cifs: fix regression with O_EXCL creates and optimize away lookup

cifs: fix regression with O_EXCL creates and optimize away lookup

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Shirish Pargaonkar <shirishp@gmail.com>
CC: Stable Kernel <stable@kernel.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index a40054faed7f..ff55fc6932cb 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -643,6 +643,15 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
                         }
         }
 
+        /*
+         * O_EXCL: optimize away the lookup, but don't hash the dentry. Let
+         * the VFS handle the create.
+         */
+        if (nd->flags & LOOKUP_EXCL) {
+                d_instantiate(direntry, NULL);
+                return 0;
+        }
+
         /* can not grab the rename sem here since it would
         deadlock in the cases (beginning of sys_rename itself)
         in which we already have the sb rename sem */