diff options
Diffstat (limited to 'block/bio.c')
| -rw-r--r-- | block/bio.c | 2102 |
1 files changed, 2102 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c new file mode 100644 index 000000000..7858b2d23 --- /dev/null +++ b/block/bio.c @@ -0,0 +1,2102 @@ +/* + * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public Licens + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111- + * + */ +#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 <trace/events/block.h> +#include "blk.h" +#include "blk-rq-qos.h" + +/* + * Test patch to inline a certain number of bi_io_vec's inside the bio + * itself, to shrink a bio data allocation from two mempool calls to one + */ +#define BIO_INLINE_VECS 4 + +/* + * if you change this list, also change bvec_alloc or things will + * break badly! cannot be bigger than what you can fit into an + * unsigned short + */ +#define BV(x, n) { .nr_vecs = x, .name = "biovec-"#n } +static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = { + BV(1, 1), BV(4, 4), BV(16, 16), BV(64, 64), BV(128, 128), BV(BIO_MAX_PAGES, max), +}; +#undef BV + +/* + * 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 struct bio_slab *bio_slabs; +static unsigned int bio_slab_nr, bio_slab_max; + +static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size) +{ + unsigned int sz = sizeof(struct bio) + extra_size; + struct kmem_cache *slab = NULL; + struct bio_slab *bslab, *new_bio_slabs; + unsigned int new_bio_slab_max; + unsigned int i, entry = -1; + + mutex_lock(&bio_slab_lock); + + i = 0; + while (i < bio_slab_nr) { + bslab = &bio_slabs[i]; + + if (!bslab->slab && entry == -1) + entry = i; + else if (bslab->slab_size == sz) { + slab = bslab->slab; + bslab->slab_ref++; + break; + } + i++; + } + + if (slab) + goto out_unlock; + + if (bio_slab_nr == bio_slab_max && entry == -1) { + new_bio_slab_max = bio_slab_max << 1; + new_bio_slabs = krealloc(bio_slabs, + new_bio_slab_max * sizeof(struct bio_slab), + GFP_KERNEL); + if (!new_bio_slabs) + goto out_unlock; + bio_slab_max = new_bio_slab_max; + bio_slabs = new_bio_slabs; + } + if (entry == -1) + entry = bio_slab_nr++; + + bslab = &bio_slabs[entry]; + + snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry); + slab = kmem_cache_create(bslab->name, sz, ARCH_KMALLOC_MINALIGN, + SLAB_HWCACHE_ALIGN, NULL); + if (!slab) + goto out_unlock; + + bslab->slab = slab; + bslab->slab_ref = 1; + bslab->slab_size = sz; +out_unlock: + mutex_unlock(&bio_slab_lock); + return slab; +} + +static void bio_put_slab(struct bio_set *bs) +{ + struct bio_slab *bslab = NULL; + unsigned int i; + + mutex_lock(&bio_slab_lock); + + for (i = 0; i < bio_slab_nr; i++) { + if (bs->bio_slab == bio_slabs[i].slab) { + bslab = &bio_slabs[i]; + break; + } + } + + if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n")) + goto out; + + WARN_ON(!bslab->slab_ref); + + if (--bslab->slab_ref) + goto out; + + kmem_cache_destroy(bslab->slab); + bslab->slab = NULL; + +out: + mutex_unlock(&bio_slab_lock); +} + +unsigned int bvec_nr_vecs(unsigned short idx) +{ + return bvec_slabs[--idx].nr_vecs; +} + +void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx) +{ + if (!idx) + return; + idx--; + + BIO_BUG_ON(idx >= BVEC_POOL_NR); + + if (idx == BVEC_POOL_MAX) { + mempool_free(bv, pool); + } else { + struct biovec_slab *bvs = bvec_slabs + idx; + + kmem_cache_free(bvs->slab, bv); + } +} + +struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx, + mempool_t *pool) +{ + struct bio_vec *bvl; + + /* + * see comment near bvec_array define! + */ + switch (nr) { + case 1: + *idx = 0; + break; + case 2 ... 4: + *idx = 1; + break; + case 5 ... 16: + *idx = 2; + break; + case 17 ... 64: + *idx = 3; + break; + case 65 ... 128: + *idx = 4; + break; + case 129 ... BIO_MAX_PAGES: + *idx = 5; + break; + default: + return NULL; + } + + /* + * idx now points to the pool we want to allocate from. only the + * 1-vec entry pool is mempool backed. + */ + if (*idx == BVEC_POOL_MAX) { +fallback: + bvl = mempool_alloc(pool, gfp_mask); + } else { + struct biovec_slab *bvs = bvec_slabs + *idx; + gfp_t __gfp_mask = gfp_mask & ~(__GFP_DIRECT_RECLAIM | __GFP_IO); + + /* + * Make this allocation restricted and don't dump info on + * allocation failures, since we'll fallback to the mempool + * in case of failure. + */ + __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN; + + /* + * Try a slab allocation. If this fails and __GFP_DIRECT_RECLAIM + * is set, retry with the 1-entry mempool + */ + bvl = kmem_cache_alloc(bvs->slab, __gfp_mask); + if (unlikely(!bvl && (gfp_mask & __GFP_DIRECT_RECLAIM))) { + *idx = BVEC_POOL_MAX; + goto fallback; + } + } + + (*idx)++; + return bvl; +} + +void bio_uninit(struct bio *bio) +{ + bio_disassociate_task(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, BVEC_POOL_IDX(bio)); + + /* + * 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) +{ + unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS); + + bio_uninit(bio); + + memset(bio, 0, BIO_RESET_BYTES); + bio->bi_flags = flags; + 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 @bio's parent 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; + + generic_make_request(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. + * + * Description: + * If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is + * backed by the @bs's mempool. + * + * When @bs is not NULL, 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 this 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 generic_make_request() (i.e. any block + * driver), bios are not submitted until after you return - see the code in + * generic_make_request() that converts recursion into iteration, to prevent + * stack overflows. + * + * This would normally mean allocating multiple bios under + * generic_make_request() 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 + * generic_make_request() 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 int nr_iovecs, + struct bio_set *bs) +{ + gfp_t saved_gfp = gfp_mask; + unsigned front_pad; + unsigned inline_vecs; + struct bio_vec *bvl = NULL; + struct bio *bio; + void *p; + + if (!bs) { + if (nr_iovecs > UIO_MAXIOV) + return NULL; + + p = kmalloc(sizeof(struct bio) + + nr_iovecs * sizeof(struct bio_vec), + gfp_mask); + front_pad = 0; + inline_vecs = nr_iovecs; + } else { + /* should not use nobvec bioset for nr_iovecs > 0 */ + if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && + nr_iovecs > 0)) + return NULL; + /* + * generic_make_request() 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 generic_make_request(). 