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dm snapshot: use per device mempools

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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: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mikulas Patocka 2008-07-21 12:00:35 +01:00 committed by Alasdair G Kergon
parent a8d41b59f3
commit 92e868122e
2 changed files with 24 additions and 18 deletions
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40
drivers/md/dm-snap.c
View file

@ -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);

2
drivers/md/dm-snap.h
View file

@ -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;