dm exception store: move cow pointer

Move COW device from snapshot to exception store.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

6 files changed, 30 insertions, 23 deletions

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 59c949b53106..2078b92470a1 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -139,7 +139,7 @@ EXPORT_SYMBOL(dm_exception_store_type_unregister);
 
 int dm_exception_store_create(const char *type_name, struct dm_target *ti,
                               chunk_t chunk_size, chunk_t chunk_mask,
-                              chunk_t chunk_shift,
+                              chunk_t chunk_shift, struct dm_dev *cow,
                               struct dm_exception_store **store)
 {
         int r = 0;
@@ -163,6 +163,8 @@ int dm_exception_store_create(const char *type_name, struct dm_target *ti,
         tmp_store->chunk_mask = chunk_mask;
         tmp_store->chunk_shift = chunk_shift;
 
+        tmp_store->cow = cow;
+
         r = type->ctr(tmp_store, 0, NULL);
         if (r) {
                 put_type(type);
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index 449a1e48f7aa..4dbf3577408e 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -99,6 +99,8 @@ struct dm_exception_store {
 
         struct dm_snapshot *snap;
 
+        struct dm_dev *cow;
+
         /* Size of data blocks saved - must be a power of 2 */
         chunk_t chunk_size;
         chunk_t chunk_mask;
@@ -155,7 +157,7 @@ int dm_exception_store_type_unregister(struct dm_exception_store_type *type);
 
 int dm_exception_store_create(const char *type_name, struct dm_target *ti,
                               chunk_t chunk_size, chunk_t chunk_mask,
-                              chunk_t chunk_shift,
+                              chunk_t chunk_shift, struct dm_dev *cow,
                               struct dm_exception_store **store);
 void dm_exception_store_destroy(struct dm_exception_store *store);
 
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index c3c58159b6e8..505afac9976f 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -189,7 +189,7 @@ static void do_metadata(struct work_struct *work)
 static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata)
 {
         struct dm_io_region where = {
-                .bdev = ps->snap->cow->bdev,
+                .bdev = ps->snap->store->cow->bdev,
                 .sector = ps->snap->store->chunk_size * chunk,
                 .count = ps->snap->store->chunk_size,
         };
@@ -253,7 +253,7 @@ static void zero_memory_area(struct pstore *ps)
 static int zero_disk_area(struct pstore *ps, chunk_t area)
 {
         struct dm_io_region where = {
-                .bdev = ps->snap->cow->bdev,
+                .bdev = ps->snap->store->cow->bdev,
                 .sector = ps->snap->store->chunk_size * area_location(ps, area),
                 .count = ps->snap->store->chunk_size,
         };
@@ -280,7 +280,7 @@ static int read_header(struct pstore *ps, int *new_snapshot)
          */
         if (!ps->snap->store->chunk_size) {
                 ps->snap->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
-                    bdev_hardsect_size(ps->snap->cow->bdev) >> 9);
+                    bdev_hardsect_size(ps->snap->store->cow->bdev) >> 9);
                 ps->snap->store->chunk_mask = ps->snap->store->chunk_size - 1;
                 ps->snap->store->chunk_shift = ffs(ps->snap->store->chunk_size)
                                                - 1;
@@ -476,7 +476,7 @@ static void persistent_fraction_full(struct dm_exception_store *store,
                                      sector_t *numerator, sector_t *denominator)
 {
         *numerator = get_info(store)->next_free * store->chunk_size;
-        *denominator = get_dev_size(store->snap->cow->bdev);
+        *denominator = get_dev_size(store->cow->bdev);
 }
 
 static void persistent_dtr(struct dm_exception_store *store)
@@ -565,7 +565,7 @@ static int persistent_prepare_exception(struct dm_exception_store *store,
         struct pstore *ps = get_info(store);
         uint32_t stride;
         chunk_t next_free;
-        sector_t size = get_dev_size(store->snap->cow->bdev);
+        sector_t size = get_dev_size(store->cow->bdev);
 
         /* Is there enough room ? */
         if (size < ((ps->next_free + 1) * store->chunk_size))
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
index c542ababb418..77f58be080c4 100644
--- a/drivers/md/dm-snap-transient.c
+++ b/drivers/md/dm-snap-transient.c
@@ -40,7 +40,7 @@ static int transient_prepare_exception(struct dm_exception_store *store,
                                        struct dm_snap_exception *e)
 {
         struct transient_c *tc = store->context;
-        sector_t size = get_dev_size(store->snap->cow->bdev);
+        sector_t size = get_dev_size(store->cow->bdev);
 
         if (size < (tc->next_free + store->chunk_size))
                 return -1;
@@ -64,7 +64,7 @@ static void transient_fraction_full(struct dm_exception_store *store,
                                     sector_t *numerator, sector_t *denominator)
 {
         *numerator = ((struct transient_c *) store->context)->next_free;
-        *denominator = get_dev_size(store->snap->cow->bdev);
+        *denominator = get_dev_size(store->cow->bdev);
 }
 
 static int transient_ctr(struct dm_exception_store *store,
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 7a90fed033fe..5c067efc665f 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -468,7 +468,8 @@ static int calc_max_buckets(void)
 /*
  * Allocate room for a suitable hash table.
  */
-static int init_hash_tables(struct dm_snapshot *s, chunk_t chunk_shift)
+static int init_hash_tables(struct dm_snapshot *s, chunk_t chunk_shift,
+                            struct dm_dev *cow)
 {
         sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets;
 