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); + } + + front_pad = bs->front_pad; + inline_vecs = BIO_INLINE_VECS; + } + + if (unlikely(!p)) + return NULL; + + bio = p + front_pad; + bio_init(bio, NULL, 0); + + if (nr_iovecs > inline_vecs) { + unsigned long idx = 0; + + bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool); + if (!bvl && gfp_mask != saved_gfp) { + punt_bios_to_rescuer(bs); + gfp_mask = saved_gfp; + bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool); + } + + if (unlikely(!bvl)) + goto err_free; + + bio->bi_flags |= idx << BVEC_POOL_OFFSET; + } else if (nr_iovecs) { + bvl = bio->bi_inline_vecs; + } + + bio->bi_pool = bs; + bio->bi_max_vecs = nr_iovecs; + bio->bi_io_vec = bvl; + return bio; + +err_free: + mempool_free(p, &bs->bio_pool); + return NULL; +} +EXPORT_SYMBOL(bio_alloc_bioset); + +void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start) +{ + unsigned long flags; + struct bio_vec bv; + struct bvec_iter iter; + + __bio_for_each_segment(bv, bio, iter, start) { + char *data = bvec_kmap_irq(&bv, &flags); + memset(data, 0, bv.bv_len); + flush_dcache_page(bv.bv_page); + bvec_kunmap_irq(data, &flags); + } +} +EXPORT_SYMBOL(zero_fill_bio_iter); + +/** + * bio_put - release a reference to a bio + * @bio: bio to release reference to + * + * Description: + * Put a reference to a &struct bio, either one you have gotten with + * bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it. + **/ +void bio_put(struct bio *bio) +{ + if (!bio_flagged(bio, BIO_REFFED)) + bio_free(bio); + else { + BIO_BUG_ON(!atomic_read(&bio->__bi_cnt)); + + /* + * last put frees it + */ + if (atomic_dec_and_test(&bio->__bi_cnt)) + bio_free(bio); + } +} +EXPORT_SYMBOL(bio_put); + +inline int bio_phys_segments(struct request_queue *q, struct bio *bio) +{ + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) + blk_recount_segments(q, bio); + + return bio->bi_phys_segments; +} +EXPORT_SYMBOL(bio_phys_segments); + +/** + * __bio_clone_fast - clone a bio that shares the original bio's biovec + * @bio: destination bio + * @bio_src: bio to clone + * + * Clone a &bio. Caller will own the returned bio, but not + * the actual data it points to. Reference count of returned + * bio will be one. + * + * Caller must ensure that @bio_src is not freed before @bio. + */ +void __bio_clone_fast(struct bio *bio, struct bio *bio_src) +{ + BUG_ON(bio->bi_pool && BVEC_POOL_IDX(bio)); + + /* + * most users will be overriding ->bi_disk with a new target, + * so we don't set nor calculate new physical/hw segment counts here + */ + bio->bi_disk = bio_src->bi_disk; + bio->bi_partno = bio_src->bi_partno; + bio_set_flag(bio, BIO_CLONED); + if (bio_flagged(bio_src, BIO_THROTTLED)) + bio_set_flag(bio, BIO_THROTTLED); + bio->bi_opf = bio_src->bi_opf; + bio->bi_ioprio = bio_src->bi_ioprio; + bio->bi_write_hint = bio_src->bi_write_hint; + bio->bi_iter = bio_src->bi_iter; + bio->bi_io_vec = bio_src->bi_io_vec; + + bio_clone_blkcg_association(bio, bio_src); +} +EXPORT_SYMBOL(__bio_clone_fast); + +/** + * bio_clone_fast - clone a bio that shares the original bio's biovec + * @bio: bio to clone + * @gfp_mask: allocation priority + * @bs: bio_set to allocate from + * + * Like __bio_clone_fast, only also allocates the returned bio + */ +struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs) +{ + struct bio *b; + + b = bio_alloc_bioset(gfp_mask, 0, bs); + if (!b) + return NULL; + + __bio_clone_fast(b, bio); + + if (bio_integrity(bio)) { + int ret; + + ret = bio_integrity_clone(b, bio, gfp_mask); + + if (ret < 0) { + bio_put(b); + return NULL; + } + } + + return b; +} +EXPORT_SYMBOL(bio_clone_fast); + +/** + * bio_add_pc_page - attempt to add page to bio + * @q: the target queue + * @bio: destination bio + * @page: page to add + * @len: vec entry length + * @offset: vec entry offset + * + * Attempt to add a page to the bio_vec maplist. This can fail for a + * number of reasons, such as the bio being full or target block device + * limitations. The target block device must allow bio's up to PAGE_SIZE, + * so it is always possible to add a single page to an empty bio. + * + * This should only be used by REQ_PC bios. + */ +int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page + *page, unsigned int len, unsigned int offset) +{ + int retried_segments = 0; + struct bio_vec *bvec; + + /* + * cloned bio must not modify vec list + */ + if (unlikely(bio_flagged(bio, BIO_CLONED))) + return 0; + + if (((bio->bi_iter.bi_size + len) >> 9) > queue_max_hw_sectors(q)) + return 0; + + /* + * For filesystems with a blocksize smaller than the pagesize + * we will often be called with the same page as last time and + * a consecutive offset. Optimize this special case. + */ + if (bio->bi_vcnt > 0) { + struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1]; + + if (page == prev->bv_page && + offset == prev->bv_offset + prev->bv_len) { + prev->bv_len += len; + bio->bi_iter.bi_size += len; + goto done; + } + + /* + * If the queue doesn't support SG gaps and adding this + * offset would create a gap, disallow