balloc.c 52.5 KB
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/*
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 *  linux/fs/ext4/balloc.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)
 *
 *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */

#include <linux/time.h>
#include <linux/capability.h>
#include <linux/fs.h>
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#include <linux/jbd2.h>
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#include <linux/ext4_fs.h>
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#include <linux/ext4_jbd2.h>
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#include <linux/quotaops.h>
#include <linux/buffer_head.h>

/*
 * balloc.c contains the blocks allocation and deallocation routines
 */

/*
 * The free blocks are managed by bitmaps.  A file system contains several
 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 * block for inodes, N blocks for the inode table and data blocks.
 *
 * The file system contains group descriptors which are located after the
 * super block.  Each descriptor contains the number of the bitmap block and
 * the free blocks count in the block.  The descriptors are loaded in memory
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 * when a file system is mounted (see ext4_read_super).
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 */


#define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)

/**
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 * ext4_get_group_desc() -- load group descriptor from disk
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 * @sb:			super block
 * @block_group:	given block group
 * @bh:			pointer to the buffer head to store the block
 *			group descriptor
 */
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struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
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					     unsigned int block_group,
					     struct buffer_head ** bh)
{
	unsigned long group_desc;
	unsigned long offset;
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	struct ext4_group_desc * desc;
	struct ext4_sb_info *sbi = EXT4_SB(sb);
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	if (block_group >= sbi->s_groups_count) {
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		ext4_error (sb, "ext4_get_group_desc",
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			    "block_group >= groups_count - "
			    "block_group = %d, groups_count = %lu",
			    block_group, sbi->s_groups_count);

		return NULL;
	}
	smp_rmb();

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	group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
	offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
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	if (!sbi->s_group_desc[group_desc]) {
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		ext4_error (sb, "ext4_get_group_desc",
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			    "Group descriptor not loaded - "
			    "block_group = %d, group_desc = %lu, desc = %lu",
			     block_group, group_desc, offset);
		return NULL;
	}

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	desc = (struct ext4_group_desc *) sbi->s_group_desc[group_desc]->b_data;
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	if (bh)
		*bh = sbi->s_group_desc[group_desc];
	return desc + offset;
}

/**
 * read_block_bitmap()
 * @sb:			super block
 * @block_group:	given block group
 *
 * Read the bitmap for a given block_group, reading into the specified
 * slot in the superblock's bitmap cache.
 *
 * Return buffer_head on success or NULL in case of failure.
 */
static struct buffer_head *
read_block_bitmap(struct super_block *sb, unsigned int block_group)
{
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	struct ext4_group_desc * desc;
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	struct buffer_head * bh = NULL;

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	desc = ext4_get_group_desc (sb, block_group, NULL);
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	if (!desc)
		goto error_out;
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	bh = sb_bread(sb, ext4_block_bitmap(desc));
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	if (!bh)
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		ext4_error (sb, "read_block_bitmap",
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			    "Cannot read block bitmap - "
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			    "block_group = %d, block_bitmap = "E3FSBLK,
			    block_group,
			    ext4_block_bitmap(desc));
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error_out:
	return bh;
}
/*
 * The reservation window structure operations
 * --------------------------------------------
 * Operations include:
 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 *
 * We use a red-black tree to represent per-filesystem reservation
 * windows.
 *
 */

/**
 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
 * @rb_root:		root of per-filesystem reservation rb tree
 * @verbose:		verbose mode
 * @fn:			function which wishes to dump the reservation map
 *
 * If verbose is turned on, it will print the whole block reservation
 * windows(start, end).	Otherwise, it will only print out the "bad" windows,
 * those windows that overlap with their immediate neighbors.
 */
#if 1
static void __rsv_window_dump(struct rb_root *root, int verbose,
			      const char *fn)
{
	struct rb_node *n;
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	struct ext4_reserve_window_node *rsv, *prev;
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	int bad;

restart:
	n = rb_first(root);
	bad = 0;
	prev = NULL;

	printk("Block Allocation Reservation Windows Map (%s):\n", fn);
	while (n) {
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		rsv = list_entry(n, struct ext4_reserve_window_node, rsv_node);
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		if (verbose)
			printk("reservation window 0x%p "
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			       "start:  "E3FSBLK", end:  "E3FSBLK"\n",
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			       rsv, rsv->rsv_start, rsv->rsv_end);
		if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
			printk("Bad reservation %p (start >= end)\n",
			       rsv);
			bad = 1;
		}
		if (prev && prev->rsv_end >= rsv->rsv_start) {
			printk("Bad reservation %p (prev->end >= start)\n",
			       rsv);
			bad = 1;
		}
		if (bad) {
			if (!verbose) {
				printk("Restarting reservation walk in verbose mode\n");
				verbose = 1;
				goto restart;
			}
		}
		n = rb_next(n);
		prev = rsv;
	}
	printk("Window map complete.\n");
	if (bad)
		BUG();
}
#define rsv_window_dump(root, verbose) \
	__rsv_window_dump((root), (verbose), __FUNCTION__)
#else
#define rsv_window_dump(root, verbose) do {} while (0)
#endif

/**
 * goal_in_my_reservation()
 * @rsv:		inode's reservation window
 * @grp_goal:		given goal block relative to the allocation block group
 * @group:		the current allocation block group
 * @sb:			filesystem super block
 *
 * Test if the given goal block (group relative) is within the file's
 * own block reservation window range.
 *
 * If the reservation window is outside the goal allocation group, return 0;
 * grp_goal (given goal block) could be -1, which means no specific
 * goal block. In this case, always return 1.
 * If the goal block is within the reservation window, return 1;
 * otherwise, return 0;
 */
static int
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goal_in_my_reservation(struct ext4_reserve_window *rsv, ext4_grpblk_t grp_goal,
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			unsigned int group, struct super_block * sb)
{
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	ext4_fsblk_t group_first_block, group_last_block;
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	group_first_block = ext4_group_first_block_no(sb, group);
	group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
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	if ((rsv->_rsv_start > group_last_block) ||
	    (rsv->_rsv_end < group_first_block))
		return 0;
	if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
		|| (grp_goal + group_first_block > rsv->_rsv_end)))
		return 0;
	return 1;
}

/**
 * search_reserve_window()
 * @rb_root:		root of reservation tree
 * @goal:		target allocation block
 *
 * Find the reserved window which includes the goal, or the previous one
 * if the goal is not in any window.
 * Returns NULL if there are no windows or if all windows start after the goal.
 */
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static struct ext4_reserve_window_node *
search_reserve_window(struct rb_root *root, ext4_fsblk_t goal)
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{
	struct rb_node *n = root->rb_node;
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	struct ext4_reserve_window_node *rsv;
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	if (!n)
		return NULL;

	do {
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		rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
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		if (goal < rsv->rsv_start)
			n = n->rb_left;
		else if (goal > rsv->rsv_end)
			n = n->rb_right;
		else
			return rsv;
	} while (n);
	/*
	 * We've fallen off the end of the tree: the goal wasn't inside
	 * any particular node.  OK, the previous node must be to one
	 * side of the interval containing the goal.  If it's the RHS,
	 * we need to back up one.
	 */
	if (rsv->rsv_start > goal) {
		n = rb_prev(&rsv->rsv_node);
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		rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
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	}
	return rsv;
}

