (index < indirect_blks && count) {
			new_blocks[index++] = current_block++;
			count--;
		}

		if (count > 0)
			break;
	}

	/* save the new block number for the first direct block */
	new_blocks[index] = current_block;

	/* total number of blocks allocated for direct blocks */
	ret = count;
	*err = 0;
	return ret;
failed_out:
	for (i = 0; i <index; i++)
563
		ext4_free_blocks(handle, inode, new_blocks[i], 1);
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	return ret;
}

/**
568
 *	ext4_alloc_branch - allocate and set up a chain of blocks.
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 *	@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
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 *	the same format as ext4_get_branch() would do. We are calling it after
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 *	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
582
 *	picture as after the successful ext4_get_block(), except that in one
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 *	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
589
 *	ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
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 *	as described above and return 0.
 */
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static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
			int indirect_blks, int *blks, ext4_fsblk_t goal,
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			int *offsets, Indirect *branch)
{
	int blocksize = inode->i_sb->s_blocksize;
	int i, n = 0;
	int err = 0;
	struct buffer_head *bh;
	int num;
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	ext4_fsblk_t new_blocks[4];
	ext4_fsblk_t current_block;
603

604
	num = ext4_alloc_blocks(handle, inode, goal, indirect_blks,
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				*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");
623
		err = ext4_journal_get_create_access(handle, bh);
624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647
		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;
		if ( n == indirect_blks) {
			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);

648 649
		BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
		err = ext4_journal_dirty_metadata(handle, bh);
650 651 652 653 654 655 656 657
		if (err)
			goto failed;
	}
	*blks = num;
	return err;
failed:
	/* Allocation failed, free what we already allocated */
	for (i = 1; i <= n ; i++) {
658
		BUFFER_TRACE(branch[i].bh, "call jbd2_journal_forget");
659
		ext4_journal_forget(handle, branch[i].bh);
660 661
	}
	for (i = 0; i <indirect_blks; i++)
662
		ext4_free_blocks(handle, inode, new_blocks[i], 1);
663

664
	ext4_free_blocks(handle, inode, new_blocks[i], num);
665 666 667 668 669

	return err;
}

/**
670
 * ext4_splice_branch - splice the allocated branch onto inode.
671 672 673
 * @inode: owner
 * @block: (logical) number of block we are adding
 * @chain: chain of indirect blocks (with a missing link - see
674
 *	ext4_alloc_branch)
675 676 677 678 679 680 681 682
 * @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.
 */
683
static int ext4_splice_branch(handle_t *handle, struct inode *inode,
684 685 686 687
			long block, Indirect *where, int num, int blks)
{
	int i;
	int err = 0;
688 689
	struct ext4_block_alloc_info *block_i;
	ext4_fsblk_t current_block;
690

691
	block_i = EXT4_I(inode)->i_block_alloc_info;
692 693 694 695 696 697 698
	/*
	 * 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");
699
		err = ext4_journal_get_write_access(handle, where->bh);
700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730
		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++)
			*(where->p + i ) = cpu_to_le32(current_block++);
	}

	/*
	 * 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 */

	inode->i_ctime = CURRENT_TIME_SEC;
731
	ext4_mark_inode_dirty(handle, inode);
732 733 734 735 736 737 738 739 740

	/* 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
741
		 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
742 743
		 */
		jbd_debug(5, "splicing indirect only\n");
744 745
		BUFFER_TRACE(where->bh, "call ext4_journal_dirty_metadata");
		err = ext4_journal_dirty_metadata(handle, where->bh);
746 747 748 749 750 751 752 753 754 755 756 757 758
		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++) {
759
		BUFFER_TRACE(where[i].bh, "call jbd2_journal_forget");
760 761
		ext4_journal_forget(handle, where[i].bh);
		ext4_free_blocks(handle,inode,le32_to_cpu(where[i-1].key),1);
762
	}
763
	ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks);
764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786

	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.
 *
 * The BKL may not be held on entry here.  Be sure to take it early.
 * return > 0, # of blocks mapped or allocated.
 * return = 0, if plain lookup failed.
 * return < 0, error case.
 */
787
int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
788 789 790 791 792 793 794 795
		sector_t iblock, unsigned long maxblocks,
		struct buffer_head *bh_result,
		int create, int extend_disksize)
{
	int err = -EIO;
	int offsets[4];
	Indirect chain[4];
	Indirect *partial;
796
	ext4_fsblk_t goal;
797 798 799
	int indirect_blks;
	int blocks_to_boundary = 0;
	int depth;
800
	struct ext4_inode_info *ei = EXT4_I(inode);
801
	int count = 0;
802
	ext4_fsblk_t first_block = 0;
803 804


A
Alex Tomas 已提交
805
	J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
806
	J_ASSERT(handle != NULL || create == 0);
807
	depth = ext4_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
808 809 810 811

	if (depth == 0)
		goto out;

812
	partial = ext4_get_branch(inode, depth, offsets, chain, &err);
813 814 815 816 817 818 819 820

	/* 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) {
821
			ext4_fsblk_t blk;
822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853

			if (!verify_chain(chain, partial)) {
				/*
				 * Indirect block might be removed by
				 * truncate while we were reading it.
				 * Handling of that case: forget what we've
				 * got now. Flag the err as EAGAIN, so it
				 * will reread.
				 */
				err = -EAGAIN;
				count = 0;
				break;
			}
			blk = le32_to_cpu(*(chain[depth-1].p + count));

			if (blk == first_block + count)
				count++;
			else
				break;
		}
		if (err != -EAGAIN)
			goto got_it;
	}

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

	mutex_lock(&ei->truncate_mutex);

	/*
	 * If the indirect block is missing while we are reading
854
	 * the chain(ext4_get_branch() returns -EAGAIN err), or
855 856 857 858 859 860 861 862 863 864 865 866 867 868
	 * if the chain has been changed after we grab the semaphore,
	 * (either because another process truncated this branch, or
	 * another get_block allocated this branch) re-grab the chain to see if
	 * the request block has been allocated or not.
	 *
	 * Since we already block the truncate/other get_block
	 * at this point, we will have the current copy of the chain when we
	 * splice the branch into the tree.
	 */
	if (err == -EAGAIN || !verify_chain(chain, partial)) {
		while (partial > chain) {
			brelse(partial->bh);
			partial--;
		}
869
		partial = ext4_get_branch(inode, depth, offsets, chain, &err);
870 871 872 873 874 875 876 877 878 879 880 881 882 883 884
		if (!partial) {
			count++;
			mutex_unlock(&ei->truncate_mutex);
			if (err)
				goto cleanup;
			clear_buffer_new(bh_result);
			goto got_it;
		}
	}

	/*
	 * 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))
885
		ext4_init_block_alloc_info(inode);
886

887
	goal = ext4_find_goal(inode, iblock, chain, partial);
888 889 890 891 892 893 894 895

	/* 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.
	 */
896
	count = ext4_blks_to_allocate(partial, indirect_blks,
897 898
					maxblocks, blocks_to_boundary);
	/*
899
	 * Block out ext4_truncate while we alter the tree
900
	 */
901
	err = ext4_alloc_branch(handle, inode, indirect_blks, &count, goal,
902 903 904
				offsets + (partial - chain), partial);

	/*
905
	 * The ext4_splice_branch call will free and forget any buffers
906 907 908 909 910 911
	 * 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)
912
		err = ext4_splice_branch(handle, inode, iblock,
913 914 915 916
					partial, indirect_blks, count);
	/*
	 * i_disksize growing is protected by truncate_mutex.  Don't forget to
	 * protect it if you're about to implement concurrent
917
	 * ext4_get_block() -bzzz
918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943
	*/
	if (!err && extend_disksize && inode->i_size > ei->i_disksize)
		ei->i_disksize = inode->i_size;
	mutex_unlock(&ei->truncate_mutex);
	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;
}

944
#define DIO_CREDITS (EXT4_RESERVE_TRANS_BLOCKS + 32)
945

946
static int ext4_get_block(struct inode *inode, sector_t iblock,
947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963
			struct buffer_head *bh_result, int create)
{
	handle_t *handle = journal_current_handle();
	int ret = 0;
	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;

	if (!create)
		goto get_block;		/* A read */

	if (max_blocks == 1)
		goto get_block;		/* A single block get */

	if (handle->h_transaction->t_state == T_LOCKED) {
		/*
		 * Huge direct-io writes can hold off commits for long
		 * periods of time.  Let this commit run.
		 */
964 965
		ext4_journal_stop(handle);
		handle = ext4_journal_start(inode, DIO_CREDITS);
966 967 968 969 970
		if (IS_ERR(handle))
			ret = PTR_ERR(handle);
		goto get_block;
	}