it. + */ + if (bvec_gap_to_prev(q, prev, offset)) + return 0; + } + + if (bio_full(bio)) + return 0; + + /* + * setup the new entry, we might clear it again later if we + * cannot add the page + */ + bvec = &bio->bi_io_vec[bio->bi_vcnt]; + bvec->bv_page = page; + bvec->bv_len = len; + bvec->bv_offset = offset; + bio->bi_vcnt++; + bio->bi_phys_segments++; + bio->bi_iter.bi_size += len; + + /* + * Perform a recount if the number of segments is greater + * than queue_max_segments(q). + */ + + while (bio->bi_phys_segments > queue_max_segments(q)) { + + if (retried_segments) + goto failed; + + retried_segments = 1; + blk_recount_segments(q, bio); + } + + /* If we may be able to merge these biovecs, force a recount */ + if (bio->bi_vcnt > 1 && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec))) + bio_clear_flag(bio, BIO_SEG_VALID); + + done: + return len; + + failed: + bvec->bv_page = NULL; + bvec->bv_len = 0; + bvec->bv_offset = 0; + bio->bi_vcnt--; + bio->bi_iter.bi_size -= len; + blk_recount_segments(q, bio); + return 0; +} +EXPORT_SYMBOL(bio_add_pc_page); + +/** + * __bio_try_merge_page - try appending data to an existing bvec. + * @bio: destination bio + * @page: page to add + * @len: length of the data to add + * @off: offset of the data in @page + * + * Try to add the data at @page + @off to the last bvec of @bio. This is a + * a useful optimisation for file systems with a block size smaller than the + * page size. + * + * Return %true on success or %false on failure. + */ +bool __bio_try_merge_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int off) +{ + if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) + return false; + + if (bio->bi_vcnt > 0) { + struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; + + if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) { + bv->bv_len += len; + bio->bi_iter.bi_size += len; + return true; + } + } + return false; +} +EXPORT_SYMBOL_GPL(__bio_try_merge_page); + +/** + * __bio_add_page - add page to a bio in a new segment + * @bio: destination bio + * @page: page to add + * @len: length of the data to add + * @off: offset of the data in @page + * + * Add the data at @page + @off to @bio as a new bvec. The caller must ensure + * that @bio has space for another bvec. + */ +void __bio_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int off) +{ + struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt]; + + WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)); + WARN_ON_ONCE(bio_full(bio)); + + bv->bv_page = page; + bv->bv_offset = off; + bv->bv_len = len; + + bio->bi_iter.bi_size += len; + bio->bi_vcnt++; +} +EXPORT_SYMBOL_GPL(__bio_add_page); + +/** + * bio_add_page - attempt to add page to bio + * @bio: destination bio + * @page: page to add + * @len: vec entry length + * @offset: vec entry offset + * + * Attempt to add a page to the bio_vec maplist. This will only fail + * if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio. + */ +int bio_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int offset) +{ + if (!__bio_try_merge_page(bio, page, len, offset)) { + if (bio_full(bio)) + return 0; + __bio_add_page(bio, page, len, offset); + } + return len; +} +EXPORT_SYMBOL(bio_add_page); + +/** + * __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio + * @bio: bio to add pages to + * @iter: iov iterator describing the region to be mapped + * + * Pins pages from *iter and appends them to @bio's bvec array. The + * pages will have to be released using put_page() when done. + * For multi-segment *iter, this function only adds pages from the + * the next non-empty segment of the iov iterator. + */ +static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) +{ + unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt, idx; + struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt; + struct page **pages = (struct page **)bv; + size_t offset; + ssize_t size; + + size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset); + if (unlikely(size <= 0)) + return size ? size : -EFAULT; + idx = nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE; + + /* + * Deep magic below: We need to walk the pinned pages backwards + * because we are abusing the space allocated for the bio_vecs + * for the page array. Because the bio_vecs are larger than the + * page pointers by definition this will always work. But it also + * means we can't use bio_add_page, so any changes to it's semantics + * need to be reflected here as well. + */ + bio->bi_iter.bi_size += size; + bio->bi_vcnt += nr_pages; + + while (idx--) { + bv[idx].bv_page = pages[idx]; + bv[idx].bv_len = PAGE_SIZE; + bv[idx].bv_offset = 0; + } + + bv[0].bv_offset += offset; + bv[0].bv_len -= offset; + bv[nr_pages - 1].bv_len -= nr_pages * PAGE_SIZE - offset - size; + + iov_iter_advance(iter, size); + return 0; +} + +/** + * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio + * @bio: bio to add pages to + * @iter: iov iterator describing the region to be mapped + * + * Pins pages from *iter and appends them to @bio's bvec array. The + * pages will have to be released using put_page() when done. + * The function tries, but does not guarantee, to pin as many pages as + * fit into the bio, or are requested in *iter, whatever is smaller. + * If MM encounters an error pinning the requested pages, it stops. + * Error is returned only if 0 pages could be pinned. + */ +int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) +{ + unsigned short orig_vcnt = bio->bi_vcnt; + + do { + int ret = __bio_iov_iter_get_pages(bio, iter); + + if (unlikely(ret)) + return bio->bi_vcnt > orig_vcnt ? 