// SPDX-License-Identifier: GPL-2.0/* * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk> */#include <linux/mm.h>#include <linux/swap.h>#include <linux/bio.h>#include <linux/blkdev.h>#include <linux/uio.h>#include <linux/iocontext.h>#include <linux/slab.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/export.h>#include <linux/mempool.h>#include <linux/workqueue.h>#include <linux/cgroup.h>#include <linux/blk-cgroup.h>#include <linux/highmem.h>#include <linux/sched/sysctl.h>#include <linux/blk-crypto.h>#include <linux/xarray.h> #include <trace/events/block.h>#include "blk.h"#include "blk-rq-qos.h" static struct biovec_slab { int nr_vecs; char *name; struct kmem_cache *slab;} bvec_slabs[] __read_mostly = { { .nr_vecs = 16, .name = "biovec-16" }, { .nr_vecs = 64, .name = "biovec-64" }, { .nr_vecs = 128, .name = "biovec-128" }, { .nr_vecs = BIO_MAX_VECS, .name = "biovec-max" },}; static struct biovec_slab *biovec_slab(unsigned short nr_vecs){ switch (nr_vecs) { /* smaller bios use inline vecs */ case 5 ... 16: return &bvec_slabs[0]; case 17 ... 64: return &bvec_slabs[1]; case 65 ... 128: return &bvec_slabs[2]; case 129 ... BIO_MAX_VECS: return &bvec_slabs[3]; default: BUG(); return NULL; }} /* * fs_bio_set is the bio_set containing bio and iovec memory pools used by * IO code that does not need private memory pools. */struct bio_set fs_bio_set;EXPORT_SYMBOL(fs_bio_set); /* * Our slab pool management */struct bio_slab { struct kmem_cache *slab; unsigned int slab_ref; unsigned int slab_size; char name[8];};static DEFINE_MUTEX(bio_slab_lock);static DEFINE_XARRAY(bio_slabs); static struct bio_slab *create_bio_slab(unsigned int size){ struct bio_slab *bslab = kzalloc(sizeof(*bslab), GFP_KERNEL); if (!bslab) return NULL; snprintf(bslab->name, sizeof(bslab->name), "bio-%d", size); bslab->slab = kmem_cache_create(bslab->name, size, ARCH_KMALLOC_MINALIGN, SLAB_HWCACHE_ALIGN, NULL); if (!bslab->slab) goto fail_alloc_slab; bslab->slab_ref = 1; bslab->slab_size = size; if (!xa_err(xa_store(&bio_slabs, size, bslab, GFP_KERNEL))) return bslab; kmem_cache_destroy(bslab->slab); fail_alloc_slab: kfree(bslab); return NULL;} static inline unsigned int bs_bio_slab_size(struct bio_set *bs){ return bs->front_pad + sizeof(struct bio) + bs->back_pad;} static struct kmem_cache *bio_find_or_create_slab(struct bio_set *bs){ unsigned int size = bs_bio_slab_size(bs); struct bio_slab *bslab; mutex_lock(&bio_slab_lock); bslab = xa_load(&bio_slabs, size); if (bslab) bslab->slab_ref++; else bslab = create_bio_slab(size); mutex_unlock(&bio_slab_lock); if (bslab) return bslab->slab; return NULL;} static void bio_put_slab(struct bio_set *bs){ struct bio_slab *bslab = NULL; unsigned int slab_size = bs_bio_slab_size(bs); mutex_lock(&bio_slab_lock); bslab = xa_load(&bio_slabs, slab_size); if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n")) goto out; WARN_ON_ONCE(bslab->slab != bs->bio_slab); WARN_ON(!bslab->slab_ref); if (--bslab->slab_ref) goto out; xa_erase(&bio_slabs, slab_size); kmem_cache_destroy(bslab->slab); kfree(bslab); out: mutex_unlock(&bio_slab_lock);} void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned short nr_vecs){ BIO_BUG_ON(nr_vecs > BIO_MAX_VECS); if (nr_vecs == BIO_MAX_VECS) mempool_free(bv, pool); else if (nr_vecs > BIO_INLINE_VECS) kmem_cache_free(biovec_slab(nr_vecs)->slab, bv);} /* * Make the first allocation restricted and don't dump info on allocation * failures, since we'll fall back to the mempool in case of