971
	if (handle->h_buffer_credits <= EXT4_RESERVE_TRANS_BLOCKS) {
972 973 974
		/*
		 * Getting low on buffer credits...
		 */
975
		ret = ext4_journal_extend(handle, DIO_CREDITS);
976 977 978 979
		if (ret > 0) {
			/*
			 * Couldn't extend the transaction.  Start a new one.
			 */
980
			ret = ext4_journal_restart(handle, DIO_CREDITS);
981 982 983 984 985
		}
	}

get_block:
	if (ret == 0) {
A
Alex Tomas 已提交
986
		ret = ext4_get_blocks_wrap(handle, inode, iblock,
987 988 989 990 991 992 993 994 995 996 997 998
					max_blocks, bh_result, create, 0);
		if (ret > 0) {
			bh_result->b_size = (ret << inode->i_blkbits);
			ret = 0;
		}
	}
	return ret;
}

/*
 * `handle' can be NULL if create is zero
 */
999
struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
1000 1001 1002 1003 1004 1005 1006 1007 1008 1009
				long block, int create, int *errp)
{
	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
1010
	err = ext4_get_blocks_wrap(handle, inode, block, 1,
1011 1012
					&dummy, create, 1);
	/*
1013
	 * ext4_get_blocks_handle() returns number of blocks
1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036
	 * 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);
			J_ASSERT(handle != 0);

			/*
			 * 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
1037
			 * writes use ext4_get_block instead, so it's not a
1038 1039 1040 1041
			 * problem.
			 */
			lock_buffer(bh);
			BUFFER_TRACE(bh, "call get_create_access");
1042
			fatal = ext4_journal_get_create_access(handle, bh);
1043 1044 1045 1046 1047
			if (!fatal && !buffer_uptodate(bh)) {
				memset(bh->b_data,0,inode->i_sb->s_blocksize);
				set_buffer_uptodate(bh);
			}
			unlock_buffer(bh);
1048 1049
			BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
			err = ext4_journal_dirty_metadata(handle, bh);
1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065
			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;
}

1066
struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1067 1068 1069 1070
			       int block, int create, int *err)
{
	struct buffer_head * bh;

1071
	bh = ext4_getblk(handle, inode, block, create, err);
1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119
	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;
}

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))
{
	struct buffer_head *bh;
	unsigned block_start, block_end;
	unsigned blocksize = head->b_size;
	int err, ret = 0;
	struct buffer_head *next;

	for (	bh = head, block_start = 0;
		ret == 0 && (bh != head || !block_start);
		block_start = block_end, bh = next)
	{
		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
1120
 * close off a transaction and start a new one between the ext4_get_block()
1121
 * and the commit_write().  So doing the jbd2_journal_start at the start of
1122 1123
 * prepare_write() is the right place.
 *
1124 1125
 * Also, this function can nest inside ext4_writepage() ->
 * block_write_full_page(). In that case, we *know* that ext4_writepage()
1126 1127 1128 1129
 * 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.
 *
1130
 * By accident, ext4 can be reentered when a transaction is open via
1131 1132 1133 1134 1135 1136
 * 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.
 *
1137
 * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1138 1139 1140 1141 1142 1143 1144 1145 1146
 * 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;
1147
	return ext4_journal_get_write_access(handle, bh);
1148 1149
}

1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209
/*
 * The idea of this helper function is following:
 * if prepare_write has allocated some blocks, but not all of them, the
 * transaction must include the content of the newly allocated blocks.
 * This content is expected to be set to zeroes by block_prepare_write().
 * 2006/10/14  SAW
 */
static int ext4_prepare_failure(struct file *file, struct page *page,
				unsigned from, unsigned to)
{
	struct address_space *mapping;
	struct buffer_head *bh, *head, *next;
	unsigned block_start, block_end;
	unsigned blocksize;
	int ret;
	handle_t *handle = ext4_journal_current_handle();

	mapping = page->mapping;
	if (ext4_should_writeback_data(mapping->host)) {
		/* optimization: no constraints about data */
skip:
		return ext4_journal_stop(handle);
	}

	head = page_buffers(page);
	blocksize = head->b_size;
	for (	bh = head, block_start = 0;
		bh != head || !block_start;
	    	block_start = block_end, bh = next)
	{
		next = bh->b_this_page;
		block_end = block_start + blocksize;
		if (block_end <= from)
			continue;
		if (block_start >= to) {
			block_start = to;
			break;
		}
		if (!buffer_mapped(bh))
		/* prepare_write failed on this bh */
			break;
		if (ext4_should_journal_data(mapping->host)) {
			ret = do_journal_get_write_access(handle, bh);
			if (ret) {
				ext4_journal_stop(handle);
				return ret;
			}
		}
	/*
	 * block_start here becomes the first block where the current iteration
	 * of prepare_write failed.
	 */
	}
	if (block_start <= from)
		goto skip;

	/* commit allocated and zeroed buffers */
	return mapping->a_ops->commit_write(file, page, from, block_start);
}

1210
static int ext4_prepare_write(struct file *file, struct page *page,
1211 1212 1213
			      unsigned from, unsigned to)
{
	struct inode *inode = page->mapping->host;
1214 1215
	int ret, ret2;
	int needed_blocks = ext4_writepage_trans_blocks(inode);
1216 1217 1218 1219
	handle_t *handle;
	int retries = 0;

retry:
1220
	handle = ext4_journal_start(inode, needed_blocks);
1221 1222
	if (IS_ERR(handle))
		return PTR_ERR(handle);
1223 1224
	if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
		ret = nobh_prepare_write(page, from, to, ext4_get_block);
1225
	else
1226
		ret = block_prepare_write(page, from, to, ext4_get_block);
1227
	if (ret)
1228
		goto failure;
1229

1230
	if (ext4_should_journal_data(inode)) {
1231 1232
		ret = walk_page_buffers(handle, page_buffers(page),
				from, to, NULL, do_journal_get_write_access);
1233 1234
		if (ret)
			/* fatal error, just put the handle and return */
R
Randy Dunlap 已提交
1235
			ext4_journal_stop(handle);
1236
	}
1237 1238 1239 1240 1241 1242
	return ret;

failure:
	ret2 = ext4_prepare_failure(file, page, from, to);
	if (ret2 < 0)
		return ret2;
1243
	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1244
		goto retry;
1245
	/* retry number exceeded, or other error like -EDQUOT */
1246 1247 1248
	return ret;
}

1249
int ext4_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
1250
{
1251
	int err = jbd2_journal_dirty_data(handle, bh);
1252
	if (err)
1253
		ext4_journal_abort_handle(__FUNCTION__, __FUNCTION__,
1254 1255 1256 1257 1258 1259 1260 1261 1262 1263
						bh, handle,err);
	return err;
}

/* For commit_write() in data=journal mode */
static int commit_write_fn(handle_t *handle, struct buffer_head *bh)
{
	if (!buffer_mapped(bh) || buffer_freed(bh))
		return 0;
	set_buffer_uptodate(bh);
1264
	return ext4_journal_dirty_metadata(handle, bh);
1265 1266 1267 1268 1269 1270
}

/*
 * 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().
 *
1271
 * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1272 1273
 * buffers are managed internally.
 */
1274
static int ext4_ordered_commit_write(struct file *file, struct page *page,
1275 1276
			     unsigned from, unsigned to)
{
1277
	handle_t *handle = ext4_journal_current_handle();
1278 1279 1280 1281
	struct inode *inode = page->mapping->host;
	int ret = 0, ret2;

	ret = walk_page_buffers(handle, page_buffers(page),
1282
		from, to, NULL, ext4_journal_dirty_data);
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292

	if (ret == 0) {
		/*
		 * generic_commit_write() will run mark_inode_dirty() if i_size
		 * changes.  So let's piggyback the i_disksize mark_inode_dirty
		 * into that.
		 */
		loff_t new_i_size;

		new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
1293 1294
		if (new_i_size > EXT4_I(inode)->i_disksize)
			EXT4_I(inode)->i_disksize = new_i_size;
1295 1296
		ret = generic_commit_write(file, page, from, to);
	}
1297
	ret2 = ext4_journal_stop(handle);
1298 1299 1300 1301 1302
	if (!ret)
		ret = ret2;
	return ret;
}

