From 2b29726c473b3f7d1b8f22d138ed12b2776bb5d2 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 19 Jul 2021 13:43:04 +0800 Subject: [PATCH] btrfs: rescue: allow ibadroots to skip bad extent tree when reading block group items When extent tree gets corrupted, normally it's not extent tree root, but one toasted tree leaf/node. In that case, rescue=ibadroots mount option won't help as it can only handle the extent tree root corruption. This patch will enhance the behavior by: - Allow fill_dummy_bgs() to ignore -EEXIST error This means we may have some block group items read from disk, but then hit some error halfway. - Fallback to fill_dummy_bgs() if any error gets hit in btrfs_read_block_groups() Of course, this still needs rescue=ibadroots mount option. With that, rescue=ibadroots can handle extent tree corruption more gracefully and allow a better recover chance. Reported-by: Zhenyu Wu Link: https://www.spinics.net/lists/linux-btrfs/msg114424.html Reviewed-by: Su Yue Reviewed-by: Anand Jain Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/block-group.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 5bd76a45037e..d5421ee0d366 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -2105,11 +2105,22 @@ static int fill_dummy_bgs(struct btrfs_fs_info *fs_info) bg->used = em->len; bg->flags = map->type; ret = btrfs_add_block_group_cache(fs_info, bg); + /* + * We may have some valid block group cache added already, in + * that case we skip to the next one. + */ + if (ret == -EEXIST) { + ret = 0; + btrfs_put_block_group(bg); + continue; + } + if (ret) { btrfs_remove_free_space_cache(bg); btrfs_put_block_group(bg); break; } + btrfs_update_space_info(fs_info, bg->flags, em->len, em->len, 0, 0, &space_info); bg->space_info = space_info; @@ -2212,6 +2223,14 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) ret = check_chunk_block_group_mappings(info); error: btrfs_free_path(path); + /* + * We've hit some error while reading the extent tree, and have + * rescue=ibadroots mount option. + * Try to fill the tree using dummy block groups so that the user can + * continue to mount and grab their data. + */ + if (ret && btrfs_test_opt(info, IGNOREBADROOTS)) + ret = fill_dummy_bgs(info); return ret; }