failure. */static inline gfp_t bvec_alloc_gfp(gfp_t gfp){ return (gfp & ~(__GFP_DIRECT_RECLAIM | __GFP_IO)) | __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;} struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs, gfp_t gfp_mask){ struct biovec_slab *bvs = biovec_slab(*nr_vecs); if (WARN_ON_ONCE(!bvs)) return NULL; /* * Upgrade the nr_vecs request to take full advantage of the allocation. * We also rely on this in the bvec_free path. */ *nr_vecs = bvs->nr_vecs; /* * Try a slab allocation first for all smaller allocations. If that * fails and __GFP_DIRECT_RECLAIM is set retry with the mempool. * The mempool is sized to handle up to BIO_MAX_VECS entries. */ if (*nr_vecs < BIO_MAX_VECS) { struct bio_vec *bvl; bvl = kmem_cache_alloc(bvs->slab, bvec_alloc_gfp(gfp_mask)); if (likely(bvl) || !(gfp_mask & __GFP_DIRECT_RECLAIM)) return bvl; *nr_vecs = BIO_MAX_VECS; } return mempool_alloc(pool, gfp_mask);} void bio_uninit(struct bio *bio){#ifdef CONFIG_BLK_CGROUP if (bio->bi_blkg) { blkg_put(bio->bi_blkg); bio->bi_blkg = NULL; }#endif if (bio_integrity(bio)) bio_integrity_free(bio); bio_crypt_free_ctx(bio);}EXPORT_SYMBOL(bio_uninit); static void bio_free(struct bio *bio){ struct bio_set *bs = bio->bi_pool; void *p; bio_uninit(bio); if (bs) { bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs); /* * If we have front padding, adjust the bio pointer before freeing */ p = bio; p -= bs->front_pad; mempool_free(p, &bs->bio_pool); } else { /* Bio was allocated by bio_kmalloc() */ kfree(bio); }} /* * Users of this function have their own bio allocation. Subsequently, * they must remember to pair any call to bio_init() with bio_uninit() * when IO has completed, or when the bio is released. */void bio_init(struct bio *bio, struct bio_vec *table, unsigned short max_vecs){ memset(bio, 0, sizeof(*bio)); atomic_set(&bio->__bi_remaining, 1); atomic_set(&bio->__bi_cnt, 1); bio->bi_io_vec = table; bio->bi_max_vecs = max_vecs;}EXPORT_SYMBOL(bio_init); /** * bio_reset - reinitialize a bio * @bio: bio to reset * * Description: * After calling bio_reset(), @bio will be in the same state as a freshly * allocated bio returned bio bio_alloc_bioset() - the only fields that are * preserved are the ones that are initialized by bio_alloc_bioset(). See * comment in struct bio. */void bio_reset(struct bio *bio){ bio_uninit(bio); memset(bio, 0, BIO_RESET_BYTES); atomic_set(&bio->__bi_remaining, 1);}EXPORT_SYMBOL(bio_reset); static struct bio *__bio_chain_endio(struct bio *bio){ struct bio *parent = bio->bi_private; if (bio->bi_status && !parent->bi_status) parent->bi_status = bio->bi_status; bio_put(bio); return parent;} static void bio_chain_endio(struct bio *bio){ bio_endio(__bio_chain_endio(bio));} /** * bio_chain - chain bio completions * @bio: the target bio * @parent: the parent bio of @bio * * The caller won't have a bi_end_io called when @bio completes - instead, * @parent's bi_end_io won't be called until both @parent and @bio have * completed; the chained bio will also be freed when it completes. * * The caller must not set bi_private or bi_end_io in @bio. */void bio_chain(struct bio *bio, struct bio *parent){ BUG_ON(bio->bi_private || bio->bi_end_io); bio->bi_private = parent; bio->bi_end_io = bio_chain_endio; bio_inc_remaining(parent);}EXPORT_SYMBOL(bio_chain); static void bio_alloc_rescue(struct work_struct *work){ struct bio_set *bs = container_of(work, struct bio_set, rescue_work); struct bio *bio; while (1) { spin_lock(&bs->rescue_lock); bio = bio_list_pop(&bs->rescue_list); spin_unlock(&bs->rescue_lock); if (!bio) break; submit_bio_noacct(bio); }} 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 * there for a stacking driver higher up in the stack, processing it * could require allocating bios from this bio_set, and doing that from * our own rescuer would be bad. * * Since bio lists are singly linked, pop them all instead of trying to * remove from the middle of the list: */ bio_list_init(&punt); bio_list_init(&nopunt); while ((bio = bio_list_pop(¤t->bio_list[0]))) bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio); current->bio_list[0] = nopunt; bio_list_init(&nopunt); while ((bio = bio_list_pop(¤t->bio_list[1]))) bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio); current->bio_list[1] = nopunt; spin_lock(&bs->rescue_lock); bio_list_merge(&bs->rescue_list, &punt); spin_unlock(&bs->rescue_lock); queue_work(bs->rescue_workqueue, &bs->rescue_work);} /** * bio_alloc_bioset - allocate a bio for I/O * @gfp_mask: the GFP_* mask given to the slab allocator * @nr_iovecs: number of iovecs to pre-allocate * @bs: the bio_set to allocate from. * * Allocate a bio from the mempools in @bs. * * If %__GFP_DIRECT_RECLAIM is set then bio_alloc will always be able to * allocate a bio. This is due to the mempool guarantees. To make this work, * callers must never allocate more than 1 bio at a time from the general pool. * Callers that need to allocate more than 1 bio must always submit the * previously allocated bio for IO before attempting to allocate a new one. * Failure to do so can cause deadlocks under memory pressure. * * Note that when running under submit_bio_noacct() (i.e. any block driver), * bios are not submitted until after you return - see the code in * submit_bio_noacct() that converts recursion into iteration, to prevent * stack overflows. * * This would normally mean allocating multiple bios under submit_bio_noacct() * would be susceptible to deadlocks, but we have * deadlock avoidance code that resubmits any blocked bios from a rescuer * thread. * * However, we do not guarantee forward progress for allocations from other * mempools. Doing multiple allocations from the same mempool under * submit_bio_noacct() should be avoided - instead, use bio_set's front_pad * for per bio allocations. * * Returns: Pointer to new bio on success, NULL on failure. */struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned short nr_iovecs, struct bio_set *bs){ gfp_t saved_gfp = gfp_mask; struct bio *bio; void *p; /* should not use nobvec bioset for nr_iovecs > 0 */ if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_iovecs > 0)) return NULL; /* * submit_bio_noacct() converts recursion to iteration; this means if * we're running beneath it, any bios we allocate and submit will not be * submitted (and thus freed) until after we return. * * This exposes us to a potential deadlock if we allocate multiple bios * from the same bio_set() while running underneath submit_bio_noacct(). * If we were to allocate multiple bios (say a stacking block driver * that was splitting bios), we would deadlock if we exhausted the * mempool's reserve. * * We solve this, and guarantee forward progress, with a rescuer * workqueue per bio_set. If we go to allocate and there are bios on * current->bio_list, we first try the allocation without * __GFP_DIRECT_RECLAIM; if that fails, we punt those bios we would be * blocking to the rescuer workqueue before we retry with