Wanpeng Li <[email protected]> writes: > 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.
Does it matter? Did you see any incorrect behaviour as a result of the current code? Cheers, Jeff > > 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; > } -- 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/
