Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1684 insertions, 0 deletions

diff --git a/block/bio.c b/block/bio.c
new file mode 100644
index 000000000..6d6e7b96b
--- /dev/null
+++ b/block/bio.c
@@ -0,0 +1,1684 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
+ */
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/uio.h>
+#include <linux/iocontext.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/mempool.h>
+#include <linux/workqueue.h>
+#include <linux/cgroup.h>
+#include <linux/blk-cgroup.h>
+#include <linux/highmem.h>
+#include <linux/sched/sysctl.h>
+#include <linux/blk-crypto.h>
+
+#include <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)
+{
+#ifdef CONFIG_BLK_CGROUP
+	if (bio->bi_blkg) {
+		blkg_put(bio->bi_blkg);
+		bio->bi_blkg = NULL;
+	}
+#endif
+	if (bio_integrity(bio))
+		bio_integrity_free(bio);
+
+	bio_crypt_free_ctx(bio);
+}
+EXPORT_SYMBOL(bio_uninit);
+
+static void bio_free(struct bio *bio)
+{
+	struct bio_set *bs = bio->bi_pool;
+	void *p;
+
+	bio_uninit(bio);
+
+	if (bs) {
+		bvec_free(&bs->bvec_pool, bio->bi_io_vec, 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 parent bio of @bio
+ *
+ * The caller won't have a bi_end_io called when @bio completes - instead,
+ * @parent's bi_end_io won't be called until both @parent and @bio have
+ * completed; the chained bio will also be freed when it completes.
+ *
+ * The caller must not set bi_private or bi_end_io in @bio.
+ */
+void bio_chain(struct bio *bio, struct bio *parent)
+{
+	BUG_ON(bio->bi_private || bio->bi_end_io);
+
+	bio->bi_private = parent;
+	bio->bi_end_io	= bio_chain_endio;
+	bio_inc_remaining(parent);
+}
+EXPORT_SYMBOL(bio_chain);
+
+static void bio_alloc_rescue(struct work_struct *work)
+{
+	struct bio_set *bs = container_of(work, struct bio_set, rescue_work);
+	struct bio *bio;
+
+	while (1) {
+		spin_lock(&bs->rescue_lock);
+		bio = bio_list_pop(&bs->rescue_list);
+		spin_unlock(&bs->rescue_lock);
+
+		if (!bio)
+			break;
+
+		submit_bio_noacct(bio);
+	}
+}
+
+static void punt_bios_to_rescuer(struct bio_set *bs)
+{
+	struct bio_list punt, nopunt;
+	struct bio *bio;
+
+	if (WARN_ON_ONCE(!bs->rescue_workqueue))
+		return;
+	/*
+	 * In order to guarantee forward progress we must punt only bios that
+	 * were allocated from this bio_set; otherwise, if there was a bio on
+	 * there for a stacking driver higher up in the stack, processing it
+	 * could require allocating bios from this bio_set, and doing that from
+	 * our own rescuer would be bad.
+	 *
+	 * Since bio lists are singly linked, pop them all instead of trying to
+	 * remove from the middle of the list:
+	 */
+
+	bio_list_init(&punt);
+	bio_list_init(&nopunt);
+
+	while ((bio = bio_list_pop(&current->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(&current->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 submit_bio_noacct() (i.e. any block
+ *   driver), bios are not submitted until after you return - see the code in
+ *   submit_bio_noacct() that converts recursion into iteration, to prevent
+ *   stack overflows.
+ *
+ *   This would normally mean allocating multiple bios under
+ *   submit_bio_noacct() would be susceptible to deadlocks, but we have
+ *   deadlock avoidance code that resubmits any blocked bios from a rescuer
+ *   thread.
+ *
+ *   However, we do not guarantee forward progress for allocations from other
+ *   mempools. Doing multiple allocations from the same mempool under
+ *   submit_bio_noacct() should be avoided - instead, use bio_set's front_pad
+ *   for per bio allocations.
+ *
+ *   RETURNS:
+ *   Pointer to new bio on success, NULL on failure.
+ */
+struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned 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(struct_size(bio, bi_inline_vecs, nr_iovecs), 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;
+		/*
+		 * submit_bio_noacct() converts recursion to iteration; this
+		 * means if we're running beneath it, any bios we allocate and
+		 * submit will not be submitted (and thus freed) until after we
+		 * return.