the original * gfp_flags. */ if (current->bio_list && (!bio_list_empty(¤t->bio_list[0]) || !bio_list_empty(¤t->bio_list[1])) && bs->rescue_workqueue) gfp_mask &= ~__GFP_DIRECT_RECLAIM; p = mempool_alloc(&bs->bio_pool, gfp_mask); if (!p && gfp_mask != saved_gfp) { punt_bios_to_rescuer(bs); gfp_mask = saved_gfp; p = mempool_alloc(&bs->bio_pool, gfp_mask); } if (unlikely(!p)) return NULL; bio = p + bs->front_pad; if (nr_iovecs > BIO_INLINE_VECS) { struct bio_vec *bvl = NULL; bvl = bvec_alloc(&bs->bvec_pool, &nr_iovecs, gfp_mask); if (!bvl && gfp_mask != saved_gfp) { punt_bios_to_rescuer(bs); gfp_mask = saved_gfp; bvl = bvec_alloc(&bs->bvec_pool, &nr_iovecs, gfp_mask); } if (unlikely(!bvl)) goto err_free; bio_init(bio, bvl, nr_iovecs); } else if (nr_iovecs) { bio_init(bio, bio->bi_inline_vecs, BIO_INLINE_VECS); } else { bio_init(bio, NULL, 0); } bio->bi_pool = bs; return bio; err_free: mempool_free(p, &bs->bio_pool); return NULL;}EXPORT_SYMBOL(bio_alloc_bioset); /** * bio_kmalloc - kmalloc a bio for I/O * @gfp_mask: the GFP_* mask given to the slab allocator * @nr_iovecs: number of iovecs to pre-allocate * * Use kmalloc to allocate and initialize a bio. * * Returns: Pointer to new bio on success, NULL on failure. */struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned short nr_iovecs){ struct bio *bio; if (nr_iovecs > UIO_MAXIOV) return NULL; bio = kmalloc(struct_size(bio, bi_inline_vecs, nr_iovecs), gfp_mask); if (unlikely(!bio)) return NULL; bio_init(bio, nr_iovecs ? bio->bi_inline_vecs : NULL, nr_iovecs); bio->bi_pool = NULL; return bio;}EXPORT_SYMBOL(bio_kmalloc); void zero_fill_bio(struct bio *bio){ unsigned long flags; struct bio_vec bv; struct bvec_iter iter;Lines 1–500 of 1621. 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// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk> */ #include <linux/mm.h> #include <linux/swap.h> #include <linux/bio.h> #include <linux/blkdev.h> #include <linux/uio.h> #include <linux/iocontext.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/export.h> #include <linux/mempool.h> #include <linux/workqueue.h> #include <linux/cgroup.h> #include <linux/blk-cgroup.h> #include <linux/highmem.h> #include <linux/sched/sysctl.h> #include <linux/blk-crypto.h> #include <linux/xarray.h> #include <trace/events/block.h> #include "blk.h" #include "blk-rq-qos.h" static struct biovec_slab { int nr_vecs; char *name; struct kmem_cache *slab; } bvec_slabs[] __read_mostly = { { .nr_vecs = 16, .name = "biovec-16" }, { .nr_vecs = 64, .name = "biovec-64" }, { .nr_vecs = 128, .name = "biovec-128" }, { .nr_vecs = BIO_MAX_VECS, .name = "biovec-max" }, }; static struct biovec_slab *biovec_slab(unsigned short nr_vecs) { switch (nr_vecs) { /* smaller bios use inline vecs */ case 5 ... 16: return &bvec_slabs[0]; case 17 ... 64: return &bvec_slabs[1]; case 65 ... 128: return &bvec_slabs[2]; case 129 ... BIO_MAX_VECS: return &bvec_slabs[3]; default: BUG(); return NULL; } } /* * fs_bio_set is the bio_set containing bio and iovec memory pools used by * IO code that does not need private memory pools. */ struct bio_set fs_bio_set; EXPORT_SYMBOL(fs_bio_set); /* * Our slab pool management */ struct bio_slab { struct kmem_cache *slab; unsigned int slab_ref; unsigned int slab_size; char name[8]; }; static DEFINE_MUTEX(bio_slab_lock); static DEFINE_XARRAY(bio_slabs); static struct bio_slab *create_bio_slab(unsigned int size) { struct bio_slab *bslab = kzalloc(sizeof(*bslab), GFP_KERNEL); if (!bslab) return