From patchwork Mon Apr 6 21:35:19 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonthan Brassow X-Patchwork-Id: 16651 Received: from hormel.redhat.com (hormel1.redhat.com [209.132.177.33]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n36LZMi0013219 for ; Mon, 6 Apr 2009 21:35:23 GMT Received: from listman.util.phx.redhat.com (listman.util.phx.redhat.com [10.8.4.110]) by hormel.redhat.com (Postfix) with ESMTP id 82D1461B218; Mon, 6 Apr 2009 17:35:23 -0400 (EDT) Received: from int-mx2.corp.redhat.com ([172.16.27.26]) by listman.util.phx.redhat.com (8.13.1/8.13.1) with ESMTP id n36LZMrL031596 for ; Mon, 6 Apr 2009 17:35:22 -0400 Received: from hydrogen.msp.redhat.com (hydrogen.msp.redhat.com [10.15.80.1]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n36LZMOU007573 for ; Mon, 6 Apr 2009 17:35:22 -0400 Received: from hydrogen.msp.redhat.com (localhost.localdomain [127.0.0.1]) by hydrogen.msp.redhat.com (8.14.1/8.14.1) with ESMTP id n36LZJ1M020946 for ; Mon, 6 Apr 2009 16:35:19 -0500 Received: (from jbrassow@localhost) by hydrogen.msp.redhat.com (8.14.1/8.14.1/Submit) id n36LZJPE020945 for dm-devel@redhat.com; Mon, 6 Apr 2009 16:35:19 -0500 Date: Mon, 6 Apr 2009 16:35:19 -0500 From: Jonathan Brassow Message-Id: <200904062135.n36LZJPE020945@hydrogen.msp.redhat.com> To: dm-devel@redhat.com X-Scanned-By: MIMEDefang 2.58 on 172.16.27.26 X-loop: dm-devel@redhat.com Subject: [dm-devel] [PATCH 17 of 33] DM Exception Store: add resume to API X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.5 Precedence: junk Reply-To: device-mapper development List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com Patch name: dm-exception-store-add-resume-to-API.patch Add 'resume' to exception store API. This is the first step to replace 'read_metadata' with 'resume'. 'resume' will populate the exception store implementation's exception cache - rather than loading the snapshot's exception cache. Relocating the 'resume' is more in line with the way device-mapper targets (and device-mapper mirror logs) work. Additionally, with future shared exception store types, we don't duplicate the cache. Signed-off-by: Jonathan Brassow --- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel Index: linux-2.6/drivers/md/dm-exception-store.h =================================================================== --- linux-2.6.orig/drivers/md/dm-exception-store.h +++ linux-2.6/drivers/md/dm-exception-store.h @@ -31,6 +31,8 @@ struct dm_exception_store_type { */ void (*dtr) (struct dm_exception_store *store); + int (*resume) (struct dm_exception_store *store); + /* * The target shouldn't read the COW device until this is * called. As exceptions are read from the COW, they are Index: linux-2.6/drivers/md/dm-snap-persistent.c =================================================================== --- linux-2.6.orig/drivers/md/dm-snap-persistent.c +++ linux-2.6/drivers/md/dm-snap-persistent.c @@ -89,6 +89,7 @@ struct commit_callback { */ struct pstore { struct dm_exception_store *store; + struct dm_exception_table *table; int version; int valid; uint32_t exceptions_per_area; @@ -130,6 +131,24 @@ struct pstore { struct workqueue_struct *metadata_wq; }; +static struct kmem_cache *exception_cache; + +static struct dm_exception *alloc_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_exception(struct dm_exception *e, void *unused) +{ + kmem_cache_free(exception_cache, e); +} + static unsigned sectors_to_pages(unsigned sectors) { return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); @@ -282,7 +301,7 @@ static int read_header(struct pstore *ps */ if (!ps->store->chunk_size) { ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, - bdev_hardsect_size(ps->store->cow->bdev) >> 9); + bdev_hardsect_size(ps->store->cow->bdev) >> 9); ps->store->chunk_mask = ps->store->chunk_size - 1; ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1; chunk_size_supplied = 0; @@ -495,6 +514,7 @@ static void persistent_dtr(struct dm_exc if (ps->callbacks) vfree(ps->callbacks); + dm_exception_table_destroy(ps->table); kfree(ps); } @@ -506,6 +526,13 @@ static int persistent_read_metadata(stru int r, uninitialized_var(new_snapshot); struct pstore *ps = get_info(store); + if (ps->callbacks) + /* + * Temporary work around for having two different functions + * that get us going... 