/**
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 * ext4_rsv_window_add() -- Insert a window to the block reservation rb tree.
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 * @sb:			super block
 * @rsv:		reservation window to add
 *
 * Must be called with rsv_lock hold.
 */
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void ext4_rsv_window_add(struct super_block *sb,
		    struct ext4_reserve_window_node *rsv)
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{
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	struct rb_root *root = &EXT4_SB(sb)->s_rsv_window_root;
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	struct rb_node *node = &rsv->rsv_node;
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	ext4_fsblk_t start = rsv->rsv_start;
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	struct rb_node ** p = &root->rb_node;
	struct rb_node * parent = NULL;
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	struct ext4_reserve_window_node *this;
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	while (*p)
	{
		parent = *p;
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		this = rb_entry(parent, struct ext4_reserve_window_node, rsv_node);
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		if (start < this->rsv_start)
			p = &(*p)->rb_left;
		else if (start > this->rsv_end)
			p = &(*p)->rb_right;
		else {
			rsv_window_dump(root, 1);
			BUG();
		}
	}

	rb_link_node(node, parent, p);
	rb_insert_color(node, root);
}

/**
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 * ext4_rsv_window_remove() -- unlink a window from the reservation rb tree
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 * @sb:			super block
 * @rsv:		reservation window to remove
 *
 * Mark the block reservation window as not allocated, and unlink it
 * from the filesystem reservation window rb tree. Must be called with
 * rsv_lock hold.
 */
static void rsv_window_remove(struct super_block *sb,
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			      struct ext4_reserve_window_node *rsv)
306
{
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	rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
	rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
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	rsv->rsv_alloc_hit = 0;
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	rb_erase(&rsv->rsv_node, &EXT4_SB(sb)->s_rsv_window_root);
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}

/*
 * rsv_is_empty() -- Check if the reservation window is allocated.
 * @rsv:		given reservation window to check
 *
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 * returns 1 if the end block is EXT4_RESERVE_WINDOW_NOT_ALLOCATED.
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 */
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static inline int rsv_is_empty(struct ext4_reserve_window *rsv)
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{
	/* a valid reservation end block could not be 0 */
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	return rsv->_rsv_end == EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
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}

/**
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 * ext4_init_block_alloc_info()
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 * @inode:		file inode structure
 *
 * Allocate and initialize the	reservation window structure, and
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 * link the window to the ext4 inode structure at last
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 *
 * The reservation window structure is only dynamically allocated
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 * and linked to ext4 inode the first time the open file
 * needs a new block. So, before every ext4_new_block(s) call, for
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 * regular files, we should check whether the reservation window
 * structure exists or not. In the latter case, this function is called.
 * Fail to do so will result in block reservation being turned off for that
 * open file.
 *
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 * This function is called from ext4_get_blocks_handle(), also called
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 * when setting the reservation window size through ioctl before the file
 * is open for write (needs block allocation).
 *
 * Needs truncate_mutex protection prior to call this function.
 */
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void ext4_init_block_alloc_info(struct inode *inode)
347
{
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	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
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	struct super_block *sb = inode->i_sb;

	block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
	if (block_i) {
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		struct ext4_reserve_window_node *rsv = &block_i->rsv_window_node;
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356 357
		rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
		rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
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		/*
		 * if filesystem is mounted with NORESERVATION, the goal
		 * reservation window size is set to zero to indicate
		 * block reservation is off
		 */
		if (!test_opt(sb, RESERVATION))
			rsv->rsv_goal_size = 0;
		else
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			rsv->rsv_goal_size = EXT4_DEFAULT_RESERVE_BLOCKS;
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		rsv->rsv_alloc_hit = 0;
		block_i->last_alloc_logical_block = 0;
		block_i->last_alloc_physical_block = 0;
	}
	ei->i_block_alloc_info = block_i;
}

/**
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 * ext4_discard_reservation()
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 * @inode:		inode
 *
 * Discard(free) block reservation window on last file close, or truncate
 * or at last iput().
 *
 * It is being called in three cases:
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 *	ext4_release_file(): last writer close the file
 *	ext4_clear_inode(): last iput(), when nobody link to this file.
 *	ext4_truncate(): when the block indirect map is about to change.
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 *
 */
388
void ext4_discard_reservation(struct inode *inode)
389
{
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	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
	struct ext4_reserve_window_node *rsv;
	spinlock_t *rsv_lock = &EXT4_SB(inode->i_sb)->s_rsv_window_lock;
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	if (!block_i)
		return;

	rsv = &block_i->rsv_window_node;
	if (!rsv_is_empty(&rsv->rsv_window)) {
		spin_lock(rsv_lock);
		if (!rsv_is_empty(&rsv->rsv_window))
			rsv_window_remove(inode->i_sb, rsv);
		spin_unlock(rsv_lock);
	}
}

/**
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 * ext4_free_blocks_sb() -- Free given blocks and update quota
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 * @handle:			handle to this transaction
 * @sb:				super block
 * @block:			start physcial block to free
 * @count:			number of blocks to free
 * @pdquot_freed_blocks:	pointer to quota
 */
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void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
			 ext4_fsblk_t block, unsigned long count,
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			 unsigned long *pdquot_freed_blocks)
{
	struct buffer_head *bitmap_bh = NULL;
	struct buffer_head *gd_bh;
	unsigned long block_group;
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	ext4_grpblk_t bit;
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	unsigned long i;
	unsigned long overflow;
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	struct ext4_group_desc * desc;
	struct ext4_super_block * es;
	struct ext4_sb_info *sbi;
428
	int err = 0, ret;
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	ext4_grpblk_t group_freed;
430 431

	*pdquot_freed_blocks = 0;
432
	sbi = EXT4_SB(sb);
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	es = sbi->s_es;
	if (block < le32_to_cpu(es->s_first_data_block) ||
	    block + count < block ||
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	    block + count > ext4_blocks_count(es)) {
437
		ext4_error (sb, "ext4_free_blocks",
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			    "Freeing blocks not in datazone - "
			    "block = "E3FSBLK", count = %lu", block, count);
		goto error_return;
	}

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	ext4_debug ("freeing block(s) %llu-%llu\n", block, block + count - 1);
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do_more:
	overflow = 0;
447
	ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
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	/*
	 * Check to see if we are freeing blocks across a group
	 * boundary.
	 */
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	if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
		overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
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		count -= overflow;
	}
	brelse(bitmap_bh);
	bitmap_bh = read_block_bitmap(sb, block_group);
	if (!bitmap_bh)
		goto error_return;
460
	desc = ext4_get_group_desc (sb, block_group, &gd_bh);
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	if (!desc)
		goto error_return;

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	if (in_range(ext4_block_bitmap(desc), block, count) ||
	    in_range(ext4_inode_bitmap(desc), block, count) ||
	    in_range(block, ext4_inode_table(desc), sbi->s_itb_per_group) ||
	    in_range(block + count - 1, ext4_inode_table(desc),
		     sbi->s_itb_per_group))
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		ext4_error (sb, "ext4_free_blocks",
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			    "Freeing blocks in system zones - "
			    "Block = "E3FSBLK", count = %lu",
			    block, count);

	/*
	 * We are about to start releasing blocks in the bitmap,
	 * so we need undo access.
	 */
	/* @@@ check errors */
	BUFFER_TRACE(bitmap_bh, "getting undo access");
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	err = ext4_journal_get_undo_access(handle, bitmap_bh);
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	if (err)
		goto error_return;

