vfs: fix propagation of atomic_open create error on negative dentry

If ->atomic_open() returns -ENOENT, we take care to return the create
error (e.g., EACCES), if any.  Do the same when ->atomic_open() returns 1
and provides a negative dentry.

This fixes a regression where an unprivileged open O_CREAT fails with
ENOENT instead of EACCES, introduced with the new atomic_open code.  It
is tested by the open/08.t test in the pjd posix test suite, and was
observed on top of fuse (backed by ceph-fuse).

Signed-off-by: Sage Weil <sage@inktank.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 26c28ec4f4af..db76b866a097 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2489,6 +2489,10 @@ static int atomic_open(struct nameidata *nd, struct dentry *dentry,
                         dput(dentry);
                         dentry = file->f_path.dentry;
                 }
+                if (create_error && dentry->d_inode == NULL) {
+                        error = create_error;
+                        goto out;
+                }
                 goto looked_up;
         }