1303
static int ext4_writeback_commit_write(struct file *file, struct page *page,
1304 1305
			     unsigned from, unsigned to)
{
1306
	handle_t *handle = ext4_journal_current_handle();
1307 1308 1309 1310 1311
	struct inode *inode = page->mapping->host;
	int ret = 0, ret2;
	loff_t new_i_size;

	new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
1312 1313
	if (new_i_size > EXT4_I(inode)->i_disksize)
		EXT4_I(inode)->i_disksize = new_i_size;
1314

1315
	if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
1316 1317 1318 1319
		ret = nobh_commit_write(file, page, from, to);
	else
		ret = generic_commit_write(file, page, from, to);

1320
	ret2 = ext4_journal_stop(handle);
1321 1322 1323 1324 1325
	if (!ret)
		ret = ret2;
	return ret;
}

1326
static int ext4_journalled_commit_write(struct file *file,
1327 1328
			struct page *page, unsigned from, unsigned to)
{
1329
	handle_t *handle = ext4_journal_current_handle();
1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345
	struct inode *inode = page->mapping->host;
	int ret = 0, ret2;
	int partial = 0;
	loff_t pos;

	/*
	 * Here we duplicate the generic_commit_write() functionality
	 */
	pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;

	ret = walk_page_buffers(handle, page_buffers(page), from,
				to, &partial, commit_write_fn);
	if (!partial)
		SetPageUptodate(page);
	if (pos > inode->i_size)
		i_size_write(inode, pos);
1346 1347 1348 1349
	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);
1350 1351 1352
		if (!ret)
			ret = ret2;
	}
1353
	ret2 = ext4_journal_stop(handle);
1354 1355 1356 1357 1358 1359 1360 1361 1362 1363
	if (!ret)
		ret = ret2;
	return ret;
}

/*
 * 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
1364
 * journal.  If somebody makes a swapfile on an ext4 data-journaling
1365 1366 1367 1368 1369 1370 1371 1372
 * 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.
 */
1373
static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
1374 1375 1376 1377 1378
{
	struct inode *inode = mapping->host;
	journal_t *journal;
	int err;

1379
	if (EXT4_I(inode)->i_state & EXT4_STATE_JDATA) {
1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390
		/*
		 * 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.)
		 *
1391
		 * NB. EXT4_STATE_JDATA is not set on files other than
1392 1393 1394 1395 1396 1397
		 * 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.
		 */

1398 1399
		EXT4_I(inode)->i_state &= ~EXT4_STATE_JDATA;
		journal = EXT4_JOURNAL(inode);
1400 1401 1402
		jbd2_journal_lock_updates(journal);
		err = jbd2_journal_flush(journal);
		jbd2_journal_unlock_updates(journal);
1403 1404 1405 1406 1407

		if (err)
			return 0;
	}

1408
	return generic_block_bmap(mapping,block,ext4_get_block);
1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422
}

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;
}

1423
static int jbd2_journal_dirty_data_fn(handle_t *handle, struct buffer_head *bh)
1424 1425
{
	if (buffer_mapped(bh))
1426
		return ext4_journal_dirty_data(handle, bh);
1427 1428 1429 1430 1431 1432
	return 0;
}

/*
 * Note that we always start a transaction even if we're not journalling
 * data.  This is to preserve ordering: any hole instantiation within
1433
 * __block_write_full_page -> ext4_get_block() should be journalled
1434 1435 1436 1437 1438 1439 1440
 * along with the data so we don't crash and then get metadata which
 * refers to old data.
 *
 * In all journalling modes block_write_full_page() will start the I/O.
 *
 * Problem:
 *
1441 1442
 *	ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
 *		ext4_writepage()
1443 1444 1445
 *
 * Similar for:
 *
1446
 *	ext4_file_write() -> generic_file_write() -> __alloc_pages() -> ...
1447
 *
1448
 * Same applies to ext4_get_block().  We will deadlock on various things like
1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481
 * lock_journal and i_truncate_mutex.
 *
 * 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.
 *
 * AKPM2: if all the page's buffers are mapped to disk and !data=journal,
 * we don't need to open a transaction here.
 */
1482
static int ext4_ordered_writepage(struct page *page,
1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496
				struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	struct buffer_head *page_bufs;
	handle_t *handle = NULL;
	int ret = 0;
	int err;

	J_ASSERT(PageLocked(page));

	/*
	 * We give up here if we're reentered, because it might be for a
	 * different filesystem.
	 */
1497
	if (ext4_journal_current_handle())
1498 1499
		goto out_fail;

1500
	handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514

	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto out_fail;
	}

	if (!page_has_buffers(page)) {
		create_empty_buffers(page, inode->i_sb->s_blocksize,
				(1 << BH_Dirty)|(1 << BH_Uptodate));
	}
	page_bufs = page_buffers(page);
	walk_page_buffers(handle, page_bufs, 0,
			PAGE_CACHE_SIZE, NULL, bget_one);

1515
	ret = block_write_full_page(page, ext4_get_block, wbc);
1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530

	/*
	 * The page can become unlocked at any point now, and
	 * truncate can then come in and change things.  So we
	 * can't touch *page from now on.  But *page_bufs is
	 * safe due to elevated refcount.
	 */

	/*
	 * And attach them to the current transaction.  But only if
	 * block_write_full_page() succeeded.  Otherwise they are unmapped,
	 * and generally junk.
	 */
	if (ret == 0) {
		err = walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE,
1531
					NULL, jbd2_journal_dirty_data_fn);
1532 1533 1534 1535 1536
		if (!ret)
			ret = err;
	}
	walk_page_buffers(handle, page_bufs, 0,
			PAGE_CACHE_SIZE, NULL, bput_one);
1537
	err = ext4_journal_stop(handle);
1538 1539 1540 1541 1542 1543 1544 1545 1546 1547
	if (!ret)
		ret = err;
	return ret;

out_fail:
	redirty_page_for_writepage(wbc, page);
	unlock_page(page);
	return ret;
}

1548
static int ext4_writeback_writepage(struct page *page,
1549 1550 1551 1552 1553 1554 1555
				struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	handle_t *handle = NULL;
	int ret = 0;
	int err;

1556
	if (ext4_journal_current_handle())
1557 1558
		goto out_fail;

1559
	handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1560 1561 1562 1563 1564
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto out_fail;
	}

1565 1566
	if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
		ret = nobh_writepage(page, ext4_get_block, wbc);
1567
	else
1568
		ret = block_write_full_page(page, ext4_get_block, wbc);
1569

1570
	err = ext4_journal_stop(handle);
1571 1572 1573 1574 1575 1576 1577 1578 1579 1580
	if (!ret)
		ret = err;
	return ret;

out_fail:
	redirty_page_for_writepage(wbc, page);
	unlock_page(page);
	return ret;
}

1581
static int ext4_journalled_writepage(struct page *page,
1582 1583 1584 1585 1586 1587 1588
				struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	handle_t *handle = NULL;
	int ret = 0;
	int err;

1589
	if (ext4_journal_current_handle())
1590 1591
		goto no_write;

1592
	handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto no_write;
	}

	if (!page_has_buffers(page) || PageChecked(page)) {
		/*
		 * It's mmapped pagecache.  Add buffers and journal it.  There
		 * doesn't seem much point in redirtying the page here.
		 */
		ClearPageChecked(page);
		ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
1605
					ext4_get_block);
1606
		if (ret != 0) {
1607
			ext4_journal_stop(handle);
1608 1609 1610 1611 1612 1613 1614 1615 1616
			goto out_unlock;
		}
		ret = walk_page_buffers(handle, page_buffers(page), 0,
			PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);

		err = walk_page_buffers(handle, page_buffers(page), 0,
				PAGE_CACHE_SIZE, NULL, commit_write_fn);
		if (ret == 0)
			ret = err;
1617
		EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
1618 1619 1620 1621 1622 1623 1624
		unlock_page(page);
	} 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.
		 */
1625
		ret = block_write_full_page(page, ext4_get_block, wbc);
1626
	}
1627
	err = ext4_journal_stop(handle);
1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639
	if (!ret)
		ret = err;
out:
	return ret;

no_write:
	redirty_page_for_writepage(wbc, page);
out_unlock:
	unlock_page(page);
	goto out;
}