	/*
	 * We are about to modify some metadata.  Call the journal APIs
	 * to unshare ->b_data if a currently-committing transaction is
	 * using it
	 */
	BUFFER_TRACE(gd_bh, "get_write_access");
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	err = ext4_journal_get_write_access(handle, gd_bh);
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	if (err)
		goto error_return;

	jbd_lock_bh_state(bitmap_bh);

	for (i = 0, group_freed = 0; i < count; i++) {
		/*
		 * An HJ special.  This is expensive...
		 */
#ifdef CONFIG_JBD_DEBUG
		jbd_unlock_bh_state(bitmap_bh);
		{
			struct buffer_head *debug_bh;
			debug_bh = sb_find_get_block(sb, block + i);
			if (debug_bh) {
				BUFFER_TRACE(debug_bh, "Deleted!");
				if (!bh2jh(bitmap_bh)->b_committed_data)
					BUFFER_TRACE(debug_bh,
						"No commited data in bitmap");
				BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
				__brelse(debug_bh);
			}
		}
		jbd_lock_bh_state(bitmap_bh);
#endif
		if (need_resched()) {
			jbd_unlock_bh_state(bitmap_bh);
			cond_resched();
			jbd_lock_bh_state(bitmap_bh);
		}
		/* @@@ This prevents newly-allocated data from being
		 * freed and then reallocated within the same
		 * transaction.
		 *
		 * Ideally we would want to allow that to happen, but to
526
		 * do so requires making jbd2_journal_forget() capable of
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		 * revoking the queued write of a data block, which
		 * implies blocking on the journal lock.  *forget()
		 * cannot block due to truncate races.
		 *
531
		 * Eventually we can fix this by making jbd2_journal_forget()
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		 * return a status indicating whether or not it was able
		 * to revoke the buffer.  On successful revoke, it is
		 * safe not to set the allocation bit in the committed
		 * bitmap, because we know that there is no outstanding
		 * activity on the buffer any more and so it is safe to
		 * reallocate it.
		 */
		BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
		J_ASSERT_BH(bitmap_bh,
				bh2jh(bitmap_bh)->b_committed_data != NULL);
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		ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
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				bh2jh(bitmap_bh)->b_committed_data);

		/*
		 * We clear the bit in the bitmap after setting the committed
		 * data bit, because this is the reverse order to that which
		 * the allocator uses.
		 */
		BUFFER_TRACE(bitmap_bh, "clear bit");
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		if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
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						bit + i, bitmap_bh->b_data)) {
			jbd_unlock_bh_state(bitmap_bh);
554
			ext4_error(sb, __FUNCTION__,
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				   "bit already cleared for block "E3FSBLK,
				   (ext4_fsblk_t)(block + i));
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			jbd_lock_bh_state(bitmap_bh);
			BUFFER_TRACE(bitmap_bh, "bit already cleared");
		} else {
			group_freed++;
		}
	}
	jbd_unlock_bh_state(bitmap_bh);

	spin_lock(sb_bgl_lock(sbi, block_group));
	desc->bg_free_blocks_count =
		cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
			group_freed);
	spin_unlock(sb_bgl_lock(sbi, block_group));
	percpu_counter_mod(&sbi->s_freeblocks_counter, count);

	/* We dirtied the bitmap block */
	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
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	err = ext4_journal_dirty_metadata(handle, bitmap_bh);
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	/* And the group descriptor block */
	BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
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	ret = ext4_journal_dirty_metadata(handle, gd_bh);
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	if (!err) err = ret;
	*pdquot_freed_blocks += group_freed;

	if (overflow && !err) {
		block += count;
		count = overflow;
		goto do_more;
	}
	sb->s_dirt = 1;
error_return:
	brelse(bitmap_bh);
590
	ext4_std_error(sb, err);
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	return;
}

/**
595
 * ext4_free_blocks() -- Free given blocks and update quota
596 597 598 599 600
 * @handle:		handle for this transaction
 * @inode:		inode
 * @block:		start physical block to free
 * @count:		number of blocks to count
 */
601 602
void ext4_free_blocks(handle_t *handle, struct inode *inode,
			ext4_fsblk_t block, unsigned long count)
603 604 605 606 607 608
{
	struct super_block * sb;
	unsigned long dquot_freed_blocks;

	sb = inode->i_sb;
	if (!sb) {
609
		printk ("ext4_free_blocks: nonexistent device");
610 611
		return;
	}
612
	ext4_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
613 614 615 616 617 618
	if (dquot_freed_blocks)
		DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
	return;
}

/**
619
 * ext4_test_allocatable()
620 621 622
 * @nr:			given allocation block group
 * @bh:			bufferhead contains the bitmap of the given block group
 *
623
 * For ext4 allocations, we must not reuse any blocks which are
624 625 626 627 628 629 630 631 632 633 634 635 636 637
 * allocated in the bitmap buffer's "last committed data" copy.  This
 * prevents deletes from freeing up the page for reuse until we have
 * committed the delete transaction.
 *
 * If we didn't do this, then deleting something and reallocating it as
 * data would allow the old block to be overwritten before the
 * transaction committed (because we force data to disk before commit).
 * This would lead to corruption if we crashed between overwriting the
 * data and committing the delete.
 *
 * @@@ We may want to make this allocation behaviour conditional on
 * data-writes at some point, and disable it for metadata allocations or
 * sync-data inodes.
 */
638
static int ext4_test_allocatable(ext4_grpblk_t nr, struct buffer_head *bh)
639 640 641 642
{
	int ret;
	struct journal_head *jh = bh2jh(bh);

643
	if (ext4_test_bit(nr, bh->b_data))
644 645 646 647 648 649
		return 0;

	jbd_lock_bh_state(bh);
	if (!jh->b_committed_data)
		ret = 1;
	else
650
		ret = !ext4_test_bit(nr, jh->b_committed_data);
651 652 653 654 655 656 657 658 659 660 661 662 663 664
	jbd_unlock_bh_state(bh);
	return ret;
}

/**
 * bitmap_search_next_usable_block()
 * @start:		the starting block (group relative) of the search
 * @bh:			bufferhead contains the block group bitmap
 * @maxblocks:		the ending block (group relative) of the reservation
 *
 * The bitmap search --- search forward alternately through the actual
 * bitmap on disk and the last-committed copy in journal, until we find a
 * bit free in both bitmaps.
 */
665 666 667
static ext4_grpblk_t
bitmap_search_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
					ext4_grpblk_t maxblocks)
668
{
669
	ext4_grpblk_t next;
670 671 672
	struct journal_head *jh = bh2jh(bh);

	while (start < maxblocks) {
673
		next = ext4_find_next_zero_bit(bh->b_data, maxblocks, start);
674 675
		if (next >= maxblocks)
			return -1;
676
		if (ext4_test_allocatable(next, bh))
677 678 679
			return next;
		jbd_lock_bh_state(bh);
		if (jh->b_committed_data)
680
			start = ext4_find_next_zero_bit(jh->b_committed_data,
681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699
							maxblocks, next);
		jbd_unlock_bh_state(bh);
	}
	return -1;
}

/**
 * find_next_usable_block()
 * @start:		the starting block (group relative) to find next
 *			allocatable block in bitmap.
 * @bh:			bufferhead contains the block group bitmap
 * @maxblocks:		the ending block (group relative) for the search
 *
 * Find an allocatable block in a bitmap.  We honor both the bitmap and
 * its last-committed copy (if that exists), and perform the "most
 * appropriate allocation" algorithm of looking for a free block near
 * the initial goal; then for a free byte somewhere in the bitmap; then
 * for any free bit in the bitmap.
 */
700 701 702
static ext4_grpblk_t
find_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
			ext4_grpblk_t maxblocks)
703
{
704
	ext4_grpblk_t here, next;
705 706 707 708 709 710 711 712
	char *p, *r;

	if (start > 0) {
		/*
		 * The goal was occupied; search forward for a free
		 * block within the next XX blocks.
		 *
		 * end_goal is more or less random, but it has to be
713
		 * less than EXT4_BLOCKS_PER_GROUP. Aligning up to the
714 715
		 * next 64-bit boundary is simple..
		 */
716
		ext4_grpblk_t end_goal = (start + 63) & ~63;
717 718
		if (end_goal > maxblocks)
			end_goal = maxblocks;
719 720
		here = ext4_find_next_zero_bit(bh->b_data, end_goal, start);
		if (here < end_goal && ext4_test_allocatable(here, bh))
721
			return here;
722
		ext4_debug("Bit not found near goal\n");
723 724 725 726 727 728 729 730 731 732
	}

	here = start;
	if (here < 0)
		here = 0;

	p = ((char *)bh->b_data) + (here >> 3);
	r = memscan(p, 0, (maxblocks - here + 7) >> 3);
	next = (r - ((char *)bh->b_data)) << 3;

