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Btrfs: fix qgroup rescan worker initialization

PATCH In review [email protected] 2 participants 2 messages Nov 24, 2016 – Nov 25, 2016 Btrfs file system

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PATCH 1/1 Btrfs: fix qgroup rescan worker initialization

From: Filipe Manana <[email protected]>

We were setting the qgroup_rescan_running flag to true only after the rescan worker started (which is a task run by a queue). So if a user space task starts a rescan and immediately after asks to wait for the rescan worker to finish, this second call might happen before the rescan worker task starts running, in which case the rescan wait ioctl returns immediatley, not waiting for the rescan worker to finish.

This was making the fstest btrfs/022 fail very often.

Fixes d2c609b834d6 (btrfs: properly track when rescan worker is running)
Cc [email protected] # 4.4+
Signed-off-by Filipe Manana <[email protected]>
---
 fs/btrfs/qgroup.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)
fs/btrfs/qgroup.c +1 -4
index 11f4fff..dfd9986 100644
@@ -2335,10 +2335,6 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
 	int err = -ENOMEM;
 	int ret = 0;
 
-	mutex_lock(&fs_info->qgroup_rescan_lock);
-	fs_info->qgroup_rescan_running = true;
-	mutex_unlock(&fs_info->qgroup_rescan_lock);
-
 	path = btrfs_alloc_path();
 	if (!path)
 		goto out;

@@ -2449,6 +2445,7 @@ qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
 		sizeof(fs_info->qgroup_rescan_progress));
 	fs_info->qgroup_rescan_progress.objectid = progress_objectid;
 	init_completion(&fs_info->qgroup_rescan_completion);
+	fs_info->qgroup_rescan_running = true;
 
 	spin_unlock(&fs_info->qgroup_lock);
 	mutex_unlock(&fs_info->qgroup_rescan_lock);
Signature · 1 line
2.7.0.rc3
Reviewed-by on v1 1/1
#1 lore raw
Quoted 9 lines · On Thu, Nov 24, 2016 at 02:18:29AM +0000, [email protected] wrote:

From: Filipe Manana <[email protected]>

We were setting the qgroup_rescan_running flag to true only after the rescan worker started (which is a task run by a queue). So if a user space task starts a rescan and immediately after asks to wait for the rescan worker to finish, this second call might happen before the rescan worker task starts running, in which case the rescan wait ioctl returns immediatley, not waiting for the rescan worker to finish.

Quoted 5 lines

This was making the fstest btrfs/022 fail very often.

Fixes d2c609b834d6 (btrfs: properly track when rescan worker is running)
Cc [email protected] # 4.4+
Signed-off-by Filipe Manana <[email protected]>
Reviewed-by David Sterba <[email protected]>