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>, Ming Lin <mlin@kernel.org>,
Neil Brown <neilb@suse.de>,
linux-raid@vger.kernel.org
Subject: [PATCH v3 07/11] md/raid5: split bio for chunk_aligned_read
Date: Wed, 6 May 2015 23:34:17 -0700 [thread overview]
Message-ID: <1430980461-5235-8-git-send-email-mlin@kernel.org> (raw)
In-Reply-To: <1430980461-5235-1-git-send-email-mlin@kernel.org>
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
Signed-off-by: Ming Lin <mlin@kernel.org>
---
drivers/md/raid5.c | 42 +++++++++++++++++++++++++++++++++++++-----
1 file changed, 37 insertions(+), 5 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7f4a717..b18f548 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4738,7 +4738,7 @@ static void raid5_align_endio(struct bio *bi, int error)
add_bio_to_retry(raid_bi, conf);
}
-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;
@@ -4747,7 +4747,7 @@ 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;
}
/*
@@ -4822,6 +4822,36 @@ 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;
+
+ if (likely(is_power_of_2(chunk_sects)))
+ sectors = chunk_sects - (sector & (chunk_sects-1));
+ else
+ sectors = chunk_sects - sector_div(sector, chunk_sects);
+
+ 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
@@ -5099,9 +5129,11 @@ 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);
--
1.9.1
next prev parent reply other threads:[~2015-05-07 6:35 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 6:34 [PATCH v3 00/11] simplify block layer based on immutable biovecs Ming Lin
2015-05-07 6:34 ` [PATCH v3 01/11] block: make generic_make_request handle arbitrarily sized bios Ming Lin
2015-05-18 16:52 ` Jeff Moyer
2015-05-18 17:22 ` Christoph Hellwig
2015-05-22 7:51 ` Ming Lin
2015-05-20 18:30 ` Ming Lin
2015-05-20 18:58 ` Jeff Moyer
2015-05-20 20:18 ` Ming Lin
2015-05-22 17:49 ` Ming Lin
2015-05-20 12:44 ` Christoph Hellwig
2015-05-20 18:16 ` Ming Lin
2015-05-07 6:34 ` [PATCH v3 02/11] block: simplify bio_add_page() Ming Lin
2015-05-07 6:34 ` [PATCH v3 03/11] block: allow __blk_queue_bounce() to handle bios larger than BIO_MAX_PAGES Ming Lin
2015-05-19 8:44 ` Christoph Hellwig
2015-05-20 18:17 ` Ming Lin
2015-05-07 6:34 ` [PATCH v3 04/11] bcache: remove driver private bio splitting code Ming Lin
2015-05-07 6:34 ` [PATCH v3 05/11] btrfs: remove bio splitting and merge_bvec_fn() calls Ming Lin
2015-05-07 6:34 ` [PATCH v3 06/11] md/raid5: get rid of bio_fits_rdev() Ming Lin
2015-05-07 6:34 ` Ming Lin [this message]
2015-05-08 4:14 ` [PATCH v3 07/11] md/raid5: split bio for chunk_aligned_read NeilBrown
2015-05-08 5:57 ` Ming Lin
2015-05-07 6:34 ` [PATCH v3 08/11] block: kill merge_bvec_fn() completely Ming Lin
2015-05-07 6:34 ` [PATCH v3 09/11] fs: use helper bio_add_page() instead of open coding on bi_io_vec Ming Lin
2015-05-07 6:34 ` [PATCH v3 10/11] md/raid10: make sync_request_write() call bio_copy_data() Ming Lin
2015-05-19 8:45 ` Christoph Hellwig
2015-05-20 3:09 ` NeilBrown
2015-05-07 6:34 ` [PATCH v3 11/11] Documentation: update notes in biovecs about arbitrarily sized bios Ming Lin
2015-05-18 16:13 ` [PATCH v3 00/11] simplify block layer based on immutable biovecs Christoph Hellwig
2015-05-20 12:48 ` Christoph Hellwig
2015-05-20 18:10 ` Ming Lin
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