From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AB89C352A4 for ; Wed, 12 Feb 2020 20:04:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6528121739 for ; Wed, 12 Feb 2020 20:04:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727923AbgBLUEW (ORCPT ); Wed, 12 Feb 2020 15:04:22 -0500 Received: from relay.sw.ru ([185.231.240.75]:47892 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727600AbgBLUEW (ORCPT ); Wed, 12 Feb 2020 15:04:22 -0500 Received: from [192.168.15.120] by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1j1yEt-0007oX-5E; Wed, 12 Feb 2020 23:04:03 +0300 Subject: Re: [PATCH v6 4/6] block: Add support for REQ_ALLOCATE flag To: "Darrick J. Wong" Cc: martin.petersen@oracle.com, bob.liu@oracle.com, axboe@kernel.dk, agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, song@kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, Chaitanya.Kulkarni@wdc.com, ming.lei@redhat.com, osandov@fb.com, jthumshirn@suse.de, minwoo.im.dev@gmail.com, damien.lemoal@wdc.com, andrea.parri@amarulasolutions.com, hare@suse.com, tj@kernel.org, ajay.joshi@wdc.com, sagi@grimberg.me, dsterba@suse.com, bvanassche@acm.org, dhowells@redhat.com, asml.silence@gmail.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <158132703141.239613.3550455492676290009.stgit@localhost.localdomain> <158132723311.239613.5269033996109738831.stgit@localhost.localdomain> <20200212165837.GL6874@magnolia> <092f2dc2-7bb7-d5dd-9a54-e9430940ece9@virtuozzo.com> <20200212183129.GO6874@magnolia> From: Kirill Tkhai Message-ID: <45b40cef-eabf-0699-50a6-c9a3b2fc4bdd@virtuozzo.com> Date: Wed, 12 Feb 2020 23:04:02 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <20200212183129.GO6874@magnolia> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 12.02.2020 21:31, Darrick J. Wong wrote: > On Wed, Feb 12, 2020 at 08:33:52PM +0300, Kirill Tkhai wrote: >> Hi, Darrick, >> >> On 12.02.2020 19:58, Darrick J. Wong wrote: >>> On Mon, Feb 10, 2020 at 12:33:53PM +0300, Kirill Tkhai wrote: >>>> This adds support for REQ_ALLOCATE extension of REQ_OP_WRITE_ZEROES >>>> operation, which encourages a block device driver to just allocate >>>> blocks (or mark them allocated) instead of actual blocks zeroing. >>>> REQ_ALLOCATE is aimed to be used for network filesystems providing >>>> a block device interface. Also, block devices, which map a file >>>> on other filesystem (like loop), may use this for less fragmentation >>>> and batching fallocate() requests. Hypervisors like QEMU may >>>> introduce optimizations of clusters allocations based on this. >>>> >>>> BLKDEV_ZERO_ALLOCATE is a new corresponding flag for >>>> blkdev_issue_zeroout(). >>>> >>>> Stacking devices start from zero max_allocate_sectors limit for now, >>>> and the support is going to be implemented separate for each device >>>> in the future. >>>> >>>> Signed-off-by: Kirill Tkhai >>>> Reviewed-by: Bob Liu >>>> --- >>>> block/blk-lib.c | 17 ++++++++++------- >>>> block/blk-settings.c | 4 ++++ >>>> fs/block_dev.c | 4 ++++ >>>> include/linux/blk_types.h | 5 ++++- >>>> include/linux/blkdev.h | 13 ++++++++++--- >>>> 5 files changed, 32 insertions(+), 11 deletions(-) >>>> >>>> diff --git a/block/blk-lib.c b/block/blk-lib.c >>>> index 3e38c93cfc53..9cd6f86523ba 100644 >>>> --- a/block/blk-lib.c >>>> +++ b/block/blk-lib.c >>>> @@ -214,7 +214,7 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev, >>>> struct bio **biop, unsigned flags) >>>> { >>>> struct bio *bio = *biop; >>>> - unsigned int max_write_zeroes_sectors; >>>> + unsigned int max_write_zeroes_sectors, req_flags = 0; >>>> struct request_queue *q = bdev_get_queue(bdev); >>>> >>>> if (!q) >>>> @@ -224,18 +224,21 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev, >>>> return -EPERM; >>>> >>>> /* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */ >>>> - max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev, 0); >>>> + max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev, flags); >>>> >>>> if (max_write_zeroes_sectors == 0) >>>> return -EOPNOTSUPP; >>>> >>>> + if (flags & BLKDEV_ZERO_NOUNMAP) >>>> + req_flags |= REQ_NOUNMAP; >>>> + if (flags & BLKDEV_ZERO_ALLOCATE) >>>> + req_flags |= REQ_ALLOCATE|REQ_NOUNMAP; >>>> + >>>> while (nr_sects) { >>>> bio = blk_next_bio(bio, 0, gfp_mask); >>>> bio->bi_iter.bi_sector = sector; >>>> bio_set_dev(bio, bdev); >>>> - bio->bi_opf = REQ_OP_WRITE_ZEROES; >>>> - if (flags & BLKDEV_ZERO_NOUNMAP) >>>> - bio->bi_opf |= REQ_NOUNMAP; >>>> + bio->bi_opf = REQ_OP_WRITE_ZEROES | req_flags; >>>> >>>> if (nr_sects > max_write_zeroes_sectors) { >>>> bio->bi_iter.bi_size = max_write_zeroes_sectors << 9; >>>> @@ -362,7 +365,7 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, >>>> sector_t bs_mask; >>>> struct bio *bio; >>>> struct blk_plug plug; >>>> - bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev, 0); >>>> + bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev, flags); >>>> >>>> bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1; >>>> if ((sector | nr_sects) & bs_mask) >>>> @@ -391,7 +394,7 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, >>>> try_write_zeroes = false; >>>> goto retry; >>>> } >>>> - if (!bdev_write_zeroes_sectors(bdev, 0)) { >>>> + if (!bdev_write_zeroes_sectors(bdev, flags)) { >>>> /* >>>> * Zeroing offload support was indicated, but the >>>> * device reported ILLEGAL REQUEST (for some devices >>>> diff --git a/block/blk-settings.c b/block/blk-settings.c >>>> index c8eda2e7b91e..8d5df9d37239 100644 >>>> --- a/block/blk-settings.c >>>> +++ b/block/blk-settings.c >>>> @@ -48,6 +48,7 @@ void blk_set_default_limits(struct queue_limits *lim) >>>> lim->chunk_sectors = 0; >>>> lim->max_write_same_sectors = 0; >>>> lim->max_write_zeroes_sectors = 0; >>>> + lim->max_allocate_sectors = 0; >>>> lim->max_discard_sectors = 0; >>>> lim->max_hw_discard_sectors = 0; >>>> lim->discard_granularity = 0; >>>> @@ -83,6 +84,7 @@ void blk_set_stacking_limits(struct queue_limits *lim) >>>> lim->max_dev_sectors = UINT_MAX; >>>> lim->max_write_same_sectors = UINT_MAX; >>>> lim->max_write_zeroes_sectors = UINT_MAX; >>>> + lim->max_allocate_sectors = 0; >>>> } >>>> EXPORT_SYMBOL(blk_set_stacking_limits); >>>> >>>> @@ -506,6 +508,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, >>>> b->max_write_same_sectors); >>>> t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors, >>>> b->max_write_zeroes_sectors); >>>> + t->max_allocate_sectors = min(t->max_allocate_sectors, >>>> + b->max_allocate_sectors); >>>> t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); >>>> >>>> t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, >>>> diff --git a/fs/block_dev.c b/fs/block_dev.c >>>> index 69bf2fb6f7cd..1ffef894b3bd 100644 >>>> --- a/fs/block_dev.c >>>> +++ b/fs/block_dev.c >>>> @@ -2122,6 +2122,10 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start, >>>> error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, >>>> GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK); >>>> break; >>>> + case FALLOC_FL_KEEP_SIZE: >>>> + error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, >>>> + GFP_KERNEL, BLKDEV_ZERO_ALLOCATE | BLKDEV_ZERO_NOFALLBACK); >>> >>> I think this should be ^^^ indented to match the other calls. >> >> The only idea I have about this is something like the below. But the below is over 90 char... >> >> error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, >> GFP_KERNEL, >> BLKDEV_ZERO_ALLOCATE | BLKDEV_ZERO_NOFALLBACK); >> >> Could you please clarify what you mean? > > I mostly meant that the indent for the nth lines ought to be more than a > single indent to make it easier to scan