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ext4: make ext4_es_lookup_extent() pass out the extent seq counter

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When querying extents in the extent status tree, we should hold the
data_sem if we want to obtain the sequence number as a valid cookie
simultaneously. However, currently, ext4_map_blocks() calls
ext4_es_lookup_extent() without holding data_sem. Therefore, we should
acquire i_es_lock instead, which also ensures that the sequence cookie
and the extent remain consistent. Consequently, make
ext4_es_lookup_extent() to pass out the sequence number when necessary.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-ID: <20251013015128.499308-4-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi
2025-10-13 09:51:19 +08:00
committed by Theodore Ts'o
parent dd064d5101
commit 7da5565cab
4 changed files with 10 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
fs/ext4/extents.c
View File

@@ -2213,7 +2213,7 @@ static int ext4_fill_es_cache_info(struct inode *inode,
while (block <= end) {
next = 0;
flags = 0;
if (!ext4_es_lookup_extent(inode, block, &next, &es))
if (!ext4_es_lookup_extent(inode, block, &next, &es, NULL))
break;
if (ext4_es_is_unwritten(&es))
flags |= FIEMAP_EXTENT_UNWRITTEN;

6
fs/ext4/extents_status.c
View File

@@ -1039,8 +1039,8 @@ void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk,
* Return: 1 on found, 0 on not
*/
int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
ext4_lblk_t *next_lblk,
struct extent_status *es)
ext4_lblk_t *next_lblk, struct extent_status *es,
u64 *pseq)
{
struct ext4_es_tree *tree;
struct ext4_es_stats *stats;
@@ -1099,6 +1099,8 @@ out:
} else
*next_lblk = 0;
}
if (pseq)
*pseq = EXT4_I(inode)->i_es_seq;
} else {
percpu_counter_inc(&stats->es_stats_cache_misses);
}

2
fs/ext4/extents_status.h
View File

@@ -148,7 +148,7 @@ extern void ext4_es_find_extent_range(struct inode *inode,
struct extent_status *es);
extern int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
ext4_lblk_t *next_lblk,
struct extent_status *es);
struct extent_status *es, u64 *pseq);
extern bool ext4_es_scan_range(struct inode *inode,
int (*matching_fn)(struct extent_status *es),
ext4_lblk_t lblk, ext4_lblk_t end);

8
fs/ext4/inode.c
View File

@@ -649,7 +649,7 @@ static int ext4_map_create_blocks(handle_t *handle, struct inode *inode,
* extent status tree.
*/
if (flags & EXT4_GET_BLOCKS_PRE_IO &&
ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
if (ext4_es_is_written(&es))
return retval;
}
@@ -723,7 +723,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
ext4_check_map_extents_env(inode);
/* Lookup extent status tree firstly */
if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
map->m_pblk = ext4_es_pblock(&es) +
map->m_lblk - es.es_lblk;
@@ -1908,7 +1908,7 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map)
ext4_check_map_extents_env(inode);
/* Lookup extent status tree firstly */
if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
map->m_len = min_t(unsigned int, map->m_len,
es.es_len - (map->m_lblk - es.es_lblk));
@@ -1961,7 +1961,7 @@ add_delayed:
* is held in write mode, before inserting a new da entry in
* the extent status tree.
*/
if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
map->m_len = min_t(unsigned int, map->m_len,
es.es_len - (map->m_lblk - es.es_lblk));