From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
When there is one merging snapshot and other non-merging snapshots, make
exceptions in non-merging snapshots while merging.
This is not yet complete (the exception is not made when remapping directly to
the origin), another patch fixes that.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm-snap.c | 31 +++++++++++++++++++++++++++++++
1 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 6a55d75..3be57ba 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -255,6 +255,8 @@ struct origin {
static struct list_head *_origins;
static struct rw_semaphore _origins_lock;
+static DECLARE_WAIT_QUEUE_HEAD(_pending_exception_done);
+
static int init_origin_hash(void)
{
int i;
@@ -653,6 +655,9 @@ static int init_hash_tables(struct dm_snapshot *s)
static void flush_bios(struct bio *bio);
static void error_bios(struct bio *bio);
+static int __origin_write(struct list_head *snapshots,
+ sector_t sector, struct bio *bio);
+
static void merge_callback(int read_err, unsigned long write_err,
void *context);
@@ -660,6 +665,9 @@ static void snapshot_merge_process(struct dm_snapshot *s)
{
int r;
chunk_t old_chunk, new_chunk;
+ struct origin *o;
+ chunk_t min_chunksize;
+ int must_wait;
struct dm_io_region src, dest;
BUG_ON(!s->merge_running);
@@ -695,6 +703,27 @@ static void snapshot_merge_process(struct dm_snapshot *s)
src.sector = chunk_to_sector(s->store, new_chunk);
src.count = dest.count;
+test_again:
+ /* Reallocate other snapshots */
+ down_read(&_origins_lock);
+ o = __lookup_origin(s->origin->bdev);
+ must_wait = 0;
+ min_chunksize = __minimum_chunk_size(o);
+ if (min_chunksize) {
+ chunk_t n;
+ for (n = 0; n < s->store->chunk_size; n += min_chunksize) {
+ r = __origin_write(&o->snapshots, dest.sector + n,
+ NULL);
+ if (r == DM_MAPIO_SUBMITTED)
+ must_wait = 1;
+ }
+ }
+ up_read(&_origins_lock);
+ if (must_wait) {
+ sleep_on_timeout(&_pending_exception_done, HZ / 100 + 1);
+ goto test_again;
+ }
+
down_write(&s->lock);
s->merge_write_interlock = old_chunk;
s->merge_write_interlock_n = 1;
@@ -1204,6 +1233,8 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success)
origin_bios = bio_list_get(&pe->origin_bios);
free_pending_exception(pe);
+ wake_up_all(&_pending_exception_done);
+
up_write(&s->lock);
/* Submit any pending write bios */
--
1.6.2.5
--
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