Patch name: dm-exception-store-add-arg-to-prepare_commit.patch

Add the 'group' paramenter to the prepare_exception function. This
is used to facilitate shared exception stores. When writing to
a snapshot, an exception is created for only that snapshot (group=0).
When writing to the origin, all snapshots are affected, so rather
than preparing_exceptions for all snapshots one at a time, we can
use the group=1 to indicate that all snapshots managed by the shared
exception store be updated.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>

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
@@ -40,9 +40,14 @@ struct dm_exception_store_type {

/*
* Find somewhere to store the next exception.
+ * If the exception store implementation is shared,
+ * the 'group' field signifies whether to operate on
+ * the group sharing one exception store, or whether
+ * to operate on just one of those in the shared
+ * exception store.
*/
int (*prepare_exception) (struct dm_exception_store *store,
- struct dm_exception *e);
+ struct dm_exception *e, int group);

/*
* Update the metadata with this exception.
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
@@ -604,7 +604,7 @@ read_metadata:
}

static int persistent_prepare_exception(struct dm_exception_store *store,
- struct dm_exception *e)
+ struct dm_exception *e, int group)
{
struct pstore *ps = get_info(store);
uint32_t stride;
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
@@ -50,7 +50,7 @@ static int transient_resume(struct dm_ex
}

static int transient_prepare_exception(struct dm_exception_store *store,
- struct dm_exception *e)
+ struct dm_exception *e, int group)
{
struct transient_c *tc = store->context;
sector_t size = get_dev_size(store->cow->bdev);
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
@@ -833,7 +833,7 @@ 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, int group)
{
struct dm_exception *e, *tmp_e;
struct dm_snap_pending_exception *pe;
@@ -877,7 +877,7 @@ __find_pending_exception(struct dm_snaps
atomic_set(&pe->ref_count, 0);
pe->started = 0;

- if (s->store->type->prepare_exception(s->store, &pe->e)) {
+ if (s->store->type->prepare_exception(s->store, &pe->e, group)) {
dm_free_exception(s->pending, &pe->e);
return NULL;
}
@@ -940,7 +940,7 @@ static int snapshot_map(struct dm_target
* writeable.
*/
if (bio_rw(bio) == WRITE) {
- pe = __find_pending_exception(s, bio);
+ pe = __find_pending_exception(s, bio, 0);
if (!pe) {
__invalidate_snapshot(s, -ENOMEM);
r = -EIO;
@@ -1120,7 +1120,7 @@ static int __origin_write(struct list_he
*/
BUG_ON(rtn != -ENOENT);

- pe = __find_pending_exception(snap, bio);
+ pe = __find_pending_exception(snap, bio, 1);
if (!pe) {
__invalidate_snapshot(snap, -ENOMEM);
goto next_snapshot;

--
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Patch name: dm-exception-store-add-arg-to-prepare_commit.patch

Add the 'group' paramenter to the prepare_exception function. This
is used to facilitate shared exception stores. When writing to
a snapshot, an exception is created for only that snapshot (group=0).
When writing to the origin, all snapshots are affected, so rather
than preparing_exceptions for all snapshots one at a time, we can
use the group=1 to indicate that all snapshots managed by the shared
exception store be updated.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>

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
@@ -40,9 +40,14 @@ struct dm_exception_store_type {

/*
* Find somewhere to store the next exception.
+ * If the exception store implementation is shared,
+ * the 'group' field signifies whether to operate on
+ * the group sharing one exception store, or whether
+ * to operate on just one of those in the shared
+ * exception store.
*/
int (*prepare_exception) (struct dm_exception_store *store,
- struct dm_exception *e);
+ struct dm_exception *e, int group);

/*
* Update the metadata with this exception.
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
@@ -604,7 +604,7 @@ read_metadata:
}

static int persistent_prepare_exception(struct dm_exception_store *store,
- struct dm_exception *e)
+ struct dm_exception *e, int group)
{
struct pstore *ps = get_info(store);
uint32_t stride;
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
@@ -50,7 +50,7 @@ static int transient_resume(struct dm_ex
}

static int transient_prepare_exception(struct dm_exception_store *store,
- struct dm_exception *e)
+ struct dm_exception *e, int group)
{
struct transient_c *tc = store->context;
sector_t size = get_dev_size(store->cow->bdev);
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
@@ -836,6 +836,12 @@ __lookup_pending_exception(struct dm_sna
}

/*
+ * __find_pending_exception
+ * @s
+ * @pe
+ * @chunk
+ * @group
+ *
* Looks to see if this snapshot already has a pending exception
* for this chunk, otherwise it allocates a new one and inserts
* it into the pending table.
@@ -845,7 +851,8 @@ __lookup_pending_exception(struct dm_sna
*/
static struct dm_snap_pending_exception *
__find_pending_exception(struct dm_snapshot *s,
- struct dm_snap_pending_exception *pe, chunk_t chunk)
+ struct dm_snap_pending_exception *pe,
+ chunk_t chunk, int group)
{
struct dm_snap_pending_exception *pe2;

@@ -862,7 +869,7 @@ __find_pending_exception(struct dm_snaps
atomic_set(&pe->ref_count, 0);
pe->started = 0;

- if (s->store->type->prepare_exception(s->store, &pe->e)) {
+ if (s->store->type->prepare_exception(s->store, &pe->e, group)) {
dm_free_exception(s->pending, &pe->e);
return NULL;
}
@@ -884,7 +891,7 @@ static void remap_exception(struct dm_sn
static int snapshot_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
- struct dm_exception *e, *tmp_e;
+ struct dm_exception *tmp_e;
struct dm_snapshot *s = ti->private;
int rtn, r = DM_MAPIO_REMAPPED;
chunk_t chunk, new_chunk;
@@ -947,7 +954,7 @@ static int snapshot_map(struct dm_target
goto out_unlock;
}

- pe = __find_pending_exception(s, pe, chunk);
+ pe = __find_pending_exception(s, pe, chunk, 0);
if (!pe) {
__invalidate_snapshot(s, -ENOMEM);
r = -EIO;
@@ -1085,7 +1092,7 @@ static int __origin_write(struct list_he
{
int rtn, r = DM_MAPIO_REMAPPED, first = 0;
struct dm_snapshot *snap;
- struct dm_exception *e, *tmp_e;
+ struct dm_exception *tmp_e;
struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL;
chunk_t chunk;
LIST_HEAD(pe_queue);
@@ -1150,7 +1157,7 @@ static int __origin_write(struct list_he
goto next_snapshot;
}

- pe = __find_pending_exception(snap, pe, chunk);
+ pe = __find_pending_exception(snap, pe, chunk, 1);
if (!pe) {
__invalidate_snapshot(snap, -ENOMEM);
goto next_snapshot;

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