[PATCH 42/41] dm: convey that all flushes are processed as empty
From: Mike Snitzer <hidden>
Date: 2010-09-07 23:49:18
Also in:
dm-devel, linux-fsdevel, linux-raid, linux-scsi, lkml
Subsystem:
device-mapper (lvm), the rest · Maintainers:
Alasdair Kergon, Mike Snitzer, Mikulas Patocka, Benjamin Marzinski, Linus Torvalds
Rename __clone_and_map_flush to __clone_and_map_empty_flush for added clarity. Reintroduce a BUG_ON() and add a few more helpful comments to the code so that it is clear that all flushes are empty. Cleanup __split_and_process_bio() so that an empty flush isn't processed by a 'sector_count' focused while loop. Signed-off-by: Mike Snitzer <redacted> --- drivers/md/dm.c | 21 +++++++++------------ 1 files changed, 9 insertions(+), 12 deletions(-) Tejun, please feel free to fold this patch into (or insert after) 0025-dm-relax-ordering-of-bio-based-flush-implementation.patch
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index cd2f7e7..9a852ee 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c@@ -622,6 +622,7 @@ static void dec_pending(struct dm_io *io, int error) return; if (!(bio->bi_rw & REQ_FLUSH) || !bio->bi_size) { + /* done with normal IO or empty flush */ trace_block_bio_complete(md->queue, bio); bio_endio(bio, io_error); } else {
@@ -1132,16 +1133,15 @@ static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti, __issue_target_request(ci, ti, request_nr, len); } -static int __clone_and_map_flush(struct clone_info *ci) +static int __clone_and_map_empty_flush(struct clone_info *ci) { unsigned target_nr = 0; struct dm_target *ti; + BUG_ON(bio_has_data(ci->bio)); while ((ti = dm_table_get_target(ci->map, target_nr++))) __issue_target_requests(ci, ti, ti->num_flush_requests, 0); - ci->sector_count = 0; - return 0; }
@@ -1302,20 +1302,17 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio) ci.sector = bio->bi_sector; ci.idx = bio->bi_idx; + start_io_acct(ci.io); if (!is_flush) { ci.bio = bio; ci.sector_count = bio_sectors(bio); + while (ci.sector_count && !error) + error = __clone_and_map(&ci); } else { ci.bio = &ci.md->flush_bio; - ci.sector_count = 1; - } - - start_io_acct(ci.io); - while (ci.sector_count && !error) { - if (!is_flush) - error = __clone_and_map(&ci); - else - error = __clone_and_map_flush(&ci); + ci.sector_count = 0; + error = __clone_and_map_empty_flush(&ci); + /* dec_pending submits any data associated with flush */ } /* drop the extra reference count */