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Commit ee18026a authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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dm snapshot: do not use map_context 



Eliminate struct map_info from dm-snap.

map_info->ptr was used in dm-snap to indicate if the bio was tracked.
If map_info->ptr was non-NULL, the bio was linked in tracked_chunk_hash.

This patch removes the use of map_info->ptr. We determine if the bio was
tracked based on hlist_unhashed(&c->node). If hlist_unhashed is true,
the bio is not tracked, if it is false, the bio is tracked.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 59c3d2c6

drivers/md/dm-snap.c

+23 −13
Original line number Diff line number Diff line
@@ -190,9 +190,19 @@ struct dm_snap_tracked_chunk { 
	chunk_t chunk;

};



static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,

						 struct bio *bio,

						 chunk_t chunk)

static void init_tracked_chunk(struct bio *bio)

{

	struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));

	INIT_HLIST_NODE(&c->node);

}



static bool is_bio_tracked(struct bio *bio)

{

	struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));

	return !hlist_unhashed(&c->node);

}



static void track_chunk(struct dm_snapshot *s, struct bio *bio, chunk_t chunk)

{

	struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));
@@ -202,13 +212,11 @@ static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s, 
	hlist_add_head(&c->node,

		       &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);

	spin_unlock_irq(&s->tracked_chunk_lock);



	return c;

}



static void stop_tracking_chunk(struct dm_snapshot *s,

				struct dm_snap_tracked_chunk *c)

static void stop_tracking_chunk(struct dm_snapshot *s, struct bio *bio)

{

	struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));

	unsigned long flags;



	spin_lock_irqsave(&s->tracked_chunk_lock, flags);
@@ -1568,6 +1576,8 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio, 
	chunk_t chunk;

	struct dm_snap_pending_exception *pe = NULL;



	init_tracked_chunk(bio);



	if (bio->bi_rw & REQ_FLUSH) {

		bio->bi_bdev = s->cow->bdev;

		return DM_MAPIO_REMAPPED;
@@ -1652,7 +1662,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio, 
		}

	} else {

		bio->bi_bdev = s->origin->bdev;

		map_context->ptr = track_chunk(s, bio, chunk);

		track_chunk(s, bio, chunk);

	}



out_unlock:
@@ -1681,12 +1691,13 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio, 
	int r = DM_MAPIO_REMAPPED;

	chunk_t chunk;



	init_tracked_chunk(bio);



	if (bio->bi_rw & REQ_FLUSH) {

		if (!dm_bio_get_target_request_nr(bio))

			bio->bi_bdev = s->origin->bdev;

		else

			bio->bi_bdev = s->cow->bdev;

		map_context->ptr = NULL;

		return DM_MAPIO_REMAPPED;

	}
@@ -1715,7 +1726,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio, 
		remap_exception(s, e, bio, chunk);



		if (bio_rw(bio) == WRITE)

			map_context->ptr = track_chunk(s, bio, chunk);

			track_chunk(s, bio, chunk);

		goto out_unlock;

	}
@@ -1737,10 +1748,9 @@ static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 
			   int error, union map_info *map_context)

{

	struct dm_snapshot *s = ti->private;

	struct dm_snap_tracked_chunk *c = map_context->ptr;



	if (c)

		stop_tracking_chunk(s, c);

	if (is_bio_tracked(bio))

		stop_tracking_chunk(s, bio);



	return 0;

}