To keep track of the max segment size, the sizes of the first and last mergeable segments in the bio are accounted, prev->bio->bi_seg_front_size and next->biotail->bi_seg_back_size will be updated if blk_phys_contig_segment is true, however, there are still some scenarios such like nonconsistent blk integrity which leads to merge fail, in addtion, futher merge fail is incurred due to bio->bi_seg_back_size + next->bi_seg_front_size > queue_max_segment_size(q) check in function blk_phys_contig_segment(). This patch fix it by updating first/last mergeable segments size iff all the conditions of merging are meet.
Signed-off-by: Wanpeng Li <[email protected]> --- block/blk-merge.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 30a0d9f..7e7bda4 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -367,6 +367,7 @@ static int req_gap_to_prev(struct request *req, struct request *next) static int ll_merge_requests_fn(struct request_queue *q, struct request *req, struct request *next) { + bool update_segment_size = false; int total_phys_segments; unsigned int seg_size = req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; @@ -391,10 +392,7 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req, total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; if (blk_phys_contig_segment(q, req->biotail, next->bio)) { - if (req->nr_phys_segments == 1) - req->bio->bi_seg_front_size = seg_size; - if (next->nr_phys_segments == 1) - next->biotail->bi_seg_back_size = seg_size; + update_segment_size = true; total_phys_segments--; } @@ -405,6 +403,12 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req, return 0; /* Merge is OK... */ + if (update_segment_size) { + if (req->nr_phys_segments == 1) + req->bio->bi_seg_front_size = seg_size; + if (next->nr_phys_segments == 1) + next->biotail->bi_seg_back_size = seg_size; + } req->nr_phys_segments = total_phys_segments; return 1; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