+		 *
+		 * This exposes us to a potential deadlock if we allocate
+		 * multiple bios from the same bio_set() while running
+		 * underneath submit_bio_noacct(). If we were to allocate
+		 * multiple bios (say a stacking block driver that was splitting
+		 * bios), we would deadlock if we exhausted the mempool's
+		 * reserve.
+		 *
+		 * We solve this, and guarantee forward progress, with a rescuer
+		 * workqueue per bio_set. If we go to allocate and there are
+		 * bios on current->bio_list, we first try the allocation
+		 * without __GFP_DIRECT_RECLAIM; if that fails, we punt those
+		 * bios we would be blocking to the rescuer workqueue before
+		 * we retry with the original gfp_flags.
+		 */
+
+		if (current->bio_list &&
+		    (!bio_list_empty(&current->bio_list[0]) ||
+		     !bio_list_empty(&current->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_truncate - truncate the bio to small size of @new_size
+ * @bio:	the bio to be truncated
+ * @new_size:	new size for truncating the bio
+ *
+ * Description:
+ *   Truncate the bio to new size of @new_size. If bio_op(bio) is
+ *   REQ_OP_READ, zero the truncated part. This function should only
+ *   be used for handling corner cases, such as bio eod.
+ */
+void bio_truncate(struct bio *bio, unsigned new_size)
+{
+	struct bio_vec bv;
+	struct bvec_iter iter;
+	unsigned int done = 0;
+	bool truncated = false;
+
+	if (new_size >= bio->bi_iter.bi_size)
+		return;
+
+	if (bio_op(bio) != REQ_OP_READ)
+		goto exit;
+
+	bio_for_each_segment(bv, bio, iter) {
+		if (done + bv.bv_len > new_size) {
+			unsigned offset;
+
+			if (!truncated)
+				offset = new_size - done;
+			else
+				offset = 0;
+			zero_user(bv.bv_page, bv.bv_offset + offset,
+				  bv.bv_len - offset);
+			truncated = true;
+		}
+		done += bv.bv_len;
+	}
+
+ exit:
+	/*
+	 * Don't touch bvec table here and make it really immutable, since
+	 * fs bio user has to retrieve all pages via bio_for_each_segment_all
+	 * in its .end_bio() callback.
+	 *
+	 * It is enough to truncate bio by updating .bi_size since we can make
+	 * correct bvec with the updated .bi_size for drivers.
+	 */
+	bio->bi_iter.bi_size = new_size;
+}
+
+/**
+ * guard_bio_eod - truncate a BIO to fit the block device
+ * @bio:	bio to truncate
+ *
+ * This allows us to do IO even on the odd last sectors of a device, even if the
+ * block size is some multiple of the physical sector size.
+ *
+ * We'll just truncate the bio to the size of the device, and clear the end of
+ * the buffer head manually.  Truly out-of-range accesses will turn into actual
+ * I/O errors, this only handles the "we need to be able to do I/O at the final
+ * sector" case.
+ */
+void guard_bio_eod(struct bio *bio)
+{
+	sector_t maxsector;
+	struct hd_struct *part;
+
+	rcu_read_lock();
+	part = __disk_get_part(bio->bi_disk, bio->bi_partno);
+	if (part)
+		maxsector = part_nr_sects_read(part);
+	else
+		maxsector = get_capacity(bio->bi_disk);
+	rcu_read_unlock();
+
+	if (!maxsector)
+		return;
+
+	/*
+	 * If the *whole* IO is past the end of the device,
+	 * let it through, and the IO layer will turn it into
+	 * an EIO.
