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| author | Theodore Ts'o <tytso@mit.edu> | 2020-11-11 14:24:18 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2020-11-11 14:24:18 -0500 |
| commit | d196e229a80c39254f4adbc312f55f5198e98941 (patch) | |
| tree | 3542a6e980e10e37782dfc7046c83e0ddefa587e /fs | |
| parent | a72b38eebea4661d4d67b194353124e63ce48f66 (diff) | |
| download | lwn-d196e229a80c39254f4adbc312f55f5198e98941.tar.gz lwn-d196e229a80c39254f4adbc312f55f5198e98941.zip | |
Revert "ext4: fix superblock checksum calculation race"
This reverts commit acaa532687cdc3a03757defafece9c27aa667546 which can
result in a ext4_superblock_csum_set() trying to sleep while a
spinlock is being held.
For more discussion of this issue, please see:
https://lore.kernel.org/r/000000000000f50cb705b313ed70@google.com
Reported-by: syzbot+7a4ba6a239b91a126c28@syzkaller.appspotmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/super.c | 11 |
1 files changed, 0 insertions, 11 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c3b864588a0b..6633b20224d5 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -289,18 +289,7 @@ void ext4_superblock_csum_set(struct super_block *sb) if (!ext4_has_metadata_csum(sb)) return; - /* - * Locking the superblock prevents the scenario - * where: - * 1) a first thread pauses during checksum calculation. - * 2) a second thread updates the superblock, recalculates - * the checksum, and updates s_checksum - * 3) the first thread resumes and finishes its checksum calculation - * and updates s_checksum with a potentially stale or torn value. - */ - lock_buffer(EXT4_SB(sb)->s_sbh); es->s_checksum = ext4_superblock_csum(sb, es); - unlock_buffer(EXT4_SB(sb)->s_sbh); } ext4_fsblk_t ext4_block_bitmap(struct super_block *sb, |