From b6debf15d4753e0075a85ff119b0bb3c7e172782 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 14 May 2018 09:38:12 +0800 Subject: [PATCH] btrfs: qgroup: Search commit root for rescan to avoid missing extent When doing qgroup rescan using the following script (modified from btrfs/017 test case), we can sometimes hit qgroup corruption. ------ umount $dev &> /dev/null umount $mnt &> /dev/null mkfs.btrfs -f -n 64k $dev mount $dev $mnt extent_size=8192 xfs_io -f -d -c "pwrite 0 $extent_size" $mnt/foo > /dev/null btrfs subvolume snapshot $mnt $mnt/snap xfs_io -f -c "reflink $mnt/foo" $mnt/foo-reflink > /dev/null xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink > /dev/null xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink2 > /dev/unll btrfs quota enable $mnt # -W is the new option to only wait rescan while not starting new one btrfs quota rescan -W $mnt btrfs qgroup show -prce $mnt umount $mnt # Need to patch btrfs-progs to report qgroup mismatch as error btrfs check $dev || _fail ------ For fast machine, we can hit some corruption which missed accounting tree blocks: ------ qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 8.00KiB 0.00B none none --- --- 0/257 8.00KiB 0.00B none none --- --- ------ This is due to the fact that we're always searching commit root for btrfs_find_all_roots() at qgroup_rescan_leaf(), but the leaf we get is from current transaction, not commit root. And if our tree blocks get modified in current transaction, we won't find any owner in commit root, thus causing the corruption. Fix it by searching commit root for extent tree for qgroup_rescan_leaf(). Reported-by: Nikolay Borisov Signed-off-by: Qu Wenruo Reviewed-by: Nikolay Borisov Signed-off-by: David Sterba --- fs/btrfs/qgroup.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 9fdac5b46aa9..641ef2679bb1 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2590,7 +2590,6 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path, struct btrfs_key found; struct extent_buffer *scratch_leaf = NULL; struct ulist *roots = NULL; - struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem); u64 num_bytes; int slot; int ret; @@ -2625,7 +2624,6 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path, btrfs_header_nritems(path->nodes[0]) - 1); fs_info->qgroup_rescan_progress.objectid = found.objectid + 1; - btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem); scratch_leaf = btrfs_clone_extent_buffer(path->nodes[0]); if (!scratch_leaf) { ret = -ENOMEM; @@ -2664,7 +2662,6 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path, btrfs_tree_read_unlock_blocking(scratch_leaf); free_extent_buffer(scratch_leaf); } - btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem); return ret; } @@ -2681,6 +2678,12 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work) path = btrfs_alloc_path(); if (!path) goto out; + /* + * Rescan should only search for commit root, and any later difference + * should be recorded by qgroup + */ + path->search_commit_root = 1; + path->skip_locking = 1; err = 0; while (!err && !btrfs_fs_closing(fs_info)) { -- GitLab