1640
static int ext4_readpage(struct file *file, struct page *page)
1641
{
1642
	return mpage_readpage(page, ext4_get_block);
1643 1644 1645
}

static int
1646
ext4_readpages(struct file *file, struct address_space *mapping,
1647 1648
		struct list_head *pages, unsigned nr_pages)
{
1649
	return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
1650 1651
}

1652
static void ext4_invalidatepage(struct page *page, unsigned long offset)
1653
{
1654
	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
1655 1656 1657 1658 1659 1660 1661

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

1662
	jbd2_journal_invalidatepage(journal, page, offset);
1663 1664
}

1665
static int ext4_releasepage(struct page *page, gfp_t wait)
1666
{
1667
	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
1668 1669 1670 1671

	WARN_ON(PageChecked(page));
	if (!page_has_buffers(page))
		return 0;
1672
	return jbd2_journal_try_to_free_buffers(journal, page, wait);
1673 1674 1675 1676 1677 1678 1679 1680 1681 1682
}

/*
 * 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
 * crashes then stale disk data _may_ be exposed inside the file.
 */
1683
static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
1684 1685 1686 1687 1688
			const struct iovec *iov, loff_t offset,
			unsigned long nr_segs)
{
	struct file *file = iocb->ki_filp;
	struct inode *inode = file->f_mapping->host;
1689
	struct ext4_inode_info *ei = EXT4_I(inode);
1690 1691 1692 1693 1694 1695 1696 1697
	handle_t *handle = NULL;
	ssize_t ret;
	int orphan = 0;
	size_t count = iov_length(iov, nr_segs);

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

1698
		handle = ext4_journal_start(inode, DIO_CREDITS);
1699 1700 1701 1702 1703
		if (IS_ERR(handle)) {
			ret = PTR_ERR(handle);
			goto out;
		}
		if (final_size > inode->i_size) {
1704
			ret = ext4_orphan_add(handle, inode);
1705 1706 1707 1708 1709 1710 1711 1712 1713
			if (ret)
				goto out_stop;
			orphan = 1;
			ei->i_disksize = inode->i_size;
		}
	}

	ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
				 offset, nr_segs,
1714
				 ext4_get_block, NULL);
1715 1716

	/*
1717
	 * Reacquire the handle: ext4_get_block() can restart the transaction
1718 1719 1720 1721 1722 1723 1724 1725
	 */
	handle = journal_current_handle();

out_stop:
	if (handle) {
		int err;

		if (orphan && inode->i_nlink)
1726
			ext4_orphan_del(handle, inode);
1727 1728 1729 1730 1731 1732 1733 1734 1735
		if (orphan && ret > 0) {
			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
1736
				 * ext4_mark_inode_dirty() to userspace.  So
1737 1738
				 * ignore it.
				 */
1739
				ext4_mark_inode_dirty(handle, inode);
1740 1741
			}
		}
1742
		err = ext4_journal_stop(handle);
1743 1744 1745 1746 1747 1748 1749 1750
		if (ret == 0)
			ret = err;
	}
out:
	return ret;
}

/*
1751
 * Pages can be marked dirty completely asynchronously from ext4's journalling
1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762
 * 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.
 */
1763
static int ext4_journalled_set_page_dirty(struct page *page)
1764 1765 1766 1767 1768
{
	SetPageChecked(page);
	return __set_page_dirty_nobuffers(page);
}

1769 1770 1771 1772
static const struct address_space_operations ext4_ordered_aops = {
	.readpage	= ext4_readpage,
	.readpages	= ext4_readpages,
	.writepage	= ext4_ordered_writepage,
1773
	.sync_page	= block_sync_page,
1774 1775 1776 1777 1778 1779
	.prepare_write	= ext4_prepare_write,
	.commit_write	= ext4_ordered_commit_write,
	.bmap		= ext4_bmap,
	.invalidatepage	= ext4_invalidatepage,
	.releasepage	= ext4_releasepage,
	.direct_IO	= ext4_direct_IO,
1780 1781 1782
	.migratepage	= buffer_migrate_page,
};

1783 1784 1785 1786
static const struct address_space_operations ext4_writeback_aops = {
	.readpage	= ext4_readpage,
	.readpages	= ext4_readpages,
	.writepage	= ext4_writeback_writepage,
1787
	.sync_page	= block_sync_page,
1788 1789 1790 1791 1792 1793
	.prepare_write	= ext4_prepare_write,
	.commit_write	= ext4_writeback_commit_write,
	.bmap		= ext4_bmap,
	.invalidatepage	= ext4_invalidatepage,
	.releasepage	= ext4_releasepage,
	.direct_IO	= ext4_direct_IO,
1794 1795 1796
	.migratepage	= buffer_migrate_page,
};

1797 1798 1799 1800
static const struct address_space_operations ext4_journalled_aops = {
	.readpage	= ext4_readpage,
	.readpages	= ext4_readpages,
	.writepage	= ext4_journalled_writepage,
1801
	.sync_page	= block_sync_page,
1802 1803 1804 1805 1806 1807
	.prepare_write	= ext4_prepare_write,
	.commit_write	= ext4_journalled_commit_write,
	.set_page_dirty	= ext4_journalled_set_page_dirty,
	.bmap		= ext4_bmap,
	.invalidatepage	= ext4_invalidatepage,
	.releasepage	= ext4_releasepage,
1808 1809
};

1810
void ext4_set_aops(struct inode *inode)
1811
{
1812 1813 1814 1815
	if (ext4_should_order_data(inode))
		inode->i_mapping->a_ops = &ext4_ordered_aops;
	else if (ext4_should_writeback_data(inode))
		inode->i_mapping->a_ops = &ext4_writeback_aops;
1816
	else
1817
		inode->i_mapping->a_ops = &ext4_journalled_aops;
1818 1819 1820
}

/*
1821
 * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
1822 1823 1824 1825
 * 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.
 */
A
Alex Tomas 已提交
1826
int ext4_block_truncate_page(handle_t *handle, struct page *page,
1827 1828
		struct address_space *mapping, loff_t from)
{
1829
	ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845
	unsigned offset = from & (PAGE_CACHE_SIZE-1);
	unsigned blocksize, iblock, length, pos;
	struct inode *inode = mapping->host;
	struct buffer_head *bh;
	int err = 0;
	void *kaddr;

	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) &&
1846
	     ext4_should_writeback_data(inode) && PageUptodate(page)) {
1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874
		kaddr = kmap_atomic(page, KM_USER0);
		memset(kaddr + offset, 0, length);
		flush_dcache_page(page);
		kunmap_atomic(kaddr, KM_USER0);
		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");
1875
		ext4_get_block(inode, iblock, bh, 0);
1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895
		/* 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;
	}

1896
	if (ext4_should_journal_data(inode)) {
1897
		BUFFER_TRACE(bh, "get write access");
1898
		err = ext4_journal_get_write_access(handle, bh);
1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910
		if (err)
			goto unlock;
	}

	kaddr = kmap_atomic(page, KM_USER0);
	memset(kaddr + offset, 0, length);
	flush_dcache_page(page);
	kunmap_atomic(kaddr, KM_USER0);

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

	err = 0;
1911 1912
	if (ext4_should_journal_data(inode)) {
		err = ext4_journal_dirty_metadata(handle, bh);
1913
	} else {
1914 1915
		if (ext4_should_order_data(inode))
			err = ext4_journal_dirty_data(handle, bh);
1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938
		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;
}

/**
1939
 *	ext4_find_shared - find the indirect blocks for partial truncation.
1940 1941
 *	@inode:	  inode in question
 *	@depth:	  depth of the affected branch
1942
 *	@offsets: offsets of pointers in that branch (see ext4_block_to_path)
1943 1944 1945
 *	@chain:	  place to store the pointers to partial indirect blocks
 *	@top:	  place to the (detached) top of branch
 *
1946
 *	This is a helper function used by ext4_truncate().
1947 1948 1949 1950 1951 1952 1953
 *
 *	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
1954
 *	past the truncation point is possible until ext4_truncate()
1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972
 *	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).  */

