Merge branch 'writeback-workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git...

Tejun writes:

-----

This is the pull request for the earlier patchset[1] with the same
name.  It's only three patches (the first one was committed to
workqueue tree) but the merge strategy is a bit involved due to the
dependencies.

* Because the conversion needs features from wq/for-3.10,
  block/for-3.10/core is based on rc3, and wq/for-3.10 has conflicts
  with rc3, I pulled mainline (rc5) into wq/for-3.10 to prevent those
  workqueue conflicts from flaring up in block tree.

* Resolving the issue that Jan and Dave raised about debugging
  requires arch-wide changes.  The patchset is being worked on[2] but
  it'll have to go through -mm after these changes show up in -next,
  and not included in this pull request.

The three commits are located in the following git branch.

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git writeback-workqueue

Pulling it into block/for-3.10/core produces a conflict in
drivers/md/raid5.c between the following two commits.

  e3620a3ad5 ("MD RAID5: Avoid accessing gendisk or queue structs when not available")
  2f6db2a707 ("raid5: use bio_reset()")

The conflict is trivial - one removes an "if ()" conditional while the
other removes "rbi->bi_next = NULL" right above it.  We just need to
remove both.  The merged branch is available at

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git block-test-merge

so that you can use it for verification.  The test merge commit has
proper merge description.

While these changes are a bit of pain to route, they make code simpler
and even have, while minute, measureable performance gain[3] even on a
workload which isn't particularly favorable to showing the benefits of
this conversion.

----

Fixed up the conflict.

Conflicts:
	drivers/md/raid5.c

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --cc drivers/block/rbd.c
Simple merge

diff --cc drivers/md/dm-verity.c
Simple merge

diff --cc drivers/md/md.c
Simple merge

diff --cc drivers/md/raid5.c
index 7bbd28546214c4a9be5a4e08bc98df4ee4d5616d,24909eb13fec1b0bf22e40caa4ff7a76967f80e4..2fefb9f2198e2269bafa26d62e60eb96dbb63aa0
--- 1/drivers/md/raid5.c
--- 2/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@@ -665,11 -666,16 +665,13 @@@ static void ops_run_io(struct stripe_he
                        bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
                        bi->bi_io_vec[0].bv_offset = 0;
                        bi->bi_size = STRIPE_SIZE;
 -                      bi->bi_next = NULL;
                        if (rrdev)
                                set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
-                       trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
-                                             bi, disk_devt(conf->mddev->gendisk),
-                                             sh->dev[i].sector);
+ 
+                       if (conf->mddev->gendisk)
+                               trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
+                                                     bi, disk_devt(conf->mddev->gendisk),
+                                                     sh->dev[i].sector);
                        generic_make_request(bi);
                }
                if (rrdev) {
@@@ -700,9 -700,13 +702,10 @@@
                        rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
                        rbi->bi_io_vec[0].bv_offset = 0;
                        rbi->bi_size = STRIPE_SIZE;
-                       trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
-                                             rbi, disk_devt(conf->mddev->gendisk),
-                                             sh->dev[i].sector);
 -                      rbi->bi_next = NULL;
+                       if (conf->mddev->gendisk)
+                               trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
+                                                     rbi, disk_devt(conf->mddev->gendisk),
+                                                     sh->dev[i].sector);
                        generic_make_request(rbi);
                }
                if (!rdev && !rrdev) {

diff --cc fs/btrfs/extent_io.c
Simple merge

diff --cc fs/btrfs/volumes.c
Simple merge