Commit 45e15720 authored by Kiyoshi Ueda's avatar Kiyoshi Ueda Committed by Linus Torvalds
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[PATCH] dm: mpath: use noflush suspending 



Implement the pushback feature for the multipath target.

The pushback request is used when:
  1) there are no valid paths;
  2) queue_if_no_path was set;
  3) a suspend is being issued with the DMF_NOFLUSH_SUSPENDING flag.
     Otherwise bios are returned to applications with -EIO.

To check whether queue_if_no_path is specified or not, you need to check
both queue_if_no_path and saved_queue_if_no_path, because presuspend saves
the original queue_if_no_path value to saved_queue_if_no_path.

The check for 1 already exists in both map_io() and do_end_io().
So this patch adds __must_push_back() to check 2 and 3.

Test results:
See the test results in the preceding patch.

Signed-off-by: default avatarKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2e93ccc1

drivers/md/dm-mpath.c

+29 −5
Original line number Diff line number Diff line
@@ -282,6 +282,23 @@ failed: 
	m->current_pg = NULL;

}



/*

 * Check whether bios must be queued in the device-mapper core rather

 * than here in the target.

 *

 * m->lock must be held on entry.

 *

 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the

 * same value then we are not between multipath_presuspend()

 * and multipath_resume() calls and we have no need to check

 * for the DMF_NOFLUSH_SUSPENDING flag.

 */

static int __must_push_back(struct multipath *m)

{

	return (m->queue_if_no_path != m->saved_queue_if_no_path &&

		dm_noflush_suspending(m->ti));

}



static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio,

		  unsigned was_queued)

{
@@ -311,10 +328,12 @@ static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio, 
			queue_work(kmultipathd, &m->process_queued_ios);

		pgpath = NULL;

		r = DM_MAPIO_SUBMITTED;

	} else if (!pgpath)

		r = -EIO;		/* Failed */

	else

	} else if (pgpath)

		bio->bi_bdev = pgpath->path.dev->bdev;

	else if (__must_push_back(m))

		r = DM_MAPIO_REQUEUE;

	else

		r = -EIO;	/* Failed */



	mpio->pgpath = pgpath;
@@ -374,6 +393,8 @@ static void dispatch_queued_ios(struct multipath *m) 
			bio_endio(bio, bio->bi_size, r);

		else if (r == DM_MAPIO_REMAPPED)

			generic_make_request(bio);

		else if (r == DM_MAPIO_REQUEUE)

			bio_endio(bio, bio->bi_size, -EIO);



		bio = next;

	}
@@ -783,7 +804,7 @@ static int multipath_map(struct dm_target *ti, struct bio *bio, 
	map_context->ptr = mpio;

	bio->bi_rw |= (1 << BIO_RW_FAILFAST);

	r = map_io(m, bio, mpio, 0);

	if (r < 0)

	if (r < 0 || r == DM_MAPIO_REQUEUE)

		mempool_free(mpio, m->mpio_pool);



	return r;
@@ -1007,7 +1028,10 @@ static int do_end_io(struct multipath *m, struct bio *bio, 


	spin_lock_irqsave(&m->lock, flags);

	if (!m->nr_valid_paths) {

		if (!m->queue_if_no_path) {

		if (__must_push_back(m)) {

			spin_unlock_irqrestore(&m->lock, flags);

			return DM_ENDIO_REQUEUE;

		} else if (!m->queue_if_no_path) {

			spin_unlock_irqrestore(&m->lock, flags);

			return -EIO;

		} else {

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