Commit 47e0fb46 authored by NeilBrown's avatar NeilBrown Committed by Jens Axboe
Browse files

blk: make the bioset rescue_workqueue optional. 



This patch converts bioset_create() to not create a workqueue by
default, so alloctions will never trigger punt_bios_to_rescuer().  It
also introduces a new flag BIOSET_NEED_RESCUER which tells
bioset_create() to preserve the old behavior.

All callers of bioset_create() that are inside block device drivers,
are given the BIOSET_NEED_RESCUER flag.

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, and one allocated by
target_core_iblock.c.

biosets used by md/raid do not need rescuing as
their usage was recently audited and 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.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Credit-to: Ming Lei <ming.lei@redhat.com> (minor fixes)
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 011067b0

block/bio.c

+11 −2
Original line number Diff line number Diff line
@@ -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(&current->bio_list[0]) ||

		     !bio_list_empty(&current->bio_list[1])))

		     !bio_list_empty(&current->bio_list[1])) &&

		    bs->rescue_workqueue)

			gfp_mask &= ~__GFP_DIRECT_RECLAIM;



		p = mempool_alloc(bs->bio_pool, gfp_mask);
@@ -1925,7 +1928,8 @@ 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 +1940,8 @@ 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, a workqueue is created 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 +1977,9 @@ 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;

block/blk-core.c

+2 −1
Original line number Diff line number Diff line
@@ -790,7 +790,8 @@ 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));

	if (!q->bio_split)

		goto fail_id;

drivers/block/drbd/drbd_main.c

+3 −1
Original line number Diff line number Diff line
@@ -2165,7 +2165,9 @@ static int drbd_create_mempools(void) 
		goto Enomem;



	/* mempools */

	drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0, BIOSET_NEED_BVECS);

	drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0,

					   BIOSET_NEED_BVECS |

					   BIOSET_NEED_RESCUER);

	if (drbd_md_io_bio_set == NULL)

		goto Enomem;

drivers/md/bcache/super.c

+6 −2
Original line number Diff line number Diff line
@@ -782,7 +782,9 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size, 


	minor *= BCACHE_MINORS;



	if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio), BIOSET_NEED_BVECS)) ||

	if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio),

					   BIOSET_NEED_BVECS |

					   BIOSET_NEED_RESCUER)) ||

	    !(d->disk = alloc_disk(BCACHE_MINORS))) {

		ida_simple_remove(&bcache_minor, minor);

		return -ENOMEM;
@@ -1516,7 +1518,9 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb) 
				sizeof(struct bbio) + sizeof(struct bio_vec) *

				bucket_pages(c))) ||

	    !(c->fill_iter = mempool_create_kmalloc_pool(1, iter_size)) ||

	    !(c->bio_split = bioset_create(4, offsetof(struct bbio, bio), BIOSET_NEED_BVECS)) ||

	    !(c->bio_split = bioset_create(4, offsetof(struct bbio, bio),

					   BIOSET_NEED_BVECS |

					   BIOSET_NEED_RESCUER)) ||

	    !(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) ||

	    !(c->moving_gc_wq = alloc_workqueue("bcache_gc",

						WQ_MEM_RECLAIM, 0)) ||

drivers/md/dm-crypt.c

+2 −1
Original line number Diff line number Diff line
@@ -2677,7 +2677,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 
		goto bad;

	}



	cc->bs = bioset_create(MIN_IOS, 0, BIOSET_NEED_BVECS);

	cc->bs = bioset_create(MIN_IOS, 0, (BIOSET_NEED_BVECS |

					    BIOSET_NEED_RESCUER));

	if (!cc->bs) {

		ti->error = "Cannot allocate crypt bioset";

		goto bad;

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