From: NeilBrown <neilb@suse.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Ming Lei <tom.leiming@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/13] blk: make the bioset rescue_workqueue optional.
Date: Wed, 03 May 2017 08:10:29 +1000 [thread overview]
Message-ID: <87zieuq59m.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20170502105859.GC1803@ming.t460p>
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On Tue, May 02 2017, Ming Lei wrote:
> On Tue, May 02, 2017 at 01:42:24PM +1000, NeilBrown wrote:
>> This patch converts bioset_create() and
>> bioset_create_nobvec() to not create a workqueue so
>> alloctions will never trigger punt_bios_to_rescuer(). It
>> also introduces bioset_create_rescued() and
>> bioset_create_nobvec_rescued() which preserve the old
>> behaviour.
>>
>> All callers of bioset_create() and bioset_create_nobvec(),
>> that are inside block device drivers, are converted to the
>> _rescued() version.
>
> The above comment about *_nobvec() need to be updated.
Yes - thanks. I'll post an updated version.
>
>>
>> biosets used by filesystems or other top-level users do not
>> need rescuing as the bio can never be queued behind other
>> bios. This includes fs_bio_set, blkdev_dio_pool,
>> btrfs_bioset, xfs_ioend_bioset, drbd_md_io_bio_set,
>> and one allocated by target_core_iblock.c.
>>
>> biosets used by md/raid to not need rescuing as
>> their usage was recently audited to revised to never
>> risk deadlock.
>>
>> It is hoped that most, if not all, of the remaining biosets
>> can end up being the non-rescued version.
>>
>> Signed-off-by: NeilBrown <neilb@suse.com>
>> ---
>> block/bio.c | 12 ++++++++++--
>> block/blk-core.c | 2 +-
>> drivers/md/bcache/super.c | 6 ++++--
>> drivers/md/dm-crypt.c | 2 +-
>> drivers/md/dm-io.c | 2 +-
>> drivers/md/dm.c | 5 +++--
>> include/linux/bio.h | 1 +
>> 7 files changed, 21 insertions(+), 9 deletions(-)
>
> DRBD can stack on block device too, so I guess it might need
> BIOSET_NEED_RESCUER?
A bioset only needs a rescuer is an allocation is made from the bioset
inside a make_request_fn.
The bioset in DRBD is drbd_md_io_bio_set is used for metadata IO, and
I think it is only used in a worker thread, where rescuing cannot help.
But that is probably subtle enough that I should leave the removal
of the rescuer to a subsequent patch.
So I'll give DRBD the flag when I update the changelog comment.
Thanks,
NeilBrown
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next prev parent reply other threads:[~2017-05-02 22:10 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-02 3:42 [PATCH 00/13] block: assorted cleanup for bio splitting and cloning NeilBrown
2017-05-02 3:42 ` [PATCH 02/13] blk: replace bioset_create_nobvec() with a flags arg to bioset_create() NeilBrown
2017-05-02 8:06 ` Christoph Hellwig
2017-05-02 21:47 ` NeilBrown
2017-05-02 9:40 ` Ming Lei
2017-05-02 3:42 ` [PATCH 01/13] blk: remove bio_set arg from blk_queue_split() NeilBrown
2017-05-02 10:44 ` javigon
2017-05-02 3:42 ` [PATCH 04/13] blk: use non-rescuing bioset for q->bio_split NeilBrown
2017-05-02 11:54 ` Ming Lei
2017-05-02 23:21 ` [PATCH 04/13 V2] " NeilBrown
2017-05-02 3:42 ` [PATCH 05/13] block: Improvements to bounce-buffer handling NeilBrown
2017-05-02 8:13 ` Christoph Hellwig
2017-05-02 11:56 ` Ming Lei
2017-05-02 3:42 ` [PATCH 03/13] blk: make the bioset rescue_workqueue optional NeilBrown
2017-05-02 8:14 ` Christoph Hellwig
2017-05-02 11:00 ` Ming Lei
2017-05-02 22:10 ` NeilBrown [this message]
2017-05-02 22:34 ` [PATCH 03/13 V2] " NeilBrown
2017-05-03 3:24 ` Ming Lei
2017-05-02 3:42 ` [PATCH 10/13] xen-blkfront: remove bio splitting NeilBrown
2017-05-02 8:15 ` Christoph Hellwig
2017-05-02 3:42 ` [PATCH 08/13] pktcdvd: use bio_clone_fast() instead of bio_clone() NeilBrown
2017-05-02 3:42 ` [PATCH 06/13] rbd: " NeilBrown
2017-05-02 3:42 ` [PATCH 09/13] lightnvm/pblk-read: use bio_clone_fast() NeilBrown
2017-05-02 8:15 ` Christoph Hellwig
2017-05-02 11:22 ` Javier González
2017-05-02 21:51 ` NeilBrown
2017-05-03 6:42 ` Javier González
2017-05-02 3:42 ` [PATCH 07/13] drbd: use bio_clone_fast() instead of bio_clone() NeilBrown
2017-05-02 23:20 ` [PATCH 07/13 V2] " NeilBrown
2017-05-02 3:42 ` [PATCH 12/13] block: remove bio_clone() and all references NeilBrown
2017-05-02 3:42 ` [PATCH 11/13] bcache: use kmalloc to allocate bio in bch_data_verify() NeilBrown
2017-05-02 3:42 ` [PATCH 13/13] block: don't check for BIO_MAX_PAGES in blk_bio_segment_split() NeilBrown
2017-05-02 8:15 ` Christoph Hellwig
2017-05-02 10:22 ` Ming Lei
2017-05-02 22:54 ` NeilBrown
2017-05-02 23:50 ` Ming Lei
2017-05-11 0:58 ` [PATCH 00/13] block: assorted cleanup for bio splitting and cloning NeilBrown
2017-06-16 5:54 ` NeilBrown
2017-06-16 6:42 ` Christoph Hellwig
2017-06-16 7:30 ` NeilBrown
2017-06-16 7:34 ` Christoph Hellwig
2017-06-16 20:45 ` Jens Axboe
2017-06-18 4:40 ` NeilBrown
2017-06-18 4:40 ` NeilBrown
-- strict thread matches above, loose matches on Subject: below --
2017-06-18 4:38 NeilBrown
2017-06-18 4:38 ` [PATCH 03/13] blk: make the bioset rescue_workqueue optional NeilBrown
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