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Commit 399caddf authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm thin: cleanup and improve no space handling 



Factor out_of_data_space() out of alloc_data_block().  Eliminate the use
of 'no_free_space' as a latch in alloc_data_block() -- this is no longer
needed now that we switch to read-only mode when we run out of data or
metadata space.  In a later patch, the 'no_free_space' flag will be
eliminated entirely (in favor of checking metadata rather than relying
on a transient flag).

Move no metdata space handling into metdata_operation_failed().  Set
no_free_space when metadata space is exhausted too.  This is useful,
because it offers consistency, for the following patch that will requeue
data IOs if no_free_space.

Also, rename no_space() to retry_bios_on_resume().

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Acked-by: default avatarJoe Thornber <ejt@redhat.com>
parent 6f7f51d4

drivers/md/dm-thin.c

+32 −29
Original line number Diff line number Diff line
@@ -198,6 +198,7 @@ struct pool { 
};



static enum pool_mode get_pool_mode(struct pool *pool);

static void out_of_data_space(struct pool *pool);

static void metadata_operation_failed(struct pool *pool, const char *op, int r);



/*
@@ -922,16 +923,8 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result) 
{

	int r;

	dm_block_t free_blocks;

	unsigned long flags;

	struct pool *pool = tc->pool;



	/*

	 * Once no_free_space is set we must not allow allocation to succeed.

	 * Otherwise it is difficult to explain, debug, test and support.

	 */

	if (pool->no_free_space)

		return -ENOSPC;



	if (get_pool_mode(pool) != PM_WRITE)

		return -EINVAL;
@@ -958,31 +951,14 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result) 
			return r;

		}



		/*

		 * If we still have no space we set a flag to avoid

		 * doing all this checking and return -ENOSPC.  This

		 * flag serves as a latch that disallows allocations from

		 * this pool until the admin takes action (e.g. resize or

		 * table reload).

		 */

		if (!free_blocks) {

			DMWARN("%s: no free data space available.",

			       dm_device_name(pool->pool_md));

			spin_lock_irqsave(&pool->lock, flags);

			pool->no_free_space = true;

			spin_unlock_irqrestore(&pool->lock, flags);

			out_of_data_space(pool);

			return -ENOSPC;

		}

	}



	r = dm_pool_alloc_data_block(pool->pmd, result);

	if (r) {

		if (r == -ENOSPC &&

		    !dm_pool_get_free_metadata_block_count(pool->pmd, &free_blocks) &&

		    !free_blocks)

			DMWARN("%s: no free metadata space available.",

			       dm_device_name(pool->pool_md));



		metadata_operation_failed(pool, "dm_pool_alloc_data_block", r);

		return r;

	}
@@ -1006,7 +982,7 @@ static void retry_on_resume(struct bio *bio) 
	spin_unlock_irqrestore(&pool->lock, flags);

}



static void no_space(struct pool *pool, struct dm_bio_prison_cell *cell)

static void retry_bios_on_resume(struct pool *pool, struct dm_bio_prison_cell *cell)

{

	struct bio *bio;

	struct bio_list bios;
@@ -1119,7 +1095,7 @@ static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block, 
		break;



	case -ENOSPC:

		no_space(pool, cell);

		retry_bios_on_resume(pool, cell);

		break;



	default:
@@ -1197,7 +1173,7 @@ static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block 
		break;



	case -ENOSPC:

		no_space(pool, cell);

		retry_bios_on_resume(pool, cell);

		break;



	default:
@@ -1446,15 +1422,42 @@ static void set_pool_mode(struct pool *pool, enum pool_mode mode) 
	}

}



static void set_no_free_space(struct pool *pool)

{

	unsigned long flags;



	spin_lock_irqsave(&pool->lock, flags);

	pool->no_free_space = true;

	spin_unlock_irqrestore(&pool->lock, flags);

}



/*

 * Rather than calling set_pool_mode directly, use these which describe the

 * reason for mode degradation.

 */

static void out_of_data_space(struct pool *pool)

{

	DMERR_LIMIT("%s: no free data space available.",

		    dm_device_name(pool->pool_md));

	set_no_free_space(pool);

	set_pool_mode(pool, PM_READ_ONLY);

}



static void metadata_operation_failed(struct pool *pool, const char *op, int r)

{

	dm_block_t free_blocks;



	DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",

		    dm_device_name(pool->pool_md), op, r);



	if (r == -ENOSPC &&

	    !dm_pool_get_free_metadata_block_count(pool->pmd, &free_blocks) &&

	    !free_blocks) {

		DMERR_LIMIT("%s: no free metadata space available.",

			    dm_device_name(pool->pool_md));

		set_no_free_space(pool);

	}



	set_pool_mode(pool, PM_READ_ONLY);

}