From 96c8ea3c5add7920b3c43840d1ea76b3354c8d2d Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Wed, 19 Aug 2026 08:49:37 -0700 Subject: [PATCH] block: save page offset gaps in cloned bio The cloned bio needs to inherit the accumulated gaps between vectors so that we can know if this bio can subscribe to the iova coalescing optimization. When cloning for a split, the gap only applies to the front bio since that's as far as has been processed. The remaining bio can reset its gaps to 0 since it advanced past the checked vectors, and will start its accounting from there on the next split check. Fixes: 2f6b2565d43c ("block: accumulate memory segment gaps per bio") Reported-by: Eric Auger Tested-by: Eric Auger Signed-off-by: Keith Busch Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/20260819154937.3903312-1-kbusch@meta.com Signed-off-by: Jens Axboe --- block/bio.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/block/bio.c b/block/bio.c index 898b2f5ef8c8..f95b63c0604a 100644 --- a/block/bio.c +++ b/block/bio.c @@ -859,6 +859,7 @@ static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp) bio->bi_ioprio = bio_src->bi_ioprio; bio->bi_write_hint = bio_src->bi_write_hint; bio->bi_write_stream = bio_src->bi_write_stream; + bio->bi_bvec_gap_bit = bio_src->bi_bvec_gap_bit; bio->bi_iter = bio_src->bi_iter; bio->bi_io_vec = bio_src->bi_io_vec; @@ -1972,6 +1973,14 @@ struct bio *bio_split(struct bio *bio, int sectors, bio_advance(bio, split->bi_iter.bi_size); + /* + * The gap bit is set when splitting to limits and only applies to the + * front bio that was split off. The remaining bio will calcualte its + * gap value when it is subsequently split to limits, so it is safe to + * re-initialize the value back to 0. + */ + bio->bi_bvec_gap_bit = 0; + if (bio_flagged(bio, BIO_TRACE_COMPLETION)) bio_set_flag(split, BIO_TRACE_COMPLETION);