733
	if (next < maxblocks && next >= start && ext4_test_allocatable(next, bh))
734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756
		return next;

	/*
	 * The bitmap search --- search forward alternately through the actual
	 * bitmap and the last-committed copy until we find a bit free in
	 * both
	 */
	here = bitmap_search_next_usable_block(here, bh, maxblocks);
	return here;
}

/**
 * claim_block()
 * @block:		the free block (group relative) to allocate
 * @bh:			the bufferhead containts the block group bitmap
 *
 * We think we can allocate this block in this bitmap.  Try to set the bit.
 * If that succeeds then check that nobody has allocated and then freed the
 * block since we saw that is was not marked in b_committed_data.  If it _was_
 * allocated and freed then clear the bit in the bitmap again and return
 * zero (failure).
 */
static inline int
757
claim_block(spinlock_t *lock, ext4_grpblk_t block, struct buffer_head *bh)
758 759 760 761
{
	struct journal_head *jh = bh2jh(bh);
	int ret;

762
	if (ext4_set_bit_atomic(lock, block, bh->b_data))
763 764
		return 0;
	jbd_lock_bh_state(bh);
765 766
	if (jh->b_committed_data && ext4_test_bit(block,jh->b_committed_data)) {
		ext4_clear_bit_atomic(lock, block, bh->b_data);
767 768 769 770 771 772 773 774 775
		ret = 0;
	} else {
		ret = 1;
	}
	jbd_unlock_bh_state(bh);
	return ret;
}

/**
776
 * ext4_try_to_allocate()
777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796
 * @sb:			superblock
 * @handle:		handle to this transaction
 * @group:		given allocation block group
 * @bitmap_bh:		bufferhead holds the block bitmap
 * @grp_goal:		given target block within the group
 * @count:		target number of blocks to allocate
 * @my_rsv:		reservation window
 *
 * Attempt to allocate blocks within a give range. Set the range of allocation
 * first, then find the first free bit(s) from the bitmap (within the range),
 * and at last, allocate the blocks by claiming the found free bit as allocated.
 *
 * To set the range of this allocation:
 *	if there is a reservation window, only try to allocate block(s) from the
 *	file's own reservation window;
 *	Otherwise, the allocation range starts from the give goal block, ends at
 *	the block group's last block.
 *
 * If we failed to allocate the desired block then we may end up crossing to a
 * new bitmap.  In that case we must release write access to the old one via
797
 * ext4_journal_release_buffer(), else we'll run out of credits.
798
 */
799 800 801 802
static ext4_grpblk_t
ext4_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
			struct buffer_head *bitmap_bh, ext4_grpblk_t grp_goal,
			unsigned long *count, struct ext4_reserve_window *my_rsv)
803
{
804 805
	ext4_fsblk_t group_first_block;
	ext4_grpblk_t start, end;
806 807 808 809
	unsigned long num = 0;

	/* we do allocation within the reservation window if we have a window */
	if (my_rsv) {
810
		group_first_block = ext4_group_first_block_no(sb, group);
811 812 813 814 815 816
		if (my_rsv->_rsv_start >= group_first_block)
			start = my_rsv->_rsv_start - group_first_block;
		else
			/* reservation window cross group boundary */
			start = 0;
		end = my_rsv->_rsv_end - group_first_block + 1;
817
		if (end > EXT4_BLOCKS_PER_GROUP(sb))
818
			/* reservation window crosses group boundary */
819
			end = EXT4_BLOCKS_PER_GROUP(sb);
820 821 822 823 824 825 826 827 828
		if ((start <= grp_goal) && (grp_goal < end))
			start = grp_goal;
		else
			grp_goal = -1;
	} else {
		if (grp_goal > 0)
			start = grp_goal;
		else
			start = 0;
829
		end = EXT4_BLOCKS_PER_GROUP(sb);
830 831
	}

832
	BUG_ON(start > EXT4_BLOCKS_PER_GROUP(sb));
833 834

repeat:
835
	if (grp_goal < 0 || !ext4_test_allocatable(grp_goal, bitmap_bh)) {
836 837 838 839 840 841 842
		grp_goal = find_next_usable_block(start, bitmap_bh, end);
		if (grp_goal < 0)
			goto fail_access;
		if (!my_rsv) {
			int i;

			for (i = 0; i < 7 && grp_goal > start &&
843
					ext4_test_allocatable(grp_goal - 1,
844 845 846 847 848 849 850
								bitmap_bh);
					i++, grp_goal--)
				;
		}
	}
	start = grp_goal;

851
	if (!claim_block(sb_bgl_lock(EXT4_SB(sb), group),
852 853 854 855 856 857 858 859 860 861 862 863 864 865
		grp_goal, bitmap_bh)) {
		/*
		 * The block was allocated by another thread, or it was
		 * allocated and then freed by another thread
		 */
		start++;
		grp_goal++;
		if (start >= end)
			goto fail_access;
		goto repeat;
	}
	num++;
	grp_goal++;
	while (num < *count && grp_goal < end
866 867
		&& ext4_test_allocatable(grp_goal, bitmap_bh)
		&& claim_block(sb_bgl_lock(EXT4_SB(sb), group),
868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912
				grp_goal, bitmap_bh)) {
		num++;
		grp_goal++;
	}
	*count = num;
	return grp_goal - num;
fail_access:
	*count = num;
	return -1;
}

/**
 *	find_next_reservable_window():
 *		find a reservable space within the given range.
 *		It does not allocate the reservation window for now:
 *		alloc_new_reservation() will do the work later.
 *
 *	@search_head: the head of the searching list;
 *		This is not necessarily the list head of the whole filesystem
 *
 *		We have both head and start_block to assist the search
 *		for the reservable space. The list starts from head,
 *		but we will shift to the place where start_block is,
 *		then start from there, when looking for a reservable space.
 *
 *	@size: the target new reservation window size
 *
 *	@group_first_block: the first block we consider to start
 *			the real search from
 *
 *	@last_block:
 *		the maximum block number that our goal reservable space
 *		could start from. This is normally the last block in this
 *		group. The search will end when we found the start of next
 *		possible reservable space is out of this boundary.
 *		This could handle the cross boundary reservation window
 *		request.
 *
 *	basically we search from the given range, rather than the whole
 *	reservation double linked list, (start_block, last_block)
 *	to find a free region that is of my size and has not
 *	been reserved.
 *
 */
static int find_next_reservable_window(
913 914
				struct ext4_reserve_window_node *search_head,
				struct ext4_reserve_window_node *my_rsv,
915
				struct super_block * sb,
916 917
				ext4_fsblk_t start_block,
				ext4_fsblk_t last_block)
918 919
{
	struct rb_node *next;
920 921
	struct ext4_reserve_window_node *rsv, *prev;
	ext4_fsblk_t cur;
922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948
	int size = my_rsv->rsv_goal_size;

	/* TODO: make the start of the reservation window byte-aligned */
	/* cur = *start_block & ~7;*/
	cur = start_block;
	rsv = search_head;
	if (!rsv)
		return -1;

	while (1) {
		if (cur <= rsv->rsv_end)
			cur = rsv->rsv_end + 1;

