diff options
author | Jens Axboe <axboe@fb.com> | 2014-05-19 08:16:41 -0600 |
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committer | Jens Axboe <axboe@fb.com> | 2014-05-19 08:34:46 -0600 |
commit | f9c78b2be2cac2a7a397d489275e7d9f9ae785f2 (patch) | |
tree | fde918d944e61dc87cc89a71bec7e886832b1829 /block/bio.c | |
parent | acb12e0a9c17ae859a05acb116a0c0a7e310c781 (diff) |
block: move bio.c and bio-integrity.c from fs/ to block/
They really belong in block/, especially now since it's not in
drivers/block/ anymore. Additionally, the get_maintainer script
gets it wrong when in fs/.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/bio.c')
-rw-r--r-- | block/bio.c | 2038 |
1 files changed, 2038 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c new file mode 100644 index 000000000000..96d28eee8a1e --- /dev/null +++ b/block/bio.c @@ -0,0 +1,2038 @@ +/* + * 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 <scsi/sg.h> /* for struct sg_iovec */ + +#include <trace/events/block.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) { .nr_vecs = x, .name = "biovec-"__stringify(x) } +static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = { + BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES), +}; +#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, 0, 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) +{ + BIO_BUG_ON(idx >= BIOVEC_NR_POOLS); + + if (idx == BIOVEC_MAX_IDX) + 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 == BIOVEC_MAX_IDX) { +fallback: + bvl = mempool_alloc(pool, gfp_mask); + } else { + struct biovec_slab *bvs = bvec_slabs + *idx; + gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __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_WAIT + * is set, retry with the 1-entry mempool + */ + bvl = kmem_cache_alloc(bvs->slab, __gfp_mask); + if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) { + *idx = BIOVEC_MAX_IDX; + goto fallback; + } + } + + return bvl; +} + +static void __bio_free(struct bio *bio) +{ + bio_disassociate_task(bio); + + if (bio_integrity(bio)) + bio_integrity_free(bio); +} + +static void bio_free(struct bio *bio) +{ + struct bio_set *bs = bio->bi_pool; + void *p; + + __bio_free(bio); + + if (bs) { + if (bio_flagged(bio, BIO_OWNS_VEC)) + bvec_free(bs->bvec_pool, bio->bi_io_vec, BIO_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); + } +} + +void bio_init(struct bio *bio) +{ + memset(bio, 0, sizeof(*bio)); + bio->bi_flags = 1 << BIO_UPTODATE; + atomic_set(&bio->bi_remaining, 1); + atomic_set(&bio->bi_cnt, 1); +} +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_free(bio); + + memset(bio, 0, BIO_RESET_BYTES); + bio->bi_flags = flags|(1 << BIO_UPTODATE); + atomic_set(&bio->bi_remaining, 1); +} +EXPORT_SYMBOL(bio_reset); + +static void bio_chain_endio(struct bio *bio, int error) +{ + bio_endio(bio->bi_private, error); + bio_put(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; + atomic_inc(&parent->bi_remaining); +} +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; + + /* + * 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(current->bio_list))) + bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio); + + *current->bio_list = 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_WAIT 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, int nr_iovecs, struct bio_set *bs) +{ + gfp_t saved_gfp = gfp_mask; + unsigned front_pad; + unsigned inline_vecs; + unsigned long idx = BIO_POOL_NONE; + 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 { + /* + * 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_WAIT; 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(current->bio_list)) + gfp_mask &= ~__GFP_WAIT; + + 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); + + if (nr_iovecs > inline_vecs) { + 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 |= 1 << BIO_OWNS_VEC; + } else if (nr_iovecs) { + bvl = bio->bi_inline_vecs; + } + + bio->bi_pool = bs; + bio->bi_flags |= idx << BIO_POOL_OFFSET; + 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(struct bio *bio) +{ + unsigned long flags; + struct bio_vec bv; + struct bvec_iter iter; + + bio_for_each_segment(bv, bio, iter) { + 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); + +/** + * 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) +{ + 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 && BIO_POOL_IDX(bio) != BIO_POOL_NONE); + + /* + * most users will be overriding ->bi_bdev with a new target, + * so we don't set nor calculate new physical/hw segment counts here + */ + bio->bi_bdev = bio_src->bi_bdev; + bio->bi_flags |= 1 << BIO_CLONED; + bio->bi_rw = bio_src->bi_rw; + bio->bi_iter = bio_src->bi_iter; + bio->bi_io_vec = bio_src->bi_io_vec; +} +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_clone_bioset - clone a bio + * @bio_src: bio to clone + * @gfp_mask: allocation priority + * @bs: bio_set to allocate from + * + * Clone bio. Caller will own the returned bio, but not the actual data it + * points to. Reference count of returned bio will be one. + */ +struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask, + struct bio_set *bs) +{ + struct bvec_iter iter; + struct bio_vec bv; + struct bio *bio; + + /* + * Pre immutable biovecs, __bio_clone() used to just do a memcpy from + * bio_src->bi_io_vec to bio->bi_io_vec. + * + * We can't do that anymore, because: + * + * - The point of cloning the biovec is to produce a bio with a biovec + * the caller can modify: bi_idx and bi_bvec_done should be 0. + * + * - The original bio could've had more than BIO_MAX_PAGES biovecs; if + * we tried to clone the whole thing bio_alloc_bioset() would fail. + * But the clone should succeed as long as the number of biovecs we + * actually need to allocate is fewer than BIO_MAX_PAGES. + * + * - Lastly, bi_vcnt should not be looked at or relied upon by code + * that does not own the bio - reason being drivers don't use it for + * iterating over the biovec anymore, so expecting it to be kept up + * to date (i.e. for clones that share the parent biovec) is just + * asking for trouble and would force extra work on + * __bio_clone_fast() anyways. + */ + + bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs); + if (!bio) + return NULL; + + bio->bi_bdev = bio_src->bi_bdev; + bio->bi_rw = bio_src->bi_rw; + bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; + bio->bi_iter.bi_size = bio_src->bi_iter.bi_size; + + if (bio->bi_rw & REQ_DISCARD) + goto integrity_clone; + + if (bio->bi_rw & REQ_WRITE_SAME) { + bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0]; + goto integrity_clone; + } + + bio_for_each_segment(bv, bio_src, iter) + bio->bi_io_vec[bio->bi_vcnt++] = bv; + +integrity_clone: + if (bio_integrity(bio_src)) { + int ret; + + ret = bio_integrity_clone(bio, bio_src, gfp_mask); + if (ret < 0) { + bio_put(bio); + return NULL; + } + } + + return bio; +} +EXPORT_SYMBOL(bio_clone_bioset); + +/** + * bio_get_nr_vecs - return approx number of vecs + * @bdev: I/O target + * + * Return the approximate number of pages we can send to this target. + * There's no guarantee that you will be able to fit this number of pages + * into a bio, it does not account for dynamic restrictions that vary + * on offset. + */ +int bio_get_nr_vecs(struct block_device *bdev) +{ + struct request_queue *q = bdev_get_queue(bdev); + int nr_pages; + + nr_pages = min_t(unsigned, + queue_max_segments(q), + queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1); + + return min_t(unsigned, nr_pages, BIO_MAX_PAGES); + +} +EXPORT_SYMBOL(bio_get_nr_vecs); + +static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page + *page, unsigned int len, unsigned int offset, + unsigned int max_sectors) +{ + 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) > max_sectors) + 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) { + unsigned int prev_bv_len = prev->bv_len; + prev->bv_len += len; + + if (q->merge_bvec_fn) { + struct bvec_merge_data bvm = { + /* prev_bvec is already charged in + bi_size, discharge it in order to + simulate merging updated prev_bvec + as new bvec. */ + .bi_bdev = bio->bi_bdev, + .bi_sector = bio->bi_iter.bi_sector, + .bi_size = bio->bi_iter.bi_size - + prev_bv_len, + .bi_rw = bio->bi_rw, + }; + + if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) { + prev->bv_len -= len; + return 0; + } + } + + goto done; + } + } + + if (bio->bi_vcnt >= bio->bi_max_vecs) + return 0; + + /* + * we might lose a segment or two here, but rather that than + * make this too complex. + */ + + while (bio->bi_phys_segments >= queue_max_segments(q)) { + + if (retried_segments) + return 0; + + retried_segments = 1; + blk_recount_segments(q, bio); + } + + /* + * 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; + + /* + * if queue has other restrictions (eg varying max sector size + * depending on offset), it can specify a merge_bvec_fn in the + * queue to get further control + */ + if (q->merge_bvec_fn) { + struct bvec_merge_data bvm = { + .bi_bdev = bio->bi_bdev, + .bi_sector = bio->bi_iter.bi_sector, + .bi_size = bio->bi_iter.bi_size, + .bi_rw = bio->bi_rw, + }; + + /* + * merge_bvec_fn() returns number of bytes it can accept + * at this offset + */ + if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) { + bvec->bv_page = NULL; + bvec->bv_len = 0; + bvec->bv_offset = 0; + return 0; + } + } + + /* If we may be able to merge these biovecs, force a recount */ + if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec))) + bio->bi_flags &= ~(1 << BIO_SEG_VALID); + + bio->bi_vcnt++; + bio->bi_phys_segments++; + done: + bio->bi_iter.bi_size += len; + return len; +} + +/** + * 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) +{ + return __bio_add_page(q, bio, page, len, offset, + queue_max_hw_sectors(q)); +} +EXPORT_SYMBOL(bio_add_pc_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 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. + */ +int bio_add_page(struct bio *bio, struct page *page, unsigned int len, + unsigned int offset) +{ + struct request_queue *q = bdev_get_queue(bio->bi_bdev); + return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q)); +} +EXPORT_SYMBOL(bio_add_page); + +struct submit_bio_ret { + struct completion event; + int error; +}; + +static void submit_bio_wait_endio(struct bio *bio, int error) +{ + struct submit_bio_ret *ret = bio->bi_private; + + ret->error = error; + complete(&ret->event); +} + +/** + * submit_bio_wait - submit a bio, and wait until it completes + * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) + * @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. + */ +int submit_bio_wait(int rw, struct bio *bio) +{ + struct submit_bio_ret ret; + + rw |= REQ_SYNC; + init_completion(&ret.event); + bio->bi_private = &ret; + bio->bi_end_io = submit_bio_wait_endio; + submit_bio(rw, bio); + wait_for_completion(&ret.event); + + return ret.error; +} +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); + +/** + * bio_alloc_pages - allocates a single page for each bvec in a bio + * @bio: bio to allocate pages for + * @gfp_mask: flags for allocation + * + * Allocates pages up to @bio->bi_vcnt. + * + * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are + * freed. + */ +int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask) +{ + int i; + struct bio_vec *bv; + + bio_for_each_segment_all(bv, bio, i) { + bv->bv_page = alloc_page(gfp_mask); + if (!bv->bv_page) { + while (--bv >= bio->bi_io_vec) + __free_page(bv->bv_page); + return -ENOMEM; + } + } + + return 0; +} +EXPORT_SYMBOL(bio_alloc_pages); + +/** + * bio_copy_data - copy contents of data buffers from one chain of bios to + * another + * @src: source bio list + * @dst: destination bio list + * + * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats + * @src and @dst