+	 */
+	if (unlikely(bio->bi_iter.bi_sector >= maxsector))
+		return;
+
+	maxsector -= bio->bi_iter.bi_sector;
+	if (likely((bio->bi_iter.bi_size >> 9) <= maxsector))
+		return;
+
+	bio_truncate(bio, maxsector << 9);
+}
+
+/**
+ * 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);
+
+/**
+ * 	__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_blkg_association(bio, bio_src);
+	blkcg_bio_issue_init(bio);
+}
+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_crypt_clone(b, bio, gfp_mask) < 0)
+		goto err_put;
+
+	if (bio_integrity(bio) &&
+	    bio_integrity_clone(b, bio, gfp_mask) < 0)
+		goto err_put;
+
+	return b;
+
+err_put:
+	bio_put(b);
+	return NULL;
+}
+EXPORT_SYMBOL(bio_clone_fast);
+
+const char *bio_devname(struct bio *bio, char *buf)
+{
+	return disk_name(bio->bi_disk, bio->bi_partno, buf);
+}
+EXPORT_SYMBOL(bio_devname);
+
+static inline bool page_is_mergeable(const struct bio_vec *bv,
+		struct page *page, unsigned int len, unsigned int off,
+		bool *same_page)
+{
+	size_t bv_end = bv->bv_offset + bv->bv_len;
+	phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) + bv_end - 1;
+	phys_addr_t page_addr = page_to_phys(page);
+
+	if (vec_end_addr + 1 != page_addr + off)
+		return false;
+	if (xen_domain() && !xen_biovec_phys_mergeable(bv, page))
+		return false;
+
+	*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
+	if (*same_page)
+		return true;
+	return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE);
+}
+
+/*
+ * Try to merge a page into a segment, while obeying the hardware segment
+ * size limit.  This is not for normal read/write bios, but for passthrough
+ * or Zone Append operations that we can't split.
+ */
+static bool bio_try_merge_hw_seg(struct request_queue *q, struct bio *bio,
+				 struct page *page, unsigned len,
+				 unsigned offset, bool *same_page)
+{
+	struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
+	unsigned long mask = queue_segment_boundary(q);
+	phys_addr_t addr1 = page_to_phys(bv->bv_page) + bv->bv_offset;
+	phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
+
+	if ((addr1 | mask) != (addr2 | mask))
+		return false;
+	if (bv->bv_len + len > queue_max_segment_size(q))
+		return false;
+	return __bio_try_merge_page(bio, page, len, offset, same_page);
+}
+
+/**
+ * bio_add_hw_page - attempt to add a page to a bio with hw constraints
+ * @q: the target queue
+ * @bio: destination bio
+ * @page: page to add
+ * @len: vec entry length
+ * @offset: vec entry offset
+ * @max_sectors: maximum number of sectors that can be added
+ * @same_page: return if the segment has been merged inside the same page
+ *
+ * Add a page to a bio while respecting the hardware max_sectors, max_segment
+ * and gap limitations.
+ */
+int bio_add_hw_page(struct request_queue *q, struct bio *bio,
+		struct page *page, unsigned int len, unsigned int offset,
+		unsigned int max_sectors, bool *same_page)
+{
+	struct bio_vec *bvec;
+
+	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
+		return 0;
+
+	if (((bio->bi_iter.bi_size + len) >> 9) > max_sectors)
+		return 0;
+
+	if (bio->bi_vcnt > 0) {
+		if (bio_try_merge_hw_seg(q, bio, page, len, offset, same_page))
+			return len;
+
+		/*
+		 * If the queue doesn't support SG gaps and adding this segment
+		 * would create a gap, disallow it.
+		 */
+		bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
+		if (bvec_gap_to_prev(q, bvec, offset))
+			return 0;
+	}
+
+	if (bio_full(bio, len))
+		return 0;
+
+	if (bio->bi_vcnt >= queue_max_segments(q))
+		return 0;
+
+	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_iter.bi_size += len;
+	return len;
+}
+
+/**
+ * bio_add_pc_page	- attempt to add page to passthrough 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 passthrough bios.
+ */
+int bio_add_pc_page(struct request_queue *q, struct bio *bio,
+		struct page *page, unsigned int len, unsigned int offset)
+{
+	bool same_page = false;
+	return bio_add_hw_page(q, bio, page, len, offset,
+			queue_max_hw_sectors(q), &same_page);
+}
+EXPORT_SYMBOL(bio_add_pc_page);
+
+/**
+ * __bio_try_merge_page - try appending data to an existing bvec.
+ * @bio: destination bio
+ * @page: start page to add
+ * @len: length of the data to add
+ * @off: offset of the data relative to @page
+ * @same_page: return if the segment has been merged inside the same page
+ *
+ * Try to add the data at @page + @off to the last bvec of @bio.  This is a
+ * useful optimisation for file systems with a block size smaller than the
+ * page size.
+ *
+ * Warn if (@len, @off) crosses pages in case that @same_page is true.