1973
static Indirect *ext4_find_shared(struct inode *inode, int depth,
1974 1975 1976 1977 1978 1979 1980 1981 1982
			int offsets[4], Indirect chain[4], __le32 *top)
{
	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--)
		;
1983
	partial = ext4_get_branch(inode, k, offsets, chain, &err);
1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
	/* 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;
	for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
		;
	/*
	 * 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;
2006
		/* Nope, don't do this in ext4.  Must leave the tree intact */
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
#if 0
		*p->p = 0;
#endif
	}
	/* Writer: end */

	while(partial > p) {
		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.
 */
2029 2030
static void ext4_clear_blocks(handle_t *handle, struct inode *inode,
		struct buffer_head *bh, ext4_fsblk_t block_to_free,
2031 2032 2033 2034 2035
		unsigned long count, __le32 *first, __le32 *last)
{
	__le32 *p;
	if (try_to_extend_transaction(handle, inode)) {
		if (bh) {
2036 2037
			BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
			ext4_journal_dirty_metadata(handle, bh);
2038
		}
2039 2040
		ext4_mark_inode_dirty(handle, inode);
		ext4_journal_test_restart(handle, inode);
2041 2042
		if (bh) {
			BUFFER_TRACE(bh, "retaking write access");
2043
			ext4_journal_get_write_access(handle, bh);
2044 2045 2046 2047 2048
		}
	}

	/*
	 * Any buffers which are on the journal will be in memory. We find
2049
	 * them on the hash table so jbd2_journal_revoke() will run jbd2_journal_forget()
2050
	 * on them.  We've already detached each block from the file, so
2051
	 * bforget() in jbd2_journal_forget() should be safe.
2052
	 *
2053
	 * AKPM: turn on bforget in jbd2_journal_forget()!!!
2054 2055 2056 2057 2058 2059 2060 2061
	 */
	for (p = first; p < last; p++) {
		u32 nr = le32_to_cpu(*p);
		if (nr) {
			struct buffer_head *bh;

			*p = 0;
			bh = sb_find_get_block(inode->i_sb, nr);
2062
			ext4_forget(handle, 0, inode, bh, nr);
2063 2064 2065
		}
	}

2066
	ext4_free_blocks(handle, inode, block_to_free, count);
2067 2068 2069
}

/**
2070
 * ext4_free_data - free a list of data blocks
2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087
 * @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.
 */
2088
static void ext4_free_data(handle_t *handle, struct inode *inode,
2089 2090 2091
			   struct buffer_head *this_bh,
			   __le32 *first, __le32 *last)
{
2092
	ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
2093 2094 2095 2096
	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 */
2097
	ext4_fsblk_t nr;		    /* Current block # */
2098 2099 2100 2101 2102 2103
	__le32 *p;			    /* Pointer into inode/ind
					       for current block */
	int err;

	if (this_bh) {				/* For indirect block */
		BUFFER_TRACE(this_bh, "get_write_access");
2104
		err = ext4_journal_get_write_access(handle, this_bh);
2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121
		/* 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 {
2122
				ext4_clear_blocks(handle, inode, this_bh,
2123 2124 2125 2126 2127 2128 2129 2130 2131 2132
						  block_to_free,
						  count, block_to_free_p, p);
				block_to_free = nr;
				block_to_free_p = p;
				count = 1;
			}
		}
	}

	if (count > 0)
2133
		ext4_clear_blocks(handle, inode, this_bh, block_to_free,
2134 2135 2136
				  count, block_to_free_p, p);

	if (this_bh) {
2137 2138
		BUFFER_TRACE(this_bh, "call ext4_journal_dirty_metadata");
		ext4_journal_dirty_metadata(handle, this_bh);
2139 2140 2141 2142
	}
}

/**
2143
 *	ext4_free_branches - free an array of branches
2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154
 *	@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.
 */
2155
static void ext4_free_branches(handle_t *handle, struct inode *inode,
2156 2157 2158
			       struct buffer_head *parent_bh,
			       __le32 *first, __le32 *last, int depth)
{
2159
	ext4_fsblk_t nr;
2160 2161 2162 2163 2164 2165 2166
	__le32 *p;

	if (is_handle_aborted(handle))
		return;

	if (depth--) {
		struct buffer_head *bh;
2167
		int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181
		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) {
2182
				ext4_error(inode->i_sb, "ext4_free_branches",
2183
					   "Read failure, inode=%lu, block=%llu",
2184 2185 2186 2187 2188 2189
					   inode->i_ino, nr);
				continue;
			}

			/* This zaps the entire block.  Bottom up. */
			BUFFER_TRACE(bh, "free child branches");
2190
			ext4_free_branches(handle, inode, bh,
2191 2192 2193 2194 2195 2196 2197 2198
					   (__le32*)bh->b_data,
					   (__le32*)bh->b_data + addr_per_block,
					   depth);

			/*
			 * 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
2199
			 * jbd2_journal_revoke().
2200 2201 2202
			 *
			 * That's easy if it's exclusively part of this
			 * transaction.  But if it's part of the committing
2203
			 * transaction then jbd2_journal_forget() will simply
2204
			 * brelse() it.  That means that if the underlying
2205
			 * block is reallocated in ext4_get_block(),
2206 2207 2208 2209 2210 2211 2212 2213
			 * 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.
			 */
2214
			ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234

			/*
			 * 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)) {
2235 2236
				ext4_mark_inode_dirty(handle, inode);
				ext4_journal_test_restart(handle, inode);
2237 2238
			}

2239
			ext4_free_blocks(handle, inode, nr, 1);
2240 2241 2242 2243 2244 2245 2246

			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");
2247
				if (!ext4_journal_get_write_access(handle,
2248 2249 2250
								   parent_bh)){
					*p = 0;
					BUFFER_TRACE(parent_bh,
2251 2252
					"call ext4_journal_dirty_metadata");
					ext4_journal_dirty_metadata(handle,
2253 2254 2255 2256 2257 2258 2259
								    parent_bh);
				}
			}
		}
	} else {
		/* We have reached the bottom of the tree. */
		BUFFER_TRACE(parent_bh, "free data blocks");
2260
		ext4_free_data(handle, inode, parent_bh, first, last);
2261 2262 2263 2264
	}
}

/*
2265
 * ext4_truncate()
2266
 *
2267 2268
 * We block out ext4_get_block() block instantiations across the entire
 * transaction, and VFS/VM ensures that ext4_truncate() cannot run
2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284
 * 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
2285
 * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
2286
 * that this inode's truncate did not complete and it will again call
2287 2288
 * 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
2289
 * that's fine - as long as they are linked from the inode, the post-crash
2290
 * ext4_truncate() run will find them and release them.
2291
 */
2292
void ext4_truncate(struct inode *inode)
2293 2294
{
	handle_t *handle;
2295
	struct ext4_inode_info *ei = EXT4_I(inode);
2296
	__le32 *i_data = ei->i_data;
2297
	int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310
	struct address_space *mapping = inode->i_mapping;
	int offsets[4];
	Indirect chain[4];
	Indirect *partial;
	__le32 nr = 0;
	int n;
	long last_block;
	unsigned blocksize = inode->i_sb->s_blocksize;
	struct page *page;

	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
	    S_ISLNK(inode->i_mode)))
		return;
2311
	if (ext4_inode_is_fast_symlink(inode))
2312 2313 2314 2315 2316 2317
		return;
	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
		return;

	/*
	 * We have to lock the EOF page here, because lock_page() nests
2318
	 * outside jbd2_journal_start().
2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329
	 */
	if ((inode->i_size & (blocksize - 1)) == 0) {
		/* Block boundary? Nothing to do */
		page = NULL;
	} else {
		page = grab_cache_page(mapping,
				inode->i_size >> PAGE_CACHE_SHIFT);
		if (!page)
			return;
	}

A
Alex Tomas 已提交
2330 2331 2332
	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
		return ext4_ext_truncate(inode, page);

