From: Mike Snitzer <snitzer@redhat.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: NeilBrown <neilb@suse.com>, Jens Axboe <axboe@kernel.dk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-block@vger.kernel.org,
device-mapper development <dm-devel@redhat.com>,
Zdenek Kabelac <zkabelac@redhat.com>
Subject: Re: new patchset to eliminate DM's use of BIOSET_NEED_RESCUER
Date: Wed, 22 Nov 2017 13:49:31 -0500 [thread overview]
Message-ID: <20171122184931.GA28348@redhat.com> (raw)
In-Reply-To: <alpine.LRH.2.02.1711221250090.21196@file01.intranet.prod.int.rdu2.redhat.com>
On Wed, Nov 22 2017 at 1:24pm -0500,
Mikulas Patocka <mpatocka@redhat.com> wrote:
> Another problem is this:
>
> struct bio *b = bio_clone_bioset(bio, GFP_NOIO, md->queue->bio_split);
> bio_advance(b, (bio_sectors(b) - ci.sector_count) << 9);
> bio_chain(b, bio);
>
> What if it blocks because the bioset is exhausted?
>
> The code basically builds a chain of bios of unlimited length (suppose for
> example a case when we are splitting on every sector boundary, so there
> will be one bio for every sector in the original bio), it could exhaust
> the bioset easily.
>
> It would be better to use mechanism from md-raid that chains all the
> sub-bios to the same master bio and doesn't create long chains of bios:
>
> if (max_sectors < bio_sectors(bio)) {
> struct bio *split = bio_split(bio, max_sectors,
> gfp, conf->bio_split);
> bio_chain(split, bio);
> generic_make_request(bio);
> bio = split;
> r1_bio->master_bio = bio;
> r1_bio->sectors = max_sectors;
> }
I'd be happy to take an incremental patch that improves on this commit:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.16&id=b46d6a08f1ae7bf53e4cde28e0ccdf91567d432e
But short of that I'll have to come back to this.
Thanks,
Mike
next prev parent reply other threads:[~2017-11-22 18:49 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-18 4:38 [PATCH 00/13] block: assorted cleanup for bio splitting and cloning NeilBrown
2017-06-18 4:38 ` [PATCH 03/13] blk: make the bioset rescue_workqueue optional NeilBrown
2017-06-18 4:38 ` [PATCH 04/13] blk: use non-rescuing bioset for q->bio_split NeilBrown
2017-06-18 4:38 ` [PATCH 01/13] blk: remove bio_set arg from blk_queue_split() NeilBrown
2017-06-18 4:38 ` [PATCH 02/13] blk: replace bioset_create_nobvec() with a flags arg to bioset_create() NeilBrown
2017-06-18 4:38 ` [PATCH 06/13] rbd: use bio_clone_fast() instead of bio_clone() NeilBrown
2017-06-18 4:38 ` [PATCH 08/13] pktcdvd: " NeilBrown
2017-06-18 4:38 ` [PATCH 05/13] block: Improvements to bounce-buffer handling NeilBrown
2017-06-18 4:38 ` [PATCH 09/13] lightnvm/pblk-read: use bio_clone_fast() NeilBrown
2017-06-18 4:38 ` [PATCH 07/13] drbd: use bio_clone_fast() instead of bio_clone() NeilBrown
2017-06-18 4:38 ` [PATCH 11/13] bcache: use kmalloc to allocate bio in bch_data_verify() NeilBrown
2017-06-18 4:38 ` [PATCH 12/13] block: remove bio_clone() and all references NeilBrown
2017-06-18 4:38 ` [PATCH 13/13] block: don't check for BIO_MAX_PAGES in blk_bio_segment_split() NeilBrown
2017-06-18 4:38 ` [PATCH 10/13] xen-blkfront: remove bio splitting NeilBrown
2017-06-18 18:41 ` [PATCH 00/13] block: assorted cleanup for bio splitting and cloning Jens Axboe
2017-06-18 21:36 ` NeilBrown
2017-11-20 16:43 ` Mike Snitzer
2017-11-21 0:34 ` [dm-devel] " NeilBrown
2017-11-21 1:35 ` Mike Snitzer
2017-11-21 12:10 ` Mike Snitzer
2017-11-21 12:43 ` Mike Snitzer
2017-11-21 19:47 ` new patchset to eliminate DM's use of BIOSET_NEED_RESCUER [was: Re: [PATCH 00/13] block: assorted cleanup for bio splitting and cloning.] Mike Snitzer
2017-11-21 21:23 ` [dm-devel] " Mikulas Patocka
2017-11-21 22:51 ` new patchset to eliminate DM's use of BIOSET_NEED_RESCUER Mike Snitzer
2017-11-22 1:21 ` Mikulas Patocka
2017-11-22 2:32 ` Mike Snitzer
2017-11-22 4:00 ` [dm-devel] " NeilBrown
2017-11-22 4:28 ` Mike Snitzer
2017-11-22 21:18 ` Mike Snitzer
2017-11-22 18:24 ` [dm-devel] " Mikulas Patocka
2017-11-22 18:49 ` Mike Snitzer [this message]
2017-11-23 5:12 ` NeilBrown
2017-11-23 22:52 ` [PATCH] dm: use cloned bio as head, not remainder, in __split_and_process_bio() NeilBrown
2017-11-27 14:23 ` Mike Snitzer
2017-11-28 22:18 ` [dm-devel] " NeilBrown
2017-11-21 23:03 ` [dm-devel] new patchset to eliminate DM's use of BIOSET_NEED_RESCUER [was: Re: [PATCH 00/13] block: assorted cleanup for bio splitting and cloning.] NeilBrown
2017-11-21 19:44 ` [dm-devel] [PATCH 00/13] block: assorted cleanup for bio splitting and cloning NeilBrown
2017-11-21 19:50 ` Mike Snitzer
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