+ *
+ * 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, bool *same_page)
+{
+	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_is_mergeable(bv, page, len, off, same_page)) {
+			if (bio->bi_iter.bi_size > UINT_MAX - len) {
+				*same_page = false;
+				return false;
+			}
+			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(s) to a bio in a new segment
+ * @bio: destination bio
+ * @page: start page to add
+ * @len: length of the data to add, may cross pages
+ * @off: offset of the data relative to @page, may cross pages
+ *
+ * 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, len));
+
+	bv->bv_page = page;
+	bv->bv_offset = off;
+	bv->bv_len = len;
+
+	bio->bi_iter.bi_size += len;
+	bio->bi_vcnt++;
+
+	if (!bio_flagged(bio, BIO_WORKINGSET) && unlikely(PageWorkingset(page)))
+		bio_set_flag(bio, BIO_WORKINGSET);
+}
+EXPORT_SYMBOL_GPL(__bio_add_page);
+
+/**
+ *	bio_add_page	-	attempt to add page(s) to bio
+ *	@bio: destination bio
+ *	@page: start page to add
+ *	@len: vec entry length, may cross pages
+ *	@offset: vec entry offset relative to @page, may cross pages
+ *
+ *	Attempt to add page(s) 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)
+{
+	bool same_page = false;
+
+	if (!__bio_try_merge_page(bio, page, len, offset, &same_page)) {
+		if (bio_full(bio, len))
+			return 0;
+		__bio_add_page(bio, page, len, offset);
+	}
+	return len;
+}
+EXPORT_SYMBOL(bio_add_page);
+
+void bio_release_pages(struct bio *bio, bool mark_dirty)
+{
+	struct bvec_iter_all iter_all;
+	struct bio_vec *bvec;
+
+	if (bio_flagged(bio, BIO_NO_PAGE_REF))
+		return;
+
+	bio_for_each_segment_all(bvec, bio, iter_all) {
+		if (mark_dirty && !PageCompound(bvec->bv_page))
+			set_page_dirty_lock(bvec->bv_page);
+		put_page(bvec->bv_page);
+	}
+}
+EXPORT_SYMBOL_GPL(bio_release_pages);
+
+static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter)
+{
+	const struct bio_vec *bv = iter->bvec;
+	unsigned int len;
+	size_t size;
+
+	if (WARN_ON_ONCE(iter->iov_offset > bv->bv_len))
+		return -EINVAL;
+
+	len = min_t(size_t, bv->bv_len - iter->iov_offset, iter->count);
+	size = bio_add_page(bio, bv->bv_page, len,
+				bv->bv_offset + iter->iov_offset);
+	if (unlikely(size != len))
+		return -EINVAL;
+	iov_iter_advance(iter, size);
+	return 0;
+}
+
+static void bio_put_pages(struct page **pages, size_t size, size_t off)
+{
+	size_t i, nr = DIV_ROUND_UP(size + (off & ~PAGE_MASK), PAGE_SIZE);
+
+	for (i = 0; i < nr; i++)
+		put_page(pages[i]);
+}
+
+#define PAGE_PTRS_PER_BVEC     (sizeof(struct bio_vec) / sizeof(struct 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
+ * 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;
+	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
+	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
+	struct page **pages = (struct page **)bv;
+	bool same_page = false;
+	ssize_t size, left;
+	unsigned len, i;
+	size_t offset;
+
+	/*
+	 * Move page array up in the allocated memory for the bio vecs as far as
+	 * possible so that we can start filling biovecs from the beginning
+	 * without overwriting the temporary page array.
+	*/
+	BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
+	pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
+
+	size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
+	if (unlikely(size <= 0))
+		return size ? size : -EFAULT;
+
+	for (left = size, i = 0; left > 0; left -= len, i++) {
+		struct page *page = pages[i];
+
+		len = min_t(size_t, PAGE_SIZE - offset, left);
+
+		if (__bio_try_merge_page(bio, page, len, offset, &same_page)) {
+			if (same_page)
+				put_page(page);
+		} else {
+			if (WARN_ON_ONCE(bio_full(bio, len))) {
+				bio_put_pages(pages + i, left, offset);
+				return -EINVAL;
+			}
+			__bio_add_page(bio, page, len, offset);
+		}
+		offset = 0;
+	}
+
+	iov_iter_advance(iter, size);
+	return 0;
+}
+
+static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
+{
+	unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
+	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
+	struct request_queue *q = bio->bi_disk->queue;
+	unsigned int max_append_sectors = queue_max_zone_append_sectors(q);
+	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
+	struct page **pages = (struct page **)bv;
+	ssize_t size, left;
+	unsigned len, i;
+	size_t offset;
+	int ret = 0;
+
+	/*
+	 * Move page array up in the allocated memory for the bio vecs as far as
+	 * possible so that we can start filling biovecs from the beginning
+	 * without overwriting the temporary page array.
