Commit d53f1faf authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm writecache: do direct write if the cache is full 



If the cache device is full, we do a direct write to the origin device.
Note that we must not do it if the written block is already in the cache.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent eaab4bde

drivers/md/dm-writecache.c

+13 −0
Original line number Diff line number Diff line
@@ -1194,6 +1194,7 @@ static int writecache_map(struct dm_target *ti, struct bio *bio) 
		}

	} else {

		do {

			bool found_entry = false;

			if (writecache_has_error(wc))

				goto unlock_error;

			e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
@@ -1204,9 +1205,21 @@ static int writecache_map(struct dm_target *ti, struct bio *bio) 
					wc->overwrote_committed = true;

					goto bio_copy;

				}

				found_entry = true;

			}

			e = writecache_pop_from_freelist(wc, (sector_t)-1);

			if (unlikely(!e)) {

				if (!found_entry) {

					e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);

					if (e) {

						sector_t next_boundary = read_original_sector(wc, e) - bio->bi_iter.bi_sector;

						BUG_ON(!next_boundary);

						if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {

							dm_accept_partial_bio(bio, next_boundary);

						}

					}

					goto unlock_remap_origin;

				}

				writecache_wait_on_freelist(wc);

				continue;

			}