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-rw-r--r--fs/btrfs/qgroup.c39
1 files changed, 29 insertions, 10 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index d275bf24b250..af97413abcf4 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2765,9 +2765,19 @@ int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans)
/*
* Old roots should be searched when inserting qgroup
- * extent record
+ * extent record.
+ *
+ * But for INCONSISTENT (NO_ACCOUNTING) -> rescan case,
+ * we may have some record inserted during
+ * NO_ACCOUNTING (thus no old_roots populated), but
+ * later we start rescan, which clears NO_ACCOUNTING,
+ * leaving some inserted records without old_roots
+ * populated.
+ *
+ * Those cases are rare and should not cause too much
+ * time spent during commit_transaction().
*/
- if (WARN_ON(!record->old_roots)) {
+ if (!record->old_roots) {
/* Search commit root to find old_roots */
ret = btrfs_find_all_roots(&ctx, false);
if (ret < 0)
@@ -3357,6 +3367,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
int err = -ENOMEM;
int ret = 0;
bool stopped = false;
+ bool did_leaf_rescans = false;
path = btrfs_alloc_path();
if (!path)
@@ -3377,6 +3388,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
}
err = qgroup_rescan_leaf(trans, path);
+ did_leaf_rescans = true;
if (err > 0)
btrfs_commit_transaction(trans);
@@ -3397,16 +3409,23 @@ out:
mutex_unlock(&fs_info->qgroup_rescan_lock);
/*
- * only update status, since the previous part has already updated the
- * qgroup info.
+ * Only update status, since the previous part has already updated the
+ * qgroup info, and only if we did any actual work. This also prevents
+ * race with a concurrent quota disable, which has already set
+ * fs_info->quota_root to NULL and cleared BTRFS_FS_QUOTA_ENABLED at
+ * btrfs_quota_disable().
*/
- trans = btrfs_start_transaction(fs_info->quota_root, 1);
- if (IS_ERR(trans)) {
- err = PTR_ERR(trans);
+ if (did_leaf_rescans) {
+ trans = btrfs_start_transaction(fs_info->quota_root, 1);
+ if (IS_ERR(trans)) {
+ err = PTR_ERR(trans);
+ trans = NULL;
+ btrfs_err(fs_info,
+ "fail to start transaction for status update: %d",
+ err);
+ }
+ } else {
trans = NULL;
- btrfs_err(fs_info,
- "fail to start transaction for status update: %d",
- err);
}
mutex_lock(&fs_info->qgroup_rescan_lock);