NULL; snprintf(bslab->name, sizeof(bslab->name), "bio-%d", size); bslab->slab = kmem_cache_create(bslab->name, size, ARCH_KMALLOC_MINALIGN, SLAB_HWCACHE_ALIGN, NULL); if (!bslab->slab) goto fail_alloc_slab; bslab->slab_ref = 1; bslab->slab_size = size; if (!xa_err(xa_store(&bio_slabs, size, bslab, GFP_KERNEL))) return bslab; kmem_cache_destroy(bslab->slab); fail_alloc_slab: kfree(bslab); return NULL; } static inline unsigned int bs_bio_slab_size(struct bio_set *bs) { return bs->front_pad + sizeof(struct bio) + bs->back_pad; } static struct kmem_cache *bio_find_or_create_slab(struct bio_set *bs) { unsigned int size = bs_bio_slab_size(bs); struct bio_slab *bslab; mutex_lock(&bio_slab_lock); bslab = xa_load(&bio_slabs, size); if (bslab) bslab->slab_ref++; else bslab = create_bio_slab(size); mutex_unlock(&bio_slab_lock); if (bslab) return bslab->slab; return NULL; } static void bio_put_slab(struct bio_set *bs) { struct bio_slab *bslab = NULL; unsigned int slab_size = bs_bio_slab_size(bs); mutex_lock(&bio_slab_lock); bslab = xa_load(&bio_slabs, slab_size); if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n")) goto out; WARN_ON_ONCE(bslab->slab != bs->bio_slab); WARN_ON(!bslab->slab_ref); if (--bslab->slab_ref) goto out; xa_erase(&bio_slabs, slab_size); kmem_cache_destroy(bslab->slab); kfree(bslab); out: mutex_unlock(&bio_slab_lock); } void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned short nr_vecs) { BIO_BUG_ON(nr_vecs > BIO_MAX_VECS); if (nr_vecs == BIO_MAX_VECS) mempool_free(bv, pool); else if (nr_vecs > BIO_INLINE_VECS) kmem_cache_free(biovec_slab(nr_vecs)->slab, bv); } /* * Make the first allocation restricted and don't dump info on allocation * failures, since we'll fall back to the mempool in case of failure. */ static inline gfp_t bvec_alloc_gfp(gfp_t gfp) { return (gfp & ~(__GFP_DIRECT_RECLAIM | __GFP_IO)) | __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN; } struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs, gfp_t gfp_mask) { struct biovec_slab *bvs = biovec_slab(*nr_vecs); if (WARN_ON_ONCE(!bvs)) return NULL; /* * Upgrade the nr_vecs request to take full advantage of the allocation. * We also rely on this in the bvec_free path. */ *nr_vecs = bvs->nr_vecs; /* * Try a slab allocation first for all smaller allocations. If that * fails and __GFP_DIRECT_RECLAIM is set retry with the mempool. * The mempool is sized to handle up to BIO_MAX_VECS entries. */ if (*nr_vecs < BIO_MAX_VECS) { struct bio_vec *bvl; bvl = kmem_cache_alloc(bvs->slab, bvec_alloc_gfp(gfp_mask)); if (likely(bvl) || !(gfp_mask & __GFP_DIRECT_RECLAIM)) return bvl; *nr_vecs = BIO_MAX_VECS; } return mempool_alloc(pool, gfp_mask); } void bio_uninit(struct bio *bio) { #ifdef CONFIG_BLK_CGROUP if (bio->bi_blkg) { blkg_put(bio->bi_blkg); bio->bi_blkg = NULL; } #endif if (bio_integrity(bio)) bio_integrity_free(bio); bio_crypt_free_ctx(bio); } EXPORT_SYMBOL(bio_uninit); static void bio_free(struct bio *bio) { struct bio_set *bs = bio->bi_pool; void *p; bio_uninit(bio); if (bs) { bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs); /* * If we have front padding, adjust the bio pointer before freeing */ p = bio; p -= bs->front_pad; mempool_free(p, &bs->bio_pool); } else { /* Bio was allocated by bio_kmalloc() */ kfree(bio); } } /* * Users of this function have their own bio allocation. Subsequently, * they must remember to pair any call to bio_init() with bio_uninit() * when IO has completed, or when the bio is released. */ void