'read_metadata' and 'resume'. + */ + goto read_metadata; + /* * Read the snapshot header. */ @@ -517,7 +544,7 @@ static int persistent_read_metadata(stru * Now we know correct chunk_size, complete the initialisation. */ ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) / - sizeof(struct disk_exception); + sizeof(struct disk_exception); ps->callbacks = dm_vcalloc(ps->exceptions_per_area, sizeof(*ps->callbacks)); if (!ps->callbacks) @@ -558,11 +585,44 @@ static int persistent_read_metadata(stru /* * Read the metadata. */ +read_metadata: r = read_exceptions(ps, callback, callback_context); return r; } +/* This function is temporary for patch cleanliness */ +static int add_exception(void *context, chunk_t old, chunk_t new) +{ + struct dm_exception_store *store = context; + struct pstore *ps = get_info(store); + struct dm_exception *e; + + e = dm_alloc_exception(ps->table); + if (!e) + return -ENOMEM; + + e->old_chunk = old; + e->new_chunk = new; + + dm_insert_exception(ps->table, e); + + return 0; +} + +/* + * persistent_resume + * @store + * + * Read metadata of the disk and store in our exception table cache. + * + * Returns: 0 on success, -Exxx on error + */ +static int persistent_resume(struct dm_exception_store *store) +{ + return persistent_read_metadata(store, add_exception, store); +} + static int persistent_prepare_exception(struct dm_exception_store *store, struct dm_exception *e) { @@ -665,6 +725,7 @@ static int persistent_ctr(struct dm_exce unsigned argc, char **argv) { struct pstore *ps; + sector_t hash_size, cow_dev_size, max_buckets; /* allocate the pstore */ ps = kzalloc(sizeof(*ps), GFP_KERNEL); @@ -682,8 +743,26 @@ static int persistent_ctr(struct dm_exce atomic_set(&ps->pending_count, 0); ps->callbacks = NULL; + cow_dev_size = get_dev_size(store->cow->bdev); + max_buckets = (2 * 1024 * 1024)/sizeof(struct list_head); + + hash_size = cow_dev_size >> store->chunk_shift; + hash_size = min(hash_size, max_buckets); + + hash_size = rounddown_pow_of_two(hash_size); + + ps->table = dm_exception_table_create(hash_size, + DM_CHUNK_CONSECUTIVE_BITS, + alloc_exception, NULL, + free_exception, NULL); + if (!ps->table) { + kfree(ps); + return -ENOMEM; + } + ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); if (!ps->metadata_wq) { + dm_exception_table_destroy(ps->table); kfree(ps); DMERR("couldn't start header metadata update thread"); return -ENOMEM; @@ -721,6 +800,7 @@ static struct dm_exception_store_type _p .module = THIS_MODULE, .ctr = persistent_ctr, .dtr = persistent_dtr, + .resume = persistent_resume, .read_metadata = persistent_read_metadata, .prepare_exception = persistent_prepare_exception, .commit_exception = persistent_commit_exception, @@ -734,6 +814,7 @@ static struct dm_exception_store_type _p .module = THIS_MODULE, .ctr = persistent_ctr, .dtr = persistent_dtr, + .resume = persistent_resume, .read_metadata = persistent_read_metadata, .prepare_exception = persistent_prepare_exception, .commit_exception = persistent_commit_exception, @@ -746,9 +827,16 @@ int dm_persistent_snapshot_init(void) { int r; + exception_cache = KMEM_CACHE(dm_exception, 0); + if (!exception_cache) { + DMERR("Couldn't create persistent exception cache."); + return -ENOMEM; + } + r = dm_exception_store_type_register(&_persistent_type); if (r) { DMERR("Unable to register persistent exception