@@ -476,7 +477,7 @@ static int init_hash_tables(struct dm_snapshot *s, chunk_t chunk_shift)
          * Calculate based on the size of the original volume or
          * the COW volume...
          */
-        cow_dev_size = get_dev_size(s->cow->bdev);
+        cow_dev_size = get_dev_size(cow->bdev);
         origin_dev_size = get_dev_size(s->origin->bdev);
         max_buckets = calc_max_buckets();
 
@@ -516,7 +517,8 @@ static ulong round_up(ulong n, ulong size)
 
 static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
                           chunk_t *chunk_size, chunk_t *chunk_mask,
-                          chunk_t *chunk_shift, char **error)
+                          chunk_t *chunk_shift, struct dm_dev *cow,
+                          char **error)
 {
         unsigned long chunk_size_ulong;
         char *value;
@@ -545,7 +547,7 @@ static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
         }
 
         /* Validate the chunk size against the device block size */
-        if (chunk_size_ulong % (bdev_hardsect_size(s->cow->bdev) >> 9)) {
+        if (chunk_size_ulong % (bdev_hardsect_size(cow->bdev) >> 9)) {
                 *error = "Chunk size is not a multiple of device blocksize";
                 return -EINVAL;
         }
@@ -569,6 +571,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         char *origin_path;
         char *cow_path;
         chunk_t chunk_size, chunk_mask, chunk_shift;
+        struct dm_dev *cow;
 
         if (argc != 4) {
                 ti->error = "requires exactly 4 arguments";
@@ -601,7 +604,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         }
 
         r = dm_get_device(ti, cow_path, 0, 0,
-                          FMODE_READ | FMODE_WRITE, &s->cow);
+                          FMODE_READ | FMODE_WRITE, &cow);
         if (r) {
                 dm_put_device(ti, s->origin);
                 ti->error = "Cannot get COW device";
@@ -609,7 +612,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         }
 
         r = set_chunk_size(s, argv[3], &chunk_size, &chunk_mask, &chunk_shift,
-                           &ti->error);
+                           cow, &ti->error);
         if (r)
                 goto bad3;
 
@@ -620,14 +623,14 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         spin_lock_init(&s->pe_lock);
 
         /* Allocate hash table for COW data */
-        if (init_hash_tables(s, chunk_shift)) {
+        if (init_hash_tables(s, chunk_shift, cow)) {
                 ti->error = "Unable to allocate hash table space";
                 r = -ENOMEM;
                 goto bad3;
         }
 
         r = dm_exception_store_create(argv[2], ti, chunk_size, chunk_mask,
-                                      chunk_shift, &s->store);
+                                      chunk_shift, cow, &s->store);
         if (r) {
                 ti->error = "Couldn't create exception store";
                 r = -EINVAL;
@@ -705,7 +708,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         exit_exception_table(&s->complete, exception_cache);
 
  bad3:
-        dm_put_device(ti, s->cow);
+        dm_put_device(ti, cow);
         dm_put_device(ti, s->origin);
 
  bad2:
@@ -732,6 +735,7 @@ static void snapshot_dtr(struct dm_target *ti)
         int i;
 #endif
         struct dm_snapshot *s = ti->private;
+        struct dm_dev *cow = s->store->cow;
 
         flush_workqueue(ksnapd);
 
@@ -759,7 +763,7 @@ static void snapshot_dtr(struct dm_target *ti)
         mempool_destroy(s->pending_pool);
 
         dm_put_device(ti, s->origin);
-        dm_put_device(ti, s->cow);
+        dm_put_device(ti, cow);
 
         kfree(s);
 }
@@ -961,7 +965,7 @@ static void start_copy(struct dm_snap_pending_exception *pe)
         src.sector = chunk_to_sector(s, pe->e.old_chunk);
         src.count = min(s->store->chunk_size, dev_size - src.sector);
 
-        dest.bdev = s->cow->bdev;
+        dest.bdev = s->store->cow->bdev;
         dest.sector = chunk_to_sector(s, pe->e.new_chunk);
         dest.count = src.count;
 
@@ -1022,7 +1026,7 @@ __find_pending_exception(struct dm_snapshot *s,
 static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e,
                             struct bio *bio, chunk_t chunk)
 {
-        bio->bi_bdev = s->cow->bdev;
+        bio->bi_bdev = s->store->cow->bdev;
         bio->bi_sector = chunk_to_sector(s, dm_chunk_number(e->new_chunk) +
                          (chunk - e->old_chunk)) +
                          (bio->bi_sector & s->store->chunk_mask);
@@ -1168,7 +1172,7 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
                  * make sense.
                  */
                 snprintf(result, maxlen, "%s %s %s %llu",
-                         snap->origin->name, snap->cow->name,
+                         snap->origin->name, snap->store->cow->name,
                          snap->store->type->name,
                          (unsigned long long)snap->store->chunk_size);
                 break;
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index c2e4ebedbd49..c8a486e0ea2c 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -27,7 +27,6 @@ struct dm_snapshot {
         struct rw_semaphore lock;
 
         struct dm_dev *origin;
-        struct dm_dev *cow;
 
         /* List of snapshots per Origin */
         struct list_head list;