From: Christoph Hellwig <hch@infradead.org>
To: NeilBrown <neilb@suse.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: Tue, 2 May 2017 01:14:25 -0700 [thread overview]
Message-ID: <20170502081425.GC5578@infradead.org> (raw)
In-Reply-To: <149369654434.5146.15331164625586213889.stgit@noble>
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.
>
> 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(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 3f1286ed301e..257606e742e0 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -363,6 +363,8 @@ static void punt_bios_to_rescuer(struct bio_set *bs)
> struct bio_list punt, nopunt;
> struct bio *bio;
>
> + if (!WARN_ON_ONCE(!bs->rescue_workqueue))
> + return;
> /*
> * In order to guarantee forward progress we must punt only bios that
> * were allocated from this bio_set; otherwise, if there was a bio on
> @@ -474,7 +476,8 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
>
> if (current->bio_list &&
> (!bio_list_empty(¤t->bio_list[0]) ||
> - !bio_list_empty(¤t->bio_list[1])))
> + !bio_list_empty(¤t->bio_list[1])) &&
> + bs->rescue_workqueue)
> gfp_mask &= ~__GFP_DIRECT_RECLAIM;
>
> p = mempool_alloc(bs->bio_pool, gfp_mask);
> @@ -1925,7 +1928,7 @@ EXPORT_SYMBOL(bioset_free);
> * bioset_create - Create a bio_set
> * @pool_size: Number of bio and bio_vecs to cache in the mempool
> * @front_pad: Number of bytes to allocate in front of the returned bio
> - * @flags: Flags to modify behavior, currently only %BIOSET_NEED_BVECS
> + * @flags: Flags to modify behavior, currently %BIOSET_NEED_BVECS and %BIOSET_NEED_RESCUER
> *
> * Description:
> * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
> @@ -1936,6 +1939,8 @@ EXPORT_SYMBOL(bioset_free);
> * or things will break badly.
> * If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated
> * for allocating iovecs. This pool is not needed e.g. for bio_clone_fast().
> + * If %BIOSET_NEED_RESCUER is set, workqueue is create which can be used to
> + * dispatch queued requests when the mempool runs out of space.
> *
> */
> struct bio_set *bioset_create(unsigned int pool_size,
> @@ -1971,6 +1976,9 @@ struct bio_set *bioset_create(unsigned int pool_size,
> goto bad;
> }
>
> + if (!(flags & BIOSET_NEED_RESCUER))
> + return bs;
> +
> bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
> if (!bs->rescue_workqueue)
> goto bad;
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 3797753f4085..ae51f159a2ca 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -730,7 +730,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
> if (q->id < 0)
> goto fail_q;
>
> - q->bio_split = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
> + q->bio_split = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS | BIOSET_NEED_RESCUER);
Please avoid > 80 char lines.
Otherwise looks fine,
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2017-05-02 8:14 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 03/13] blk: make the bioset rescue_workqueue optional NeilBrown
2017-05-02 8:14 ` Christoph Hellwig [this message]
2017-05-02 11:00 ` Ming Lei
2017-05-02 22:10 ` NeilBrown
2017-05-02 22:34 ` [PATCH 03/13 V2] " NeilBrown
2017-05-03 3:24 ` Ming Lei
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 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 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 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 10/13] xen-blkfront: remove bio splitting NeilBrown
2017-05-02 8:15 ` Christoph Hellwig
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 06/13] rbd: " NeilBrown
2017-05-02 3:42 ` [PATCH 08/13] pktcdvd: " 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
2017-05-02 3:42 ` [PATCH 11/13] bcache: use kmalloc to allocate bio in bch_data_verify() NeilBrown
2017-05-02 3:42 ` [PATCH 12/13] block: remove bio_clone() and all references NeilBrown
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
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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