--- /dev/null
+/*
+ * 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 <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, 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)
+{
+ 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 {
+ /* should not use nobvec bioset for nr_iovecs > 0 */
+ if (WARN_ON_ONCE(!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_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;
+ }
+ }
+
+ 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 (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS) &&
+ bvec_gap_to_prev(prev, offset))
+ return 0;
+ }
+
+ if (bio->bi_vcnt >= bio->bi_max_vecs)
+ 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 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 - len,
+ .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)
+ goto failed;
+ }
+
+ /* If we may be able to merge these biovecs, force a recount */
+ if (bio->bi_vcnt > 1 && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
+ bio->bi_flags &= ~(1 << 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;
+}
+
+/**
+ * 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);
+ unsigned int max_sectors;
+
+ max_sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector);
+ if ((max_sectors < (len >> 9)) && !bio->bi_iter.bi_size)
+ max_sectors = len >> 9;
+
+ return __bio_add_page(q, bio, page, len, offset, max_sectors);
+}
+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 is_our_pages;
+ struct iov_iter iter;
+ struct iovec iov[];
+};
+
+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 iovec) * iov_count, gfp_mask);
+}
+
+/**
+ * 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;
+}
+
+static 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);
+}
+
+/**
+ * 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.
+ */
+ if (current->mm && 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;
+}
+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)
+ * @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,
+ const struct iov_iter *iter,
+ gfp_t gfp_mask)
+{
+ struct bio_map_data *bmd;
+ struct page *page;
+ struct bio *bio;
+ int i, ret;
+ int nr_pages = 0;
+ unsigned int len = iter->count;
+ unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
+
+ for (i = 0; i < iter->nr_segs; i++) {
+ unsigned long uaddr;
+ unsigned long end;
+ unsigned long start;
+
+ uaddr = (unsigned long) iter->iov[i].iov_base;
+ end = (uaddr + iter->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;
+ }
+
+ if (offset)
+ nr_pages++;
+
+ bmd = bio_alloc_map_data(iter->nr_segs, 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;
+ memcpy(bmd->iov, iter->iov, sizeof(struct iovec) * iter->nr_segs);
+ iov_iter_init(&bmd->iter, iter->type, bmd->iov,
+ iter->nr_segs, iter->count);
+
+ ret = -ENOMEM;
+ bio = bio_kmalloc(gfp_mask, nr_pages);
+ if (!bio)
+ goto out_bmd;
+
+ if (iter->type & WRITE)
+ 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_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)
+ break;
+
+ len -= bytes;
+ offset = 0;
+ }
+
+ if (ret)
+ goto cleanup;
+
+ /*
+ * 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;
+ }
+
+ bio->bi_private = bmd;
+ 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,
+ const struct iov_iter *iter,
+ gfp_t gfp_mask)
+{
+ int j;
+ int nr_pages = 0;
+ struct page **pages;
+ struct bio *bio;
+ int cur_page = 0;
+ int ret, offset;
+ struct iov_iter i;
+ struct iovec iov;
+
+ iov_for_each(iov, i, *iter) {
+ unsigned long uaddr = (unsigned long) iov.iov_base;
+ unsigned long len = iov.iov_len;
+ unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ unsigned long start = uaddr >> PAGE_SHIFT;
+
+ /*
+ * Overflow, abort
+ */
+ if (end < start)
+ return ERR_PTR(-EINVAL);
+
+ nr_pages += end - start;
+ /*
+ * buffer must be aligned to at least hardsector size for now
+ */
+ if (uaddr & queue_dma_alignment(q))
+ return ERR_PTR(-EINVAL);
+ }
+
+ if (!nr_pages)
+ return ERR_PTR(-EINVAL);
+
+ bio = bio_kmalloc(gfp_mask, nr_pages);
+ if (!bio)
+ return ERR_PTR(-ENOMEM);
+
+ ret = -ENOMEM;
+ pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
+ if (!pages)
+ goto out;
+
+ iov_for_each(iov, i, *iter) {
+ unsigned long uaddr = (unsigned long) iov.iov_base;
+ unsigned long len = iov.iov_len;
+ unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ unsigned long start = uaddr >> PAGE_SHIFT;
+ const int local_nr_pages = end - start;
+ const int page_limit = cur_page + local_nr_pages;
+
+ ret = get_user_pages_fast(uaddr, local_nr_pages,
+ (iter->type & WRITE) != WRITE,
+ &pages[cur_page]);
+ if (ret < local_nr_pages) {
+ ret = -EFAULT;
+ goto out_unmap;
+ }
+
+ offset = uaddr & ~PAGE_MASK;
+ for (j = cur_page; j < page_limit; j++) {
+ unsigned int bytes = PAGE_SIZE - offset;
+
+ if (len <= 0)
+ break;
+
+ if (bytes > len)
+ bytes = len;
+
+ /*
+ * sorry...
