move mount_capable() calls to vfs_get_tree()

sget_fc() is called only from ->get_tree() instances and
the only instance not calling it is legacy_get_tree(),
which calls mount_capable() directly.

In all sget_fc() callers the checks could be moved to the
very beginning of ->get_tree() - ->user_ns is not changed
in between.  So lifting the checks to the only caller of
->get_tree() is OK.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/super.c b/fs/super.c
index d1e2f46bad7e..2c38541cd89f 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -514,12 +514,6 @@ struct super_block *sget_fc(struct fs_context *fc,
         struct user_namespace *user_ns = fc->global ? &init_user_ns : fc->user_ns;
         int err;
 
-        if (!(fc->sb_flags & SB_KERNMOUNT) &&
-            fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
-                if (!mount_capable(fc))
-                        return ERR_PTR(-EPERM);
-        }
-
 retry:
         spin_lock(&sb_lock);
         if (test) {
@@ -1421,6 +1415,12 @@ int vfs_get_tree(struct fs_context *fc)
         if (fc->root)
                 return -EBUSY;
 
+        if (!(fc->sb_flags & SB_KERNMOUNT) &&
+            fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
+                if (!mount_capable(fc))
+                        return -EPERM;
+        }
+
         /* Get the mountable root in fc->root, with a ref on the root and a ref
          * on the superblock.
          */