		/* TODO?
		 * in the case we could not find a reservable space
		 * that is what is expected, during the re-search, we could
		 * remember what's the largest reservable space we could have
		 * and return that one.
		 *
		 * For now it will fail if we could not find the reservable
		 * space with expected-size (or more)...
		 */
		if (cur > last_block)
			return -1;		/* fail */

		prev = rsv;
		next = rb_next(&rsv->rsv_node);
949
		rsv = list_entry(next,struct ext4_reserve_window_node,rsv_node);
950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991

		/*
		 * Reached the last reservation, we can just append to the
		 * previous one.
		 */
		if (!next)
			break;

		if (cur + size <= rsv->rsv_start) {
			/*
			 * Found a reserveable space big enough.  We could
			 * have a reservation across the group boundary here
			 */
			break;
		}
	}
	/*
	 * we come here either :
	 * when we reach the end of the whole list,
	 * and there is empty reservable space after last entry in the list.
	 * append it to the end of the list.
	 *
	 * or we found one reservable space in the middle of the list,
	 * return the reservation window that we could append to.
	 * succeed.
	 */

	if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
		rsv_window_remove(sb, my_rsv);

	/*
	 * Let's book the whole avaliable window for now.  We will check the
	 * disk bitmap later and then, if there are free blocks then we adjust
	 * the window size if it's larger than requested.
	 * Otherwise, we will remove this node from the tree next time
	 * call find_next_reservable_window.
	 */
	my_rsv->rsv_start = cur;
	my_rsv->rsv_end = cur + size - 1;
	my_rsv->rsv_alloc_hit = 0;

	if (prev != my_rsv)
992
		ext4_rsv_window_add(sb, my_rsv);
993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033

	return 0;
}

/**
 *	alloc_new_reservation()--allocate a new reservation window
 *
 *		To make a new reservation, we search part of the filesystem
 *		reservation list (the list that inside the group). We try to
 *		allocate a new reservation window near the allocation goal,
 *		or the beginning of the group, if there is no goal.
 *
 *		We first find a reservable space after the goal, then from
 *		there, we check the bitmap for the first free block after
 *		it. If there is no free block until the end of group, then the
 *		whole group is full, we failed. Otherwise, check if the free
 *		block is inside the expected reservable space, if so, we
 *		succeed.
 *		If the first free block is outside the reservable space, then
 *		start from the first free block, we search for next available
 *		space, and go on.
 *
 *	on succeed, a new reservation will be found and inserted into the list
 *	It contains at least one free block, and it does not overlap with other
 *	reservation windows.
 *
 *	failed: we failed to find a reservation window in this group
 *
 *	@rsv: the reservation
 *
 *	@grp_goal: The goal (group-relative).  It is where the search for a
 *		free reservable space should start from.
 *		if we have a grp_goal(grp_goal >0 ), then start from there,
 *		no grp_goal(grp_goal = -1), we start from the first block
 *		of the group.
 *
 *	@sb: the super block
 *	@group: the group we are trying to allocate in
 *	@bitmap_bh: the block group block bitmap
 *
 */
1034 1035
static int alloc_new_reservation(struct ext4_reserve_window_node *my_rsv,
		ext4_grpblk_t grp_goal, struct super_block *sb,
1036 1037
		unsigned int group, struct buffer_head *bitmap_bh)
{
1038 1039 1040 1041
	struct ext4_reserve_window_node *search_head;
	ext4_fsblk_t group_first_block, group_end_block, start_block;
	ext4_grpblk_t first_free_block;
	struct rb_root *fs_rsv_root = &EXT4_SB(sb)->s_rsv_window_root;
1042 1043
	unsigned long size;
	int ret;
1044
	spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
1045

1046 1047
	group_first_block = ext4_group_first_block_no(sb, group);
	group_end_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084

	if (grp_goal < 0)
		start_block = group_first_block;
	else
		start_block = grp_goal + group_first_block;

	size = my_rsv->rsv_goal_size;

	if (!rsv_is_empty(&my_rsv->rsv_window)) {
		/*
		 * if the old reservation is cross group boundary
		 * and if the goal is inside the old reservation window,
		 * we will come here when we just failed to allocate from
		 * the first part of the window. We still have another part
		 * that belongs to the next group. In this case, there is no
		 * point to discard our window and try to allocate a new one
		 * in this group(which will fail). we should
		 * keep the reservation window, just simply move on.
		 *
		 * Maybe we could shift the start block of the reservation
		 * window to the first block of next group.
		 */

		if ((my_rsv->rsv_start <= group_end_block) &&
				(my_rsv->rsv_end > group_end_block) &&
				(start_block >= my_rsv->rsv_start))
			return -1;

		if ((my_rsv->rsv_alloc_hit >
		     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
			/*
			 * if the previously allocation hit ratio is
			 * greater than 1/2, then we double the size of
			 * the reservation window the next time,
			 * otherwise we keep the same size window
			 */
			size = size * 2;
1085 1086
			if (size > EXT4_MAX_RESERVE_BLOCKS)
				size = EXT4_MAX_RESERVE_BLOCKS;
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 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169
			my_rsv->rsv_goal_size= size;
		}
	}

	spin_lock(rsv_lock);
	/*
	 * shift the search start to the window near the goal block
	 */
	search_head = search_reserve_window(fs_rsv_root, start_block);

	/*
	 * find_next_reservable_window() simply finds a reservable window
	 * inside the given range(start_block, group_end_block).
	 *
	 * To make sure the reservation window has a free bit inside it, we
	 * need to check the bitmap after we found a reservable window.
	 */
retry:
	ret = find_next_reservable_window(search_head, my_rsv, sb,
						start_block, group_end_block);

	if (ret == -1) {
		if (!rsv_is_empty(&my_rsv->rsv_window))
			rsv_window_remove(sb, my_rsv);
		spin_unlock(rsv_lock);
		return -1;
	}

	/*
	 * On success, find_next_reservable_window() returns the
	 * reservation window where there is a reservable space after it.
	 * Before we reserve this reservable space, we need
	 * to make sure there is at least a free block inside this region.
	 *
	 * searching the first free bit on the block bitmap and copy of
	 * last committed bitmap alternatively, until we found a allocatable
	 * block. Search start from the start block of the reservable space
	 * we just found.
	 */
	spin_unlock(rsv_lock);
	first_free_block = bitmap_search_next_usable_block(
			my_rsv->rsv_start - group_first_block,
			bitmap_bh, group_end_block - group_first_block + 1);

	if (first_free_block < 0) {
		/*
		 * no free block left on the bitmap, no point
		 * to reserve the space. return failed.
		 */
		spin_lock(rsv_lock);
		if (!rsv_is_empty(&my_rsv->rsv_window))
			rsv_window_remove(sb, my_rsv);
		spin_unlock(rsv_lock);
		return -1;		/* failed */
	}

	start_block = first_free_block + group_first_block;
	/*
	 * check if the first free block is within the
	 * free space we just reserved
	 */
	if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
		return 0;		/* success */
	/*
	 * if the first free bit we found is out of the reservable space
	 * continue search for next reservable space,
	 * start from where the free block is,
	 * we also shift the list head to where we stopped last time
	 */
	search_head = my_rsv;
	spin_lock(rsv_lock);
	goto retry;
}

