From 5bb5e6ee6f5c557dcd19822eccd7bcced1e1a410 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 30 Oct 2019 12:15:10 -0400 Subject: [PATCH] ceph: don't try to handle hashed dentries in non-O_CREAT atomic_open 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 Signed-off-by: Jeff Layton Signed-off-by: Ilya Dryomov --- fs/ceph/file.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/ceph/file.c b/fs/ceph/file.c index d277f71abe0b..d2854cd2f4f5 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 */