From fa8db4948f5224dae33a0e783e7dec682e145f88 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Tue, 5 Feb 2019 17:07:58 -0500 Subject: [PATCH] dm: don't use bio_trim() afterall bio_trim() has an early return, which makes it _not_ idempotent, if the offset is 0 and the bio's bi_size already matches the requested size. Prior to DM, all users of bio_trim() were fine with this. But DM has exposed the fact that bio_trim()'s early return is incompatible with a cloned bio whose integrity payload must be trimmed via bio_integrity_trim(). Fix this by reverting DM back to doing the equivalent of bio_trim() but in an idempotent manner (so bio_integrity_trim is always performed). Follow-on work is needed to assess what benefit bio_trim()'s early return is providing to its existing callers. Reported-by: Milan Broz Fixes: 57c36519e4b94 ("dm: fix clone_bio() to trigger blk_recount_segments()") Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index a0972a9..515e6af 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1336,7 +1336,11 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio, return r; } - bio_trim(clone, sector - clone->bi_iter.bi_sector, len); + bio_advance(clone, to_bytes(sector - clone->bi_iter.bi_sector)); + clone->bi_iter.bi_size = to_bytes(len); + + if (bio_integrity(bio)) + bio_integrity_trim(clone); return 0; } -- 2.7.4