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Commit 7e201b35 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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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: default avatarMikulas Patocka <mpatocka@redhat.com>
Reviewed-by: default avatarMike Snitzer <snitzer@redhat.com>
Reviewed-by: default avatarJonathan Brassow <jbrassow@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 102c6ddb

drivers/md/dm-snap.c

+22 −12
Original line number Diff line number Diff line
@@ -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,