From: Ming Lin <mlin@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Kent Overstreet <kent.overstreet@gmail.com>,
Dongsu Park <dpark@posteo.net>, Mike Snitzer <snitzer@redhat.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Ming Lin <mlin@kernel.org>, Ming Lin <ming.l@ssi.samsung.com>,
Neil Brown <neilb@suse.de>,
linux-raid@vger.kernel.org
Subject: [PATCH v6 06/11] md/raid5: split bio for chunk_aligned_read
Date: Wed, 12 Aug 2015 00:07:16 -0700 [thread overview]
Message-ID: <1439363241-31772-7-git-send-email-mlin@kernel.org> (raw)
In-Reply-To: <1439363241-31772-1-git-send-email-mlin@kernel.org>
From: Ming Lin <ming.l@ssi.samsung.com>
If a read request fits entirely in a chunk, it will be passed directly to the
underlying device (providing it hasn't failed of course). If it doesn't fit,
the slightly less efficient path that uses the stripe_cache is used.
Requests that get to the stripe cache are always completely split up as
necessary.
So with RAID5, ripping out the merge_bvec_fn doesn't cause it to stop work,
but could cause it to take the less efficient path more often.
All that is needed to manage this is for 'chunk_aligned_read' do some bio
splitting, much like the RAID0 code does.
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
---
drivers/md/raid5.c | 37 ++++++++++++++++++++++++++++++++-----
1 file changed, 32 insertions(+), 5 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f757023..d572639 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4806,7 +4806,7 @@ static int bio_fits_rdev(struct bio *bi)
return 1;
}
-static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
+static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
{
struct r5conf *conf = mddev->private;
int dd_idx;
@@ -4815,7 +4815,7 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
sector_t end_sector;
if (!in_chunk_boundary(mddev, raid_bio)) {
- pr_debug("chunk_aligned_read : non aligned\n");
+ pr_debug("%s: non aligned\n", __func__);
return 0;
}
/*
@@ -4892,6 +4892,31 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
}
}
+static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
+{
+ struct bio *split;
+
+ do {
+ sector_t sector = raid_bio->bi_iter.bi_sector;
+ unsigned chunk_sects = mddev->chunk_sectors;
+ unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
+
+ if (sectors < bio_sectors(raid_bio)) {
+ split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
+ bio_chain(split, raid_bio);
+ } else
+ split = raid_bio;
+
+ if (!raid5_read_one_chunk(mddev, split)) {
+ if (split != raid_bio)
+ generic_make_request(raid_bio);
+ return split;
+ }
+ } while (split != raid_bio);
+
+ return NULL;
+}
+
/* __get_priority_stripe - get the next stripe to process
*
* Full stripe writes are allowed to pass preread active stripes up until
@@ -5169,9 +5194,11 @@ static void make_request(struct mddev *mddev, struct bio * bi)
* data on failed drives.
*/
if (rw == READ && mddev->degraded == 0 &&
- mddev->reshape_position == MaxSector &&
- chunk_aligned_read(mddev,bi))
- return;
+ mddev->reshape_position == MaxSector) {
+ bi = chunk_aligned_read(mddev, bi);
+ if (!bi)
+ return;
+ }
if (unlikely(bi->bi_rw & REQ_DISCARD)) {
make_discard_request(mddev, bi);
--
2.1.4
next prev parent reply other threads:[~2015-08-12 7:08 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 7:07 [PATCH v6 00/11] simplify block layer based on immutable biovecs Ming Lin
2015-08-12 7:07 ` [PATCH v6 01/11] block: make generic_make_request handle arbitrarily sized bios Ming Lin
2015-08-12 7:07 ` [PATCH v6 02/11] block: simplify bio_add_page() Ming Lin
2015-08-12 7:07 ` [PATCH v6 03/11] bcache: remove driver private bio splitting code Ming Lin
2016-01-08 1:53 ` Eric Wheeler
2015-08-12 7:07 ` [PATCH v6 04/11] btrfs: remove bio splitting and merge_bvec_fn() calls Ming Lin
2015-08-12 7:07 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same} Ming Lin
2015-10-13 11:50 ` Christoph Hellwig
2015-10-13 17:44 ` Ming Lin
2015-10-14 13:27 ` Christoph Hellwig
2015-10-14 16:38 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same}B Keith Busch
2015-10-14 16:50 ` Christoph Hellwig
2015-10-21 16:02 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same} Mike Snitzer
2015-10-21 16:19 ` Mike Snitzer
2015-10-21 16:33 ` Martin K. Petersen
2015-10-21 17:33 ` Ming Lin
2015-10-21 18:18 ` Mike Snitzer
2015-10-21 20:13 ` Ming Lin
2015-10-22 10:24 ` Christoph Hellwig
2015-10-22 11:22 ` Christoph Hellwig
2015-10-21 7:21 ` Christoph Hellwig
2015-10-21 13:39 ` Jeff Moyer
2015-10-21 15:01 ` Ming Lin
2015-10-21 15:33 ` Mike Snitzer
2015-10-21 17:18 ` Ming Lin
2015-08-12 7:07 ` Ming Lin [this message]
2015-08-12 7:07 ` [PATCH v6 07/11] md/raid5: get rid of bio_fits_rdev() Ming Lin
2015-08-12 7:07 ` [PATCH v6 08/11] block: kill merge_bvec_fn() completely Ming Lin
2015-08-12 7:07 ` [PATCH v6 09/11] fs: use helper bio_add_page() instead of open coding on bi_io_vec Ming Lin
2015-08-12 7:07 ` [PATCH v6 10/11] block: remove bio_get_nr_vecs() Ming Lin
2015-08-12 7:07 ` [PATCH v6 11/11] Documentation: update notes in biovecs about arbitrarily sized bios Ming Lin
2015-08-13 16:51 ` [PATCH v6 00/11] simplify block layer based on immutable biovecs Jens Axboe
2015-08-13 17:03 ` Ming Lin
2015-08-13 17:07 ` Jens Axboe
2015-08-13 17:36 ` Ming Lin
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