From cfc0eed0ec89db7c4a8d461174cabfaa4a0912c7 Mon Sep 17 00:00:00 2001
From: ethanwu <ethanwu@synology.com>
Date: Fri, 7 Feb 2020 17:38:17 +0800
Subject: [PATCH] btrfs: backref, only search backref entries from leaves of
 the same root

We could have some nodes/leaves in subvolume whose owner are not the
that subvolume. In this way, when we resolve normal backrefs of that
subvolume, we should avoid collecting those references from these blocks.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: ethanwu <ethanwu@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/backref.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 04e9d2efa9588..19a3ae79a0a88 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -443,11 +443,14 @@ static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
 	 *    slot == nritems.
 	 * 2. We are searching for normal backref but bytenr of this leaf
 	 *    matches shared data backref
+	 * 3. The leaf owner is not equal to the root we are searching
+	 *
 	 * For these cases, go to the next leaf before we continue.
 	 */
 	eb = path->nodes[0];
 	if (path->slots[0] >= btrfs_header_nritems(eb) ||
-	    is_shared_data_backref(preftrees, eb->start)) {
+	    is_shared_data_backref(preftrees, eb->start) ||
+	    ref->root_id != btrfs_header_owner(eb)) {
 		if (time_seq == SEQ_LAST)
 			ret = btrfs_next_leaf(root, path);
 		else
@@ -466,9 +469,12 @@ static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
 
 		/*
 		 * We are searching for normal backref but bytenr of this leaf
-		 * matches shared data backref.
+		 * matches shared data backref, OR
+		 * the leaf owner is not equal to the root we are searching for
 		 */
-		if (slot == 0 && is_shared_data_backref(preftrees, eb->start)) {
+		if (slot == 0 &&
+		    (is_shared_data_backref(preftrees, eb->start) ||
+		     ref->root_id != btrfs_header_owner(eb))) {
 			if (time_seq == SEQ_LAST)
 				ret = btrfs_next_leaf(root, path);
 			else