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Message-ID: <555EDFE7.2020304@kernel.org>
Date: Fri, 22 May 2015 00:51:03 -0700
From: Ming Lin <mlin@...nel.org>
To: Christoph Hellwig <hch@....de>, Jeff Moyer <jmoyer@...hat.com>
CC: linux-kernel@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
Kent Overstreet <kent.overstreet@...il.com>,
Dongsu Park <dpark@...teo.net>,
Christoph Hellwig <hch@...radead.org>,
Al Viro <viro@...iv.linux.org.uk>,
Ming Lei <ming.lei@...onical.com>, Neil Brown <neilb@...e.de>,
Alasdair Kergon <agk@...hat.com>,
Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
Lars Ellenberg <drbd-dev@...ts.linbit.com>,
drbd-user@...ts.linbit.com, Jiri Kosina <jkosina@...e.cz>,
Geoff Levand <geoff@...radead.org>, Jim Paris <jim@...n.com>,
Joshua Morris <josh.h.morris@...ibm.com>,
Philip Kelleher <pjk1939@...ux.vnet.ibm.com>,
Minchan Kim <minchan@...nel.org>,
Nitin Gupta <ngupta@...are.org>,
Oleg Drokin <oleg.drokin@...el.com>,
Andreas Dilger <andreas.dilger@...el.com>
Subject: Re: [PATCH v3 01/11] block: make generic_make_request handle arbitrarily
sized bios
On 05/18/2015 10:22 AM, Christoph Hellwig wrote:
> On Mon, May 18, 2015 at 12:52:03PM -0400, Jeff Moyer wrote:
>>> + return bio_split(bio, split_sectors, GFP_NOIO, bs);
>>
>> Much of this function is cut-n-paste from blk-lib.c. Is there any way
>> to factor it out?
>
> The code in blk-lib.c can go away now that any driver that cares
> does the split.
How about below?
>From 23aec71f3e44a21aece46f7939715e022b7d3daa Mon Sep 17 00:00:00 2001
From: Ming Lin <mlin@...nel.org>
Date: Fri, 22 May 2015 00:46:56 -0700
Subject: [PATCH] block: remove split code in blkdev_issue_discard
The split code in blkdev_issue_discard() can go away now
that any driver that cares does the split.
Signed-off-by: Ming Lin <mlin@...nel.org>
---
block/blk-lib.c | 73 +++++++++++----------------------------------------------
1 file changed, 14 insertions(+), 59 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 7688ee3..3bf3c4a 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -43,34 +43,17 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
DECLARE_COMPLETION_ONSTACK(wait);
struct request_queue *q = bdev_get_queue(bdev);
int type = REQ_WRITE | REQ_DISCARD;
- unsigned int max_discard_sectors, granularity;
- int alignment;
struct bio_batch bb;
struct bio *bio;
int ret = 0;
struct blk_plug plug;
- if (!q)
+ if (!q || !nr_sects)
return -ENXIO;
if (!blk_queue_discard(q))
return -EOPNOTSUPP;
- /* Zero-sector (unknown) and one-sector granularities are the same. */
- granularity = max(q->limits.discard_granularity >> 9, 1U);
- alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
-
- /*
- * Ensure that max_discard_sectors is of the proper
- * granularity, so that requests stay aligned after a split.
- */
- max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
- max_discard_sectors -= max_discard_sectors % granularity;
- if (unlikely(!max_discard_sectors)) {
- /* Avoid infinite loop below. Being cautious never hurts. */
- return -EOPNOTSUPP;
- }
-
if (flags & BLKDEV_DISCARD_SECURE) {
if (!blk_queue_secdiscard(q))
return -EOPNOTSUPP;
@@ -82,52 +65,24 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
bb.wait = &wait;
blk_start_plug(&plug);
- while (nr_sects) {
- unsigned int req_sects;
- sector_t end_sect, tmp;
- bio = bio_alloc(gfp_mask, 1);
- if (!bio) {
- ret = -ENOMEM;
- break;
- }
+ bio = bio_alloc(gfp_mask, 1);
+ if (!bio) {
+ ret = -ENOMEM;
+ goto out;
+ }
- req_sects = min_t(sector_t, nr_sects, max_discard_sectors);
-
- /*
- * If splitting a request, and the next starting sector would be
- * misaligned, stop the discard at the previous aligned sector.
- */
- end_sect = sector + req_sects;
- tmp = end_sect;
- if (req_sects < nr_sects &&
- sector_div(tmp, granularity) != alignment) {
- end_sect = end_sect - alignment;
- sector_div(end_sect, granularity);
- end_sect = end_sect * granularity + alignment;
- req_sects = end_sect - sector;
- }
+ bio->bi_iter.bi_sector = sector;
+ bio->bi_end_io = bio_batch_end_io;
+ bio->bi_bdev = bdev;
+ bio->bi_private = &bb;
- bio->bi_iter.bi_sector = sector;
- bio->bi_end_io = bio_batch_end_io;
- bio->bi_bdev = bdev;
- bio->bi_private = &bb;
+ bio->bi_iter.bi_size = nr_sects << 9;
- bio->bi_iter.bi_size = req_sects << 9;
- nr_sects -= req_sects;
- sector = end_sect;
+ atomic_inc(&bb.done);
+ submit_bio(type, bio);
- atomic_inc(&bb.done);
- submit_bio(type, bio);
-
- /*
- * We can loop for a long time in here, if someone does
- * full device discards (like mkfs). Be nice and allow
- * us to schedule out to avoid softlocking if preempt
- * is disabled.
- */
- cond_resched();
- }
+out:
blk_finish_plug(&plug);
/* Wait for bios in-flight */
--
1.9.1
--
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