Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 1759 insertions, 0 deletions

diff --git a/block/bio.c b/block/bio.c
new file mode 100644
index 000000000..6c22dd7b6
--- /dev/null
+++ b/block/bio.c
@@ -0,0 +1,1759 @@
+// 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/highmem.h>
+#include <linux/sched/sysctl.h>
+#include <linux/blk-crypto.h>
+#include <linux/xarray.h>
+
+#include <trace/events/block.h>
+#include "blk.h"
+#include "blk-rq-qos.h"
+#include "blk-cgroup.h"
+
+struct bio_alloc_cache {
+	struct bio		*free_list;
+	unsigned int		nr;
+};
+
+static struct biovec_slab {
+	int nr_vecs;
+	char *name;
+	struct kmem_cache *slab;
+} bvec_slabs[] __read_mostly = {
+	{ .nr_vecs = 16, .name = "biovec-16" },
+	{ .nr_vecs = 64, .name = "biovec-64" },
+	{ .nr_vecs = 128, .name = "biovec-128" },
+	{ .nr_vecs = BIO_MAX_VECS, .name = "biovec-max" },
+};
+
+static struct biovec_slab *biovec_slab(unsigned short nr_vecs)
+{
+	switch (nr_vecs) {
+	/* smaller bios use inline vecs */
+	case 5 ... 16:
+		return &bvec_slabs[0];
+	case 17 ... 64:
+		return &bvec_slabs[1];
+	case 65 ... 128:
+		return &bvec_slabs[2];
+	case 129 ... BIO_MAX_VECS:
+		return &bvec_slabs[3];
+	default:
+		BUG();
+		return NULL;
+	}
+}
+
+/*
+ * fs_bio_set is the bio_set containing bio and iovec memory pools used by
+ * IO code that does not need private memory pools.
+ */
+struct bio_set fs_bio_set;
+EXPORT_SYMBOL(fs_bio_set);
+
+/*
+ * Our slab pool management
+ */
+struct bio_slab {
+	struct kmem_cache *slab;
+	unsigned int slab_ref;
+	unsigned int slab_size;
+	char name[8];
+};
+static DEFINE_MUTEX(bio_slab_lock);
+static DEFINE_XARRAY(bio_slabs);
+
+static struct bio_slab *create_bio_slab(unsigned int size)
+{
+	struct bio_slab *bslab = kzalloc(sizeof(*bslab), GFP_KERNEL);
+
+	if (!bslab)
+		return NULL;
+
+	snprintf(bslab->name, sizeof(bslab->name), "bio-%d", size);
+	bslab->slab = kmem_cache_create(bslab->name, size,
+			ARCH_KMALLOC_MINALIGN,
+			SLAB_HWCACHE_ALIGN | SLAB_TYPESAFE_BY_RCU, NULL);
+	if (!bslab->slab)
+		goto fail_alloc_slab;
+
+	bslab->slab_ref = 1;
+	bslab->slab_size = size;
+
+	if (!xa_err(xa_store(&bio_slabs, size, bslab, GFP_KERNEL)))
+		return bslab;
+
+	kmem_cache_destroy(bslab->slab);
+
+fail_alloc_slab:
+	kfree(bslab);
+	return NULL;
+}
+
+static inline unsigned int bs_bio_slab_size(struct bio_set *bs)
+{
+	return bs->front_pad + sizeof(struct bio) + bs->back_pad;
+}
+
+static struct kmem_cache *bio_find_or_create_slab(struct bio_set *bs)
+{
+	unsigned int size = bs_bio_slab_size(bs);
+	struct bio_slab *bslab;
+
+	mutex_lock(&bio_slab_lock);
+	bslab = xa_load(&bio_slabs, size);
+	if (bslab)
+		bslab->slab_ref++;
+	else
+		bslab = create_bio_slab(size);
+	mutex_unlock(&bio_slab_lock);
+
+	if (bslab)
+		return bslab->slab;
+	return NULL;
+}
+
+static void bio_put_slab(struct bio_set *bs)
