From 429d6275d50199dd4c3a5876754003ae06c7f927 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 12 Dec 2017 15:34:26 +0800 Subject: [PATCH] btrfs: qgroup: Fix wrong qgroup reservation update for relationship modification When modifying qgroup relationship, for qgroup which only owns exclusive extents, we will go through quick update path. In this path, we will add/subtract exclusive and reference number for parent qgroup, since the source (child) qgroup only has exclusive extents, destination (parent) qgroup will also own or lose those extents exclusively. The same should be the same for reservation, since later reservation adding/releasing will also affect parent qgroup, without the reservation carried from child, parent will underflow reservation or have dead reservation which will never be freed. However original code doesn't do the same thing for reservation. It handles qgroup reservation quite differently: It removes qgroup reservation, as it's allocating space from the reserved qgroup for relationship adding. But does nothing for qgroup reservation if we're removing a qgroup relationship. According to the original code, it looks just like because we're adding qgroup->rfer, the code assumes we're writing new data, so it's follows the normal write routine, by reducing qgroup->reserved and adding qgroup->rfer/excl. This old behavior is wrong, and should be fixed to follow the same excl/rfer behavior. Just fix it by using the correct behavior described above. Fixes: 31193213f1f9 ("Btrfs: qgroup: Introduce a may_use to account space_info->bytes_may_use.") Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/qgroup.c | 44 +++++++++++++++++++++++--------------------- 1 file changed, 23 insertions(+), 21 deletions(-) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 58a8b69..87672d0 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -1076,21 +1076,30 @@ static void report_reserved_underflow(struct btrfs_fs_info *fs_info, #endif qgroup->reserved = 0; } + /* - * The easy accounting, if we are adding/removing the only ref for an extent - * then this qgroup and all of the parent qgroups get their reference and - * exclusive counts adjusted. + * The easy accounting, we're updating qgroup relationship whose child qgroup + * only has exclusive extents. + * + * In this case, all exclsuive extents will also be exlusive for parent, so + * excl/rfer just get added/removed. + * + * So is qgroup reservation space, which should also be added/removed to + * parent. + * Or when child tries to release reservation space, parent will underflow its + * reservation (for relationship adding case). * * Caller should hold fs_info->qgroup_lock. */ static int __qgroup_excl_accounting(struct btrfs_fs_info *fs_info, struct ulist *tmp, u64 ref_root, - u64 num_bytes, int sign) + struct btrfs_qgroup *src, int sign) { struct btrfs_qgroup *qgroup; struct btrfs_qgroup_list *glist; struct ulist_node *unode; struct ulist_iterator uiter; + u64 num_bytes = src->excl; int ret = 0; qgroup = find_qgroup_rb(fs_info, ref_root); @@ -1103,13 +1112,11 @@ static int __qgroup_excl_accounting(struct btrfs_fs_info *fs_info, WARN_ON(sign < 0 && qgroup->excl < num_bytes); qgroup->excl += sign * num_bytes; qgroup->excl_cmpr += sign * num_bytes; - if (sign > 0) { - trace_qgroup_update_reserve(fs_info, qgroup, -(s64)num_bytes); - if (qgroup->reserved < num_bytes) - report_reserved_underflow(fs_info, qgroup, num_bytes); - else - qgroup->reserved -= num_bytes; - } + + if (sign > 0) + qgroup_rsv_add_by_qgroup(qgroup, src); + else + qgroup_rsv_release_by_qgroup(qgroup, src); qgroup_dirty(fs_info, qgroup); @@ -1129,15 +1136,10 @@ static int __qgroup_excl_accounting(struct btrfs_fs_info *fs_info, qgroup->rfer_cmpr += sign * num_bytes; WARN_ON(sign < 0 && qgroup->excl < num_bytes); qgroup->excl += sign * num_bytes; - if (sign > 0) { - trace_qgroup_update_reserve(fs_info, qgroup, - -(s64)num_bytes); - if (qgroup->reserved < num_bytes) - report_reserved_underflow(fs_info, qgroup, - num_bytes); - else - qgroup->reserved -= num_bytes; - } + if (sign > 0) + qgroup_rsv_add_by_qgroup(qgroup, src); + else + qgroup_rsv_release_by_qgroup(qgroup, src); qgroup->excl_cmpr += sign * num_bytes; qgroup_dirty(fs_info, qgroup); @@ -1180,7 +1182,7 @@ static int quick_update_accounting(struct btrfs_fs_info *fs_info, if (qgroup->excl == qgroup->rfer) { ret = 0; err = __qgroup_excl_accounting(fs_info, tmp, dst, - qgroup->excl, sign); + qgroup, sign); if (err < 0) { ret = err; goto out; -- 2.7.4