While the reason why qgroup reserved space may underflow is still under
investigation, such WARN_ON will help us to expose the bug more easily,
and for end-user we can detect and avoid underflow.
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
fs/btrfs/qgroup.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 8db2e29..8532587 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1061,8 +1061,12 @@ 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)
- qgroup->reserved -= num_bytes;
+ if (sign > 0) {
+ if (WARN_ON(qgroup->reserved < num_bytes))
+ qgroup->reserved = 0;
+ else
+ qgroup->reserved -= num_bytes;
+ }
qgroup_dirty(fs_info, qgroup);
@@ -1082,8 +1086,12 @@ 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)
- qgroup->reserved -= num_bytes;
+ if (sign > 0) {
+ if (WARN_ON(qgroup->reserved < num_bytes))
+ qgroup->reserved = 0;
+ else
+ qgroup->reserved -= num_bytes;
+ }
qgroup->excl_cmpr += sign * num_bytes;
qgroup_dirty(fs_info, qgroup);
@@ -2201,7 +2209,10 @@ void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
qg = u64_to_ptr(unode->aux);
- qg->reserved -= num_bytes;
+ if (WARN_ON(qgroup->reserved < num_bytes))
+ qgroup->reserved = 0;
+ else
+ qgroup->reserved -= num_bytes;
list_for_each_entry(glist, &qg->groups, next_group) {
ret = ulist_add(fs_info->qgroup_ulist,
--
2.10.0
--
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