[PATCH 4.14 056/146] block: fix blk_rq_append_bio

Greg Kroah-Hartman
2018-01-01T14:41:59Z

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 *);