This is a note to let you know that I've just added the patch titled

block: fix blk_rq_append_bio

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: block-fix-blk_rq_append_bio.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 0abc2a10389f0c9070f76ca906c7382788036b93 Mon Sep 17 00:00:00 2001

From: Jens Axboe axboe@kernel.dk Date: Mon, 18 Dec 2017 15:40:44 +0800 Subject: block: fix blk_rq_append_bio

From: Jens Axboe axboe@kernel.dk

commit 0abc2a10389f0c9070f76ca906c7382788036b93 upstream.

Commit caa4b02476e3(blk-map: call blk_queue_bounce from blk_rq_append_bio) moves blk_queue_bounce() into blk_rq_append_bio(), but don't consider the fact that the bounced bio becomes invisible to caller since the parameter type is 'struct bio *'. Make it a pointer to a pointer to a bio, so the caller sees the right bio also after a bounce.

Fixes: caa4b02476e3 ("blk-map: call blk_queue_bounce from blk_rq_append_bio") Cc: Christoph Hellwig hch@lst.de Reported-by: Michele Ballabio barra_cuda@katamail.com (handling failure of blk_rq_append_bio(), only call bio_get() after blk_rq_append_bio() returns OK) Tested-by: Michele Ballabio barra_cuda@katamail.com Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- block/blk-map.c | 38 +++++++++++++++++++++---------------- drivers/scsi/osd/osd_initiator.c | 4 ++- drivers/target/target_core_pscsi.c | 4 +-- include/linux/blkdev.h | 2 - 4 files changed, 28 insertions(+), 20 deletions(-)

--- a/block/blk-map.c +++ b/block/blk-map.c @@ -12,22 +12,29 @@ #include "blk.h"

/* - * Append a bio to a passthrough request. Only works can be merged into - * the request based on the driver constraints. + * Append a bio to a passthrough request. Only works if the bio can be merged + * into the request based on the driver constraints. */ -int blk_rq_append_bio(struct request *rq, struct bio *bio) +int blk_rq_append_bio(struct request *rq, struct bio **bio) { - blk_queue_bounce(rq->q, &bio); + struct bio *orig_bio = *bio; + + blk_queue_bounce(rq->q, bio);

if (!rq->bio) { - blk_rq_bio_prep(rq->q, rq, bio); + blk_rq_bio_prep(rq->q, rq, *bio); } else { - if (!ll_back_merge_fn(rq->q, rq, bio)) + if (!ll_back_merge_fn(rq->q, rq, *bio)) { + if (orig_bio != *bio) { + bio_put(*bio); + *bio = orig_bio; + } return -EINVAL; + }

- rq->biotail->bi_next = bio; - rq->biotail = bio; - rq->__data_len += bio->bi_iter.bi_size; + rq->biotail->bi_next = *bio; + rq->biotail = *bio; + rq->__data_len += (*bio)->bi_iter.bi_size; }

return 0; @@ -80,14 +87,12 @@ static int __blk_rq_map_user_iov(struct * We link the bounce buffer in and could have to traverse it * later so we have to get a ref to prevent it from being freed */ - ret = blk_rq_append_bio(rq, bio); - bio_get(bio); + ret = blk_rq_append_bio(rq, &bio); if (ret) { - bio_endio(bio); __blk_rq_unmap_user(orig_bio); - bio_put(bio); return ret; } + bio_get(bio);

return 0; } @@ -220,7 +225,7 @@ int blk_rq_map_kern(struct request_queue int reading = rq_data_dir(rq) == READ; unsigned long addr = (unsigned long) kbuf; int do_copy = 0; - struct bio *bio; + struct bio *bio, *orig_bio; int ret;

if (len > (queue_max_hw_sectors(q) << 9)) @@ -243,10 +248,11 @@ int blk_rq_map_kern(struct request_queue if (do_copy) rq->rq_flags |= RQF_COPY_USER;

- ret = blk_rq_append_bio(rq, bio); + orig_bio = bio; + ret = blk_rq_append_bio(rq, &bio); if (unlikely(ret)) { /* request is too big */ - bio_put(bio); + bio_put(orig_bio); return ret; }

--- a/drivers/scsi/osd/osd_initiator.c +++ b/drivers/scsi/osd/osd_initiator.c @@ -1576,7 +1576,9 @@ static struct request *_make_request(str return req;

for_each_bio(bio) { - ret = blk_rq_append_bio(req, bio); + struct bio *bounce_bio = bio; + + ret = blk_rq_append_bio(req, &bounce_bio); if (ret) return ERR_PTR(ret); } --- a/drivers/target/target_core_pscsi.c +++ b/drivers/target/target_core_pscsi.c @@ -920,7 +920,7 @@ pscsi_map_sg(struct se_cmd *cmd, struct " %d i: %d bio: %p, allocating another" " bio\n", bio->bi_vcnt, i, bio);

- rc = blk_rq_append_bio(req, bio); + rc = blk_rq_append_bio(req, &bio); if (rc) { pr_err("pSCSI: failed to append bio\n"); goto fail; @@ -938,7 +938,7 @@ pscsi_map_sg(struct se_cmd *cmd, struct }

if (bio) { - rc = blk_rq_append_bio(req, bio); + rc = blk_rq_append_bio(req, &bio); if (rc) { pr_err("pSCSI: failed to append bio\n"); goto fail; --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -952,7 +952,7 @@ extern int blk_rq_prep_clone(struct requ extern void blk_rq_unprep_clone(struct request *rq); extern blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq); -extern int blk_rq_append_bio(struct request *rq, struct bio *bio); +extern int blk_rq_append_bio(struct request *rq, struct bio **bio); extern void blk_delay_queue(struct request_queue *, unsigned long); extern void blk_queue_split(struct request_queue *, struct bio **); extern void blk_recount_segments(struct request_queue *, struct bio *);

Patches currently in stable-queue which might be from axboe@kernel.dk are

queue-4.14/block-don-t-let-passthrough-io-go-into-.make_request_fn.patch queue-4.14/block-fix-blk_rq_append_bio.patch