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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index 509fe1e..76741d8 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -194,7 +194,7 @@
 		return err;
 	err = -ENOENT;
 	while (path.dentry == path.mnt->mnt_root) {
-		if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
+		if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 			if (test(&path, data)) {
 				path_get(&path);
 				if (!err) /* already found some */
@@ -212,7 +212,7 @@
 
 static int test_by_dev(struct path *path, void *p)
 {
-	return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
+	return path->dentry->d_sb->s_dev == *(dev_t *)p;
 }
 
 static int test_by_type(struct path *path, void *p)
@@ -538,11 +538,11 @@
 			err = find_autofs_mount(name, &path, test_by_type, &type);
 		if (err)
 			goto out;
-		devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
+		devid = new_encode_dev(path.dentry->d_sb->s_dev);
 		err = 0;
 		if (path.mnt->mnt_root == path.dentry) {
 			err = 1;
-			magic = path.mnt->mnt_sb->s_magic;
+			magic = path.dentry->d_sb->s_magic;
 		}
 	} else {
 		dev_t dev = sbi->sb->s_dev;
@@ -556,7 +556,7 @@
 		err = have_submounts(path.dentry);
 
 		if (follow_down_one(&path))
-			magic = path.mnt->mnt_sb->s_magic;
+			magic = path.dentry->d_sb->s_magic;
 	}
 
 	param->ismountpoint.out.devid = devid;