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Commit 50f3c3ef authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm thin: switch to an atomic_t for tracking pending new block preparations 



Previously we used separate boolean values to track quiescing and
copying actions.  By switching to an atomic_t we can support blocks that
need a partial copy and partial zero.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 6afbc01d

drivers/md/dm-thin.c

+16 −13
Original line number Diff line number Diff line
@@ -554,11 +554,16 @@ static void remap_and_issue(struct thin_c *tc, struct bio *bio, 
struct dm_thin_new_mapping {

	struct list_head list;



	bool quiesced:1;

	bool prepared:1;

	bool pass_discard:1;

	bool definitely_not_shared:1;



	/*

	 * Track quiescing, copying and zeroing preparation actions.  When this

	 * counter hits zero the block is prepared and can be inserted into the

	 * btree.

	 */

	atomic_t prepare_actions;



	int err;

	struct thin_c *tc;

	dm_block_t virt_block;
@@ -575,11 +580,11 @@ struct dm_thin_new_mapping { 
	bio_end_io_t *saved_bi_end_io;

};



static void __maybe_add_mapping(struct dm_thin_new_mapping *m)

static void __complete_mapping_preparation(struct dm_thin_new_mapping *m)

{

	struct pool *pool = m->tc->pool;



	if (m->quiesced && m->prepared) {

	if (atomic_dec_and_test(&m->prepare_actions)) {

		list_add_tail(&m->list, &pool->prepared_mappings);

		wake_worker(pool);

	}
@@ -594,8 +599,7 @@ static void copy_complete(int read_err, unsigned long write_err, void *context) 
	m->err = read_err || write_err ? -EIO : 0;



	spin_lock_irqsave(&pool->lock, flags);

	m->prepared = true;

	__maybe_add_mapping(m);

	__complete_mapping_preparation(m);

	spin_unlock_irqrestore(&pool->lock, flags);

}
@@ -609,8 +613,7 @@ static void overwrite_endio(struct bio *bio, int err) 
	m->err = err;



	spin_lock_irqsave(&pool->lock, flags);

	m->prepared = true;

	__maybe_add_mapping(m);

	__complete_mapping_preparation(m);

	spin_unlock_irqrestore(&pool->lock, flags);

}
@@ -836,7 +839,9 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block, 
	m->cell = cell;



	if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))

		m->quiesced = true;

		atomic_set(&m->prepare_actions, 1); /* copy only */

	else

		atomic_set(&m->prepare_actions, 2); /* quiesce + copy */



	/*

	 * IO to pool_dev remaps to the pool target's data_dev.
@@ -896,8 +901,7 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block, 
	struct pool *pool = tc->pool;

	struct dm_thin_new_mapping *m = get_next_mapping(pool);



	m->quiesced = true;

	m->prepared = false;

	atomic_set(&m->prepare_actions, 1); /* no need to quiesce */

	m->tc = tc;

	m->virt_block = virt_block;

	m->data_block = data_block;
@@ -3361,8 +3365,7 @@ static int thin_endio(struct dm_target *ti, struct bio *bio, int err) 
		spin_lock_irqsave(&pool->lock, flags);

		list_for_each_entry_safe(m, tmp, &work, list) {

			list_del(&m->list);

			m->quiesced = true;

			__maybe_add_mapping(m);

			__complete_mapping_preparation(m);

		}

		spin_unlock_irqrestore(&pool->lock, flags);

	}