+	 */
+	BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
+	pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
+
+	size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
+	if (unlikely(size <= 0))
+		return size ? size : -EFAULT;
+
+	for (left = size, i = 0; left > 0; left -= len, i++) {
+		struct page *page = pages[i];
+		bool same_page = false;
+
+		len = min_t(size_t, PAGE_SIZE - offset, left);
+		if (bio_add_hw_page(q, bio, page, len, offset,
+				max_append_sectors, &same_page) != len) {
+			bio_put_pages(pages + i, left, offset);
+			ret = -EINVAL;
+			break;
+		}
+		if (same_page)
+			put_page(page);
+		offset = 0;
+	}
+
+	iov_iter_advance(iter, size - left);
+	return ret;
+}
+
+/**
+ * bio_iov_iter_get_pages - add user or kernel pages to a bio
+ * @bio: bio to add pages to
+ * @iter: iov iterator describing the region to be added
+ *
+ * This takes either an iterator pointing to user memory, or one pointing to
+ * kernel pages (BVEC iterator). If we're adding user pages, we pin them and
+ * map them into the kernel. On IO completion, the caller should put those
+ * pages. If we're adding kernel pages, and the caller told us it's safe to
+ * do so, we just have to add the pages to the bio directly. We don't grab an
+ * extra reference to those pages (the user should already have that), and we
+ * don't put the page on IO completion. The caller needs to check if the bio is
+ * flagged BIO_NO_PAGE_REF on IO completion. If it isn't, then pages should be
+ * released.
+ *
+ * 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)
+{
+	const bool is_bvec = iov_iter_is_bvec(iter);
+	int ret;
+
+	if (WARN_ON_ONCE(bio->bi_vcnt))
+		return -EINVAL;
+
+	do {
+		if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
+			if (WARN_ON_ONCE(is_bvec))
+				return -EINVAL;
+			ret = __bio_iov_append_get_pages(bio, iter);
+		} else {
+			if (is_bvec)
+				ret = __bio_iov_bvec_add_pages(bio, iter);
+			else
+				ret = __bio_iov_iter_get_pages(bio, iter);
+		}
+	} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
+
+	if (is_bvec)
+		bio_set_flag(bio, BIO_NO_PAGE_REF);
+	return bio->bi_vcnt ? 0 : ret;
+}
+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);
+	unsigned long hang_check;
+
+	bio->bi_private = &done;
+	bio->bi_end_io = submit_bio_wait_endio;
+	bio->bi_opf |= REQ_SYNC;
+	submit_bio(bio);
+
+	/* Prevent hang_check timer from firing at us during very long I/O */
+	hang_check = sysctl_hung_task_timeout_secs;
+	if (hang_check)
+		while (!wait_for_completion_io_timeout(&done,
+					hang_check * (HZ/2)))
+			;
+	else
+		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_crypt_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);
+
+void bio_free_pages(struct bio *bio)
+{
+	struct bio_vec *bvec;
+	struct bvec_iter_all iter_all;
+
+	bio_for_each_segment_all(bvec, bio, iter_all)
+		__free_page(bvec->bv_page);
+}
+EXPORT_SYMBOL(bio_free_pages);
+
+/*
+ * 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;
+	struct bvec_iter_all iter_all;
+
+	bio_for_each_segment_all(bvec, bio, iter_all) {
+		if (!PageCompound(bvec->bv_page))
+			set_page_dirty_lock(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_release_pages(bio, true);
+		bio_put(bio);
+	}
+}
+
+void bio_check_pages_dirty(struct bio *bio)
+{
+	struct bio_vec *bvec;
+	unsigned long flags;
+	struct bvec_iter_all iter_all;
+
+	bio_for_each_segment_all(bvec, bio, iter_all) {
+		if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page))
+			goto defer;
+	}
+
+	bio_release_pages(bio, false);
+	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);
+}
+
+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);
+		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
+ * neither @bio nor @bs are freed before the split bio.
+ */
+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));
+
+	/* Zone append commands cannot be split */
+	if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND))
+		return NULL;
+
+	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);
+
+	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_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);
+
+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);
+
+	BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);
+
+	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);