ovl_copy_up() will retrieve sb_writers, and ovl_want_write will also retrieve sb_writers, adjusting the order of their execution to avoid deadlocks. Reported-by: syzbot+b778ac10fe2a0cd72517@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx> --- fs/overlayfs/dir.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 116f542442dd..ab65e98a1def 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -1314,10 +1314,6 @@ static int ovl_create_tmpfile(struct file *file, struct dentry *dentry, int flags = file->f_flags | OVL_OPEN_FLAGS; int err; - err = ovl_copy_up(dentry->d_parent); - if (err) - return err; - old_cred = ovl_override_creds(dentry->d_sb); err = ovl_setup_cred_for_create(dentry, inode, mode, old_cred); if (err) @@ -1360,6 +1356,10 @@ static int ovl_tmpfile(struct mnt_idmap *idmap, struct inode *dir, if (!OVL_FS(dentry->d_sb)->tmpfile) return -EOPNOTSUPP; + err = ovl_copy_up(dentry->d_parent); + if (err) + return err; + err = ovl_want_write(dentry); if (err) return err; -- 2.43.0
