Commit 42ad7b23 authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

ext4: make __es_remove_extent() check extent status 



Currently, __es_remove_extent() unconditionally removes extent status
entries within the specified range. In order to prepare for extending
the ext4_es_cache_extent() function to cache on-disk extents, which may
overwrite some existing short-length extents with the same status, allow
__es_remove_extent() to check the specified extent type before removing
it, and return error and pass out the conflicting extent if the status
does not match.

Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarBaokun Li <libaokun1@huawei.com>
Message-ID: <20251129103247.686136-11-yi.zhang@huaweicloud.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent ef46e0d7

fs/ext4/extents_status.c

+41 −8
Original line number Diff line number Diff line
@@ -178,7 +178,8 @@ static struct kmem_cache *ext4_pending_cachep; 
static int __es_insert_extent(struct inode *inode, struct extent_status *newes,

			      struct extent_status *prealloc);

static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,

			      ext4_lblk_t end, int *reserved,

			      ext4_lblk_t end, unsigned int status,

			      int *reserved, struct extent_status *res,

			      struct extent_status *prealloc);

static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan);

static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
@@ -242,6 +243,21 @@ static inline void ext4_es_inc_seq(struct inode *inode) 
	WRITE_ONCE(ei->i_es_seq, ei->i_es_seq + 1);

}



static inline int __es_check_extent_status(struct extent_status *es,

					   unsigned int status,

					   struct extent_status *res)

{

	if (ext4_es_type(es) & status)

		return 0;



	if (res) {

		res->es_lblk = es->es_lblk;

		res->es_len = es->es_len;

		res->es_pblk = es->es_pblk;

	}

	return -EINVAL;

}



/*

 * search through the tree for an delayed extent with a given offset.  If

 * it can't be found, try to find next extent.
@@ -929,7 +945,7 @@ void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk, 
		pr = __alloc_pending(true);

	write_lock(&EXT4_I(inode)->i_es_lock);



	err1 = __es_remove_extent(inode, lblk, end, &resv_used, es1);

	err1 = __es_remove_extent(inode, lblk, end, 0, &resv_used, NULL, es1);

	if (err1 != 0)

		goto error;

	/* Free preallocated extent if it didn't get used. */
@@ -1409,23 +1425,27 @@ static unsigned int get_rsvd(struct inode *inode, ext4_lblk_t end, 
	return rc->ndelayed;

}





/*

 * __es_remove_extent - removes block range from extent status tree

 *

 * @inode - file containing range

 * @lblk - first block in range

 * @end - last block in range

 * @status - the extent status to be checked

 * @reserved - number of cluster reservations released

 * @res - return the extent if the status is not match

 * @prealloc - pre-allocated es to avoid memory allocation failures

 *

 * If @reserved is not NULL and delayed allocation is enabled, counts

 * block/cluster reservations freed by removing range and if bigalloc

 * enabled cancels pending reservations as needed. Returns 0 on success,

 * error code on failure.

 * enabled cancels pending reservations as needed. If @status is not

 * zero, check extent status type while removing extent, return -EINVAL

 * and pass out the extent through @res if not match.  Returns 0 on

 * success, error code on failure.

 */

static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,

			      ext4_lblk_t end, int *reserved,

			      ext4_lblk_t end, unsigned int status,

			      int *reserved, struct extent_status *res,

			      struct extent_status *prealloc)

{

	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
@@ -1440,6 +1460,8 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, 


	if (reserved == NULL || !test_opt(inode->i_sb, DELALLOC))

		count_reserved = false;

	if (status == 0)

		status = ES_TYPE_MASK;



	es = __es_tree_search(&tree->root, lblk);

	if (!es)
@@ -1447,6 +1469,10 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, 
	if (es->es_lblk > end)

		return 0;



	err = __es_check_extent_status(es, status, res);

	if (err)

		return err;



	/* Simply invalidate cache_es. */

	tree->cache_es = NULL;

	if (count_reserved)
@@ -1509,6 +1535,9 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, 
	}



	while (es && ext4_es_end(es) <= end) {

		err = __es_check_extent_status(es, status, res);

		if (err)

			return err;

		if (count_reserved)

			count_rsvd(inode, es->es_lblk, es->es_len, es, &rc);

		node = rb_next(&es->rb_node);
@@ -1524,6 +1553,10 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, 
	if (es && es->es_lblk < end + 1) {

		ext4_lblk_t orig_len = es->es_len;



		err = __es_check_extent_status(es, status, res);

		if (err)

			return err;



		len1 = ext4_es_end(es) - end;

		if (count_reserved)

			count_rsvd(inode, es->es_lblk, orig_len - len1,
@@ -1581,7 +1614,7 @@ void ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk, 
	 * is reclaimed.

	 */

	write_lock(&EXT4_I(inode)->i_es_lock);

	err = __es_remove_extent(inode, lblk, end, &reserved, es);

	err = __es_remove_extent(inode, lblk, end, 0, &reserved, NULL, es);

	if (err)

		goto error;

	/* Free preallocated extent if it didn't get used. */
@@ -2173,7 +2206,7 @@ void ext4_es_insert_delayed_extent(struct inode *inode, ext4_lblk_t lblk, 
	}

	write_lock(&EXT4_I(inode)->i_es_lock);



	err1 = __es_remove_extent(inode, lblk, end, NULL, es1);

	err1 = __es_remove_extent(inode, lblk, end, 0, NULL, NULL, es1);

	if (err1 != 0)

		goto error;

	/* Free preallocated extent if it didn't get used. */