AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

blk-merge: recaculate segment if it isn't less than max segments

Browse Source 
The problem is introduced by commit 764f612c6c3c231b(blk-merge:
don't compute bi_phys_segments from bi_vcnt for cloned bio),
and merge is needed if number of current segment isn't less than
max segments.

Strictly speaking, bio->bi_vcnt shouldn't be used here since
it may not be accurate in cases of both cloned bio or bio cloned
from, but bio_segments() is a bit expensive, and bi_vcnt is still
the biggest number, so the approach should work.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2014-10-22 08:30:30 +08:00 committed by Jens Axboe
parent 432f16e64f
commit 76d8137a31
1 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
block/blk-merge.c
View File

@ -99,16 +99,17 @@ void blk_recount_segments(struct request_queue *q, struct bio *bio)
{ {
bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,
&q->queue_flags); &q->queue_flags);
bool merge_not_need = bio->bi_vcnt < queue_max_segments(q);
if (no_sg_merge && !bio_flagged(bio, BIO_CLONED) && if (no_sg_merge && !bio_flagged(bio, BIO_CLONED) &&
bio->bi_vcnt < queue_max_segments(q)) merge_not_need)
bio->bi_phys_segments = bio->bi_vcnt; bio->bi_phys_segments = bio->bi_vcnt;
else { else {
struct bio *nxt = bio->bi_next; struct bio *nxt = bio->bi_next;
bio->bi_next = NULL; bio->bi_next = NULL;
bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio,
no_sg_merge); no_sg_merge && merge_not_need);
bio->bi_next = nxt; bio->bi_next = nxt;
} }