as linked lists of bios. + * + * 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, dst_iter; + struct bio_vec src_bv, dst_bv; + void *src_p, *dst_p; + unsigned bytes; + + src_iter = src->bi_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; + } + + 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); + + bio_advance_iter(src, &src_iter, bytes); + bio_advance_iter(dst, &dst_iter, bytes); + } +} +EXPORT_SYMBOL(bio_copy_data); + +struct bio_map_data { + int nr_sgvecs; + int is_our_pages; + struct sg_iovec sgvecs[]; +}; + +static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio, + const struct sg_iovec *iov, int iov_count, + int is_our_pages) +{ + memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count); + bmd->nr_sgvecs = iov_count; + bmd->is_our_pages = is_our_pages; + bio->bi_private = bmd; +} + +static struct bio_map_data *bio_alloc_map_data(unsigned int iov_count, + gfp_t gfp_mask) +{ + if (iov_count > UIO_MAXIOV) + return NULL; + + return kmalloc(sizeof(struct bio_map_data) + + sizeof(struct sg_iovec) * iov_count, gfp_mask); +} + +static int __bio_copy_iov(struct bio *bio, const struct sg_iovec *iov, int iov_count, + int to_user, int from_user, int do_free_page) +{ + int ret = 0, i; + struct bio_vec *bvec; + int iov_idx = 0; + unsigned int iov_off = 0; + + bio_for_each_segment_all(bvec, bio, i) { + char *bv_addr = page_address(bvec->bv_page); + unsigned int bv_len = bvec->bv_len; + + while (bv_len && iov_idx < iov_count) { + unsigned int bytes; + char __user *iov_addr; + + bytes = min_t(unsigned int, + iov[iov_idx].iov_len - iov_off, bv_len); + iov_addr = iov[iov_idx].iov_base + iov_off; + + if (!ret) { + if (to_user) + ret = copy_to_user(iov_addr, bv_addr, + bytes); + + if (from_user) + ret = copy_from_user(bv_addr, iov_addr, + bytes); + + if (ret) + ret = -EFAULT; + } + + bv_len -= bytes; + bv_addr += bytes; + iov_addr += bytes; + iov_off += bytes; + + if (iov[iov_idx].iov_len == iov_off) { + iov_idx++; + iov_off = 0; + } + } + + if (do_free_page) + __free_page(bvec->bv_page); + } + + return ret; +} + +/** + * bio_uncopy_user - finish previously mapped bio + * @bio: bio being terminated + * + * Free pages allocated from bio_copy_user() 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; + struct bio_vec *bvec; + int ret = 0, i; + + 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. + */ + if (current->mm) + ret = __bio_copy_iov(bio, bmd->sgvecs, bmd->nr_sgvecs, + bio_data_dir(bio) == READ, + 0, bmd->is_our_pages); + else if (bmd->is_our_pages) + bio_for_each_segment_all(bvec, bio, i) + __free_page(bvec->bv_page); + } + kfree(bmd); + bio_put(bio); + return ret; +} +EXPORT_SYMBOL(bio_uncopy_user); + +/** + * 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) + * @iov: the iovec. + * @iov_count: number of elements in the iovec + * @write_to_vm: bool indicating writing to pages or not + * @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, + const struct sg_iovec *iov, int iov_count, + int write_to_vm, gfp_t gfp_mask) +{ + struct bio_map_data *bmd; + struct bio_vec *bvec; + struct page *page; + struct bio *bio; + int i, ret; + int nr_pages = 0; + unsigned int len = 0; + unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0; + + for (i = 0; i < iov_count; i++) { + unsigned long uaddr; + unsigned long end; + unsigned long start; + + uaddr = (unsigned long)iov[i].iov_base; + end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT; + start = uaddr >> PAGE_SHIFT; + + /* + * Overflow, abort + */ + if (end < start) + return ERR_PTR(-EINVAL); + + nr_pages += end - start; + len += iov[i].iov_len; + } + + if (offset) + nr_pages++; + + bmd = bio_alloc_map_data(iov_count, gfp_mask); + if (!bmd) + return ERR_PTR(-ENOMEM); + + ret = -ENOMEM; + bio = bio_kmalloc(gfp_mask, nr_pages); + if (!bio) + goto out_bmd; + + if (!write_to_vm) + bio->bi_rw |= REQ_WRITE; + + 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_p |