+{
+	struct bio_slab *bslab = NULL;
+	unsigned int slab_size = bs_bio_slab_size(bs);
+
+	mutex_lock(&bio_slab_lock);
+
+	bslab = xa_load(&bio_slabs, slab_size);
+	if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
+		goto out;
+
+	WARN_ON_ONCE(bslab->slab != bs->bio_slab);
+
+	WARN_ON(!bslab->slab_ref);
+
+	if (--bslab->slab_ref)
+		goto out;
+
+	xa_erase(&bio_slabs, slab_size);
+
+	kmem_cache_destroy(bslab->slab);
+	kfree(bslab);
+
+out:
+	mutex_unlock(&bio_slab_lock);
+}
+
+void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned short nr_vecs)
+{
+	BUG_ON(nr_vecs > BIO_MAX_VECS);
+
+	if (nr_vecs == BIO_MAX_VECS)
+		mempool_free(bv, pool);
+	else if (nr_vecs > BIO_INLINE_VECS)
+		kmem_cache_free(biovec_slab(nr_vecs)->slab, bv);
+}
+
+/*
+ * Make the first allocation restricted and don't dump info on allocation
+ * failures, since we'll fall back to the mempool in case of failure.
+ */
+static inline gfp_t bvec_alloc_gfp(gfp_t gfp)
+{
+	return (gfp & ~(__GFP_DIRECT_RECLAIM | __GFP_IO)) |
+		__GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
+}
+
+struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs,
+		gfp_t gfp_mask)
+{
+	struct biovec_slab *bvs = biovec_slab(*nr_vecs);
+
+	if (WARN_ON_ONCE(!bvs))
+		return NULL;
+
+	/*
+	 * Upgrade the nr_vecs request to take full advantage of the allocation.
+	 * We also rely on this in the bvec_free path.
+	 */
+	*nr_vecs = bvs->nr_vecs;
+
+	/*
+	 * Try a slab allocation first for all smaller allocations.  If that
+	 * fails and __GFP_DIRECT_RECLAIM is set retry with the mempool.
+	 * The mempool is sized to handle up to BIO_MAX_VECS entries.
+	 */
+	if (*nr_vecs < BIO_MAX_VECS) {
+		struct bio_vec *bvl;
+
+		bvl = kmem_cache_alloc(bvs->slab, bvec_alloc_gfp(gfp_mask));
+		if (likely(bvl) || !(gfp_mask & __GFP_DIRECT_RECLAIM))
+			return bvl;
+		*nr_vecs = BIO_MAX_VECS;
+	}
+
+	return mempool_alloc(pool, gfp_mask);
+}
+
+void bio_uninit(struct bio *bio)
+{
+#ifdef CONFIG_BLK_CGROUP
+	if (bio->bi_blkg) {
+		blkg_put(bio->bi_blkg);
+		bio->bi_blkg = NULL;
+	}
+#endif
+	if (bio_integrity(bio))
+		bio_integrity_free(bio);
+
+	bio_crypt_free_ctx(bio);
+}
+EXPORT_SYMBOL(bio_uninit);
+
+static void bio_free(struct bio *bio)
+{
+	struct bio_set *bs = bio->bi_pool;
+	void *p = bio;
+
+	WARN_ON_ONCE(!bs);
+
+	bio_uninit(bio);
+	bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs);
+	mempool_free(p - bs->front_pad, &bs->bio_pool);
+}
+
+/*
+ * 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 block_device *bdev, struct bio_vec *table,
+	      unsigned short max_vecs, blk_opf_t opf)
+{
+	bio->bi_next = NULL;
+	bio->bi_bdev = bdev;
+	bio->bi_opf = opf;
+	bio->bi_flags = 0;
+	bio->bi_ioprio = 0;
+	bio->bi_status = 0;
+	bio->bi_iter.bi_sector = 0;
+	bio->bi_iter.bi_size = 0;
+	bio->bi_iter.bi_idx = 0;
