From: Jeff Layton jlayton@kernel.org
commit 5bb5e6ee6f5c557dcd19822eccd7bcced1e1a410 upstream.
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.
Cc: stable@vger.kernel.org Reported-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Jeff Layton jlayton@kernel.org Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ceph/file.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -458,6 +458,9 @@ int ceph_atomic_open(struct inode *dir, 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 */