Workaround Mac server problem

Mac server returns that they support CIFS Unix Extensions but
doesn't actually support QUERY_FILE_UNIX_BASIC so mount fails.

Workaround this problem by disabling use of Unix CIFS protocol
extensions if server returns an EOPNOTSUPP error on
QUERY_FILE_UNIX_BASIC during mount.

Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index c23bdec805c5..197cb503d528 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -960,11 +960,18 @@ struct inode *cifs_root_iget(struct super_block *sb)
         struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 
         xid = get_xid();
-        if (tcon->unix_ext)
+        if (tcon->unix_ext) {
                 rc = cifs_get_inode_info_unix(&inode, "", sb, xid);
-        else
-                rc = cifs_get_inode_info(&inode, "", NULL, sb, xid, NULL);
+                /* some servers mistakenly claim POSIX support */
+                if (rc != -EOPNOTSUPP)
+                        goto iget_no_retry;
+                cifs_dbg(VFS, "server does not support POSIX extensions");
+                tcon->unix_ext = false;
+        }
+
+        rc = cifs_get_inode_info(&inode, "", NULL, sb, xid, NULL);
 
+iget_no_retry:
         if (!inode) {
                 inode = ERR_PTR(rc);
                 goto out;