0 : ret; + + } while (iov_iter_count(iter) && !bio_full(bio)); + + return 0; +} +EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages); + +static void submit_bio_wait_endio(struct bio *bio) +{ + complete(bio->bi_private); +} + +/** + * submit_bio_wait - submit a bio, and wait until it completes + * @bio: The &struct bio which describes the I/O + * + * Simple wrapper around submit_bio(). Returns 0 on success, or the error from + * bio_endio() on failure. + * + * WARNING: Unlike to how submit_bio() is usually used, this function does not + * result in bio reference to be consumed. The caller must drop the reference + * on his own. + */ +int submit_bio_wait(struct bio *bio) +{ + DECLARE_COMPLETION_ONSTACK_MAP(done, bio->bi_disk->lockdep_map); + + bio->bi_private = &done; + bio->bi_end_io = submit_bio_wait_endio; + bio->bi_opf |= REQ_SYNC; + submit_bio(bio); + wait_for_completion_io(&done); + + return blk_status_to_errno(bio->bi_status); +} +EXPORT_SYMBOL(submit_bio_wait); + +/** + * bio_advance - increment/complete a bio by some number of bytes + * @bio: bio to advance + * @bytes: number of bytes to complete + * + * This updates bi_sector, bi_size and bi_idx; if the number of bytes to + * complete doesn't align with a bvec boundary, then bv_len and bv_offset will + * be updated on the last bvec as well. + * + * @bio will then represent the remaining, uncompleted portion of the io. + */ +void bio_advance(struct bio *bio, unsigned bytes) +{ + if (bio_integrity(bio)) + bio_integrity_advance(bio, bytes); + + bio_advance_iter(bio, &bio->bi_iter, bytes); +} +EXPORT_SYMBOL(bio_advance); + +void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter, + struct bio *src, struct bvec_iter *src_iter) +{ + struct bio_vec src_bv, dst_bv; + void *src_p, *dst_p; + unsigned bytes; + + while (src_iter->bi_size && dst_iter->bi_size) { + src_bv = bio_iter_iovec(src, *src_iter); + dst_bv = bio_iter_iovec(dst, *dst_iter); + + bytes = min(src_bv.bv_len, dst_bv.bv_len); + + src_p = kmap_atomic(src_bv.bv_page); + dst_p = kmap_atomic(dst_bv.bv_page); + + memcpy(dst_p + dst_bv.bv_offset, + src_p + src_bv.bv_offset, + bytes); + + kunmap_atomic(dst_p); + kunmap_atomic(src_p); + + flush_dcache_page(dst_bv.bv_page); + + bio_advance_iter(src, src_iter, bytes); + bio_advance_iter(dst, dst_iter, bytes); + } +} +EXPORT_SYMBOL(bio_copy_data_iter); + +/** + * bio_copy_data - copy contents of data buffers from one bio to another + * @src: source bio + * @dst: destination bio + * + * Stops when it reaches the end of either @src or @dst - that is, copies + * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios). + */ +void bio_copy_data(struct bio *dst, struct bio *src) +{ + struct bvec_iter src_iter = src->bi_iter; + struct bvec_iter dst_iter = dst->bi_iter; + + bio_copy_data_iter(dst, &dst_iter, src, &src_iter); +} +EXPORT_SYMBOL(bio_copy_data); + +/** + * bio_list_copy_data - copy contents of data buffers from one chain of bios to + * another + * @src: source bio list + * @dst: destination bio list + * + * Stops when it reaches the end of either the @src list or @dst list - that is, + * copies min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of + * bios). + */ +void bio_list_copy_data(struct bio *dst, struct bio *src) +{ + struct bvec_iter src_iter = src->bi_iter; + struct bvec_iter dst_iter = dst->bi_iter; + + while (1) { + if (!src_iter.bi_size) { + src = src->bi_next; + if (!src) + break; + + src_iter = src->bi_iter; + } + + if (!dst_iter.bi_size) { + dst = dst->bi_next; + if (!dst) + break; + + dst_iter = dst->bi_iter; + } + + bio_copy_data_iter(dst, &dst_iter, src, &src_iter); + } +} +EXPORT_SYMBOL(bio_list_copy_data); + +struct bio_map_data { + int is_our_pages; + struct iov_iter iter; + struct iovec iov[]; +}; + +static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data, + gfp_t gfp_mask) +{ + struct bio_map_data *bmd; + if (data->nr_segs > UIO_MAXIOV) + return NULL; + + bmd = kmalloc(sizeof(struct bio_map_data) + + sizeof(struct iovec) * data->nr_segs, gfp_mask); + if (!bmd) + return NULL; + memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs); + bmd->iter = *data; + bmd->iter.iov = bmd->iov; + return bmd; +} + +/** + * bio_copy_from_iter - copy all pages from iov_iter to bio + * @bio: The &struct bio which describes the I/O as destination + * @iter: iov_iter as source + * + * Copy all pages from iov_iter to bio. + * Returns 0 on success, or error on failure. + */ +static int bio_copy_from_iter(struct bio *bio, struct iov_iter *iter) +{ + int i; + struct bio_vec *bvec; + + bio_for_each_segment_all(bvec, bio, i) { + ssize_t ret; + + ret = copy_page_from_iter(bvec->bv_page, + bvec->bv_offset, + bvec->bv_len, + iter); + + if (!iov_iter_count(iter)) + break; + + if (ret < bvec->bv_len) + return -EFAULT; + } + + return 0; +} + +/** + * bio_copy_to_iter - copy all pages from bio to iov_iter + * @bio: The &struct bio which describes the I/O as source + * @iter: iov_iter as destination + * + * Copy all pages from bio to iov_iter. + * Returns 0 on success, or error on failure. + */ +static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter) +{ + int i; + struct bio_vec *bvec; + + bio_for_each_segment_all(bvec, bio, i) { + ssize_t ret; + + ret = copy_page_to_iter(bvec->bv_page, + bvec->bv_offset, + bvec->bv_len, + &iter); + + if (!iov_iter_count(&iter)) + break; + + if (ret < bvec->bv_len) + return -EFAULT; + } + + return 0; +} + +void bio_free_pages(struct bio *bio) +{ + struct bio_vec *bvec; + int i; + + bio_for_each_segment_all(bvec, bio, i) + __free_page(bvec->bv_page); +} +EXPORT_SYMBOL(bio_free_pages); + +/** + * bio_uncopy_user - finish previously mapped bio + * @bio: bio being terminated + * + * Free pages allocated from bio_copy_user_iov() and write back data + * to user space in case of a read. + */ +int bio_uncopy_user(struct bio *bio) +{ + struct bio_map_data *bmd = bio->bi_private; + int ret = 0; + + if (!bio_flagged(bio, BIO_NULL_MAPPED)) { + /* + * if we're in a workqueue, the request