/**
 * try_to_extend_reservation()
 * @my_rsv:		given reservation window
 * @sb:			super block
 * @size:		the delta to extend
 *
 * Attempt to expand the reservation window large enough to have
 * required number of free blocks
 *
1170
 * Since ext4_try_to_allocate() will always allocate blocks within
1171 1172 1173 1174 1175
 * the reservation window range, if the window size is too small,
 * multiple blocks allocation has to stop at the end of the reservation
 * window. To make this more efficient, given the total number of
 * blocks needed and the current size of the window, we try to
 * expand the reservation window size if necessary on a best-effort
1176
 * basis before ext4_new_blocks() tries to allocate blocks,
1177
 */
1178
static void try_to_extend_reservation(struct ext4_reserve_window_node *my_rsv,
1179 1180
			struct super_block *sb, int size)
{
1181
	struct ext4_reserve_window_node *next_rsv;
1182
	struct rb_node *next;
1183
	spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
1184 1185 1186 1187 1188 1189 1190 1191 1192

	if (!spin_trylock(rsv_lock))
		return;

	next = rb_next(&my_rsv->rsv_node);

	if (!next)
		my_rsv->rsv_end += size;
	else {
1193
		next_rsv = list_entry(next, struct ext4_reserve_window_node, rsv_node);
1194 1195 1196 1197 1198 1199 1200 1201 1202 1203

		if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
			my_rsv->rsv_end += size;
		else
			my_rsv->rsv_end = next_rsv->rsv_start - 1;
	}
	spin_unlock(rsv_lock);
}

/**
1204
 * ext4_try_to_allocate_with_rsv()
1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231
 * @sb:			superblock
 * @handle:		handle to this transaction
 * @group:		given allocation block group
 * @bitmap_bh:		bufferhead holds the block bitmap
 * @grp_goal:		given target block within the group
 * @count:		target number of blocks to allocate
 * @my_rsv:		reservation window
 * @errp:		pointer to store the error code
 *
 * This is the main function used to allocate a new block and its reservation
 * window.
 *
 * Each time when a new block allocation is need, first try to allocate from
 * its own reservation.  If it does not have a reservation window, instead of
 * looking for a free bit on bitmap first, then look up the reservation list to
 * see if it is inside somebody else's reservation window, we try to allocate a
 * reservation window for it starting from the goal first. Then do the block
 * allocation within the reservation window.
 *
 * This will avoid keeping on searching the reservation list again and
 * again when somebody is looking for a free block (without
 * reservation), and there are lots of free blocks, but they are all
 * being reserved.
 *
 * We use a red-black tree for the per-filesystem reservation list.
 *
 */
1232 1233
static ext4_grpblk_t
ext4_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1234
			unsigned int group, struct buffer_head *bitmap_bh,
1235 1236
			ext4_grpblk_t grp_goal,
			struct ext4_reserve_window_node * my_rsv,
1237 1238
			unsigned long *count, int *errp)
{
1239 1240
	ext4_fsblk_t group_first_block, group_last_block;
	ext4_grpblk_t ret = 0;
1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251
	int fatal;
	unsigned long num = *count;

	*errp = 0;

	/*
	 * Make sure we use undo access for the bitmap, because it is critical
	 * that we do the frozen_data COW on bitmap buffers in all cases even
	 * if the buffer is in BJ_Forget state in the committing transaction.
	 */
	BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1252
	fatal = ext4_journal_get_undo_access(handle, bitmap_bh);
1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264
	if (fatal) {
		*errp = fatal;
		return -1;
	}

	/*
	 * we don't deal with reservation when
	 * filesystem is mounted without reservation
	 * or the file is not a regular file
	 * or last attempt to allocate a block with reservation turned on failed
	 */
	if (my_rsv == NULL ) {
1265
		ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
1266 1267 1268 1269 1270
						grp_goal, count, NULL);
		goto out;
	}
	/*
	 * grp_goal is a group relative block number (if there is a goal)
1271
	 * 0 < grp_goal < EXT4_BLOCKS_PER_GROUP(sb)
1272 1273 1274
	 * first block is a filesystem wide block number
	 * first block is the block number of the first block in this group
	 */
1275 1276
	group_first_block = ext4_group_first_block_no(sb, group);
	group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313

	/*
	 * Basically we will allocate a new block from inode's reservation
	 * window.
	 *
	 * We need to allocate a new reservation window, if:
	 * a) inode does not have a reservation window; or
	 * b) last attempt to allocate a block from existing reservation
	 *    failed; or
	 * c) we come here with a goal and with a reservation window
	 *
	 * We do not need to allocate a new reservation window if we come here
	 * at the beginning with a goal and the goal is inside the window, or
	 * we don't have a goal but already have a reservation window.
	 * then we could go to allocate from the reservation window directly.
	 */
	while (1) {
		if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
			!goal_in_my_reservation(&my_rsv->rsv_window,
						grp_goal, group, sb)) {
			if (my_rsv->rsv_goal_size < *count)
				my_rsv->rsv_goal_size = *count;
			ret = alloc_new_reservation(my_rsv, grp_goal, sb,
							group, bitmap_bh);
			if (ret < 0)
				break;			/* failed */

			if (!goal_in_my_reservation(&my_rsv->rsv_window,
							grp_goal, group, sb))
				grp_goal = -1;
		} else if (grp_goal > 0 &&
			  (my_rsv->rsv_end-grp_goal+1) < *count)
			try_to_extend_reservation(my_rsv, sb,
					*count-my_rsv->rsv_end + grp_goal - 1);

		if ((my_rsv->rsv_start > group_last_block) ||
				(my_rsv->rsv_end < group_first_block)) {
1314
			rsv_window_dump(&EXT4_SB(sb)->s_rsv_window_root, 1);
1315 1316
			BUG();
		}
1317
		ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329
					   grp_goal, &num, &my_rsv->rsv_window);
		if (ret >= 0) {
			my_rsv->rsv_alloc_hit += num;
			*count = num;
			break;				/* succeed */
		}
		num = *count;
	}
out:
	if (ret >= 0) {
		BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
					"bitmap block");
1330
		fatal = ext4_journal_dirty_metadata(handle, bitmap_bh);
1331 1332 1333 1334 1335 1336 1337 1338
		if (fatal) {
			*errp = fatal;
			return -1;
		}
		return ret;
	}

	BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1339
	ext4_journal_release_buffer(handle, bitmap_bh);
1340 1341 1342 1343
	return ret;
}

/**
1344
 * ext4_has_free_blocks()
1345 1346 1347 1348
 * @sbi:		in-core super block structure.
 *
 * Check if filesystem has at least 1 free block available for allocation.
 */
1349
static int ext4_has_free_blocks(struct ext4_sb_info *sbi)
1350
{
1351
	ext4_fsblk_t free_blocks, root_blocks;
1352 1353

	free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
L
Laurent Vivier 已提交
1354
	root_blocks = ext4_r_blocks_count(sbi->s_es);
1355 1356 1357 1358 1359 1360 1361 1362 1363
	if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
		sbi->s_resuid != current->fsuid &&
		(sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
		return 0;
	}
	return 1;
}

/**
1364
 * ext4_should_retry_alloc()
1365 1366 1367
 * @sb:			super block
 * @retries		number of attemps has been made
 *
1368
 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
1369 1370 1371 1372 1373 1374
 * it is profitable to retry the operation, this function will wait
 * for the current or commiting transaction to complete, and then
 * return TRUE.
 *
 * if the total number of retries exceed three times, return FALSE.
 */
1375
int ext4_should_retry_alloc(struct super_block *sb, int *retries)
1376
{
1377
	if (!ext4_has_free_blocks(EXT4_SB(sb)) || (*retries)++ > 3)
1378 1379 1380 1381
		return 0;

	jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);

1382
	return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
1383 1384 1385
}

