diff options
| author | Zhang Yi <yi.zhang@huawei.com> | 2025-04-23 16:52:53 +0800 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2025-05-14 10:42:12 -0400 |
| commit | f22a0ef2231a7d8374bb021eb86404d0e9de5a02 (patch) | |
| tree | e5f548b862779def0d2efe7d3a11eeaa7ef8d22e | |
| parent | 151ff9325e5e17c97839a00b740726656b04647b (diff) | |
ext4: prevent stale extent cache entries caused by concurrent get es_cache
The EXT4_IOC_GET_ES_CACHE and EXT4_IOC_PRECACHE_EXTENTS currently
invokes ext4_ext_precache() to preload the extent cache without holding
the inode's i_rwsem. This can result in stale extent cache entries when
competing with operations such as ext4_collapse_range() which calls
ext4_ext_remove_space() or ext4_ext_shift_extents().
The problem arises when ext4_ext_remove_space() temporarily releases
i_data_sem due to insufficient journal credits. During this interval, a
concurrent EXT4_IOC_GET_ES_CACHE or EXT4_IOC_PRECACHE_EXTENTS may cache
extent entries that are about to be deleted. As a result, these cached
entries become stale and inconsistent with the actual extents.
Loading the extents cache without holding the inode's i_rwsem or the
mapping's invalidate_lock is not permitted besides during the writeback.
Fix this by holding the i_rwsem during EXT4_IOC_GET_ES_CACHE and
EXT4_IOC_PRECACHE_EXTENTS.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250423085257.122685-6-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/extents.c | 2 | ||||
| -rw-r--r-- | fs/ext4/ioctl.c | 8 |
2 files changed, 9 insertions, 1 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 3adf05fbdd59..b5eb89ef7ae2 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -5011,7 +5011,9 @@ int ext4_get_es_cache(struct inode *inode, struct fiemap_extent_info *fieinfo, } if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) { + inode_lock_shared(inode); error = ext4_ext_precache(inode); + inode_unlock_shared(inode); if (error) return error; fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE; diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index d17207386ead..0e240013c84d 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -1505,8 +1505,14 @@ resizefs_out: return 0; } case EXT4_IOC_PRECACHE_EXTENTS: - return ext4_ext_precache(inode); + { + int ret; + inode_lock_shared(inode); + ret = ext4_ext_precache(inode); + inode_unlock_shared(inode); + return ret; + } case FS_IOC_SET_ENCRYPTION_POLICY: if (!ext4_has_feature_encrypt(sb)) return -EOPNOTSUPP; |