+	bio->bi_iter.bi_bvec_done = 0;
+	bio->bi_end_io = NULL;
+	bio->bi_private = NULL;
+#ifdef CONFIG_BLK_CGROUP
+	bio->bi_blkg = NULL;
+	bio->bi_issue.value = 0;
+	if (bdev)
+		bio_associate_blkg(bio);
+#ifdef CONFIG_BLK_CGROUP_IOCOST
+	bio->bi_iocost_cost = 0;
+#endif
+#endif
+#ifdef CONFIG_BLK_INLINE_ENCRYPTION
+	bio->bi_crypt_context = NULL;
+#endif
+#ifdef CONFIG_BLK_DEV_INTEGRITY
+	bio->bi_integrity = NULL;
+#endif
+	bio->bi_vcnt = 0;
+
+	atomic_set(&bio->__bi_remaining, 1);
+	atomic_set(&bio->__bi_cnt, 1);
+	bio->bi_cookie = BLK_QC_T_NONE;
+
+	bio->bi_max_vecs = max_vecs;
+	bio->bi_io_vec = table;
+	bio->bi_pool = NULL;
+}
+EXPORT_SYMBOL(bio_init);
+
+/**
+ * bio_reset - reinitialize a bio
+ * @bio:	bio to reset
+ * @bdev:	block device to use the bio for
+ * @opf:	operation and flags for bio
+ *
+ * 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, struct block_device *bdev, blk_opf_t opf)
+{
+	bio_uninit(bio);
+	memset(bio, 0, BIO_RESET_BYTES);
+	atomic_set(&bio->__bi_remaining, 1);
+	bio->bi_bdev = bdev;
+	if (bio->bi_bdev)
+		bio_associate_blkg(bio);
+	bio->bi_opf = opf;
+}
+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);
+
+struct bio *blk_next_bio(struct bio *bio, struct block_device *bdev,
+		unsigned int nr_pages, blk_opf_t opf, gfp_t gfp)
+{
+	struct bio *new = bio_alloc(bdev, nr_pages, opf, gfp);
+
+	if (bio) {
+		bio_chain(bio, new);
+		submit_bio(bio);
+	}
+
+	return new;
+}
+EXPORT_SYMBOL_GPL(blk_next_bio);
+
+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);
+}
+
+static struct bio *bio_alloc_percpu_cache(struct block_device *bdev,
+		unsigned short nr_vecs, blk_opf_t opf, gfp_t gfp,
+		struct bio_set *bs)
+{
+	struct bio_alloc_cache *cache;
+	struct bio *bio;
+
+	cache = per_cpu_ptr(bs->cache, get_cpu());
+	if (!cache->free_list) {
+		put_cpu();
+		return NULL;
+	}
+	bio = cache->free_list;
+	cache->free_list = bio->bi_next;
+	cache->nr--;
+	put_cpu();
+
+	bio_init(bio, bdev, nr_vecs ? bio->bi_inline_vecs : NULL, nr_vecs, opf);
+	bio->bi_pool = bs;
+	return bio;
+}
+
+/**
+ * bio_alloc_bioset - allocate a bio for I/O
+ * @bdev:	block device to allocate the bio for (can be %NULL)
+ * @nr_vecs:	number of bvecs to pre-allocate
+ * @opf:	operation and flags for bio
+ * @gfp_mask:   the GFP_* mask given to the slab allocator
+ * @bs:		the bio_set to allocate from.
+ *
+ * Allocate a bio from the mempools in @bs.
+ *
+ * If %__GFP_DIRECT_RECLAIM is set then bio_alloc will always be able to
+ * allocate a bio.  This is due to the mempool guarantees.  To make this work,
+ * callers must never allocate more than 1 bio at a time from the general pool.
+ * Callers that need to allocate more than 1 bio must always submit the
+ * previously allocated bio for IO before attempting to allocate a new one.
+ * Failure to do so can cause deadlocks under memory pressure.
