If ceph_atomic_open is handed a !d_in_lookup dentry, then that means
that it already passed d_revalidate so we *know* that it's negative (or
at least was very recently). Just return -ENOENT in that case.
This also addresses a subtle bug in dentry handling. Non-O_CREAT opens
call atomic_open with the parent's i_rwsem shared, but calling
d_splice_alias on a hashed dentry requires the exclusive lock.
If ceph_atomic_open receives a hashed, negative dentry on a non-O_CREAT
open, and another client were to race in and create the file before we
issue our OPEN, ceph_fill_trace could end up calling d_splice_alias on
the dentry with the new inode with insufficient locks.
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/ceph/file.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index e9689e7bea08..bd77adb64bfd 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -462,6 +462,9 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
err = ceph_security_init_secctx(dentry, mode, &as_ctx);
if (err < 0)
goto out_ctx;
+ } else if (!d_in_lookup(dentry)) {
+ /* If it's not being looked up, it's negative */
+ return -ENOENT;
}
/* do the open */
--
2.21.0