bio_init(struct bio *bio, struct bio_vec *table, unsigned short max_vecs) { memset(bio, 0, sizeof(*bio)); atomic_set(&bio->__bi_remaining, 1); atomic_set(&bio->__bi_cnt, 1); bio->bi_io_vec = table; bio->bi_max_vecs = max_vecs; } EXPORT_SYMBOL(bio_init); /** * bio_reset - reinitialize a bio * @bio: bio to reset * * Description: * After calling bio_reset(), @bio will be in the same state as a freshly * allocated bio returned bio bio_alloc_bioset() - the only fields that are * preserved are the ones that are initialized by bio_alloc_bioset(). See * comment in struct bio. */ void bio_reset(struct bio *bio) { bio_uninit(bio); memset(bio, 0, BIO_RESET_BYTES); atomic_set(&bio->__bi_remaining, 1); } EXPORT_SYMBOL(bio_reset); static struct bio *__bio_chain_endio(struct bio *bio) { struct bio *parent = bio->bi_private; if (bio->bi_status && !parent->bi_status) parent->bi_status = bio->bi_status; bio_put(bio); return parent; } static void bio_chain_endio(struct bio *bio) { bio_endio(__bio_chain_endio(bio)); } /** * bio_chain - chain bio completions * @bio: the target bio * @parent: the parent bio of @bio * * The caller won't have a bi_end_io called when @bio completes - instead, * @parent's bi_end_io won't be called until both @parent and @bio have * completed; the chained bio will also be freed when it completes. * * The caller must not set bi_private or bi_end_io in @bio. */ void bio_chain(struct bio *bio, struct bio *parent) { BUG_ON(bio->bi_private || bio->bi_end_io); bio->bi_private = parent; bio->bi_end_io = bio_chain_endio; bio_inc_remaining(parent); } EXPORT_SYMBOL(bio_chain); static void bio_alloc_rescue(struct work_struct *work) { struct bio_set *bs = container_of(work, struct bio_set, rescue_work); struct bio *bio; while (1) { spin_lock(&bs->rescue_lock); bio = bio_list_pop(&bs->rescue_list); spin_unlock(&bs->rescue_lock); if (!bio) break; submit_bio_noacct(bio); } } 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 * there for a stacking driver higher up in the stack, processing it * could require allocating bios from this bio_set, and doing that from * our own rescuer would be bad. * * Since bio lists are singly linked, pop them all instead of trying to * remove from the middle of the list: */ bio_list_init(&punt); bio_list_init(&nopunt); while ((bio = bio_list_pop(¤t->bio_list[0]))) bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio); current->bio_list[0] = nopunt; bio_list_init(&nopunt); while ((bio = bio_list_pop(¤t->bio_list[1]))) bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio); current->bio_list[1] = nopunt; spin_lock(&bs->rescue_lock); bio_list_merge(&bs->rescue_list, &punt); spin_unlock(&bs->rescue_lock); queue_work(bs->rescue_workqueue, &bs->rescue_work); } /** * bio_alloc_bioset - allocate a bio for I/O * @gfp_mask: the GFP_* mask given to the slab allocator * @nr_iovecs: number of iovecs to pre-allocate * @bs: the bio_set to allocate from. * * Allocate a bio from the mempools in @bs. * * If %__GFP_DIRECT_RECLAIM is set then bio_alloc will always be able to * allocate a bio. This is due to the mempool guarantees. To make this work, * callers must never allocate more than 1 bio at a time from the general pool. * Callers that need to allocate more than 1 bio must always submit the * previously allocated bio for IO before attempting to allocate a new one. * Failure to do so can cause deadlocks under memory pressure. * * Note that when running under submit_bio_noacct() (i.e. any block driver), * bios