2021-09-28 06:41:21

by Jinyoung Choi

Subject: [PATCH] block-map: added error handling for bio_copy_kern()

When new pages are allocated to bio through alloc_page() in
bio_copy_kern(), the pages must be freed in error handling after that.

There is little chance of an error occurring in blk_rq_append_bio(), but
in the code flow, pages additionally allocated to bio must be released.

Signed-off-by: Jinyoung Choi <[email protected]>
---
block/blk-map.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index 4526adde0156..584369a7837f 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -628,6 +628,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
int reading = rq_data_dir(rq) == READ;
unsigned long addr = (unsigned long) kbuf;
struct bio *bio;
+ int do_copy = 0;
int ret;

if (len > (queue_max_hw_sectors(q) << 9))
@@ -635,8 +636,9 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
if (!len || !kbuf)
return -EINVAL;

- if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
- blk_queue_may_bounce(q))
+ do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
+ blk_queue_may_bounce(q);
+ if (do_copy)
bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
else
bio = bio_map_kern(q, kbuf, len, gfp_mask);
@@ -648,8 +650,11 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
bio->bi_opf |= req_op(rq);

ret = blk_rq_append_bio(rq, bio);
- if (unlikely(ret))
+ if (unlikely(ret)) {
+ if (do_copy)
+ bio_free_pages(bio);
bio_put(bio);
+ }
return ret;
}
EXPORT_SYMBOL(blk_rq_map_kern);
--
2.25.1

2021-10-12 06:27:18

by Christoph Hellwig

Subject: Re: [PATCH] block-map: added error handling for bio_copy_kern()

> + int do_copy = 0;

Please make this a bool. Otherwise the patch looks good.

2021-10-12 08:56:58

by Jinyoung Choi

Subject: RE: [PATCH] block-map: added error handling for bio_copy_kern()

Hi, Christoph.

Thanks for your review.

>> +       int do_copy = 0;
>
>Please make this a bool.  Otherwise the patch looks good.

Yes, bool is better. Will update in the next version. Thanks.

Best Regards,
Jinyoung Choi