[PATCH 0/1] btrfs: compressed writeback cgroup attribution

[PATCH 0/1] btrfs: compressed writeback cgroup attribution

[Dennis Zhou]

Hello,

I was looking at some blk-cgroup attribution stuff due to an ask
regarding io_uring and was thinking back to this work. I noticed that
the cgroup attribution for writeback is gone. Josef or Chris, can you
comment if this is still desired / the state of REQ_CGROUP_PUNT?

Thanks,
Dennis

Dennis Zhou (1):
  btrfs: fix btrfs_submit_compressed_write cgroup attribution

 fs/btrfs/compression.c | 8 ++++++++
 1 file changed, 8 insertions(+)

-- 
2.34.1

[PATCH 1/1] btrfs: fix btrfs_submit_compressed_write cgroup attribution

[Dennis Zhou]

This restores the logic from commit 46bcff2bfc5e
("btrfs: fix compressed write bio blkcg attribution") which added cgroup
attribution to btrfs writeback. It also adds back the REQ_CGROUP_PUNT
flag for these ios.

Fixes: 91507240482e ("btrfs: determine stripe boundary at bio allocation time in btrfs_submit_compressed_write")
Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
 fs/btrfs/compression.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index be476f094300..19bf36d8ffea 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -537,6 +537,9 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
 	cb->orig_bio = NULL;
 	cb->nr_pages = nr_pages;
 
+	if (blkcg_css)
+		kthread_associate_blkcg(blkcg_css);
+
 	while (cur_disk_bytenr < disk_start + compressed_len) {
 		u64 offset = cur_disk_bytenr - disk_start;
 		unsigned int index = offset >> PAGE_SHIFT;
@@ -555,6 +558,8 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
 				bio = NULL;
 				goto finish_cb;
 			}
+			if (blkcg_css)
+				bio->bi_opf |= REQ_CGROUP_PUNT;
 		}
 		/*
 		 * We should never reach next_stripe_start start as we will
@@ -612,6 +617,9 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
 	return 0;
 
 finish_cb:
+	if (blkcg_css)
+		kthread_associate_blkcg(NULL);
+
 	if (bio) {
 		bio->bi_status = ret;
 		bio_endio(bio);
-- 
2.34.1

Re: [PATCH 1/1] btrfs: fix btrfs_submit_compressed_write cgroup attribution

[David Sterba]

On Thu, Mar 31, 2022 at 02:58:28PM -0700, Dennis Zhou wrote:
> This restores the logic from commit 46bcff2bfc5e
> ("btrfs: fix compressed write bio blkcg attribution") which added cgroup
> attribution to btrfs writeback. It also adds back the REQ_CGROUP_PUNT
> flag for these ios.
> 
> Fixes: 91507240482e ("btrfs: determine stripe boundary at bio allocation time in btrfs_submit_compressed_write")
> Signed-off-by: Dennis Zhou <dennis@kernel.org>

Looks like this got lost in the refactoring. Added to misc-next, thanks.