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authorMikulas Patocka <mpatocka@redhat.com>2009-12-10 23:52:08 +0000
committerAlasdair G Kergon <agk@redhat.com>2009-12-10 23:52:08 +0000
commit7e201b35132a1f02c931a0a06760766c846bb49b (patch)
tree02ab2bcf4609763ab9780db2a87b9f37aa77186f
parent102c6ddb1d081a6a1fede38c43a42c9811313ec7 (diff)
dm snapshot: abstract minimum_chunk_size fn
The origin needs to find minimum chunksize of all snapshots. This logic is moved to a separate function because it will be used at another place in the snapshot merge patches. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-snap.c34
1 files changed, 22 insertions, 12 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 8a4a9c838afd..48978ab42ae5 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -523,6 +523,25 @@ static int dm_add_exception(void *context, chunk_t old, chunk_t new)
return 0;
}
+#define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r)))
+
+/*
+ * Return a minimum chunk size of all snapshots that have the specified origin.
+ * Return zero if the origin has no snapshots.
+ */
+static sector_t __minimum_chunk_size(struct origin *o)
+{
+ struct dm_snapshot *snap;
+ unsigned chunk_size = 0;
+
+ if (o)
+ list_for_each_entry(snap, &o->snapshots, list)
+ chunk_size = min_not_zero(chunk_size,
+ snap->store->chunk_size);
+
+ return chunk_size;
+}
+
/*
* Hard coded magic.
*/
@@ -1395,8 +1414,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
}
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
/*
* Set the target "split_io" field to the minimum of all the snapshots'
* chunk sizes.
@@ -1404,19 +1421,12 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
static void origin_resume(struct dm_target *ti)
{
struct dm_dev *dev = ti->private;
- struct dm_snapshot *snap;
- struct origin *o;
- unsigned chunk_size = 0;
down_read(&_origins_lock);
- o = __lookup_origin(dev->bdev);
- if (o)
- list_for_each_entry (snap, &o->snapshots, list)
- chunk_size = min_not_zero(chunk_size,
- snap->store->chunk_size);
- up_read(&_origins_lock);
- ti->split_io = chunk_size;
+ ti->split_io = __minimum_chunk_size(__lookup_origin(dev->bdev));
+
+ up_read(&_origins_lock);
}
static int origin_status(struct dm_target *ti, status_type_t type, char *result,