/**
1386
 * ext4_new_blocks() -- core block(s) allocation function
1387 1388 1389 1390 1391 1392
 * @handle:		handle to this transaction
 * @inode:		file inode
 * @goal:		given target block(filesystem wide)
 * @count:		target number of blocks to allocate
 * @errp:		error code
 *
1393
 * ext4_new_blocks uses a goal block to assist allocation.  It tries to
1394 1395 1396 1397 1398
 * allocate block(s) from the block group contains the goal block first. If that
 * fails, it will try to allocate block(s) from other block groups without
 * any specific goal block.
 *
 */
1399 1400
ext4_fsblk_t ext4_new_blocks(handle_t *handle, struct inode *inode,
			ext4_fsblk_t goal, unsigned long *count, int *errp)
1401 1402 1403
{
	struct buffer_head *bitmap_bh = NULL;
	struct buffer_head *gdp_bh;
1404
	unsigned long group_no;
1405
	int goal_group;
1406 1407 1408
	ext4_grpblk_t grp_target_blk;	/* blockgroup relative goal block */
	ext4_grpblk_t grp_alloc_blk;	/* blockgroup-relative allocated block*/
	ext4_fsblk_t ret_block;		/* filesyetem-wide allocated block */
1409 1410 1411
	int bgi;			/* blockgroup iteration index */
	int fatal = 0, err;
	int performed_allocation = 0;
1412
	ext4_grpblk_t free_blocks;	/* number of free blocks in a group */
1413
	struct super_block *sb;
1414 1415 1416 1417 1418
	struct ext4_group_desc *gdp;
	struct ext4_super_block *es;
	struct ext4_sb_info *sbi;
	struct ext4_reserve_window_node *my_rsv = NULL;
	struct ext4_block_alloc_info *block_i;
1419
	unsigned short windowsz = 0;
1420
#ifdef EXT4FS_DEBUG
1421 1422 1423 1424 1425 1426 1427 1428
	static int goal_hits, goal_attempts;
#endif
	unsigned long ngroups;
	unsigned long num = *count;

	*errp = -ENOSPC;
	sb = inode->i_sb;
	if (!sb) {
1429
		printk("ext4_new_block: nonexistent device");
1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440
		return 0;
	}

	/*
	 * Check quota for allocation of this block.
	 */
	if (DQUOT_ALLOC_BLOCK(inode, num)) {
		*errp = -EDQUOT;
		return 0;
	}

1441 1442 1443
	sbi = EXT4_SB(sb);
	es = EXT4_SB(sb)->s_es;
	ext4_debug("goal=%lu.\n", goal);
1444 1445 1446 1447 1448
	/*
	 * Allocate a block from reservation only when
	 * filesystem is mounted with reservation(default,-o reservation), and
	 * it's a regular file, and
	 * the desired window size is greater than 0 (One could use ioctl
1449
	 * command EXT4_IOC_SETRSVSZ to set the window size to 0 to turn off
1450 1451
	 * reservation on that particular file)
	 */
1452
	block_i = EXT4_I(inode)->i_block_alloc_info;
1453 1454 1455
	if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
		my_rsv = &block_i->rsv_window_node;

1456
	if (!ext4_has_free_blocks(sbi)) {
1457 1458 1459 1460 1461 1462 1463 1464
		*errp = -ENOSPC;
		goto out;
	}

	/*
	 * First, test whether the goal block is free.
	 */
	if (goal < le32_to_cpu(es->s_first_data_block) ||
L
Laurent Vivier 已提交
1465
	    goal >= ext4_blocks_count(es))
1466
		goal = le32_to_cpu(es->s_first_data_block);
1467
	ext4_get_group_no_and_offset(sb, goal, &group_no, &grp_target_blk);
1468 1469
	goal_group = group_no;
retry_alloc:
1470
	gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486
	if (!gdp)
		goto io_error;

	free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
	/*
	 * if there is not enough free blocks to make a new resevation
	 * turn off reservation for this allocation
	 */
	if (my_rsv && (free_blocks < windowsz)
		&& (rsv_is_empty(&my_rsv->rsv_window)))
		my_rsv = NULL;

	if (free_blocks > 0) {
		bitmap_bh = read_block_bitmap(sb, group_no);
		if (!bitmap_bh)
			goto io_error;
1487
		grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
1488 1489 1490 1491 1492 1493 1494 1495
					group_no, bitmap_bh, grp_target_blk,
					my_rsv,	&num, &fatal);
		if (fatal)
			goto out;
		if (grp_alloc_blk >= 0)
			goto allocated;
	}

1496
	ngroups = EXT4_SB(sb)->s_groups_count;
1497 1498 1499 1500 1501 1502 1503 1504 1505 1506
	smp_rmb();

	/*
	 * Now search the rest of the groups.  We assume that
	 * i and gdp correctly point to the last group visited.
	 */
	for (bgi = 0; bgi < ngroups; bgi++) {
		group_no++;
		if (group_no >= ngroups)
			group_no = 0;
1507
		gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527
		if (!gdp) {
			*errp = -EIO;
			goto out;
		}
		free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
		/*
		 * skip this group if the number of
		 * free blocks is less than half of the reservation
		 * window size.
		 */
		if (free_blocks <= (windowsz/2))
			continue;

		brelse(bitmap_bh);
		bitmap_bh = read_block_bitmap(sb, group_no);
		if (!bitmap_bh)
			goto io_error;
		/*
		 * try to allocate block(s) from this group, without a goal(-1).
		 */
1528
		grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553
					group_no, bitmap_bh, -1, my_rsv,
					&num, &fatal);
		if (fatal)
			goto out;
		if (grp_alloc_blk >= 0)
			goto allocated;
	}
	/*
	 * We may end up a bogus ealier ENOSPC error due to
	 * filesystem is "full" of reservations, but
	 * there maybe indeed free blocks avaliable on disk
	 * In this case, we just forget about the reservations
	 * just do block allocation as without reservations.
	 */
	if (my_rsv) {
		my_rsv = NULL;
		group_no = goal_group;
		goto retry_alloc;
	}
	/* No space left on the device */
	*errp = -ENOSPC;
	goto out;

allocated:

1554
	ext4_debug("using block group %d(%d)\n",
1555 1556 1557
			group_no, gdp->bg_free_blocks_count);

	BUFFER_TRACE(gdp_bh, "get_write_access");
1558
	fatal = ext4_journal_get_write_access(handle, gdp_bh);
1559 1560 1561
	if (fatal)
		goto out;

1562
	ret_block = grp_alloc_blk + ext4_group_first_block_no(sb, group_no);
1563

L
Laurent Vivier 已提交
1564 1565 1566 1567 1568 1569
	if (in_range(ext4_block_bitmap(gdp), ret_block, num) ||
	    in_range(ext4_block_bitmap(gdp), ret_block, num) ||
	    in_range(ret_block, ext4_inode_table(gdp),
		     EXT4_SB(sb)->s_itb_per_group) ||
	    in_range(ret_block + num - 1, ext4_inode_table(gdp),
		     EXT4_SB(sb)->s_itb_per_group))
1570
		ext4_error(sb, "ext4_new_block",
1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594
			    "Allocating block in system zone - "
			    "blocks from "E3FSBLK", length %lu",
			     ret_block, num);

	performed_allocation = 1;

#ifdef CONFIG_JBD_DEBUG
	{
		struct buffer_head *debug_bh;

		/* Record bitmap buffer state in the newly allocated block */
		debug_bh = sb_find_get_block(sb, ret_block);
		if (debug_bh) {
			BUFFER_TRACE(debug_bh, "state when allocated");
			BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
			brelse(debug_bh);
		}
	}
	jbd_lock_bh_state(bitmap_bh);
	spin_lock(sb_bgl_lock(sbi, group_no));
	if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
		int i;

		for (i = 0; i < num; i++) {
1595
			if (ext4_test_bit(grp_alloc_blk+i,
1596 1597 1598 1599 1600 1601
					bh2jh(bitmap_bh)->b_committed_data)) {
				printk("%s: block was unexpectedly set in "
					"b_committed_data\n", __FUNCTION__);
			}
		}
	}
1602
	ext4_debug("found bit %d\n", grp_alloc_blk);
1603 1604 1605 1606
	spin_unlock(sb_bgl_lock(sbi, group_no));
	jbd_unlock_bh_state(bitmap_bh);
#endif

