| Message ID | 20230512133901.1053543-2-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/8] block: tidy up the bio full checks in bio_add_hw_page | expand |
Hi, Christoph. >@@ -1014,6 +1014,10 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio, > if (bio_try_merge_hw_seg(q, bio, page, len, offset, same_page)) > return len; > >+ if (bio->bi_vcnt >= >+ min(bio->bi_max_vecs, queue_max_segments(q))) >+ return 0; >+ > /* > * If the queue doesn't support SG gaps and adding this segment > * would create a gap, disallow it. >@@ -1023,12 +1027,6 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio, > return 0; > } > >- if (bio_full(bio, len)) >- return 0; >- >- if (bio->bi_vcnt >= queue_max_segments(q)) >- return 0; >- > bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, offset); > bio->bi_vcnt++; > bio->bi_iter.bi_size += len; >-- >2.39.2 If the wrong bi_max_vecs is set in bio_init(e.g. bi_max_vec = 0), I think we need a code to defend against page_add. If modified in this way, it may be added to bvec normally and cause inconsistency in the information of bio. Best Regards, Jinyoung.
diff --git a/block/bio.c b/block/bio.c index 043944fd46ebbc..1528ca0f3df6dc 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1014,6 +1014,10 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio, if (bio_try_merge_hw_seg(q, bio, page, len, offset, same_page)) return len; + if (bio->bi_vcnt >= + min(bio->bi_max_vecs, queue_max_segments(q))) + return 0; + /* * If the queue doesn't support SG gaps and adding this segment * would create a gap, disallow it. @@ -1023,12 +1027,6 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio, return 0; } - if (bio_full(bio, len)) - return 0; - - if (bio->bi_vcnt >= queue_max_segments(q)) - return 0; - bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, offset); bio->bi_vcnt++; bio->bi_iter.bi_size += len;
bio_add_hw_page already checks if the number of bytes trying to be added even fit into max_hw_sectors limit of the queue. Remove the call to bio_full and just do a check for the smaller of the number of segments in the bio and the queue max segments limit, and do this cheap check before the more expensive gap to previous check. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/bio.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)