store type"); + kmem_cache_destroy(exception_cache); return r; } @@ -757,6 +845,7 @@ int dm_persistent_snapshot_init(void) DMERR("Unable to register old-style persistent exception " "store type"); dm_exception_store_type_unregister(&_persistent_type); + kmem_cache_destroy(exception_cache); return r; } @@ -767,4 +856,5 @@ void dm_persistent_snapshot_exit(void) { dm_exception_store_type_unregister(&_persistent_type); dm_exception_store_type_unregister(&_persistent_compat_type); + kmem_cache_destroy(exception_cache); } Index: linux-2.6/drivers/md/dm-snap-transient.c =================================================================== --- linux-2.6.orig/drivers/md/dm-snap-transient.c +++ linux-2.6/drivers/md/dm-snap-transient.c @@ -19,12 +19,29 @@ * Implementation of the store for non-persistent snapshots. *---------------------------------------------------------------*/ struct transient_c { + struct dm_exception_table *table; + sector_t next_free; }; +/* Could use better allocation policies - like in dm-snap-persistent.c */ +static struct dm_exception *alloc_exception(void *unused) +{ + return kmalloc(sizeof(struct dm_exception), GFP_KERNEL); +} + +static void free_exception(struct dm_exception *e, void *unused) +{ + kfree(e); +} + static void transient_dtr(struct dm_exception_store *store) { - kfree(store->context); + struct transient_c *tc = store->context; + + dm_exception_table_destroy(tc->table); + + kfree(tc); } static int transient_read_metadata(struct dm_exception_store *store, @@ -35,6 +52,11 @@ static int transient_read_metadata(struc return 0; } +static int transient_resume(struct dm_exception_store *store) +{ + return 0; +} + static int transient_prepare_exception(struct dm_exception_store *store, struct dm_exception *e) { @@ -70,6 +92,7 @@ static int transient_ctr(struct dm_excep unsigned argc, char **argv) { struct transient_c *tc; + sector_t hash_size, cow_dev_size, max_buckets; tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); if (!tc) @@ -78,6 +101,23 @@ static int transient_ctr(struct dm_excep tc->next_free = 0; store->context = tc; + cow_dev_size = get_dev_size(store->cow->bdev); + max_buckets = (2 * 1024 * 1024)/sizeof(struct list_head); + + hash_size = cow_dev_size >> store->chunk_shift; + hash_size = min(hash_size, max_buckets); + + hash_size = rounddown_pow_of_two(hash_size); + + tc->table = dm_exception_table_create(hash_size, + DM_CHUNK_CONSECUTIVE_BITS, + alloc_exception, NULL, + free_exception, NULL); + if (!tc->table) { + kfree(tc); + return -ENOMEM; + } + return 0; } @@ -108,6 +148,7 @@ static struct dm_exception_store_type _t .module = THIS_MODULE, .ctr = transient_ctr, .dtr = transient_dtr, + .resume = transient_resume, .read_metadata = transient_read_metadata, .prepare_exception = transient_prepare_exception, .commit_exception = transient_commit_exception, @@ -120,6 +161,7 @@ static struct dm_exception_store_type _t .module = THIS_MODULE, .ctr = transient_ctr, .dtr = transient_dtr, + .resume = transient_resume, .read_metadata = transient_read_metadata, .prepare_exception = transient_prepare_exception, .commit_exception = transient_commit_exception, 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 @@ -1078,10 +1078,22 @@ static int snapshot_end_io(struct dm_tar static void snapshot_resume(struct dm_target *ti) { + int r; struct dm_snapshot *s = ti->private; + /* + * Target resumes cannot fail, which leaves us in a tight spot. + * We read the exception store, the snapshot may be invalid + * or we may have failed to resume for a different reason (EIO?). + * If invalid, mark the snapshot as such. However, if other, + * what can we do? Mark 'not active'? + */ + r = s->store->type->resume(s->store); + if (r == -EINVAL) + r = s->valid = 0; + down_write(&s->lock); - s->active = 1; + s->active = (r) ? 0 : 1; up_write(&s->lock); }