is orphaned, so + * don't copy into a random user address space, just free + * and return -EINTR so user space doesn't expect any data. + */ + if (!current->mm) + ret = -EINTR; + else if (bio_data_dir(bio) == READ) + ret = bio_copy_to_iter(bio, bmd->iter); + if (bmd->is_our_pages) + bio_free_pages(bio); + } + kfree(bmd); + bio_put(bio); + return ret; +} + +/** + * bio_copy_user_iov - copy user data to bio + * @q: destination block queue + * @map_data: pointer to the rq_map_data holding pages (if necessary) + * @iter: iovec iterator + * @gfp_mask: memory allocation flags + * + * Prepares and returns a bio for indirect user io, bouncing data + * to/from kernel pages as necessary. Must be paired with + * call bio_uncopy_user() on io completion. + */ +struct bio *bio_copy_user_iov(struct request_queue *q, + struct rq_map_data *map_data, + struct iov_iter *iter, + gfp_t gfp_mask) +{ + struct bio_map_data *bmd; + struct page *page; + struct bio *bio; + int i = 0, ret; + int nr_pages; + unsigned int len = iter->count; + unsigned int offset = map_data ? offset_in_page(map_data->offset) : 0; + + bmd = bio_alloc_map_data(iter, gfp_mask); + if (!bmd) + return ERR_PTR(-ENOMEM); + + /* + * We need to do a deep copy of the iov_iter including the iovecs. + * The caller provided iov might point to an on-stack or otherwise + * shortlived one. + */ + bmd->is_our_pages = map_data ? 0 : 1; + + nr_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE); + if (nr_pages > BIO_MAX_PAGES) + nr_pages = BIO_MAX_PAGES; + + ret = -ENOMEM; + bio = bio_kmalloc(gfp_mask, nr_pages); + if (!bio) + goto out_bmd; + + ret = 0; + + if (map_data) { + nr_pages = 1 << map_data->page_order; + i = map_data->offset / PAGE_SIZE; + } + while (len) { + unsigned int bytes = PAGE_SIZE; + + bytes -= offset; + + if (bytes > len) + bytes = len; + + if (map_data) { + if (i == map_data->nr_entries * nr_pages) { + ret = -ENOMEM; + break; + } + + page = map_data->pages[i / nr_pages]; + page += (i % nr_pages); + + i++; + } else { + page = alloc_page(q->bounce_gfp | gfp_mask); + if (!page) { + ret = -ENOMEM; + break; + } + } + + if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) { + if (!map_data) + __free_page(page); + break; + } + + len -= bytes; + offset = 0; + } + + if (ret) + goto cleanup; + + if (map_data) + map_data->offset += bio->bi_iter.bi_size; + + /* + * success + */ + if (((iter->type & WRITE) && (!map_data || !map_data->null_mapped)) || + (map_data && map_data->from_user)) { + ret = bio_copy_from_iter(bio, iter); + if (ret) + goto cleanup; + } else { + if (bmd->is_our_pages) + zero_fill_bio(bio); + iov_iter_advance(iter, bio->bi_iter.bi_size); + } + + bio->bi_private = bmd; + if (map_data && map_data->null_mapped) + bio_set_flag(bio, BIO_NULL_MAPPED); + return bio; +cleanup: + if (!map_data) + bio_free_pages(bio); + bio_put(bio); +out_bmd: + kfree(bmd); + return ERR_PTR(ret); +} + +/** + * bio_map_user_iov - map user iovec into bio + * @q: the struct request_queue for the bio + * @iter: iovec iterator + * @gfp_mask: memory allocation flags + * + * Map the user space address into a bio suitable for io to a block + * device. Returns an error pointer in case of error. + */ +struct bio *bio_map_user_iov(struct request_queue *q, + struct iov_iter *iter, + gfp_t gfp_mask) +{ + int j; + struct bio *bio; + int ret; + struct bio_vec *bvec; + + if (!iov_iter_count(iter)) + return ERR_PTR(-EINVAL); + + bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_PAGES)); + if (!bio) + return ERR_PTR(-ENOMEM); + + while (iov_iter_count(iter)) { + struct page **pages; + ssize_t bytes; + size_t offs, added = 0; + int npages; + + bytes = iov_iter_get_pages_alloc(iter, &pages, LONG_MAX, &offs); + if (unlikely(bytes <= 0)) { + ret = bytes ? bytes : -EFAULT; + goto out_unmap; + } + + npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE); + + if (unlikely(offs & queue_dma_alignment(q))) { + ret = -EINVAL; + j = 0; + } else { + for (j = 0; j < npages; j++) { + struct page *page = pages[j]; + unsigned int n = PAGE_SIZE - offs; + unsigned short prev_bi_vcnt = bio->bi_vcnt; + + if (n > bytes) + n = bytes; + + if (!bio_add_pc_page(q, bio, page, n, offs)) + break; + + /* + * check if vector was merged with previous + * drop page reference if needed + */ + if (bio->bi_vcnt == prev_bi_vcnt) + put_page(page); + + added += n; + bytes -= n; + offs = 0; + } + iov_iter_advance(iter, added); + } + /* + * release the pages we didn't map into the bio, if any + */ + while (j < npages) + put_page(pages[j++]); + kvfree(pages); + /* couldn't stuff something into bio? */ + if (bytes) + break; + } + + bio_set_flag(bio, BIO_USER_MAPPED); + + /* + * subtle -- if bio_map_user_iov() ended up bouncing a bio, + * it would normally disappear when its bi_end_io is run. + * however, we need it for the unmap, so grab an extra + * reference to it + */ + bio_get(bio); + return bio; + + out_unmap: + bio_for_each_segment_all(bvec, bio, j) { + put_page(bvec->bv_page); + } + bio_put(bio); + return ERR_PTR(ret); +} + +static void __bio_unmap_user(struct bio *bio) +{ + struct bio_vec *bvec; + int i; + + /* + * make sure we dirty pages we wrote to + */ + bio_for_each_segment_all(bvec, bio, i) { + if (bio_data_dir(bio) == READ) + set_page_dirty_lock(bvec->bv_page); + + put_page(bvec->bv_page); + } + + bio_put(bio); +} + +/** + * bio_unmap_user - unmap a bio + * @bio: the bio being unmapped + * + * Unmap a bio previously mapped by bio_map_user_iov(). Must be called from + * process context. + * + * bio_unmap_user() may sleep. + */ +void bio_unmap_user(struct bio *bio) +{ + __bio_unmap_user(bio); + bio_put(bio); +} + +static void bio_map_kern_endio(struct bio *bio) +{ + bio_put(bio); +} + +/** + * bio_map_kern - map kernel address into bio + * @q: the struct request_queue for the bio + * @data: pointer