From: Josef Bacik <josef@toxicpanda.com>
Date: Fri, 6 Dec 2019 09:37:17 -0500
Git-commit: 9bc574de590510eff899c3ca8dbaf013566b5efe
Patch-mainline: 5.5-rc3
Subject: [PATCH] btrfs: skip log replay on orphaned roots
References: bsc#1161935

My fsstress modifications coupled with generic/475 uncovered a failure
to mount and replay the log if we hit a orphaned root.  We do not want
to replay the log for an orphan root, but it's completely legitimate to
have an orphaned root with a log attached.  Fix this by simply skipping
replaying the log.  We still need to pin it's root node so that we do
not overwrite it while replaying other logs, as we re-read the log root
at every stage of the replay.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/tree-log.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 883693e190b6..7ce9e9ad7de2 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -6497,9 +6497,28 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 		wc.replay_dest = btrfs_read_fs_root_no_name(fs_info, &tmp_key);
 		if (IS_ERR(wc.replay_dest)) {
 			ret = PTR_ERR(wc.replay_dest);
+
+			/*
+			 * We didn't find the subvol, likely because it was
+			 * deleted.  This is ok, simply skip this log and go to
+			 * the next one.
+			 *
+			 * We need to exclude the root because we can't have
+			 * other log replays overwriting this log as we'll read
+			 * it back in a few more times.  This will keep our
+			 * block from being modified, and we'll just bail for
+			 * each subsequent pass.
+			 */
+			if (ret == -ENOENT)
+				ret = btrfs_pin_extent_for_log_replay(fs_info,
+							log->node->start,
+							log->node->len);
 			free_extent_buffer(log->node);
 			free_extent_buffer(log->commit_root);
 			kfree(log);
+
+			if (!ret)
+				goto next;
 			btrfs_handle_fs_error(fs_info, ret,
 				"Couldn't read target root for tree log recovery.");
 			goto error;
@@ -6531,7 +6550,6 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 						  &root->highest_objectid);
 		}
 
-		key.offset = found_key.offset - 1;
 		wc.replay_dest->log_root = NULL;
 		free_extent_buffer(log->node);
 		free_extent_buffer(log->commit_root);
@@ -6539,9 +6557,10 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 
 		if (ret)
 			goto error;
-
+next:
 		if (found_key.offset == 0)
 			break;
+		key.offset = found_key.offset - 1;
 	}
 	btrfs_release_path(path);
 
-- 
2.16.4