2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344
	handle = start_transaction(inode);
	if (IS_ERR(handle)) {
		if (page) {
			clear_highpage(page);
			flush_dcache_page(page);
			unlock_page(page);
			page_cache_release(page);
		}
		return;		/* AKPM: return what? */
	}

	last_block = (inode->i_size + blocksize-1)
2345
					>> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
2346 2347

	if (page)
2348
		ext4_block_truncate_page(handle, page, mapping, inode->i_size);
2349

2350
	n = ext4_block_to_path(inode, last_block, offsets, NULL);
2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362
	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.
	 */
2363
	if (ext4_orphan_add(handle, inode))
2364 2365 2366 2367 2368 2369 2370
		goto out_stop;

	/*
	 * 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
2371
	 * ext4 *really* writes onto the disk inode.
2372 2373 2374 2375
	 */
	ei->i_disksize = inode->i_size;

	/*
2376
	 * From here we block out all ext4_get_block() callers who want to
2377 2378 2379 2380 2381
	 * modify the block allocation tree.
	 */
	mutex_lock(&ei->truncate_mutex);

	if (n == 1) {		/* direct blocks */
2382 2383
		ext4_free_data(handle, inode, NULL, i_data+offsets[0],
			       i_data + EXT4_NDIR_BLOCKS);
2384 2385 2386
		goto do_indirects;
	}

2387
	partial = ext4_find_shared(inode, n, offsets, chain, &nr);
2388 2389 2390 2391
	/* Kill the top of shared branch (not detached) */
	if (nr) {
		if (partial == chain) {
			/* Shared branch grows from the inode */
2392
			ext4_free_branches(handle, inode, NULL,
2393 2394 2395 2396 2397 2398 2399 2400 2401
					   &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");
2402
			ext4_free_branches(handle, inode, partial->bh,
2403 2404 2405 2406 2407 2408
					partial->p,
					partial->p+1, (chain+n-1) - partial);
		}
	}
	/* Clear the ends of indirect blocks on the shared branch */
	while (partial > chain) {
2409
		ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
2410 2411 2412 2413 2414 2415 2416 2417 2418 2419
				   (__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:
2420
		nr = i_data[EXT4_IND_BLOCK];
2421
		if (nr) {
2422 2423
			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
			i_data[EXT4_IND_BLOCK] = 0;
2424
		}
2425 2426
	case EXT4_IND_BLOCK:
		nr = i_data[EXT4_DIND_BLOCK];
2427
		if (nr) {
2428 2429
			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
			i_data[EXT4_DIND_BLOCK] = 0;
2430
		}
2431 2432
	case EXT4_DIND_BLOCK:
		nr = i_data[EXT4_TIND_BLOCK];
2433
		if (nr) {
2434 2435
			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
			i_data[EXT4_TIND_BLOCK] = 0;
2436
		}
2437
	case EXT4_TIND_BLOCK:
2438 2439 2440
		;
	}

2441
	ext4_discard_reservation(inode);
2442 2443 2444

	mutex_unlock(&ei->truncate_mutex);
	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
2445
	ext4_mark_inode_dirty(handle, inode);
2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457

	/*
	 * 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
2458
	 * ext4_delete_inode(), and we allow that function to clean up the
2459 2460 2461
	 * orphan info for us.
	 */
	if (inode->i_nlink)
2462
		ext4_orphan_del(handle, inode);
2463

2464
	ext4_journal_stop(handle);
2465 2466
}

2467 2468
static ext4_fsblk_t ext4_get_inode_block(struct super_block *sb,
		unsigned long ino, struct ext4_iloc *iloc)
2469 2470 2471
{
	unsigned long desc, group_desc, block_group;
	unsigned long offset;
2472
	ext4_fsblk_t block;
2473
	struct buffer_head *bh;
2474
	struct ext4_group_desc * gdp;
2475

2476
	if (!ext4_valid_inum(sb, ino)) {
2477 2478 2479 2480 2481 2482 2483 2484
		/*
		 * 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;
	}

2485 2486 2487
	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
	if (block_group >= EXT4_SB(sb)->s_groups_count) {
		ext4_error(sb,"ext4_get_inode_block","group >= groups count");
2488 2489 2490
		return 0;
	}
	smp_rmb();
2491 2492 2493
	group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
	desc = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
	bh = EXT4_SB(sb)->s_group_desc[group_desc];
2494
	if (!bh) {
2495
		ext4_error (sb, "ext4_get_inode_block",
2496 2497 2498 2499
			    "Descriptor not loaded");
		return 0;
	}

2500 2501
	gdp = (struct ext4_group_desc *)((__u8 *)bh->b_data +
		desc * EXT4_DESC_SIZE(sb));
2502 2503 2504
	/*
	 * Figure out the offset within the block group inode table
	 */
2505 2506
	offset = ((ino - 1) % EXT4_INODES_PER_GROUP(sb)) *
		EXT4_INODE_SIZE(sb);
2507 2508
	block = ext4_inode_table(sb, gdp) +
		(offset >> EXT4_BLOCK_SIZE_BITS(sb));
2509 2510

	iloc->block_group = block_group;
2511
	iloc->offset = offset & (EXT4_BLOCK_SIZE(sb) - 1);
2512 2513 2514 2515
	return block;
}

/*
2516
 * ext4_get_inode_loc returns with an extra refcount against the inode's
2517 2518 2519 2520
 * 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.
 */
2521 2522
static int __ext4_get_inode_loc(struct inode *inode,
				struct ext4_iloc *iloc, int in_mem)
2523
{
2524
	ext4_fsblk_t block;
2525 2526
	struct buffer_head *bh;

2527
	block = ext4_get_inode_block(inode->i_sb, inode->i_ino, iloc);
2528 2529 2530 2531 2532
	if (!block)
		return -EIO;

	bh = sb_getblk(inode->i_sb, block);
	if (!bh) {
2533
		ext4_error (inode->i_sb, "ext4_get_inode_loc",
2534
				"unable to read inode block - "
2535
				"inode=%lu, block=%llu",
2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553
				 inode->i_ino, block);
		return -EIO;
	}
	if (!buffer_uptodate(bh)) {
		lock_buffer(bh);
		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;
2554
			struct ext4_group_desc *desc;
2555 2556 2557 2558 2559 2560
			int inodes_per_buffer;
			int inode_offset, i;
			int block_group;
			int start;

			block_group = (inode->i_ino - 1) /
2561
					EXT4_INODES_PER_GROUP(inode->i_sb);
2562
			inodes_per_buffer = bh->b_size /
2563
				EXT4_INODE_SIZE(inode->i_sb);
2564
			inode_offset = ((inode->i_ino - 1) %
2565
					EXT4_INODES_PER_GROUP(inode->i_sb));
2566 2567 2568
			start = inode_offset & ~(inodes_per_buffer - 1);

			/* Is the inode bitmap in cache? */
2569
			desc = ext4_get_group_desc(inode->i_sb,
2570 2571 2572 2573 2574
						block_group, NULL);
			if (!desc)
				goto make_io;

			bitmap_bh = sb_getblk(inode->i_sb,
2575
				ext4_inode_bitmap(inode->i_sb, desc));
2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590
			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;
2591
				if (ext4_test_bit(i, bitmap_bh->b_data))
2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614
					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)) {
2615
			ext4_error(inode->i_sb, "ext4_get_inode_loc",
2616
					"unable to read inode block - "
2617
					"inode=%lu, block=%llu",
2618 2619 2620 2621 2622 2623 2624 2625 2626 2627
					inode->i_ino, block);
			brelse(bh);
			return -EIO;
		}
	}
has_buffer:
	iloc->bh = bh;
	return 0;
}

2628
int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
2629 2630
{
	/* We have all inode data except xattrs in memory here. */
2631 2632
	return __ext4_get_inode_loc(inode, iloc,
		!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR));
2633 2634
}

2635
void ext4_set_inode_flags(struct inode *inode)
2636
{
2637
	unsigned int flags = EXT4_I(inode)->i_flags;
2638 2639

	inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
2640
	if (flags & EXT4_SYNC_FL)
2641
		inode->i_flags |= S_SYNC;
2642
	if (flags & EXT4_APPEND_FL)
2643
		inode->i_flags |= S_APPEND;
2644
	if (flags & EXT4_IMMUTABLE_FL)
2645
		inode->i_flags |= S_IMMUTABLE;
2646
	if (flags & EXT4_NOATIME_FL)
2647
		inode->i_flags |= S_NOATIME;
2648
	if (flags & EXT4_DIRSYNC_FL)
2649 2650 2651
		inode->i_flags |= S_DIRSYNC;
}