through the code, but you're > right, the kernel indentation style is uglier. I could suggest > something like this, which actually does fit: > > case FALLOC_FL_KEEP_SIZE: > error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, > GFP_KERNEL, > BLKDEV_ZERO_ALLOCATE | BLKDEV_ZERO_NOFALLBACK); > break; > > But that's apparently apocryphal. :/ Just to mention. We could also introduce BLKDEV_ZERO_ALLOCATE_NOFALLBACK, which is combination of both bits. But this does not look good for me, since this make grep over kernel code more difficult. And it won't good to introduce a new identifier for a single place. > --D > >>>> case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE: >>>> error = blkdev_issue_discard(bdev, start >> 9, len >> 9, >>>> GFP_KERNEL, 0); >>>> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h >>>> index 70254ae11769..86accd2caa4e 100644 >>>> --- a/include/linux/blk_types.h >>>> +++ b/include/linux/blk_types.h >>>> @@ -335,7 +335,9 @@ enum req_flag_bits { >>>> >>>> /* command specific flags for REQ_OP_WRITE_ZEROES: */ >>>> __REQ_NOUNMAP, /* do not free blocks when zeroing */ >>>> - >>>> + __REQ_ALLOCATE, /* only notify about allocated blocks, >>>> + * and do not actually zero them >>> >>> "only notify"? Is someone getting a notification? Or are we simply >>> "notifying" the device that it must ensure allocated blocks? >>> >>> If it's that last one, then perhaps this should be reworded: >>> >>> /* >>> * Ensure the LBA range is backed by physical storage >>> * without writing zeroes to the blocks. >>> */ >> >> Sounds good. >> >>>> + */ >>>> __REQ_HIPRI, >>>> >>>> /* for driver use */ >>>> @@ -362,6 +364,7 @@ enum req_flag_bits { >>>> #define REQ_CGROUP_PUNT (1ULL << __REQ_CGROUP_PUNT) >>>> >>>> #define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP) >>>> +#define REQ_ALLOCATE (1ULL << __REQ_ALLOCATE) >>>> #define REQ_HIPRI (1ULL << __REQ_HIPRI) >>>> >>>> #define REQ_DRV (1ULL << __REQ_DRV) >>>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h >>>> index 55a714161684..40707f980a2e 100644 >>>> --- a/include/linux/blkdev.h >>>> +++ b/include/linux/blkdev.h >>>> @@ -336,6 +336,7 @@ struct queue_limits { >>>> unsigned int max_hw_discard_sectors; >>>> unsigned int max_write_same_sectors; >>>> unsigned int max_write_zeroes_sectors; >>>> + unsigned int max_allocate_sectors; >>>> unsigned int discard_granularity; >>>> unsigned int discard_alignment; >>>> >>>> @@ -990,6 +991,8 @@ static inline struct bio_vec req_bvec(struct request *rq) >>>> static inline unsigned int blk_queue_get_max_write_zeroes_sectors( >>>> struct request_queue *q, unsigned int op_flags) >>>> { >>>> + if (op_flags & REQ_ALLOCATE) >>>> + return q->limits.max_allocate_sectors; >>>> return q->limits.max_write_zeroes_sectors; >>>> } >>>> >>>> @@ -1226,6 +1229,7 @@ extern int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, >>>> >>>> #define BLKDEV_ZERO_NOUNMAP (1 << 0) /* do not free blocks */ >>>> #define BLKDEV_ZERO_NOFALLBACK (1 << 1) /* don't write explicit zeroes */ >>>> +#define BLKDEV_ZERO_ALLOCATE (1 << 2) /* allocate range of blocks */ >>>> >>>> extern int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, >>>> sector_t nr_sects, gfp_t gfp_mask, struct bio **biop, >>>> @@ -1430,10 +1434,13 @@ static inline unsigned int bdev_write_zeroes_sectors(struct block_device *bdev, >>>> { >>>> struct request_queue *q = bdev_get_queue(bdev); >>>> >>>> - if (q) >>>> - return q->limits.max_write_zeroes_sectors; >>>> + if (!q) >>>> + return 0; >>>> >>>> - return 0; >>>> + if (flags & BLKDEV_ZERO_ALLOCATE) >>>> + return q->limits.max_allocate_sectors; >>>> + else >>>> + return q->limits.max_write_zeroes_sectors; >>>> } >>>> >>>> static inline enum blk_zoned_model bdev_zoned_model(struct block_device *bdev) >>>> >>>> >> >> Thanks, >> Kirill