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Commit 022c2611 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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dm: merge pushback and deferred bio lists 



Merge pushback and deferred lists into one list - use deferred list
for both deferred and pushed-back bios.

This will be needed for proper support of barrier bios: it is impossible to
support ordering correctly with two lists because the requests on both lists
will be mixed up.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 401600df

drivers/md/dm.c

+16 −21
Original line number Diff line number Diff line
@@ -102,7 +102,6 @@ union map_info *dm_get_mapinfo(struct bio *bio) 
struct mapped_device {

	struct rw_semaphore io_lock;

	struct mutex suspend_lock;

	spinlock_t pushback_lock;

	rwlock_t map_lock;

	atomic_t holders;

	atomic_t open_count;
@@ -122,7 +121,7 @@ struct mapped_device { 
	wait_queue_head_t wait;

	struct work_struct work;

	struct bio_list deferred;

	struct bio_list pushback;

	spinlock_t deferred_lock;



	/*

	 * Processing queue (flush/barriers)
@@ -445,7 +444,9 @@ static int queue_io(struct mapped_device *md, struct bio *bio) 
		return 1;

	}



	spin_lock_irq(&md->deferred_lock);

	bio_list_add(&md->deferred, bio);

	spin_unlock_irq(&md->deferred_lock);



	up_write(&md->io_lock);

	return 0;		/* deferred successfully */
@@ -529,16 +530,14 @@ static void dec_pending(struct dm_io *io, int error) 
		if (io->error == DM_ENDIO_REQUEUE) {

			/*

			 * Target requested pushing back the I/O.

			 * This must be handled before the sleeper on

			 * suspend queue merges the pushback list.

			 */

			spin_lock_irqsave(&md->pushback_lock, flags);

			spin_lock_irqsave(&md->deferred_lock, flags);

			if (__noflush_suspending(md))

				bio_list_add(&md->pushback, io->bio);

				bio_list_add(&md->deferred, io->bio);

			else

				/* noflush suspend was interrupted. */

				io->error = -EIO;

			spin_unlock_irqrestore(&md->pushback_lock, flags);

			spin_unlock_irqrestore(&md->deferred_lock, flags);

		}



		end_io_acct(io);
@@ -1096,7 +1095,7 @@ static struct mapped_device *alloc_dev(int minor) 


	init_rwsem(&md->io_lock);

	mutex_init(&md->suspend_lock);

	spin_lock_init(&md->pushback_lock);

	spin_lock_init(&md->deferred_lock);

	rwlock_init(&md->map_lock);

	atomic_set(&md->holders, 1);

	atomic_set(&md->open_count, 0);
@@ -1410,25 +1409,21 @@ static void dm_wq_work(struct work_struct *work) 


	down_write(&md->io_lock);



	while ((c = bio_list_pop(&md->deferred)))

next_bio:

	spin_lock_irq(&md->deferred_lock);

	c = bio_list_pop(&md->deferred);

	spin_unlock_irq(&md->deferred_lock);



	if (c) {

		__split_and_process_bio(md, c);

		goto next_bio;

	}



	clear_bit(DMF_BLOCK_IO, &md->flags);



	up_write(&md->io_lock);

}



static void __merge_pushback_list(struct mapped_device *md)

{

	unsigned long flags;



	spin_lock_irqsave(&md->pushback_lock, flags);

	clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);

	bio_list_merge_head(&md->deferred, &md->pushback);

	bio_list_init(&md->pushback);

	spin_unlock_irqrestore(&md->pushback_lock, flags);

}



static void dm_queue_flush(struct mapped_device *md)

{

	queue_work(md->wq, &md->work);
@@ -1572,7 +1567,7 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) 
	remove_wait_queue(&md->wait, &wait);



	if (noflush)

		__merge_pushback_list(md);

		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);

	up_write(&md->io_lock);



	/* were we interrupted ? */