2652
void ext4_read_inode(struct inode * inode)
2653
{
2654 2655 2656
	struct ext4_iloc iloc;
	struct ext4_inode *raw_inode;
	struct ext4_inode_info *ei = EXT4_I(inode);
2657 2658 2659
	struct buffer_head *bh;
	int block;

2660 2661 2662
#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
	ei->i_acl = EXT4_ACL_NOT_CACHED;
	ei->i_default_acl = EXT4_ACL_NOT_CACHED;
2663 2664 2665
#endif
	ei->i_block_alloc_info = NULL;

2666
	if (__ext4_get_inode_loc(inode, &iloc, 0))
2667 2668
		goto bad_inode;
	bh = iloc.bh;
2669
	raw_inode = ext4_raw_inode(&iloc);
2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693
	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);
	if(!(test_opt (inode->i_sb, NO_UID32))) {
		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);
	inode->i_size = le32_to_cpu(raw_inode->i_size);
	inode->i_atime.tv_sec = le32_to_cpu(raw_inode->i_atime);
	inode->i_ctime.tv_sec = le32_to_cpu(raw_inode->i_ctime);
	inode->i_mtime.tv_sec = le32_to_cpu(raw_inode->i_mtime);
	inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = inode->i_mtime.tv_nsec = 0;

	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 ||
2694
		    !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705
			/* this inode is deleted */
			brelse (bh);
			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. */
	}
	inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
2706
#ifdef EXT4_FRAGMENTS
2707 2708 2709 2710 2711
	ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
	ei->i_frag_no = raw_inode->i_frag;
	ei->i_frag_size = raw_inode->i_fsize;
#endif
	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
2712 2713
	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
	    cpu_to_le32(EXT4_OS_HURD))
B
Badari Pulavarty 已提交
2714 2715
		ei->i_file_acl |=
			((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728
	if (!S_ISREG(inode->i_mode)) {
		ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
	} else {
		inode->i_size |=
			((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
	}
	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!
	 */
2729
	for (block = 0; block < EXT4_N_BLOCKS; block++)
2730 2731 2732
		ei->i_data[block] = raw_inode->i_block[block];
	INIT_LIST_HEAD(&ei->i_orphan);

2733 2734
	if (inode->i_ino >= EXT4_FIRST_INO(inode->i_sb) + 1 &&
	    EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
2735 2736
		/*
		 * When mke2fs creates big inodes it does not zero out
2737
		 * the unused bytes above EXT4_GOOD_OLD_INODE_SIZE,
2738 2739 2740
		 * so ignore those first few inodes.
		 */
		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
2741 2742
		if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
		    EXT4_INODE_SIZE(inode->i_sb))
2743 2744 2745
			goto bad_inode;
		if (ei->i_extra_isize == 0) {
			/* The extra space is currently unused. Use it. */
2746 2747
			ei->i_extra_isize = sizeof(struct ext4_inode) -
					    EXT4_GOOD_OLD_INODE_SIZE;
2748 2749
		} else {
			__le32 *magic = (void *)raw_inode +
2750
					EXT4_GOOD_OLD_INODE_SIZE +
2751
					ei->i_extra_isize;
2752 2753
			if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
				 ei->i_state |= EXT4_STATE_XATTR;
2754 2755 2756 2757 2758
		}
	} else
		ei->i_extra_isize = 0;

	if (S_ISREG(inode->i_mode)) {
2759 2760 2761
		inode->i_op = &ext4_file_inode_operations;
		inode->i_fop = &ext4_file_operations;
		ext4_set_aops(inode);
2762
	} else if (S_ISDIR(inode->i_mode)) {
2763 2764
		inode->i_op = &ext4_dir_inode_operations;
		inode->i_fop = &ext4_dir_operations;
2765
	} else if (S_ISLNK(inode->i_mode)) {
2766 2767
		if (ext4_inode_is_fast_symlink(inode))
			inode->i_op = &ext4_fast_symlink_inode_operations;
2768
		else {
2769 2770
			inode->i_op = &ext4_symlink_inode_operations;
			ext4_set_aops(inode);
2771 2772
		}
	} else {
2773
		inode->i_op = &ext4_special_inode_operations;
2774 2775 2776 2777 2778 2779 2780 2781
		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])));
	}
	brelse (iloc.bh);
2782
	ext4_set_inode_flags(inode);
2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796
	return;

bad_inode:
	make_bad_inode(inode);
	return;
}

/*
 * 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.
 */
2797
static int ext4_do_update_inode(handle_t *handle,
2798
				struct inode *inode,
2799
				struct ext4_iloc *iloc)
2800
{
2801 2802
	struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
	struct ext4_inode_info *ei = EXT4_I(inode);
2803 2804 2805 2806 2807
	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. */
2808 2809
	if (ei->i_state & EXT4_STATE_NEW)
		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843

	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
	if(!(test_opt(inode->i_sb, NO_UID32))) {
		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
 */
		if(!ei->i_dtime) {
			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);
	raw_inode->i_size = cpu_to_le32(ei->i_disksize);
	raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
	raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
	raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
	raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
2844
#ifdef EXT4_FRAGMENTS
2845 2846 2847 2848
	raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
	raw_inode->i_frag = ei->i_frag_no;
	raw_inode->i_fsize = ei->i_frag_size;
#endif
2849 2850
	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
	    cpu_to_le32(EXT4_OS_HURD))
B
Badari Pulavarty 已提交
2851 2852
		raw_inode->i_file_acl_high =
			cpu_to_le16(ei->i_file_acl >> 32);
2853 2854 2855 2856 2857 2858 2859 2860
	raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
	if (!S_ISREG(inode->i_mode)) {
		raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
	} else {
		raw_inode->i_size_high =
			cpu_to_le32(ei->i_disksize >> 32);
		if (ei->i_disksize > 0x7fffffffULL) {
			struct super_block *sb = inode->i_sb;
2861 2862 2863 2864
			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)) {
2865 2866 2867
			       /* If this is the first large file
				* created, add a flag to the superblock.
				*/
2868 2869
				err = ext4_journal_get_write_access(handle,
						EXT4_SB(sb)->s_sbh);
2870 2871
				if (err)
					goto out_brelse;
2872 2873 2874
				ext4_update_dynamic_rev(sb);
				EXT4_SET_RO_COMPAT_FEATURE(sb,
					EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
2875 2876
				sb->s_dirt = 1;
				handle->h_sync = 1;
2877 2878
				err = ext4_journal_dirty_metadata(handle,
						EXT4_SB(sb)->s_sbh);
2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893
			}
		}
	}
	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;
		}
2894
	} else for (block = 0; block < EXT4_N_BLOCKS; block++)
2895 2896 2897 2898 2899
		raw_inode->i_block[block] = ei->i_data[block];

	if (ei->i_extra_isize)
		raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);

2900 2901
	BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
	rc = ext4_journal_dirty_metadata(handle, bh);
2902 2903
	if (!err)
		err = rc;
2904
	ei->i_state &= ~EXT4_STATE_NEW;
2905 2906 2907

out_brelse:
	brelse (bh);
2908
	ext4_std_error(inode->i_sb, err);
2909 2910 2911 2912
	return err;
}

/*
2913
 * ext4_write_inode()
2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929
 *
 * 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
2930
 * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946
 * 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.
 */
2947
int ext4_write_inode(struct inode *inode, int wait)
2948 2949 2950 2951
{
	if (current->flags & PF_MEMALLOC)
		return 0;

2952
	if (ext4_journal_current_handle()) {
2953 2954 2955 2956 2957 2958 2959 2960
		jbd_debug(0, "called recursively, non-PF_MEMALLOC!\n");
		dump_stack();
		return -EIO;
	}

	if (!wait)
		return 0;

