From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Theodore Ts'o <tytso@mit.edu>,
Omar Sandoval <osandov@fb.com>, Sagi Grimberg <sagi@grimberg.me>,
Dave Chinner <dchinner@redhat.com>,
Kent Overstreet <kent.overstreet@gmail.com>,
Mike Snitzer <snitzer@redhat.com>,
dm-devel@redhat.com, Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, Shaohua Li <shli@kernel.org>,
linux-raid@vger.kernel.org, David Sterba <dsterba@suse.com>,
linux-btrfs@vger.kernel.org,
"Darrick J . Wong" <darrick.wong@oracle.com>,
linux-xfs@vger.kernel.org, Gao Xiang <gaoxiang25@huawei.com>,
Christoph Hellwig <hch@lst.de>,
linux-ext4@vger.kernel.org, Coly Li <colyli@suse.de>,
linux-bcache@vger.kernel.org, Boaz Harrosh <ooo@electrozaur.com>,
Bob Peterson <rpeterso@redhat.com>,
cluster-devel@redhat.com, Ming Lei <ming.lei@redhat.com>
Subject: [PATCH V12 10/20] block: use bio_for_each_bvec() to map sg
Date: Mon, 26 Nov 2018 10:17:10 +0800 [thread overview]
Message-ID: <20181126021720.19471-11-ming.lei@redhat.com> (raw)
In-Reply-To: <20181126021720.19471-1-ming.lei@redhat.com>
It is more efficient to use bio_for_each_bvec() to map sg, meantime
we have to consider splitting multipage bvec as done in blk_bio_segment_split().
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-merge.c | 70 +++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 50 insertions(+), 20 deletions(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 2d8f388d43de..20b5b0c3e182 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -462,6 +462,54 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
return biovec_phys_mergeable(q, &end_bv, &nxt_bv);
}
+static struct scatterlist *blk_next_sg(struct scatterlist **sg,
+ struct scatterlist *sglist)
+{
+ if (!*sg)
+ return sglist;
+
+ /*
+ * If the driver previously mapped a shorter list, we could see a
+ * termination bit prematurely unless it fully inits the sg table
+ * on each mapping. We KNOW that there must be more entries here
+ * or the driver would be buggy, so force clear the termination bit
+ * to avoid doing a full sg_init_table() in drivers for each command.
+ */
+ sg_unmark_end(*sg);
+ return sg_next(*sg);
+}
+
+static unsigned blk_bvec_map_sg(struct request_queue *q,
+ struct bio_vec *bvec, struct scatterlist *sglist,
+ struct scatterlist **sg)
+{
+ unsigned nbytes = bvec->bv_len;
+ unsigned nsegs = 0, total = 0, offset = 0;
+
+ while (nbytes > 0) {
+ unsigned seg_size;
+ struct page *pg;
+ unsigned idx;
+
+ *sg = blk_next_sg(sg, sglist);
+
+ seg_size = get_max_segment_size(q, bvec->bv_offset + total);
+ seg_size = min(nbytes, seg_size);
+
+ offset = (total + bvec->bv_offset) % PAGE_SIZE;
+ idx = (total + bvec->bv_offset) / PAGE_SIZE;
+ pg = nth_page(bvec->bv_page, idx);
+
+ sg_set_page(*sg, pg, seg_size, offset);
+
+ total += seg_size;
+ nbytes -= seg_size;
+ nsegs++;
+ }
+
+ return nsegs;
+}
+
static inline void
__blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
struct scatterlist *sglist, struct bio_vec *bvprv,
@@ -479,25 +527,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
(*sg)->length += nbytes;
} else {
new_segment:
- if (!*sg)
- *sg = sglist;
- else {
- /*
- * If the driver previously mapped a shorter
- * list, we could see a termination bit
- * prematurely unless it fully inits the sg
- * table on each mapping. We KNOW that there
- * must be more entries here or the driver
- * would be buggy, so force clear the
- * termination bit to avoid doing a full
- * sg_init_table() in drivers for each command.
- */
- sg_unmark_end(*sg);
- *sg = sg_next(*sg);
- }
-
- sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset);
- (*nsegs)++;
+ (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg);
}
*bvprv = *bvec;
}
@@ -519,7 +549,7 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
int nsegs = 0;
for_each_bio(bio)
- bio_for_each_segment(bvec, bio, iter)
+ bio_for_each_bvec(bvec, bio, iter)
__blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg,
&nsegs);
--
2.9.5
next prev parent reply other threads:[~2018-11-26 2:17 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 2:17 [PATCH V12 00/20] block: support multi-page bvec Ming Lei
2018-11-26 2:17 ` [PATCH V12 01/20] btrfs: remove various bio_offset arguments Ming Lei
2018-11-26 22:28 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 02/20] btrfs: look at bi_size for repair decisions Ming Lei
2018-11-26 22:46 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 03/20] block: remove the "cluster" flag Ming Lei
2018-11-26 22:12 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 04/20] block: don't use bio->bi_vcnt to figure out segment number Ming Lei
2018-11-26 22:14 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 05/20] block: remove bvec_iter_rewind() Ming Lei
2018-11-26 12:53 ` Christoph Hellwig
2018-11-26 22:16 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 06/20] block: rename bvec helpers Ming Lei
2018-11-26 8:17 ` Miguel Ojeda
2018-11-26 12:54 ` Christoph Hellwig
2018-11-26 22:18 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 07/20] block: introduce multi-page " Ming Lei
2018-11-26 12:55 ` Christoph Hellwig
2018-11-26 2:17 ` [PATCH V12 08/20] block: introduce bio_for_each_bvec() and rq_for_each_bvec() Ming Lei
2018-11-26 12:55 ` Christoph Hellwig
2018-11-26 2:17 ` [PATCH V12 09/20] block: use bio_for_each_bvec() to compute multi-page bvec count Ming Lei
2018-11-26 13:11 ` Christoph Hellwig
2018-11-26 22:37 ` Omar Sandoval
2018-11-26 2:17 ` Ming Lei [this message]
2018-11-26 13:11 ` [PATCH V12 10/20] block: use bio_for_each_bvec() to map sg Christoph Hellwig
2018-11-26 2:17 ` [PATCH V12 11/20] block: introduce bvec_last_segment() Ming Lei
2018-11-26 2:17 ` [PATCH V12 12/20] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2018-11-26 2:17 ` [PATCH V12 13/20] block: loop: pass multi-page bvec to iov_iter Ming Lei
2018-11-26 22:39 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 14/20] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages() Ming Lei
2018-11-26 22:40 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 15/20] block: allow bio_for_each_segment_all() to iterate over multi-page bvec Ming Lei
2018-11-26 22:42 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 16/20] block: enable multipage bvecs Ming Lei
2018-11-26 12:58 ` Christoph Hellwig
2018-11-27 2:25 ` Ming Lei
2018-11-26 22:56 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 17/20] block: always define BIO_MAX_PAGES as 256 Ming Lei
2018-11-26 22:44 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 18/20] block: document usage of bio iterator helpers Ming Lei
2018-11-26 12:59 ` Christoph Hellwig
2018-11-26 22:43 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 19/20] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2018-11-26 2:17 ` [PATCH V12 20/20] block: kill BLK_MQ_F_SG_MERGE Ming Lei
2018-11-28 13:44 ` [PATCH V12 00/20] block: support multi-page bvec Jens Axboe
2018-11-29 1:30 ` Ming Lei
2018-11-29 2:20 ` Jens Axboe
2018-11-29 3:30 ` Ming Lei
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