L
Laurent Vivier 已提交
1607
	if (ret_block + num - 1 >= ext4_blocks_count(es)) {
1608
		ext4_error(sb, "ext4_new_block",
L
Laurent Vivier 已提交
1609
			    "block("E3FSBLK") >= blocks count("E3FSBLK") - "
1610
			    "block_group = %lu, es == %p ", ret_block,
L
Laurent Vivier 已提交
1611
			ext4_blocks_count(es), group_no, es);
1612 1613 1614 1615 1616 1617 1618 1619
		goto out;
	}

	/*
	 * It is up to the caller to add the new buffer to a journal
	 * list of some description.  We don't know in advance whether
	 * the caller wants to use it as metadata or data.
	 */
1620
	ext4_debug("allocating block %lu. Goal hits %d of %d.\n",
1621 1622 1623 1624 1625 1626 1627 1628 1629
			ret_block, goal_hits, goal_attempts);

	spin_lock(sb_bgl_lock(sbi, group_no));
	gdp->bg_free_blocks_count =
			cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)-num);
	spin_unlock(sb_bgl_lock(sbi, group_no));
	percpu_counter_mod(&sbi->s_freeblocks_counter, -num);

	BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1630
	err = ext4_journal_dirty_metadata(handle, gdp_bh);
1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648
	if (!fatal)
		fatal = err;

	sb->s_dirt = 1;
	if (fatal)
		goto out;

	*errp = 0;
	brelse(bitmap_bh);
	DQUOT_FREE_BLOCK(inode, *count-num);
	*count = num;
	return ret_block;

io_error:
	*errp = -EIO;
out:
	if (fatal) {
		*errp = fatal;
1649
		ext4_std_error(sb, fatal);
1650 1651 1652 1653 1654 1655 1656 1657 1658 1659
	}
	/*
	 * Undo the block allocation
	 */
	if (!performed_allocation)
		DQUOT_FREE_BLOCK(inode, *count);
	brelse(bitmap_bh);
	return 0;
}

1660 1661
ext4_fsblk_t ext4_new_block(handle_t *handle, struct inode *inode,
			ext4_fsblk_t goal, int *errp)
1662 1663 1664
{
	unsigned long count = 1;

1665
	return ext4_new_blocks(handle, inode, goal, &count, errp);
1666 1667 1668
}

/**
1669
 * ext4_count_free_blocks() -- count filesystem free blocks
1670 1671 1672 1673
 * @sb:		superblock
 *
 * Adds up the number of free blocks from each block group.
 */
1674
ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
1675
{
1676 1677
	ext4_fsblk_t desc_count;
	struct ext4_group_desc *gdp;
1678
	int i;
1679 1680 1681 1682
	unsigned long ngroups = EXT4_SB(sb)->s_groups_count;
#ifdef EXT4FS_DEBUG
	struct ext4_super_block *es;
	ext4_fsblk_t bitmap_count;
1683 1684 1685
	unsigned long x;
	struct buffer_head *bitmap_bh = NULL;

1686
	es = EXT4_SB(sb)->s_es;
1687 1688 1689 1690 1691 1692
	desc_count = 0;
	bitmap_count = 0;
	gdp = NULL;

	smp_rmb();
	for (i = 0; i < ngroups; i++) {
1693
		gdp = ext4_get_group_desc(sb, i, NULL);
1694 1695 1696 1697 1698 1699 1700 1701
		if (!gdp)
			continue;
		desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
		brelse(bitmap_bh);
		bitmap_bh = read_block_bitmap(sb, i);
		if (bitmap_bh == NULL)
			continue;

1702
		x = ext4_count_free(bitmap_bh, sb->s_blocksize);
1703 1704 1705 1706 1707
		printk("group %d: stored = %d, counted = %lu\n",
			i, le16_to_cpu(gdp->bg_free_blocks_count), x);
		bitmap_count += x;
	}
	brelse(bitmap_bh);
1708
	printk("ext4_count_free_blocks: stored = "E3FSBLK
1709
		", computed = "E3FSBLK", "E3FSBLK"\n",
L
Laurent Vivier 已提交
1710
	       EXT4_FREE_BLOCKS_COUNT(es),
1711 1712 1713 1714 1715 1716
		desc_count, bitmap_count);
	return bitmap_count;
#else
	desc_count = 0;
	smp_rmb();
	for (i = 0; i < ngroups; i++) {
1717
		gdp = ext4_get_group_desc(sb, i, NULL);
1718 1719 1720 1721 1722 1723 1724 1725 1726 1727
		if (!gdp)
			continue;
		desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
	}

	return desc_count;
#endif
}

static inline int
1728
block_in_use(ext4_fsblk_t block, struct super_block *sb, unsigned char *map)
1729
{
1730 1731 1732 1733
	ext4_grpblk_t offset;

	ext4_get_group_no_and_offset(sb, block, NULL, &offset);
	return ext4_test_bit (offset, map);
1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744
}

static inline int test_root(int a, int b)
{
	int num = b;

	while (a > num)
		num *= b;
	return num == a;
}

1745
static int ext4_group_sparse(int group)
1746 1747 1748 1749 1750 1751 1752 1753 1754 1755
{
	if (group <= 1)
		return 1;
	if (!(group & 1))
		return 0;
	return (test_root(group, 7) || test_root(group, 5) ||
		test_root(group, 3));
}

/**
1756
 *	ext4_bg_has_super - number of blocks used by the superblock in group
1757 1758 1759 1760 1761 1762
 *	@sb: superblock for filesystem
 *	@group: group number to check
 *
 *	Return the number of blocks used by the superblock (primary or backup)
 *	in this group.  Currently this will be only 0 or 1.
 */
1763
int ext4_bg_has_super(struct super_block *sb, int group)
1764
{
1765 1766 1767
	if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
				EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
			!ext4_group_sparse(group))
1768 1769 1770 1771
		return 0;
	return 1;
}

1772
static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, int group)
1773
{
1774 1775 1776
	unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
	unsigned long first = metagroup * EXT4_DESC_PER_BLOCK(sb);
	unsigned long last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
1777 1778 1779 1780 1781 1782

	if (group == first || group == first + 1 || group == last)
		return 1;
	return 0;
}

1783
static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, int group)
1784
{
1785 1786 1787
	if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
				EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
			!ext4_group_sparse(group))
1788
		return 0;
1789
	return EXT4_SB(sb)->s_gdb_count;
1790 1791 1792
}

/**
1793
 *	ext4_bg_num_gdb - number of blocks used by the group table in group
1794 1795 1796 1797 1798 1799 1800
 *	@sb: superblock for filesystem
 *	@group: group number to check
 *
 *	Return the number of blocks used by the group descriptor table
 *	(primary or backup) in this group.  In the future there may be a
 *	different number of descriptor blocks in each group.
 */
1801
unsigned long ext4_bg_num_gdb(struct super_block *sb, int group)
1802 1803
{
	unsigned long first_meta_bg =
1804 1805
			le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
	unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
1806

1807
	if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
1808
			metagroup < first_meta_bg)
1809
		return ext4_bg_num_gdb_nometa(sb,group);
1810

1811
	return ext4_bg_num_gdb_meta(sb,group);
1812 1813

}