are not submitted until after you return - see the code in * submit_bio_noacct() that converts recursion into iteration, to prevent * stack overflows. * * This would normally mean allocating multiple bios under submit_bio_noacct() * would be susceptible to deadlocks, but we have * deadlock avoidance code that resubmits any blocked bios from a rescuer * thread. * * However, we do not guarantee forward progress for allocations from other * mempools. Doing multiple allocations from the same mempool under * submit_bio_noacct() should be avoided - instead, use bio_set's front_pad * for per bio allocations. * * Returns: Pointer to new bio on success, NULL on failure. */ struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned short nr_iovecs, struct bio_set *bs) { gfp_t saved_gfp = gfp_mask; struct bio *bio; void *p; /* should not use nobvec bioset for nr_iovecs > 0 */ if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_iovecs > 0)) return NULL; /* * submit_bio_noacct() converts recursion to iteration; this means if * we're running beneath it, any bios we allocate and submit will not be * submitted (and thus freed) until after we return. * * This exposes us to a potential deadlock if we allocate multiple bios * from the same bio_set() while running underneath submit_bio_noacct(). * If we were to allocate multiple bios (say a stacking block driver * that was splitting bios), we would deadlock if we exhausted the * mempool's reserve. * * We solve this, and guarantee forward progress, with a rescuer * workqueue per bio_set. If we go to allocate and there are bios on * current->bio_list, we first try the allocation without * __GFP_DIRECT_RECLAIM; if that fails, we punt those bios we would be * blocking to the rescuer workqueue before we retry with the original * gfp_flags. */ if (current->bio_list && (!bio_list_empty(¤t->bio_list[0]) || !bio_list_empty(¤t->bio_list[1])) && bs->rescue_workqueue) gfp_mask &= ~__GFP_DIRECT_RECLAIM; p = mempool_alloc(&bs->bio_pool, gfp_mask); if (!p && gfp_mask != saved_gfp) { punt_bios_to_rescuer(bs); gfp_mask = saved_gfp; p = mempool_alloc(&bs->bio_pool, gfp_mask); } if (unlikely(!p)) return NULL; bio = p + bs->front_pad; if (nr_iovecs > BIO_INLINE_VECS) { struct bio_vec *bvl = NULL; bvl = bvec_alloc(&bs->bvec_pool, &nr_iovecs, gfp_mask); if (!bvl && gfp_mask != saved_gfp) { punt_bios_to_rescuer(bs); gfp_mask = saved_gfp; bvl = bvec_alloc(&bs->bvec_pool, &nr_iovecs, gfp_mask); } if (unlikely(!bvl)) goto err_free; bio_init(bio, bvl, nr_iovecs); } else if (nr_iovecs) { bio_init(bio, bio->bi_inline_vecs, BIO_INLINE_VECS); } else { bio_init(bio, NULL, 0); } bio->bi_pool = bs; return bio; err_free: mempool_free(p, &bs->bio_pool); return NULL; } EXPORT_SYMBOL(bio_alloc_bioset); /** * bio_kmalloc - kmalloc a bio for I/O * @gfp_mask: the GFP_* mask given to the slab allocator * @nr_iovecs: number of iovecs to pre-allocate * * Use kmalloc to allocate and initialize a bio. * * Returns: Pointer to new bio on success, NULL on failure. */ struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned short nr_iovecs) { struct bio *bio; if (nr_iovecs > UIO_MAXIOV) return NULL; bio = kmalloc(struct_size(bio, bi_inline_vecs, nr_iovecs), gfp_mask); if (unlikely(!bio)) return NULL; bio_init(bio, nr_iovecs ? bio->bi_inline_vecs : NULL, nr_iovecs); bio->bi_pool = NULL; return bio; } EXPORT_SYMBOL(bio_kmalloc); void zero_fill_bio(struct bio *bio) { unsigned long flags; struct bio_vec bv; struct bvec_iter iter;