2961
	return ext4_force_commit(inode->i_sb);
2962 2963 2964
}

/*
2965
 * ext4_setattr()
2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980
 *
 * 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.)
 *
 * Called with inode->sem down.
 */
2981
int ext4_setattr(struct dentry *dentry, struct iattr *attr)
2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996
{
	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) */
2997 2998
		handle = ext4_journal_start(inode, 2*(EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)+
					EXT4_QUOTA_DEL_BLOCKS(inode->i_sb))+3);
2999 3000 3001 3002 3003 3004
		if (IS_ERR(handle)) {
			error = PTR_ERR(handle);
			goto err_out;
		}
		error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
		if (error) {
3005
			ext4_journal_stop(handle);
3006 3007 3008 3009 3010 3011 3012 3013
			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;
3014 3015
		error = ext4_mark_inode_dirty(handle, inode);
		ext4_journal_stop(handle);
3016 3017 3018 3019 3020 3021
	}

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

3022
		handle = ext4_journal_start(inode, 3);
3023 3024 3025 3026 3027
		if (IS_ERR(handle)) {
			error = PTR_ERR(handle);
			goto err_out;
		}

3028 3029 3030
		error = ext4_orphan_add(handle, inode);
		EXT4_I(inode)->i_disksize = attr->ia_size;
		rc = ext4_mark_inode_dirty(handle, inode);
3031 3032
		if (!error)
			error = rc;
3033
		ext4_journal_stop(handle);
3034 3035 3036 3037
	}

	rc = inode_setattr(inode, attr);

3038
	/* If inode_setattr's call to ext4_truncate failed to get a
3039 3040 3041
	 * transaction handle at all, we need to clean up the in-core
	 * orphan list manually. */
	if (inode->i_nlink)
3042
		ext4_orphan_del(NULL, inode);
3043 3044

	if (!rc && (ia_valid & ATTR_MODE))
3045
		rc = ext4_acl_chmod(inode);
3046 3047

err_out:
3048
	ext4_std_error(inode->i_sb, error);
3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066
	if (!error)
		error = rc;
	return error;
}


/*
 * How many blocks doth make a writepage()?
 *
 * With N blocks per page, it may be:
 * N data blocks
 * 2 indirect block
 * 2 dindirect
 * 1 tindirect
 * N+5 bitmap blocks (from the above)
 * N+5 group descriptor summary blocks
 * 1 inode block
 * 1 superblock.
3067
 * 2 * EXT4_SINGLEDATA_TRANS_BLOCKS for the quote files
3068
 *
3069
 * 3 * (N + 5) + 2 + 2 * EXT4_SINGLEDATA_TRANS_BLOCKS
3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081
 *
 * With ordered or writeback data it's the same, less the N data blocks.
 *
 * If the inode's direct blocks can hold an integral number of pages then a
 * page cannot straddle two indirect blocks, and we can only touch one indirect
 * and dindirect block, and the "5" above becomes "3".
 *
 * This still overestimates under most circumstances.  If we were to pass the
 * start and end offsets in here as well we could do block_to_path() on each
 * block and work out the exact number of indirects which are touched.  Pah.
 */

A
Alex Tomas 已提交
3082
int ext4_writepage_trans_blocks(struct inode *inode)
3083
{
3084 3085
	int bpp = ext4_journal_blocks_per_page(inode);
	int indirects = (EXT4_NDIR_BLOCKS % bpp) ? 5 : 3;
3086 3087
	int ret;

A
Alex Tomas 已提交
3088 3089 3090
	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
		return ext4_ext_writepage_trans_blocks(inode, bpp);

3091
	if (ext4_should_journal_data(inode))
3092 3093 3094 3095 3096 3097 3098
		ret = 3 * (bpp + indirects) + 2;
	else
		ret = 2 * (bpp + indirects) + 2;

#ifdef CONFIG_QUOTA
	/* We know that structure was already allocated during DQUOT_INIT so
	 * we will be updating only the data blocks + inodes */
3099
	ret += 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
3100 3101 3102 3103 3104 3105
#endif

	return ret;
}

/*
3106
 * The caller must have previously called ext4_reserve_inode_write().
3107 3108
 * Give this, we know that the caller already has write access to iloc->bh.
 */
3109 3110
int ext4_mark_iloc_dirty(handle_t *handle,
		struct inode *inode, struct ext4_iloc *iloc)
3111 3112 3113 3114 3115 3116
{
	int err = 0;

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

3117
	/* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
3118
	err = ext4_do_update_inode(handle, inode, iloc);
3119 3120 3121 3122 3123 3124 3125 3126 3127 3128
	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
3129 3130
ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
			 struct ext4_iloc *iloc)
3131 3132 3133
{
	int err = 0;
	if (handle) {
3134
		err = ext4_get_inode_loc(inode, iloc);
3135 3136
		if (!err) {
			BUFFER_TRACE(iloc->bh, "get_write_access");
3137
			err = ext4_journal_get_write_access(handle, iloc->bh);
3138 3139 3140 3141 3142 3143
			if (err) {
				brelse(iloc->bh);
				iloc->bh = NULL;
			}
		}
	}
3144
	ext4_std_error(inode->i_sb, err);
3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168
	return err;
}

/*
 * 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.
 */
3169
int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
3170
{
3171
	struct ext4_iloc iloc;
3172 3173 3174
	int err;

	might_sleep();
3175
	err = ext4_reserve_inode_write(handle, inode, &iloc);
3176
	if (!err)
3177
		err = ext4_mark_iloc_dirty(handle, inode, &iloc);
3178 3179 3180 3181
	return err;
}

/*
3182
 * ext4_dirty_inode() is called from __mark_inode_dirty()
3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194
 *
 * 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.
 */
3195
void ext4_dirty_inode(struct inode *inode)
3196
{
3197
	handle_t *current_handle = ext4_journal_current_handle();
3198 3199
	handle_t *handle;

3200
	handle = ext4_journal_start(inode, 2);
3201 3202 3203 3204 3205 3206 3207 3208 3209 3210
	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",
		       __FUNCTION__);
	} else {
		jbd_debug(5, "marking dirty.  outer handle=%p\n",
				current_handle);
3211
		ext4_mark_inode_dirty(handle, inode);
3212
	}
3213
	ext4_journal_stop(handle);
3214 3215 3216 3217 3218 3219 3220 3221
out:
	return;
}

#if 0
/*
 * Bind an inode's backing buffer_head into this transaction, to prevent
 * it from being flushed to disk early.  Unlike
3222
 * ext4_reserve_inode_write, this leaves behind no bh reference and
3223 3224 3225
 * returns no iloc structure, so the caller needs to repeat the iloc
 * lookup to mark the inode dirty later.
 */
3226
static int ext4_pin_inode(handle_t *handle, struct inode *inode)
3227
{
3228
	struct ext4_iloc iloc;
3229 3230 3231

	int err = 0;
	if (handle) {
3232
		err = ext4_get_inode_loc(inode, &iloc);
3233 3234
		if (!err) {
			BUFFER_TRACE(iloc.bh, "get_write_access");
3235
			err = jbd2_journal_get_write_access(handle, iloc.bh);
3236
			if (!err)
3237
				err = ext4_journal_dirty_metadata(handle,
3238 3239 3240 3241
								  iloc.bh);
			brelse(iloc.bh);
		}
	}
3242
	ext4_std_error(inode->i_sb, err);
3243 3244 3245 3246
	return err;
}
#endif

3247
int ext4_change_inode_journal_flag(struct inode *inode, int val)
3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262
{
	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.
	 */

3263
	journal = EXT4_JOURNAL(inode);
3264 3265 3266
	if (is_journal_aborted(journal) || IS_RDONLY(inode))
		return -EROFS;

3267 3268
	jbd2_journal_lock_updates(journal);
	jbd2_journal_flush(journal);
3269 3270 3271 3272 3273 3274 3275 3276 3277 3278

	/*
	 * 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)
3279
		EXT4_I(inode)->i_flags |= EXT4_JOURNAL_DATA_FL;
3280
	else
3281 3282
		EXT4_I(inode)->i_flags &= ~EXT4_JOURNAL_DATA_FL;
	ext4_set_aops(inode);
3283

3284
	jbd2_journal_unlock_updates(journal);
3285 3286 3287

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

3288
	handle = ext4_journal_start(inode, 1);
3289 3290 3291
	if (IS_ERR(handle))
		return PTR_ERR(handle);

3292
	err = ext4_mark_inode_dirty(handle, inode);
3293
	handle->h_sync = 1;
3294 3295
	ext4_journal_stop(handle);
	ext4_std_error(inode->i_sb, err);
3296 3297 3298

	return err;
}