to buffer to map + * @len: length in bytes + * @gfp_mask: allocation flags for bio allocation + * + * Map the kernel address into a bio suitable for io to a block + * device. Returns an error pointer in case of error. + */ +struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len, + gfp_t gfp_mask) +{ + unsigned long kaddr = (unsigned long)data; + unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; + unsigned long start = kaddr >> PAGE_SHIFT; + const int nr_pages = end - start; + int offset, i; + struct bio *bio; + + bio = bio_kmalloc(gfp_mask, nr_pages); + if (!bio) + return ERR_PTR(-ENOMEM); + + offset = offset_in_page(kaddr); + for (i = 0; i < nr_pages; i++) { + unsigned int bytes = PAGE_SIZE - offset; + + if (len <= 0) + break; + + if (bytes > len) + bytes = len; + + if (bio_add_pc_page(q, bio, virt_to_page(data), bytes, + offset) < bytes) { + /* we don't support partial mappings */ + bio_put(bio); + return ERR_PTR(-EINVAL); + } + + data += bytes; + len -= bytes; + offset = 0; + } + + bio->bi_end_io = bio_map_kern_endio; + return bio; +} +EXPORT_SYMBOL(bio_map_kern); + +static void bio_copy_kern_endio(struct bio *bio) +{ + bio_free_pages(bio); + bio_put(bio); +} + +static void bio_copy_kern_endio_read(struct bio *bio) +{ + char *p = bio->bi_private; + struct bio_vec *bvec; + int i; + + bio_for_each_segment_all(bvec, bio, i) { + memcpy(p, page_address(bvec->bv_page), bvec->bv_len); + p += bvec->bv_len; + } + + bio_copy_kern_endio(bio); +} + +/** + * bio_copy_kern - copy kernel address into bio + * @q: the struct request_queue for the bio + * @data: pointer to buffer to copy + * @len: length in bytes + * @gfp_mask: allocation flags for bio and page allocation + * @reading: data direction is READ + * + * copy the kernel address into a bio suitable for io to a block + * device. Returns an error pointer in case of error. + */ +struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len, + gfp_t gfp_mask, int reading) +{ + unsigned long kaddr = (unsigned long)data; + unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; + unsigned long start = kaddr >> PAGE_SHIFT; + struct bio *bio; + void *p = data; + int nr_pages = 0; + + /* + * Overflow, abort + */ + if (end < start) + return ERR_PTR(-EINVAL); + + nr_pages = end - start; + bio = bio_kmalloc(gfp_mask, nr_pages); + if (!bio) + return ERR_PTR(-ENOMEM); + + while (len) { + struct page *page; + unsigned int bytes = PAGE_SIZE; + + if (bytes > len) + bytes = len; + + page = alloc_page(q->bounce_gfp | __GFP_ZERO | gfp_mask); + if (!page) + goto cleanup; + + if (!reading) + memcpy(page_address(page), p, bytes); + + if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) + break; + + len -= bytes; + p += bytes; + } + + if (reading) { + bio->bi_end_io = bio_copy_kern_endio_read; + bio->bi_private = data; + } else { + bio->bi_end_io = bio_copy_kern_endio; + } + + return bio; + +cleanup: + bio_free_pages(bio); + bio_put(bio); + return ERR_PTR(-ENOMEM); +} + +/* + * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions + * for performing direct-IO in BIOs. + * + * The problem is that we cannot run set_page_dirty() from interrupt context + * because the required locks are not interrupt-safe. So what we can do is to + * mark the pages dirty _before_ performing IO. And in interrupt context, + * check that the pages are still dirty. If so, fine. If not, redirty them + * in process context. + * + * We special-case compound pages here: normally this means reads into hugetlb + * pages. The logic in here doesn't really work right for compound pages + * because the VM does not uniformly chase down the head page in all cases. + * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't + * handle them at all. So we skip compound pages here at an early stage. + * + * Note that this code is very hard to test under normal circumstances because + * direct-io pins the pages with get_user_pages(). This makes + * is_page_cache_freeable return false, and the VM will not clean the pages. + * But other code (eg, flusher threads) could clean the pages if they are mapped + * pagecache. + * + * Simply disabling the call to bio_set_pages_dirty() is a good way to test the + * deferred bio dirtying paths. + */ + +/* + * bio_set_pages_dirty() will mark all the bio's pages as dirty. + */ +void bio_set_pages_dirty(struct bio *bio) +{ + struct bio_vec *bvec; + int i; + + bio_for_each_segment_all(bvec, bio, i) { + if (!PageCompound(bvec->bv_page)) + set_page_dirty_lock(bvec->bv_page); + } +} +EXPORT_SYMBOL_GPL(bio_set_pages_dirty); + +static void bio_release_pages(struct bio *bio) +{ + struct bio_vec *bvec; + int i; + + bio_for_each_segment_all(bvec, bio, i) + put_page(bvec->bv_page); +} + +/* + * bio_check_pages_dirty() will check that all the BIO's pages are still dirty. + * If they are, then fine. If, however, some pages are clean then they must + * have been written out during the direct-IO read. So we take another ref on + * the BIO and re-dirty the pages in process context. + * + * It is expected that bio_check_pages_dirty() will wholly own the BIO from + * here on. It will run one put_page() against each page and will run one + * bio_put() against the BIO. + */ + +static void bio_dirty_fn(struct work_struct *work); + +static DECLARE_WORK(bio_dirty_work, bio_dirty_fn); +static DEFINE_SPINLOCK(bio_dirty_lock); +static struct bio *bio_dirty_list; + +/* + * This runs in process context + */ +static void bio_dirty_fn(struct work_struct *work) +{ + struct bio *bio, *next; + + spin_lock_irq(&bio_dirty_lock); + next = bio_dirty_list; + bio_dirty_list = NULL; + spin_unlock_irq(&bio_dirty_lock); + + while ((bio = next) != NULL) { + next = bio->bi_private; + + bio_set_pages_dirty(bio); + bio_release_pages(bio); + bio_put(bio); + } +} + +void bio_check_pages_dirty(struct bio *bio) +{ + struct bio_vec *bvec; + unsigned long flags; + int i; + + bio_for_each_segment_all(bvec, bio, i) { + if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page)) + goto defer; + } + + bio_release_pages(bio); + bio_put(bio); + return; +defer: + spin_lock_irqsave(&bio_dirty_lock, flags); + bio->bi_private = bio_dirty_list; + bio_dirty_list = bio; + spin_unlock_irqrestore(&bio_dirty_lock, flags); + schedule_work(&bio_dirty_work); +} +EXPORT_SYMBOL_GPL(bio_check_pages_dirty); + +void generic_start_io_acct(struct request_queue *q, int op, + unsigned long sectors, struct hd_struct *part) +{ + const int sgrp = op_stat_group(op); + int cpu = part_stat_lock(); + + part_round_stats(q, cpu, part); + part_stat_inc(cpu, part, ios[sgrp]); + part_stat_add(cpu, part, sectors[sgrp], sectors); + part_inc_in_flight(q, part, op_is_write(op)); + + part_stat_unlock(); +} +EXPORT_SYMBOL(generic_start_io_acct); + +void generic_end_io_acct(struct request_queue *q, int req_op, + struct hd_struct *part, unsigned long start_time) +{ + unsigned long duration = jiffies - start_time; + const int sgrp = op_stat_group(req_op); + int cpu = part_stat_lock(); + + part_stat_add(cpu, part, nsecs[sgrp], jiffies_to_nsecs(duration)); + part_round_stats(q, cpu, part); + part_dec_in_flight(q, part, op_is_write(req_op)); + + part_stat_unlock(); +} +EXPORT_SYMBOL(generic_end_io_acct); + +#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE +void bio_flush_dcache_pages(struct bio *bi) +{ + struct bio_vec bvec; + struct bvec_iter iter; + + bio_for_each_segment(bvec, bi, iter) + flush_dcache_page(bvec.bv_page); +} +EXPORT_SYMBOL(bio_flush_dcache_pages); +#endif + +static inline bool bio_remaining_done(struct bio *bio) +{ + /* + * If we're not chaining, then ->__bi_remaining is always 1 and + * we always end io on the first invocation. + */ + if (!bio_flagged(bio, BIO_CHAIN)) + return true; + + BUG_ON(atomic_read(&bio->__bi_remaining) <= 0); + + if (atomic_dec_and_test(&bio->__bi_remaining)) { + bio_clear_flag(bio, BIO_CHAIN); + return true; + } + + return false; +} + +/** + * bio_endio - end I/O on a bio + * @bio: bio + * + * Description: + * bio_endio() will end I/O on the whole bio. bio_endio() is the preferred + * way to end I/O on a bio. No one should call bi_end_io() directly on a + * bio unless they own it and thus know that it has an end_io function. + * + * bio_endio() can be called several times on a bio that has been chained + * using bio_chain(). The ->bi_end_io() function will only be called the + * last time. At this point the BLK_TA_COMPLETE tracing event will be + * generated if BIO_TRACE_COMPLETION is set. + **/ +void bio_endio(struct bio *bio) +{ +again: + if (!bio_remaining_done(bio)) + return; + if (!bio_integrity_endio(bio)) + return; + + if (bio->bi_disk) + rq_qos_done_bio(bio->bi_disk->queue, bio); + + /* + * Need to have a real endio function for chained bios, otherwise + * various corner cases will break (like stacking block devices that + * save/restore bi_end_io) - however, we want to avoid unbounded + * recursion and blowing the stack. Tail call optimization would + * handle this, but compiling with frame pointers also disables + * gcc's sibling call optimization. + */ + if (bio->bi_end_io == bio_chain_endio) { + bio = __bio_chain_endio(bio); + goto again; + } + + if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) { + trace_block_bio_complete(bio->bi_disk->queue, bio, + blk_status_to_errno(bio->bi_status)); + bio_clear_flag(bio, BIO_TRACE_COMPLETION); + } + + blk_throtl_bio_endio(bio); + /* release cgroup info */ + bio_uninit(bio); + if (bio->bi_end_io) + bio->bi_end_io(bio); +} +EXPORT_SYMBOL(bio_endio); + +/** + * bio_split - split a bio + * @bio: bio to split + * @sectors: number of sectors to split from the front of @bio + * @gfp: gfp mask + * @bs: bio set to allocate from + * + * Allocates and returns a new bio which represents @sectors from the start of + * @bio, and updates @bio to represent the remaining sectors. + * + * Unless this is a discard request the newly allocated bio will point + * to @bio's bi_io_vec; it is the caller's responsibility to ensure that + * @bio is not freed before the split. + */ +struct bio *bio_split(struct bio *bio, int sectors, + gfp_t gfp, struct bio_set *bs) +{ + struct bio *split; + + BUG_ON(sectors <= 0); + BUG_ON(sectors >= bio_sectors(bio)); + + split = bio_clone_fast(bio, gfp, bs); + if (!split) + return NULL; + + split->bi_iter.bi_size = sectors << 9; + + if (bio_integrity(split)) + bio_integrity_trim(split); + + bio_advance(bio, split->bi_iter.bi_size); + bio->bi_iter.bi_done = 0; + + if (bio_flagged(bio, BIO_TRACE_COMPLETION)) + bio_set_flag(split, BIO_TRACE_COMPLETION); + + return split; +} +EXPORT_SYMBOL(bio_split); + +/** + * bio_trim - trim a bio + * @bio: bio to trim + * @offset: number of sectors to trim from the front of @bio + * @size: size we want to trim @bio to, in sectors + */ +void bio_trim(struct bio *bio, int offset, int size) +{ + /* 'bio' is a cloned bio which we need to trim to match + * the given offset and size. + */ + + size <<= 9; + if (offset == 0 && size == bio->bi_iter.bi_size) + return; + + bio_clear_flag(bio, BIO_SEG_VALID); + + bio_advance(bio, offset << 9); + + bio->bi_iter.bi_size = size; + + if (bio_integrity(bio)) + bio_integrity_trim(bio); + +} +EXPORT_SYMBOL_GPL(bio_trim); + +/* + * create memory pools for biovec's in a bio_set. + * use the global biovec slabs created for general use. + */ +int biovec_init_pool(mempool_t *pool, int pool_entries) +{ + struct biovec_slab *bp = bvec_slabs + BVEC_POOL_MAX; + + return mempool_init_slab_pool(pool, pool_entries, bp->slab); +} + +/* + * bioset_exit - exit a bioset initialized with bioset_init() + * + * May be called on a zeroed but uninitialized bioset (i.e. allocated with + * kzalloc()). + */ +void bioset_exit(struct bio_set *bs) +{ + if (bs->rescue_workqueue) + destroy_workqueue(bs->rescue_workqueue); + bs->rescue_workqueue = NULL; + + mempool_exit(&bs->bio_pool); + mempool_exit(&bs->bvec_pool); + + bioset_integrity_free(bs); + if (bs->bio_slab) + bio_put_slab(bs); + bs->bio_slab = NULL; +} +EXPORT_SYMBOL(bioset_exit); + +/** + * bioset_init - Initialize a bio_set + * @bs: pool to initialize + * @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 %BIOSET_NEED_BVECS + * and %BIOSET_NEED_RESCUER + * + * Description: + * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller + * to ask for a number of bytes to be allocated in front of the bio. + * Front pad allocation is useful for embedding the bio inside + * another structure, to avoid allocating extra data to go with the bio. + * Note that the bio must be embedded at the END of that structure always, + * 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. + * + */ +int bioset_init(struct bio_set *bs, + unsigned int pool_size, + unsigned int front_pad, + int flags) +{ + unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec); + + bs->front_pad = front_pad; + + spin_lock_init(&bs->rescue_lock); + bio_list_init(&bs->rescue_list); + INIT_WORK(&bs->rescue_work, bio_alloc_rescue); + + bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad); + if (!bs->bio_slab) + return -ENOMEM; + + if (mempool_init_slab_pool(&bs->bio_pool, pool_size, bs->bio_slab)) + goto bad; + + if ((flags & BIOSET_NEED_BVECS) && + biovec_init_pool(&bs->bvec_pool, pool_size)) + goto bad; + + if (!(flags & BIOSET_NEED_RESCUER)) + return 0; + + bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0); + if (!bs->rescue_workqueue) + goto bad; + + return 0; +bad: + bioset_exit(bs); + return -ENOMEM; +} +EXPORT_SYMBOL(bioset_init); + +/* + * Initialize and setup a new bio_set, based on the settings from + * another bio_set. + */ +int bioset_init_from_src(struct bio_set *bs, struct bio_set *src) +{ + int flags; + + flags = 0; + if (src->bvec_pool.min_nr) + flags |= BIOSET_NEED_BVECS; + if (src->rescue_workqueue) + flags |= BIOSET_NEED_RESCUER; + + return bioset_init(bs, src->bio_pool.min_nr, src->front_pad, flags); +} +EXPORT_SYMBOL(bioset_init_from_src); + +#ifdef CONFIG_BLK_CGROUP + +#ifdef CONFIG_MEMCG +/** + * bio_associate_blkcg_from_page - associate a bio with the page's blkcg + * @bio: target bio + * @page: the page to lookup the blkcg from + * + * Associate @bio with the blkcg from @page's owning memcg. This works like + * every other associate function wrt references. + */ +int bio_associate_blkcg_from_page(struct bio *bio, struct page *page) +{ + struct cgroup_subsys_state *blkcg_css; + + if (unlikely(bio->bi_css)) + return -EBUSY; + if (!page->mem_cgroup) + return 0; + blkcg_css = cgroup_get_e_css(page->mem_cgroup->css.cgroup, + &io_cgrp_subsys); + bio->bi_css = blkcg_css; + return 0; +} +#endif /* CONFIG_MEMCG */ + +/** + * bio_associate_blkcg - associate a bio with the specified blkcg + * @bio: target bio + * @blkcg_css: css of the blkcg to associate + * + * Associate @bio with the blkcg specified by @blkcg_css. Block layer will + * treat @bio as if it were issued by a task which belongs to the blkcg. + * + * This function takes an extra reference of @blkcg_css which will be put + * when @bio is released. The caller must own @bio and is responsible for + * synchronizing calls to this function. + */ +int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css) +{ + if (unlikely(bio->bi_css)) + return -EBUSY; + css_get(blkcg_css); + bio->bi_css = blkcg_css; + return 0; +} +EXPORT_SYMBOL_GPL(bio_associate_blkcg); + +/** + * bio_associate_blkg - associate a bio with the specified blkg + * @bio: target bio + * @blkg: the blkg to associate + * + * Associate @bio with the blkg specified by @blkg. This is the queue specific + * blkcg information associated with the @bio, a reference will be taken on the + * @blkg and will be freed when the bio is freed. + */ +int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg) +{ + if (unlikely(bio->bi_blkg)) + return -EBUSY; + if (!blkg_try_get(blkg)) + return -ENODEV; + bio->bi_blkg = blkg; + return 0; +} + +/** + * bio_disassociate_task - undo bio_associate_current() + * @bio: target bio + */ +void bio_disassociate_task(struct bio *bio) +{ + if (bio->bi_ioc) { + put_io_context(bio->bi_ioc); + bio->bi_ioc = NULL; + } + if (bio->bi_css) { + css_put(bio->bi_css); + bio->bi_css = NULL; + } + if (bio->bi_blkg) { + blkg_put(bio->bi_blkg); + bio->bi_blkg = NULL; + } +} + +/** + * bio_clone_blkcg_association - clone blkcg association from src to dst bio + * @dst: destination bio + * @src: source bio + */ +void bio_clone_blkcg_association(struct bio *dst, struct bio *src) +{ + if (src->bi_css) + WARN_ON(bio_associate_blkcg(dst, src->bi_css)); +} +EXPORT_SYMBOL_GPL(bio_clone_blkcg_association); +#endif /* CONFIG_BLK_CGROUP */ + +static void __init biovec_init_slabs(void) +{ + int i; + + for (i = 0; i < BVEC_POOL_NR; i++) { + int size; + struct biovec_slab *bvs = bvec_slabs + i; + + if (bvs->nr_vecs <= BIO_INLINE_VECS) { + bvs->slab = NULL; + continue; + } + + size = bvs->nr_vecs * sizeof(struct bio_vec); + bvs->slab = kmem_cache_create(bvs->name, size, 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); + } +} + +static int __init init_bio(void) +{ + bio_slab_max = 2; + bio_slab_nr = 0; + bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab), + GFP_KERNEL); + if (!bio_slabs) + panic("bio: can't allocate bios\n"); + + bio_integrity_init(); + biovec_init_slabs(); + + if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS)) + panic("bio: can't allocate bios\n"); + + if (bioset_integrity_create(&fs_bio_set, BIO_POOL_SIZE)) + panic("bio: can't create integrity pool\n"); + + return 0; +} +subsys_initcall(init_bio); |