From 326e1dbb57368087a36607aaebe9795b8d5453e5 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 22 May 2015 09:14:03 -0400 Subject: block: remove management of bi_remaining when restoring original bi_end_io Commit c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") regressed all existing callers that followed this pattern: 1) saving a bio's original bi_end_io 2) wiring up an intermediate bi_end_io 3) restoring the original bi_end_io from intermediate bi_end_io 4) calling bio_endio() to execute the restored original bi_end_io The regression was due to BIO_CHAIN only ever getting set if bio_inc_remaining() is called. For the above pattern it isn't set until step 3 above (step 2 would've needed to establish BIO_CHAIN). As such the first bio_endio(), in step 2 above, never decremented __bi_remaining before calling the intermediate bi_end_io -- leaving __bi_remaining with the value 1 instead of 0. When bio_inc_remaining() occurred during step 3 it brought it to a value of 2. When the second bio_endio() was called, in step 4 above, it should've called the original bi_end_io but it didn't because there was an extra reference that wasn't dropped (due to atomic operations being optimized away since BIO_CHAIN wasn't set upfront). Fix this issue by removing the __bi_remaining management complexity for all callers that use the above pattern -- bio_chain() is the only interface that _needs_ to be concerned with __bi_remaining. For the above pattern callers just expect the bi_end_io they set to get called! Remove bio_endio_nodec() and also remove all bio_inc_remaining() calls that aren't associated with the bio_chain() interface. Also, the bio_inc_remaining() interface has been moved local to bio.c. Fixes: c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Mike Snitzer Signed-off-by: Jens Axboe --- drivers/md/bcache/io.c | 2 +- drivers/md/dm-cache-target.c | 6 ------ drivers/md/dm-raid1.c | 2 -- drivers/md/dm-snap.c | 1 - drivers/md/dm-thin.c | 9 +++------ drivers/md/dm-verity.c | 2 +- 6 files changed, 5 insertions(+), 17 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c index fa028fa82df4..cb64e64a4789 100644 --- a/drivers/md/bcache/io.c +++ b/drivers/md/bcache/io.c @@ -55,7 +55,7 @@ static void bch_bio_submit_split_done(struct closure *cl) s->bio->bi_end_io = s->bi_end_io; s->bio->bi_private = s->bi_private; - bio_endio_nodec(s->bio, 0); + bio_endio(s->bio, 0); closure_debug_destroy(&s->cl); mempool_free(s, s->p->bio_split_hook); diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 705eb7b99d69..41b2594a80c6 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -86,12 +86,6 @@ static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio) { bio->bi_end_io = h->bi_end_io; bio->bi_private = h->bi_private; - - /* - * Must bump bi_remaining to allow bio to complete with - * restored bi_end_io. - */ - bio_inc_remaining(bio); } /*----------------------------------------------------------------*/ diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index d6a1c096b777..743fa9bbae9e 100644 --- a/drivers/md/dm-raid1.c +++ b/drivers/md/dm-raid1.c @@ -1254,8 +1254,6 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio, int error) dm_bio_restore(bd, bio); bio_record->details.bi_bdev = NULL; - bio_inc_remaining(bio); - queue_bio(ms, bio, rw); return DM_ENDIO_INCOMPLETE; } diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 8bfeae218531..7c82d3ccce87 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1478,7 +1478,6 @@ out: if (full_bio) { full_bio->bi_end_io = pe->full_bio_end_io; full_bio->bi_private = pe->full_bio_private; - bio_inc_remaining(full_bio); } increment_pending_exceptions_done_count(); diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 342dbdad6131..e852602c0091 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -793,10 +793,9 @@ static void inc_remap_and_issue_cell(struct thin_c *tc, static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m) { - if (m->bio) { + if (m->bio) m->bio->bi_end_io = m->saved_bi_end_io; - bio_inc_remaining(m->bio); - } + cell_error(m->tc->pool, m->cell); list_del(&m->list); mempool_free(m, m->tc->pool->mapping_pool); @@ -810,10 +809,8 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m) int r; bio = m->bio; - if (bio) { + if (bio) bio->bi_end_io = m->saved_bi_end_io; - bio_inc_remaining(bio); - } if (m->err) { cell_error(pool, m->cell); diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c index 66616db33e6f..bb9c6a00e4b0 100644 --- a/drivers/md/dm-verity.c +++ b/drivers/md/dm-verity.c @@ -459,7 +459,7 @@ static void verity_finish_io(struct dm_verity_io *io, int error) bio->bi_end_io = io->orig_bi_end_io; bio->bi_private = io->orig_bi_private; - bio_endio_nodec(bio, error); + bio_endio(bio, error); } static void verity_work(struct work_struct *w) -- cgit v1.2.3