From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
With the current two exception store implementations (persistent and
transient), snapshots are independent. Each snapshot has own cow disk
and dm_snapshot struct.
With shared exception store code, snapshots are not independent. They
are stored in a single cow disk and has only one dm_snapshot struct.
So the shared exception store code needs to identify snapshot in
prepare_exception() and lookup_completed_exception().
[Needs more thought regarding unique snapshot IDs - AGK]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
---
drivers/md/dm-exception-store.c | 4 ++--
drivers/md/dm-snap.c | 22 ++++++++++++----------
drivers/md/dm-snap.h | 6 ++++--
3 files changed, 18 insertions(+), 14 deletions(-)
Index: linux-2.6.28-rc3/drivers/md/dm-exception-store.c
===================================================================
--- linux-2.6.28-rc3.orig/drivers/md/dm-exception-store.c 2008-11-07 13:15:32.000000000 +0000
+++ linux-2.6.28-rc3/drivers/md/dm-exception-store.c 2008-11-07 13:15:48.000000000 +0000
@@ -552,7 +552,7 @@ static int persistent_read_metadata(stru
}
static int persistent_prepare(struct exception_store *store,
- struct dm_snap_exception *e)
+ struct dm_snap_exception *e, u64 snapid)
{
struct pstore *ps = get_info(store);
uint32_t stride;
@@ -705,7 +705,7 @@ static int transient_read_metadata(struc
}
static int transient_prepare(struct exception_store *store,
- struct dm_snap_exception *e)
+ struct dm_snap_exception *e, u64 snapid)
{
struct transient_c *tc = (struct transient_c *) store->context;
sector_t size = get_dev_size(store->snap->cow->bdev);
Index: linux-2.6.28-rc3/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.28-rc3.orig/drivers/md/dm-snap.c 2008-11-07 13:15:44.000000000 +0000
+++ linux-2.6.28-rc3/drivers/md/dm-snap.c 2008-11-07 13:15:48.000000000 +0000
@@ -350,10 +350,12 @@ static struct dm_snap_exception *lookup_
}
struct dm_snap_exception *lookup_complete_exception(struct dm_snapshot *s,
- chunk_t chunk)
+ chunk_t chunk,
+ u64 snapid)
{
if (s->store.lookup_completed_exception)
- return s->store.lookup_completed_exception(&s->store, chunk);
+ return s->store.lookup_completed_exception(&s->store, chunk,
+ snapid);
else
return lookup_exception(&s->complete, chunk);
}
@@ -986,7 +988,7 @@ static void start_copy(struct dm_snap_pe
* this.
*/
static struct dm_snap_pending_exception *
-__find_pending_exception(struct dm_snapshot *s, struct bio *bio)
+__find_pending_exception(struct dm_snapshot *s, struct bio *bio, u64 snapid)
{
struct dm_snap_exception *e;
struct dm_snap_pending_exception *pe;
@@ -1029,7 +1031,7 @@ __find_pending_exception(struct dm_snaps
atomic_set(&pe->ref_count, 0);
pe->started = 0;
- if (s->store.prepare_exception(&s->store, &pe->e)) {
+ if (s->store.prepare_exception(&s->store, &pe->e, snapid)) {
free_pending_exception(pe);
return NULL;
}
@@ -1051,7 +1053,7 @@ static void remap_exception(struct dm_sn
}
static int do_snapshot_map(struct dm_snapshot *s, struct bio *bio,
- union map_info *map_context)
+ union map_info *map_context, u64 snapid)
{
struct dm_snap_exception *e;
int r = DM_MAPIO_REMAPPED;
@@ -1075,7 +1077,7 @@ static int do_snapshot_map(struct dm_sna
}
/* If the block is already remapped - use that, else remap it */
- e = lookup_complete_exception(s, chunk);
+ e = lookup_complete_exception(s, chunk, snapid);
if (e) {
remap_exception(s, e, bio, chunk);
goto out_unlock;
@@ -1087,7 +1089,7 @@ static int do_snapshot_map(struct dm_sna
* writeable.
*/
if (bio_rw(bio) == WRITE) {
- pe = __find_pending_exception(s, bio);
+ pe = __find_pending_exception(s, bio, snapid);
if (!pe) {
__invalidate_snapshot(s, -ENOMEM);
r = -EIO;
@@ -1122,7 +1124,7 @@ static int snapshot_map(struct dm_target
{
struct dm_snapshot *s = ti->private;
- return do_snapshot_map(s, bio, map_context);
+ return do_snapshot_map(s, bio, map_context, 0);
}
static int do_snapshot_end_io(struct dm_snapshot *s, struct bio *bio,
@@ -1231,11 +1233,11 @@ static int __origin_write(struct list_he
* ref_count is initialised to 1 so pending_complete()
* won't destroy the primary_pe while we're inside this loop.
*/
- e = lookup_complete_exception(snap, chunk);
+ e = lookup_complete_exception(snap, chunk, ORIGIN_SNAPID);
if (e)
goto next_snapshot;
- pe = __find_pending_exception(snap, bio);
+ pe = __find_pending_exception(snap, bio, ORIGIN_SNAPID);
if (!pe) {
__invalidate_snapshot(snap, -ENOMEM);
goto next_snapshot;
Index: linux-2.6.28-rc3/drivers/md/dm-snap.h
===================================================================
--- linux-2.6.28-rc3.orig/drivers/md/dm-snap.h 2008-11-07 13:15:41.000000000 +0000
+++ linux-2.6.28-rc3/drivers/md/dm-snap.h 2008-11-07 13:15:48.000000000 +0000
@@ -83,6 +83,8 @@ static inline void dm_consecutive_chunk_
# endif
+#define ORIGIN_SNAPID ULLONG_MAX
+
/*
* Abstraction to handle the meta/layout of exception stores (the
* COW device).
@@ -104,7 +106,7 @@ struct exception_store {
* Find somewhere to store the next exception.
*/
int (*prepare_exception) (struct exception_store *store,
- struct dm_snap_exception *e);
+ struct dm_snap_exception *e, u64 snapid);
/*
* Update the metadata with this exception.
@@ -130,7 +132,7 @@ struct exception_store {
* look up if a chunk is in completed exception.
*/
struct dm_snap_exception *(*lookup_completed_exception)
- (struct exception_store *store, chunk_t chunk);
+ (struct exception_store *store, chunk_t chunk, u64 snapid);
/*
* let exception store code to handle the message hook in