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Commit 6d6f10df authored by Milan Broz's avatar Milan Broz Committed by Alasdair G Kergon
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dm: refactor deferred bio_list processing 



Refactor deferred bio_list processing.

 - use separate _merge_pushback_list function
 - move deferred bio list pick up to flush function
 - use bio_list_pop instead of bio_list_get
 - simplify noflush flag use

No real functional change in this patch.

Signed-off-by: default avatarMilan Broz <mbroz@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 6ed7ade8

drivers/md/dm.c

+29 −38
Original line number Diff line number Diff line
@@ -1262,19 +1262,27 @@ EXPORT_SYMBOL_GPL(dm_put); 
/*

 * Process the deferred bios

 */

static void __flush_deferred_io(struct mapped_device *md, struct bio *c)

static void __flush_deferred_io(struct mapped_device *md)

{

	struct bio *n;

	struct bio *c;



	while (c) {

		n = c->bi_next;

		c->bi_next = NULL;

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

		if (__split_bio(md, c))

			bio_io_error(c);

		c = n;

	}

}



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);

}



/*

 * Swap in a new table (destroying old one).

 */
@@ -1346,9 +1354,7 @@ static void unlock_fs(struct mapped_device *md) 
int dm_suspend(struct mapped_device *md, unsigned suspend_flags)

{

	struct dm_table *map = NULL;

	unsigned long flags;

	DECLARE_WAITQUEUE(wait, current);

	struct bio *def;

	int r = -EINVAL;

	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;

	int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
@@ -1378,17 +1384,17 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) 
			r = -ENOMEM;

			goto flush_and_out;

		}

	}



		/*

	 * Flush I/O to the device.

	 * noflush supersedes do_lockfs, because lock_fs() needs to flush I/Os.

		 * Flush I/O to the device. noflush supersedes do_lockfs,

		 * because lock_fs() needs to flush I/Os.

		 */

	if (do_lockfs && !noflush) {

		if (do_lockfs) {

			r = lock_fs(md);

			if (r)

				goto out;

		}

	}



	/*

	 * First we set the BLOCK_IO flag so no more ios will be mapped.
@@ -1421,20 +1427,14 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) 
	down_write(&md->io_lock);

	remove_wait_queue(&md->wait, &wait);



	if (noflush) {

		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);

	}

	if (noflush)

		__merge_pushback_list(md);



	/* were we interrupted ? */

	r = -EINTR;

	if (atomic_read(&md->pending)) {

		clear_bit(DMF_BLOCK_IO, &md->flags);

		def = bio_list_get(&md->deferred);

		__flush_deferred_io(md, def);

		__flush_deferred_io(md);

		up_write(&md->io_lock);

		unlock_fs(md);

		goto out; /* pushback list is already flushed, so skip flush */
@@ -1454,15 +1454,8 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) 
		 * flush them before return.

		 */

		down_write(&md->io_lock);



		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);



		def = bio_list_get(&md->deferred);

		__flush_deferred_io(md, def);

		__merge_pushback_list(md);

		__flush_deferred_io(md);

		up_write(&md->io_lock);

	}
@@ -1482,7 +1475,6 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) 
int dm_resume(struct mapped_device *md)

{

	int r = -EINVAL;

	struct bio *def;

	struct dm_table *map = NULL;



	mutex_lock(&md->suspend_lock);
@@ -1500,8 +1492,7 @@ int dm_resume(struct mapped_device *md) 
	down_write(&md->io_lock);

	clear_bit(DMF_BLOCK_IO, &md->flags);



	def = bio_list_get(&md->deferred);

	__flush_deferred_io(md, def);

	__flush_deferred_io(md);

	up_write(&md->io_lock);



	unlock_fs(md);