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ocfs2: use inode_lock_nested() for orphan dir locking

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PREEMPT_RT's rtmutex PI chain walker warns about a lock dependency cycle
when inode_lock(orphan_dir_inode) is called while holding
inode_lock(file_inode):

  ocfs2_file_write_iter()
    inode_lock(file_inode)               [class 0]
      ocfs2_dio_end_io_write()
        ocfs2_del_inode_from_orphan()
          inode_lock(orphan_dir_inode)   [class 0] <- warning!

However this is a false positive.  write_iter() is never called on a
directory, and orphan_dir is always a directory, so these two locks can
never actually conflict in practice.

Fix by using inode_lock_nested(orphan_dir_inode, I_MUTEX_NONDIR2) in all
three places where orphan_dir_inode is locked in namei.c, placing it in a
separate lock class so the rtmutex PI chain walker understands these locks
have distinct roles and does not warn about their ordering.

Link: https://lore.kernel.org/20260620231223.46588-1-kartikey406@gmail.com
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reported-by: syzbot+ce129763ce7d7e914739@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ce129763ce7d7e914739
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>
Cc: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Deepanshu Kartikey
2026-06-21 04:42:23 +05:30
committed by Andrew Morton
parent 688bc88e20
commit 2fdf181afd
1 changed files with 3 additions and 3 deletions
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6
fs/ocfs2/namei.c
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@@ -2126,7 +2126,7 @@ static int ocfs2_lookup_lock_orphan_dir(struct ocfs2_super *osb,
return ret;
}
inode_lock(orphan_dir_inode);
inode_lock_nested(orphan_dir_inode, I_MUTEX_NONDIR2);
ret = ocfs2_inode_lock(orphan_dir_inode, &orphan_dir_bh, 1);
if (ret < 0) {
@@ -2725,7 +2725,7 @@ int ocfs2_del_inode_from_orphan(struct ocfs2_super *osb,
goto bail;
}
inode_lock(orphan_dir_inode);
inode_lock_nested(orphan_dir_inode, I_MUTEX_NONDIR2);
status = ocfs2_inode_lock(orphan_dir_inode, &orphan_dir_bh, 1);
if (status < 0) {
inode_unlock(orphan_dir_inode);
@@ -2838,7 +2838,7 @@ int ocfs2_mv_orphaned_inode_to_new(struct inode *dir,
goto leave;
}
inode_lock(orphan_dir_inode);
inode_lock_nested(orphan_dir_inode, I_MUTEX_NONDIR2);
status = ocfs2_inode_lock(orphan_dir_inode, &orphan_dir_bh, 1);
if (status < 0) {