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Commit 92e86812 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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dm snapshot: use per device mempools 



Change snapshot per-module mempool to per-device mempool.

Per-module mempools could cause a deadlock if multiple
snapshot devices are stacked above each other.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent a8d41b59

drivers/md/dm-snap.c

+22 −18
Original line number Diff line number Diff line
@@ -96,7 +96,6 @@ struct dm_snap_pending_exception { 
 */

static struct kmem_cache *exception_cache;

static struct kmem_cache *pending_cache;

static mempool_t *pending_pool;



struct dm_snap_tracked_chunk {

	struct hlist_node node;
@@ -364,14 +363,19 @@ static void free_exception(struct dm_snap_exception *e) 
	kmem_cache_free(exception_cache, e);

}



static struct dm_snap_pending_exception *alloc_pending_exception(void)

static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s)

{

	return mempool_alloc(pending_pool, GFP_NOIO);

	struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool,

							     GFP_NOIO);



	pe->snap = s;



	return pe;

}



static void free_pending_exception(struct dm_snap_pending_exception *pe)

{

	mempool_free(pe, pending_pool);

	mempool_free(pe, pe->snap->pending_pool);

}



static void insert_completed_exception(struct dm_snapshot *s,
@@ -627,12 +631,18 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 
		goto bad5;

	}



	s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache);

	if (!s->pending_pool) {

		ti->error = "Could not allocate mempool for pending exceptions";

		goto bad6;

	}



	s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS,

							 tracked_chunk_cache);

	if (!s->tracked_chunk_pool) {

		ti->error = "Could not allocate tracked_chunk mempool for "

			    "tracking reads";

		goto bad6;

		goto bad_tracked_chunk_pool;

	}



	for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
@@ -669,6 +679,9 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 
 bad_load_and_register:

	mempool_destroy(s->tracked_chunk_pool);



 bad_tracked_chunk_pool:

	mempool_destroy(s->pending_pool);



 bad6:

	dm_kcopyd_client_destroy(s->kcopyd_client);
@@ -723,6 +736,8 @@ static void snapshot_dtr(struct dm_target *ti) 


	__free_exceptions(s);



	mempool_destroy(s->pending_pool);



	dm_put_device(ti, s->origin);

	dm_put_device(ti, s->cow);
@@ -969,7 +984,7 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio) 
	 * to hold the lock while we do this.

	 */

	up_write(&s->lock);

	pe = alloc_pending_exception();

	pe = alloc_pending_exception(s);

	down_write(&s->lock);



	if (!s->valid) {
@@ -989,7 +1004,6 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio) 
	bio_list_init(&pe->snapshot_bios);

	pe->primary_pe = NULL;

	atomic_set(&pe->ref_count, 0);

	pe->snap = s;

	pe->started = 0;



	if (s->store.prepare_exception(&s->store, &pe->e)) {
@@ -1418,24 +1432,15 @@ static int __init dm_snapshot_init(void) 
		goto bad5;

	}



	pending_pool = mempool_create_slab_pool(128, pending_cache);

	if (!pending_pool) {

		DMERR("Couldn't create pending pool.");

		r = -ENOMEM;

		goto bad_pending_pool;

	}



	ksnapd = create_singlethread_workqueue("ksnapd");

	if (!ksnapd) {

		DMERR("Failed to create ksnapd workqueue.");

		r = -ENOMEM;

		goto bad6;

		goto bad_pending_pool;

	}



	return 0;



      bad6:

	mempool_destroy(pending_pool);

      bad_pending_pool:

	kmem_cache_destroy(tracked_chunk_cache);

      bad5:
@@ -1466,7 +1471,6 @@ static void __exit dm_snapshot_exit(void) 
		DMERR("origin unregister failed %d", r);



	exit_origin_hash();

	mempool_destroy(pending_pool);

	kmem_cache_destroy(pending_cache);

	kmem_cache_destroy(exception_cache);

	kmem_cache_destroy(tracked_chunk_cache);

drivers/md/dm-snap.h

+2 −0
Original line number Diff line number Diff line
@@ -161,6 +161,8 @@ struct dm_snapshot { 
	/* The last percentage we notified */

	int last_percent;



	mempool_t *pending_pool;



	struct exception_table pending;

	struct exception_table complete;