From: Kent Overstreet <kent.overstreet@gmail.com>
Date: Tue, 8 May 2018 21:33:56 -0400
Subject: [PATCH] block: Add warning for bi_next not NULL in bio_endio()
Git-commit: 0ba99ca4838bc75481a4bf0e70bad20b0a5457c7
Patch-mainline: v4.18-rc1
References: bsc#1104967,FATE#325924
Recently found a bug where a driver left bi_next not NULL and then
called bio_endio(), and then the submitter of the bio used
bio_copy_data() which was treating src and dst as lists of bios.
Fixed that bug by splitting out bio_list_copy_data(), but in case other
things are depending on bi_next in weird ways, add a warning to help
avoid more bugs like that in the future.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
block/bio.c | 3 +++
block/blk-core.c | 8 +++++++-
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c
index 2112ad01b52c..d8bcc12d5aa4 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1775,6 +1775,9 @@ void bio_endio(struct bio *bio)
if (!bio_integrity_endio(bio))
return;
+ if (WARN_ONCE(bio->bi_next, "driver left bi_next not NULL"))
+ bio->bi_next = NULL;
+
/*
* Need to have a real endio function for chained bios, otherwise
* various corner cases will break (like stacking block devices that
diff --git a/block/blk-core.c b/block/blk-core.c
index b431558f39bc..43370faee935 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -279,6 +279,10 @@ static void req_bio_endio(struct request *rq, struct bio *bio,
bio_advance(bio, nbytes);
/* don't actually finish bio if it's part of flush sequence */
+ /*
+ * XXX this code looks suspicious - it's not consistent with advancing
+ * req->bio in caller
+ */
if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
bio_endio(bio);
}
@@ -3083,8 +3087,10 @@ bool blk_update_request(struct request *req, blk_status_t error,
struct bio *bio = req->bio;
unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
- if (bio_bytes == bio->bi_iter.bi_size)
+ if (bio_bytes == bio->bi_iter.bi_size) {
req->bio = bio->bi_next;
+ bio->bi_next = NULL;
+ }
/* Completion has already been traced */
bio_clear_flag(bio, BIO_TRACE_COMPLETION);
--
2.12.3