dm snapshot: move cow ref from exception store to snap core
Store the reference to the snapshot cow device in the core snapshot
code instead of each exception store. It can be accessed through the
new function dm_snap_cow(). Exception stores should each now maintain a
reference to their parent snapshot struct.
This is cleaner and makes part of the forthcoming snapshot merge code simpler.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Reviewed-by: Jonathan Brassow <jbrassow@redhat.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 2052159..2b7907b 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -172,7 +172,8 @@
}
/* Validate the chunk size against the device block size */
- if (chunk_size % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
+ if (chunk_size %
+ (bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9)) {
*error = "Chunk size is not a multiple of device blocksize";
return -EINVAL;
}
@@ -190,6 +191,7 @@
}
int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
+ struct dm_snapshot *snap,
unsigned *args_used,
struct dm_exception_store **store)
{
@@ -198,7 +200,7 @@
struct dm_exception_store *tmp_store;
char persistent;
- if (argc < 3) {
+ if (argc < 2) {
ti->error = "Insufficient exception store arguments";
return -EINVAL;
}
@@ -209,7 +211,7 @@
return -ENOMEM;
}
- persistent = toupper(*argv[1]);
+ persistent = toupper(*argv[0]);
if (persistent == 'P')
type = get_type("P");
else if (persistent == 'N')
@@ -227,32 +229,23 @@
}
tmp_store->type = type;
- tmp_store->ti = ti;
+ tmp_store->snap = snap;
- r = dm_get_device(ti, argv[0], 0, 0,
- FMODE_READ | FMODE_WRITE, &tmp_store->cow);
- if (r) {
- ti->error = "Cannot get COW device";
- goto bad_cow;
- }
-
- r = set_chunk_size(tmp_store, argv[2], &ti->error);
+ r = set_chunk_size(tmp_store, argv[1], &ti->error);
if (r)
- goto bad_ctr;
+ goto bad;
r = type->ctr(tmp_store, 0, NULL);
if (r) {
ti->error = "Exception store type constructor failed";
- goto bad_ctr;
+ goto bad;
}
- *args_used = 3;
+ *args_used = 2;
*store = tmp_store;
return 0;
-bad_ctr:
- dm_put_device(ti, tmp_store->cow);
-bad_cow:
+bad:
put_type(type);
bad_type:
kfree(tmp_store);
@@ -263,7 +256,6 @@
void dm_exception_store_destroy(struct dm_exception_store *store)
{
store->type->dtr(store);
- dm_put_device(store->ti, store->cow);
put_type(store->type);
kfree(store);
}
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index 366c8b1..bb88746 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -94,11 +94,11 @@
struct list_head list;
};
+struct dm_snapshot;
+
struct dm_exception_store {
struct dm_exception_store_type *type;
- struct dm_target *ti;
-
- struct dm_dev *cow;
+ struct dm_snapshot *snap;
/* Size of data blocks saved - must be a power of 2 */
unsigned chunk_size;
@@ -109,6 +109,11 @@
};
/*
+ * Obtain the cow device used by a given snapshot.
+ */
+struct dm_dev *dm_snap_cow(struct dm_snapshot *snap);
+
+/*
* Funtions to manipulate consecutive chunks
*/
# if defined(CONFIG_LBDAF) || (BITS_PER_LONG == 64)
@@ -173,6 +178,7 @@
char **error);
int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
+ struct dm_snapshot *snap,
unsigned *args_used,
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 767065f..157999e 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -214,7 +214,7 @@
int metadata)
{
struct dm_io_region where = {
- .bdev = ps->store->cow->bdev,
+ .bdev = dm_snap_cow(ps->store->snap)->bdev,
.sector = ps->store->chunk_size * chunk,
.count = ps->store->chunk_size,
};
@@ -294,7 +294,8 @@
*/
if (!ps->store->chunk_size) {
ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
- bdev_logical_block_size(ps->store->cow->bdev) >> 9);
+ bdev_logical_block_size(dm_snap_cow(ps->store->snap)->
+ 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;
@@ -497,7 +498,7 @@
struct pstore *ps = get_info(store);
*sectors_allocated = ps->next_free * store->chunk_size;
- *total_sectors = get_dev_size(store->cow->bdev);
+ *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
/*
* First chunk is the fixed header.
@@ -596,7 +597,7 @@
struct pstore *ps = get_info(store);
uint32_t stride;
chunk_t next_free;
- sector_t size = get_dev_size(store->cow->bdev);
+ sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
/* Is there enough room ? */
if (size < ((ps->next_free + 1) * store->chunk_size))
@@ -733,8 +734,7 @@
case STATUSTYPE_INFO:
break;
case STATUSTYPE_TABLE:
- DMEMIT(" %s P %llu", store->cow->name,
- (unsigned long long)store->chunk_size);
+ DMEMIT(" P %llu", (unsigned long long)store->chunk_size);
}
return sz;
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
index 245a50c..a0898a6 100644
--- a/drivers/md/dm-snap-transient.c
+++ b/drivers/md/dm-snap-transient.c
@@ -39,7 +39,7 @@
struct dm_exception *e)
{
struct transient_c *tc = store->context;
- sector_t size = get_dev_size(store->cow->bdev);
+ sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
if (size < (tc->next_free + store->chunk_size))
return -1;
@@ -65,7 +65,7 @@
sector_t *metadata_sectors)
{
*sectors_allocated = ((struct transient_c *) store->context)->next_free;
- *total_sectors = get_dev_size(store->cow->bdev);
+ *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
*metadata_sectors = 0;
}
@@ -94,8 +94,7 @@
case STATUSTYPE_INFO:
break;
case STATUSTYPE_TABLE:
- DMEMIT(" %s N %llu", store->cow->name,
- (unsigned long long)store->chunk_size);
+ DMEMIT(" N %llu", (unsigned long long)store->chunk_size);
}
return sz;
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 8bd77cb..dc500a6 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -59,6 +59,9 @@
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 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 @@
* 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 @@
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);
- if (r) {
- ti->error = "Couldn't create exception store";
- r = -EINVAL;
- goto bad_args;
- }
-
- 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;
+ 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_store;
+ }
+
+ argv += args_used;
+ argc -= args_used;
+
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 @@
dm_put_device(ti, s->origin);
bad_origin:
+ dm_exception_store_destroy(s->store);
+
+bad_store:
+ dm_put_device(ti, s->cow);
+
+bad_cow:
kfree(s);
-bad_snap:
- dm_exception_store_destroy(store);
-
-bad_args:
+bad:
return r;
}
@@ -777,6 +799,8 @@
dm_exception_store_destroy(s->store);
+ dm_put_device(ti, s->cow);
+
kfree(s);
}
@@ -839,7 +863,7 @@
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 @@
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 @@
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 @@
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 @@
* 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 @@
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;
/*