dm snapshot: move cow ref from exception store to snap core

[mv-sheeva.git] / drivers / md / dm-snap.c

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 8bd77cbd7e4542302b5d4c9892e2f06aa6c533c3..dc500a6f6232cd8c1c2701549232f5965d184326 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -59,6 +59,9 @@ struct dm_snapshot {
        struct rw_semaphore lock;
 
        struct dm_dev *origin;
+       struct dm_dev *cow;
+
+       struct dm_target *ti;
 
        /* List of snapshots per Origin */
        struct list_head list;
@@ -97,6 +100,12 @@ struct dm_snapshot {
        struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
 };
 
+struct dm_dev *dm_snap_cow(struct dm_snapshot *s)
+{
+       return s->cow;
+}
+EXPORT_SYMBOL(dm_snap_cow);
+
 static struct workqueue_struct *ksnapd;
 static void flush_queued_bios(struct work_struct *work);
 
@@ -558,7 +567,7 @@ static int init_hash_tables(struct dm_snapshot *s)
         * Calculate based on the size of the original volume or
         * the COW volume...
         */
-       cow_dev_size = get_dev_size(s->store->cow->bdev);
+       cow_dev_size = get_dev_size(s->cow->bdev);
        origin_dev_size = get_dev_size(s->origin->bdev);
        max_buckets = calc_max_buckets();
 
@@ -596,45 +605,55 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
        struct dm_snapshot *s;
        int i;
        int r = -EINVAL;
-       char *origin_path;
-       struct dm_exception_store *store;
+       char *origin_path, *cow_path;
        unsigned args_used;
 
        if (argc != 4) {
                ti->error = "requires exactly 4 arguments";
                r = -EINVAL;
-               goto bad_args;
+               goto bad;
        }
 
        origin_path = argv[0];
        argv++;
        argc--;
 
-       r = dm_exception_store_create(ti, argc, argv, &args_used, &store);
+       s = kmalloc(sizeof(*s), GFP_KERNEL);
+       if (!s) {
+               ti->error = "Cannot allocate snapshot context private "
+                   "structure";
+               r = -ENOMEM;
+               goto bad;
+       }
+
+       cow_path = argv[0];
+       argv++;
+       argc--;
+
+       r = dm_get_device(ti, cow_path, 0, 0,
+                         FMODE_READ | FMODE_WRITE, &s->cow);
+       if (r) {
+               ti->error = "Cannot get COW device";
+               goto bad_cow;
+       }
+
+       r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store);
        if (r) {
                ti->error = "Couldn't create exception store";
                r = -EINVAL;
-               goto bad_args;
+               goto bad_store;
        }
 
        argv += args_used;
        argc -= args_used;
 
-       s = kmalloc(sizeof(*s), GFP_KERNEL);
-       if (!s) {
-               ti->error = "Cannot allocate snapshot context private "
-                   "structure";
-               r = -ENOMEM;
-               goto bad_snap;
-       }
-
        r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin);
        if (r) {
                ti->error = "Cannot get origin device";
                goto bad_origin;
        }
 
-       s->store = store;
+       s->ti = ti;
        s->valid = 1;
        s->active = 0;
        atomic_set(&s->pending_exceptions_count, 0);
@@ -723,12 +742,15 @@ bad_hash_tables:
        dm_put_device(ti, s->origin);
 
 bad_origin:
-       kfree(s);
+       dm_exception_store_destroy(s->store);
 
-bad_snap:
-       dm_exception_store_destroy(store);
+bad_store:
+       dm_put_device(ti, s->cow);
 
-bad_args:
+bad_cow:
+       kfree(s);
+
+bad:
        return r;
 }
 
@@ -777,6 +799,8 @@ static void snapshot_dtr(struct dm_target *ti)
 
        dm_exception_store_destroy(s->store);
 
+       dm_put_device(ti, s->cow);
+
        kfree(s);
 }
 
@@ -839,7 +863,7 @@ static void __invalidate_snapshot(struct dm_snapshot *s, int err)
 
        s->valid = 0;
 
-       dm_table_event(s->store->ti->table);
+       dm_table_event(s->ti->table);
 }
 
 static void get_pending_exception(struct dm_snap_pending_exception *pe)
@@ -977,7 +1001,7 @@ static void start_copy(struct dm_snap_pending_exception *pe)
        src.sector = chunk_to_sector(s->store, pe->e.old_chunk);
        src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector);
 
-       dest.bdev = s->store->cow->bdev;
+       dest.bdev = s->cow->bdev;
        dest.sector = chunk_to_sector(s->store, pe->e.new_chunk);
        dest.count = src.count;
 
@@ -1038,7 +1062,7 @@ __find_pending_exception(struct dm_snapshot *s,
 static void remap_exception(struct dm_snapshot *s, struct dm_exception *e,
                            struct bio *bio, chunk_t chunk)
 {
-       bio->bi_bdev = s->store->cow->bdev;
+       bio->bi_bdev = s->cow->bdev;
        bio->bi_sector = chunk_to_sector(s->store,
                                         dm_chunk_number(e->new_chunk) +
                                         (chunk - e->old_chunk)) +
@@ -1056,7 +1080,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
        struct dm_snap_pending_exception *pe = NULL;
 
        if (unlikely(bio_empty_barrier(bio))) {
-               bio->bi_bdev = s->store->cow->bdev;
+               bio->bi_bdev = s->cow->bdev;
                return DM_MAPIO_REMAPPED;
        }
 
@@ -1200,7 +1224,7 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
                 * to make private copies if the output is to
                 * make sense.
                 */
-               DMEMIT("%s", snap->origin->name);
+               DMEMIT("%s %s", snap->origin->name, snap->cow->name);
                snap->store->type->status(snap->store, type, result + sz,
                                          maxlen - sz);
                break;
@@ -1240,7 +1264,7 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
                        goto next_snapshot;
 
                /* Nothing to do if writing beyond end of snapshot */
-               if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table))
+               if (bio->bi_sector >= dm_table_get_size(snap->ti->table))
                        goto next_snapshot;
 
                /*