+ */
+ if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
+ bytes)
+ break;
+
+ len -= bytes;
+ offset = 0;
+ }
+
+ cur_page = j;
+ /*
+ * release the pages we didn't map into the bio, if any
+ */
+ while (j < page_limit)
+ page_cache_release(pages[j++]);
+ }
+
+ kfree(pages);
+
+ /*
+ * set data direction, and check if mapped pages need bouncing
+ */
+ if (iter->type & WRITE)
+ bio->bi_rw |= REQ_WRITE;
+
+ bio->bi_flags |= (1 << BIO_USER_MAPPED);
+
+ /*
+ * subtle -- if __bio_map_user() 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:
+ for (j = 0; j < nr_pages; j++) {
+ if (!pages[j])
+ break;
+ page_cache_release(pages[j]);
+ }
+ out:
+ kfree(pages);
+ 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);
+
+ page_cache_release(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(). Must be called with
+ * a process context.
+ *
+ * bio_unmap_user() may sleep.
+ */
+void bio_unmap_user(struct bio *bio)
+{
+ __bio_unmap_user(bio);
+ bio_put(bio);
+}
+EXPORT_SYMBOL(bio_unmap_user);
+
+static void bio_map_kern_endio(struct bio *bio, int err)
+{
+ 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, int err)
+{
+ bio_free_pages(bio);
+ bio_put(bio);
+}
+
+static void bio_copy_kern_endio_read(struct bio *bio, int err)
+{
+ 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, err);
+}
+
+/**
+ * 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_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;
+ bio->bi_rw |= REQ_WRITE;
+ }
+
+ return bio;
+
+cleanup:
+ bio_free_pages(bio);
+ bio_put(bio);
+ return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL(bio_copy_kern);
+
+/*
+ * 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) {
+ struct page *page = bvec->bv_page;
+
+ if (page && !PageCompound(page))
+ set_page_dirty_lock(page);
+ }
+}
+
+static void bio_release_pages(struct bio *bio)
+{
+ struct bio_vec *bvec;
+ int i;
+
+ bio_for_each_segment_all(bvec, bio, i) {
+ struct page *page = bvec->bv_page;
+
+ if (page)
+ put_page(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 the offending pages 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 page_cache_release() 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)
+{
+ unsigned long flags;
+ struct bio *bio;
+
+ spin_lock_irqsave(&bio_dirty_lock, flags);
+ bio = bio_dirty_list;
+ bio_dirty_list = NULL;
+ spin_unlock_irqrestore(&bio_dirty_lock, flags);
+
+ while (bio) {
+ struct bio *next = bio->bi_private;
+
+ bio_set_pages_dirty(bio);
+ bio_release_pages(bio);
+ bio_put(bio);
+ bio = next;
+ }
+}
+
+void bio_check_pages_dirty(struct bio *bio)
+{
+ struct bio_vec *bvec;
+ int nr_clean_pages = 0;
+ int i;
+
+ bio_for_each_segment_all(bvec, bio, i) {
+ struct page *page = bvec->bv_page;
+
+ if (PageDirty(page) || PageCompound(page)) {
+ page_cache_release(page);
+ bvec->bv_page = NULL;
+ } else {
+ nr_clean_pages++;
+ }
+ }
+
+ if (nr_clean_pages) {
+ unsigned long flags;
+
+ 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);
+ } else {
+ bio_put(bio);
+ }
+}
+
+void generic_start_io_acct(int rw, unsigned long sectors,
+ struct hd_struct *part)
+{
+ int cpu = part_stat_lock();
+
+ part_round_stats(cpu, part);
+ part_stat_inc(cpu, part, ios[rw]);
+ part_stat_add(cpu, part, sectors[rw], sectors);
+ part_inc_in_flight(part, rw);
+
+ part_stat_unlock();
+}
+EXPORT_SYMBOL(generic_start_io_acct);
+
+void generic_end_io_acct(int rw, struct hd_struct *part,
+ unsigned long start_time)
+{
+ unsigned long duration = jiffies - start_time;
+ int cpu = part_stat_lock();
+
+ part_stat_add(cpu, part, ticks[rw], duration);
+ part_round_stats(cpu, part);
+ part_dec_in_flight(part, rw);
+
+ 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
+
+/**
+ * bio_endio - end I/O on a bio
+ * @bio: bio
+ * @error: error, if any
+ *
+ * Description:
+ * bio_endio() will end I/O on the whole bio. bio_endio() is the
+ * preferred way to end I/O on a bio, it takes care of clearing
+ * BIO_UPTODATE on error. @error is 0 on success, and and one of the
+ * established -Exxxx (-EIO, for instance) error values in case
+ * something went wrong. 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.
+ **/
+void bio_endio(struct bio *bio, int error)
+{
+ while (bio) {
+ BUG_ON(atomic_read(&bio->bi_remaining) <= 0);
+
+ if (error)
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+ error = -EIO;
+
+ if (!atomic_dec_and_test(&bio->bi_remaining))
+ return;
+
+ /*
+ * 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) {
+ struct bio *parent = bio->bi_private;
+ bio_put(bio);
+ bio = parent;
+ } else {
+ if (bio->bi_end_io)
+ bio->bi_end_io(bio, error);
+ bio = NULL;
+ }
+ }
+}
+EXPORT_SYMBOL(bio_endio);
+
+/**
+ * bio_endio_nodec - end I/O on a bio, without decrementing bi_remaining
+ * @bio: bio
+ * @error: error, if any
+ *
+ * For code that has saved and restored bi_end_io; thing hard before using this
+ * function, probably you should've cloned the entire bio.
