vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 5d81e92..5ec59b2 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2198,7 +2198,7 @@
 	if (error)
 		return error;
 	/* Quota file not on the same filesystem? */
-	if (path->mnt->mnt_sb != sb)
+	if (path->dentry->d_sb != sb)
 		error = -EXDEV;
 	else
 		error = vfs_load_quota_inode(path->dentry->d_inode, type,