archives/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-03-08 03:24:45 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

ocfs2: avoid potential ABBA deadlock by reordering tl_inode lock

Browse source 
In ocfs2_move_extent(), tl_inode is currently locked after the global
bitmap inode.  However, in ocfs2_flush_truncate_log(), the lock order is
reversed: tl_inode is locked first, followed by the global bitmap inode.

This creates a classic ABBA deadlock scenario if two threads attempt these
operations concurrently and acquire the locks in different orders.

To prevent this, move the tl_inode locking earlier in ocfs2_move_extent(),
so that it always precedes the global bitmap inode lock.

No functional changes beyond lock ordering.

Link: https://lkml.kernel.org/r/20250708020640.387741-1-ipravdin.official@gmail.com
Reported-by: syzbot+6bf948e47f9bac7aacfa@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/67d5645c.050a0220.1dc86f.0004.GAE@google.com/
Signed-off-by: Ivan Pravdin <ipravdin.official@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ivan Pravdin 2025-07-07 22:06:40 -04:00 • committed by Andrew Morton
parent 97103dcec2
commit 08eabe4b9e
1 changed files with 9 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

19
fs/ocfs2/move_extents.c
View file

@ -617,6 +617,8 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
*/
credits += OCFS2_INODE_UPDATE_CREDITS + 1;
inode_lock(tl_inode);
/*
* ocfs2_move_extent() didn't reserve any clusters in lock_allocators()
* logic, while we still need to lock the global_bitmap.
@ -626,7 +628,7 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
if (!gb_inode) {
mlog(ML_ERROR, "unable to get global_bitmap inode\n");
ret = -EIO;
goto out;
goto out_unlock_tl_inode;
}
inode_lock(gb_inode);
@ -634,16 +636,14 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
ret = ocfs2_inode_lock(gb_inode, &gb_bh, 1);
if (ret) {
mlog_errno(ret);
goto out_unlock_gb_mutex;
goto out_unlock_gb_inode;
}
inode_lock(tl_inode);
handle = ocfs2_start_trans(osb, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
mlog_errno(ret);
goto out_unlock_tl_inode;
goto out_unlock;
}
new_phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, *new_phys_cpos);
@ -703,15 +703,14 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
out_commit:
ocfs2_commit_trans(osb, handle);
brelse(gd_bh);
out_unlock_tl_inode:
inode_unlock(tl_inode);
out_unlock:
ocfs2_inode_unlock(gb_inode, 1);
out_unlock_gb_mutex:
out_unlock_gb_inode:
inode_unlock(gb_inode);
brelse(gb_bh);
iput(gb_inode);
out_unlock_tl_inode:
inode_unlock(tl_inode);
out:
if (context->meta_ac) {