+ **/
+void bio_endio_nodec(struct bio *bio, int error)
+{
+ atomic_inc(&bio->bi_remaining);
+ bio_endio(bio, error);
+}
+EXPORT_SYMBOL(bio_endio_nodec);
+
+/**
+ * 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.
+ *
+ * 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 = NULL;
+
+ 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, 0, sectors);
+
+ bio_advance(bio, split->bi_iter.bi_size);
+
+ 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;
+
+ clear_bit(BIO_SEG_VALID, &bio->bi_flags);
+
+ bio_advance(bio, offset << 9);
+
+ bio->bi_iter.bi_size = size;
+}
+EXPORT_SYMBOL_GPL(bio_trim);
+
+/*
+ * create memory pools for biovec's in a bio_set.
+ * use the global biovec slabs created for general use.
+ */
+mempool_t *biovec_create_pool(int pool_entries)
+{
+ struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
+
+ return mempool_create_slab_pool(pool_entries, bp->slab);
+}
+
+void bioset_free(struct bio_set *bs)
+{
+ if (bs->rescue_workqueue)
+ destroy_workqueue(bs->rescue_workqueue);
+
+ if (bs->bio_pool)
+ mempool_destroy(bs->bio_pool);
+
+ if (bs->bvec_pool)
+ mempool_destroy(bs->bvec_pool);
+
+ bioset_integrity_free(bs);
+ bio_put_slab(bs);
+
+ kfree(bs);
+}
+EXPORT_SYMBOL(bioset_free);
+
+static struct bio_set *__bioset_create(unsigned int pool_size,
+ unsigned int front_pad,
+ bool create_bvec_pool)
+{
+ unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
+ struct bio_set *bs;
+
+ bs = kzalloc(sizeof(*bs), GFP_KERNEL);
+ if (!bs)
+ return NULL;
+
+ 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) {
+ kfree(bs);
+ return NULL;
+ }
+
+ bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
+ if (!bs->bio_pool)
+ goto bad;
+
+ if (create_bvec_pool) {
+ bs->bvec_pool = biovec_create_pool(pool_size);
+ if (!bs->bvec_pool)
+ goto bad;
+ }
+
+ bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
+ if (!bs->rescue_workqueue)
+ goto bad;
+
+ return bs;
+bad:
+ bioset_free(bs);
+ return NULL;
+}
+
+/**
+ * bioset_create - Create a bio_set
+ * @pool_size: Number of bio and bio_vecs to cache in the mempool
+ * @front_pad: Number of bytes to allocate in front of the returned bio
+ *
+ * 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.
+ */
+struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
+{
+ return __bioset_create(pool_size, front_pad, true);
+}
+EXPORT_SYMBOL(bioset_create);
+
+/**
+ * bioset_create_nobvec - Create a bio_set without bio_vec mempool
+ * @pool_size: Number of bio to cache in the mempool
+ * @front_pad: Number of bytes to allocate in front of the returned bio
+ *
+ * Description:
+ * Same functionality as bioset_create() except that mempool is not
+ * created for bio_vecs. Saving some memory for bio_clone_fast() users.
+ */
+struct bio_set *bioset_create_nobvec(unsigned int pool_size, unsigned int front_pad)
+{
+ return __bioset_create(pool_size, front_pad, false);
+}
+EXPORT_SYMBOL(bioset_create_nobvec);
+
+#ifdef CONFIG_BLK_CGROUP
+/**
+ * bio_associate_current - associate a bio with %current
+ * @bio: target bio
+ *
+ * Associate @bio with %current if it hasn't been associated yet. Block
+ * layer will treat @bio as if it were issued by %current no matter which
+ * task actually issues it.
+ *
+ * This function takes an extra reference of @task's io_context and blkcg
+ * which will be put when @bio is released. The caller must own @bio,
+ * ensure %current->io_context exists, and is responsible for synchronizing
+ * calls to this function.
+ */
+int bio_associate_current(struct bio *bio)
+{
+ struct io_context *ioc;
+ struct cgroup_subsys_state *css;
+
+ if (bio->bi_ioc)
+ return -EBUSY;
+
+ ioc = current->io_context;
+ if (!ioc)
+ return -ENOENT;
+
+ /* acquire active ref on @ioc and associate */
+ get_io_context_active(ioc);
+ bio->bi_ioc = ioc;
+
+ /* associate blkcg if exists */
+ rcu_read_lock();
+ css = task_css(current, blkio_cgrp_id);
+ if (css && css_tryget_online(css))
+ bio->bi_css = css;
+ rcu_read_unlock();
+
+ 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;
+ }
+}
+
+#endif /* CONFIG_BLK_CGROUP */
+
+static void __init biovec_init_slabs(void)
+{
+ int i;
+
+ for (i = 0; i < BIOVEC_NR_POOLS; 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 = kzalloc(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();
+
+ fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
+ if (!fs_bio_set)
+ 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);
Code Review / kvmfornfv.git / blobdiff