Patch name: dm-snapshot-find-min-chunksize-function.patch
The origin needs to find minimum chunksize of all snapshots.
This logic is moved to separate function because it will be used at other place
in snapshot merge.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Reviewed-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
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
@@ -519,6 +519,25 @@ static int dm_add_exception(void *contex
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;
+ sector_t 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.
*/
@@ -1378,8 +1397,6 @@ static int origin_map(struct dm_target *
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.
@@ -1387,19 +1404,14 @@ static int origin_map(struct dm_target *
static void origin_resume(struct dm_target *ti)
{
struct dm_dev *dev = ti->private;
- struct dm_snapshot *snap;
struct origin *o;
- chunk_t 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 = minimum_chunk_size(o);
- ti->split_io = chunk_size;
+ up_read(&_origins_lock);
}
static int origin_status(struct dm_target *ti, status_type_t type, char *result,
--
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