diff mbox series

[16/17] btrfs: avoid start and commit empty transaction when starting qgroup rescan

Message ID fc34290c4f32cbba64f89372f8a21789998225d9.1690383587.git.fdmanana@suse.com (mailing list archive)
State New, archived
Headers show
Series btrfs: some misc stuff around space flushing and enospc handling | expand

Commit Message

Filipe Manana July 26, 2023, 3:57 p.m. UTC 
From: Filipe Manana <fdmanana@suse.com>

When starting a qgroup rescan, we try to join a running transaction, with
btrfs_join_transaction(), and then commit the transaction. However using
btrfs_join_transaction() will result in creating a new transaction in case
there isn't any running or if there's an existing one already committing.
This is pointless as we only need to attach to an existing one that is
not committing and in case there's an existing one committing, wait for
its commit to complete. Creating and committing an empty transaction is
wasteful, pointless IO and unnecessary rotation of the backup roots.

So use btrfs_attach_transaction_barrier() instead, to avoid creating and
committing empty transactions.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/qgroup.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 2637d6b157ff..1ef60ea8f0bc 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -3590,15 +3590,16 @@  btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
 	 * going to clear all tracking information for a clean start.
 	 */
 
-	trans = btrfs_join_transaction(fs_info->fs_root);
-	if (IS_ERR(trans)) {
+	trans = btrfs_attach_transaction_barrier(fs_info->fs_root);
+	if (IS_ERR(trans) && trans != ERR_PTR(-ENOENT)) {
 		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
 		return PTR_ERR(trans);
-	}
-	ret = btrfs_commit_transaction(trans);
-	if (ret) {
-		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
-		return ret;
+	} else if (trans != ERR_PTR(-ENOENT)) {
+		ret = btrfs_commit_transaction(trans);
+		if (ret) {
+			fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
+			return ret;
+		}
 	}
 
 	qgroup_rescan_zero_tracking(fs_info);