No need for snapshots to keep track of completed exceptions
anymore, since the exception store implementations can do
that (better) now.
RFC-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Index: linux-2.6/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap.c
+++ linux-2.6/drivers/md/dm-snap.c
@@ -70,7 +70,6 @@ struct dm_snapshot {
atomic_t pending_exceptions_count;
struct dm_exception_table *pending;
- struct dm_exception_table *complete;
/*
* pe_lock protects all pending_exception operations and access
@@ -157,7 +156,6 @@ struct dm_snap_pending_exception {
* Hash table mapping origin volumes to lists of snapshots and
* a lock to protect it
*/
-static struct kmem_cache *exception_cache;
static struct kmem_cache *pending_cache;
struct dm_snap_tracked_chunk {
@@ -337,22 +335,6 @@ static void unregister_snapshot(struct d
up_write(&_origins_lock);
}
-static struct dm_exception *alloc_completed_exception(void *unused)
-{
- struct dm_exception *e;
-
- e = kmem_cache_alloc(exception_cache, GFP_NOIO);
- if (!e)
- e = kmem_cache_alloc(exception_cache, GFP_ATOMIC);
-
- return e;
-}
-
-static void free_completed_exception(struct dm_exception *e, void *unused)
-{
- kmem_cache_free(exception_cache, e);
-}
-
static struct dm_exception *alloc_pending_exception(void *context)
{
struct dm_snapshot *s = context;
@@ -379,29 +361,6 @@ static void free_pending_exception(struc
}
/*
- * Callback used by the exception stores to load exceptions when
- * initialising.
- */
-static int dm_add_exception(void *context, chunk_t old, chunk_t new)
-{
- struct dm_snapshot *s = context;
- struct dm_exception *e;
-
- e = dm_alloc_exception(s->complete);
- if (!e)
- return -ENOMEM;
-
- e->old_chunk = old;
-
- /* Consecutive_count is implicitly initialised to zero */
- e->new_chunk = new;
-
- dm_insert_exception(s->complete, e);
-
- return 0;
-}
-
-/*
* Hard coded magic.
*/
static int calc_max_buckets(void)
@@ -432,18 +391,6 @@ static int init_hash_tables(struct dm_sn
hash_size = min(hash_size, max_buckets);
hash_size = rounddown_pow_of_two(hash_size);
-
- s->complete = dm_exception_table_create(hash_size,
- DM_CHUNK_CONSECUTIVE_BITS,
- alloc_completed_exception, NULL,
- free_completed_exception, NULL);
- if (!s->complete)
- return -ENOMEM;
-
- /*
- * Allocate hash table for in-flight exceptions
- * Make this smaller than the real hash table
- */
hash_size >>= 3;
if (hash_size < 64)
hash_size = 64;
@@ -451,10 +398,8 @@ static int init_hash_tables(struct dm_sn
s->pending = dm_exception_table_create(hash_size, 0,
alloc_pending_exception, s,
free_pending_exception, NULL);
- if (!s->pending) {
- dm_exception_table_destroy(s->complete);
+ if (!s->pending)
return -ENOMEM;
- }
return 0;
}
@@ -606,18 +551,6 @@ static int snapshot_ctr(struct dm_target
INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]);
spin_lock_init(&s->tracked_chunk_lock);
-
- /* Metadata must only be loaded into one table at once */
- r = s->store->type->read_metadata(s->store, dm_add_exception,
- (void *)s);
- if (r < 0) {
- ti->error = "Failed to read snapshot metadata";
- goto bad_load_and_register;
- } else if (r > 0) {
- s->valid = 0;
- DMWARN("Snapshot is marked invalid.");
- }
-
bio_list_init(&s->queued_bios);
INIT_WORK(&s->queued_bios_work, flush_queued_bios);
@@ -645,7 +578,6 @@ bad_pending_pool:
bad_kcopyd:
dm_exception_table_destroy(s->pending);
- dm_exception_table_destroy(s->complete);
bad_hash_tables:
dm_put_device(ti, s->origin);
@@ -665,7 +597,6 @@ static void __free_exceptions(struct dm_
s->kcopyd_client = NULL;
dm_exception_table_destroy(s->pending);
- dm_exception_table_destroy(s->complete);
}
static void snapshot_dtr(struct dm_target *ti)
@@ -804,7 +735,6 @@ static struct bio *put_pending_exception
static void pending_complete(struct dm_snap_pending_exception *pe, int success)
{
- struct dm_exception *e;
struct dm_snapshot *s = pe->snap;
struct bio *origin_bios = NULL;
struct bio *snapshot_bios = NULL;
@@ -818,18 +748,8 @@ static void pending_complete(struct dm_s
goto out;
}
- e = dm_alloc_exception(s->complete);
- if (!e) {
- down_write(&s->lock);
- __invalidate_snapshot(s, -ENOMEM);
- error = 1;
- goto out;
- }
- *e = pe->e;
-
down_write(&s->lock);
if (!s->valid) {
- dm_free_exception(s->complete, e);
error = 1;
goto out;
}
@@ -841,12 +761,6 @@ static void pending_complete(struct dm_s
while (__chunk_is_tracked(s, pe->e.old_chunk))
msleep(1);
- /*
- * Add a proper exception, and remove the
- * in-flight exception from the list.
- */
- dm_insert_exception(s->complete, e);
-
out:
dm_remove_exception(&pe->e);
snapshot_bios = bio_list_get(&pe->snapshot_bios);
@@ -1408,25 +1322,18 @@ static int __init dm_snapshot_init(void)
goto bad2;
}
- exception_cache = KMEM_CACHE(dm_exception, 0);
- if (!exception_cache) {
- DMERR("Couldn't create exception cache.");
- r = -ENOMEM;
- goto bad3;
- }
-
pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0);
if (!pending_cache) {
DMERR("Couldn't create pending cache.");
r = -ENOMEM;
- goto bad4;
+ goto bad3;
}
tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0);
if (!tracked_chunk_cache) {
DMERR("Couldn't create cache to track chunks in use.");
r = -ENOMEM;
- goto bad5;
+ goto bad4;
}
ksnapd = create_singlethread_workqueue("ksnapd");
@@ -1440,10 +1347,8 @@ static int __init dm_snapshot_init(void)
bad_pending_pool:
kmem_cache_destroy(tracked_chunk_cache);
-bad5:
- kmem_cache_destroy(pending_cache);
bad4:
- kmem_cache_destroy(exception_cache);
+ kmem_cache_destroy(pending_cache);
bad3:
exit_origin_hash();
bad2:
@@ -1464,7 +1369,6 @@ static void __exit dm_snapshot_exit(void
exit_origin_hash();
kmem_cache_destroy(pending_cache);
- kmem_cache_destroy(exception_cache);
kmem_cache_destroy(tracked_chunk_cache);
dm_exception_store_exit();
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
