1 files changed, 24 insertions, 19 deletions

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index f49d684edd96..3758965d73d5 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -657,31 +657,36 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
         }
         cFYI(1, ("Full path: %s inode = 0x%p", full_path, direntry->d_inode));
 
+        /* Posix open is only called (at lookup time) for file create now.
+         * For opens (rather than creates), because we do not know if it
+         * is a file or directory yet, and current Samba no longer allows
+         * us to do posix open on dirs, we could end up wasting an open call
+         * on what turns out to be a dir. For file opens, we wait to call posix
+         * open till cifs_open.  It could be added here (lookup) in the future
+         * but the performance tradeoff of the extra network request when EISDIR
+         * or EACCES is returned would have to be weighed against the 50%
+         * reduction in network traffic in the other paths.
+         */
         if (pTcon->unix_ext) {
                 if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY)) &&
-                     (nd->flags & LOOKUP_OPEN) && !pTcon->broken_posix_open) {
-                        if (!((nd->intent.open.flags & O_CREAT) &&
-                                        (nd->intent.open.flags & O_EXCL))) {
-                                rc = cifs_posix_open(full_path, &newInode,
+                     (nd->flags & LOOKUP_OPEN) && !pTcon->broken_posix_open &&
+                     (nd->intent.open.flags & O_CREAT)) {
+                        rc = cifs_posix_open(full_path, &newInode,
                                         parent_dir_inode->i_sb,
                                         nd->intent.open.create_mode,
                                         nd->intent.open.flags, &oplock,
                                         &fileHandle, xid);
-                                /*
-                                 * This code works around a bug in
-                                 * samba posix open in samba versions 3.3.1
-                                 * and earlier where create works
-                                 * but open fails with invalid parameter.
-                                 * If either of these error codes are
-                                 * returned, follow the normal lookup.
-                                 * Otherwise, the error during posix open
-                                 * is handled.
-                                 */
-                                if ((rc != -EINVAL) && (rc != -EOPNOTSUPP))
-                                        posix_open = true;
-                                else
-                                        pTcon->broken_posix_open = true;
-                        }
+                        /*
+                         * The check below works around a bug in POSIX
+                         * open in samba versions 3.3.1 and earlier where
+                         * open could incorrectly fail with invalid parameter.
+                         * If either that or op not supported returned, follow
+                         * the normal lookup.
+                         */
+                        if ((rc == 0) || (rc == -ENOENT))
+                                posix_open = true;
+                        else if ((rc == -EINVAL) || (rc != -EOPNOTSUPP))
+                                pTcon->broken_posix_open = true;
                 }
                 if (!posix_open)
                         rc = cifs_get_inode_info_unix(&newInode, full_path,