+ *
+ * Note that when running under submit_bio_noacct() (i.e. any block driver),
+ * bios are not submitted until after you return - see the code in
+ * submit_bio_noacct() that converts recursion into iteration, to prevent
+ * stack overflows.
+ *
+ * This would normally mean allocating multiple bios under submit_bio_noacct()
+ * would be susceptible to deadlocks, but we have
+ * deadlock avoidance code that resubmits any blocked bios from a rescuer
+ * thread.
+ *
+ * However, we do not guarantee forward progress for allocations from other
+ * mempools. Doing multiple allocations from the same mempool under
+ * submit_bio_noacct() should be avoided - instead, use bio_set's front_pad
+ * for per bio allocations.
+ *
+ * If REQ_ALLOC_CACHE is set, the final put of the bio MUST be done from process
+ * context, not hard/soft IRQ.
+ *
+ * Returns: Pointer to new bio on success, NULL on failure.
+ */
+struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs,
+			     blk_opf_t opf, gfp_t gfp_mask,
+			     struct bio_set *bs)
+{
+	gfp_t saved_gfp = gfp_mask;
+	struct bio *bio;
+	void *p;
+
+	/* should not use nobvec bioset for nr_vecs > 0 */
+	if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_vecs > 0))
+		return NULL;
+
+	if (opf & REQ_ALLOC_CACHE) {
+		if (bs->cache && nr_vecs <= BIO_INLINE_VECS) {
+			bio = bio_alloc_percpu_cache(bdev, nr_vecs, opf,
+						     gfp_mask, bs);
+			if (bio)
+				return bio;
+			/*
+			 * No cached bio available, bio returned below marked with
+			 * REQ_ALLOC_CACHE to particpate in per-cpu alloc cache.
+			 */
+		} else {
+			opf &= ~REQ_ALLOC_CACHE;
+		}
+	}
+
+	/*
+	 * 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);
+	}
+	if (unlikely(!p))
+		return NULL;
+
+	bio = p + bs->front_pad;
+	if (nr_vecs > BIO_INLINE_VECS) {
+		struct bio_vec *bvl = NULL;
+
+		bvl = bvec_alloc(&bs->bvec_pool, &nr_vecs, gfp_mask);
+		if (!bvl && gfp_mask != saved_gfp) {
+			punt_bios_to_rescuer(bs);
+			gfp_mask = saved_gfp;
+			bvl = bvec_alloc(&bs->bvec_pool, &nr_vecs, gfp_mask);
+		}
+		if (unlikely(!bvl))
+			goto err_free;
+
+		bio_init(bio, bdev, bvl, nr_vecs, opf);
+	} else if (nr_vecs) {
+		bio_init(bio, bdev, bio->bi_inline_vecs, BIO_INLINE_VECS, opf);
+	} else {
+		bio_init(bio, bdev, NULL, 0, opf);
+	}
+
+	bio->bi_pool = bs;
+	return bio;
+
+err_free:
+	mempool_free(p, &bs->bio_pool);
+	return NULL;
+}
+EXPORT_SYMBOL(bio_alloc_bioset);
+
+/**
+ * bio_kmalloc - kmalloc a bio
+ * @nr_vecs:	number of bio_vecs to allocate
+ * @gfp_mask:   the GFP_* mask given to the slab allocator
+ *
+ * Use kmalloc to allocate a bio (including bvecs).  The bio must be initialized
+ * using bio_init() before use.  To free a bio returned from this function use
+ * kfree() after calling bio_uninit().  A bio returned from this function can
+ * be reused by calling bio_uninit() before calling bio_init() again.
+ *
+ * Note that unlike bio_alloc() or bio_alloc_bioset() allocations from this
+ * function are not backed by a mempool can fail.  Do not use this function
+ * for allocations in the file system I/O path.
+ *
+ * Returns: Pointer to new bio on success, NULL on failure.
+ */
+struct bio *bio_kmalloc(unsigned short nr_vecs, gfp_t gfp_mask)
+{
+	struct bio *bio;
+
+	if (nr_vecs > UIO_MAXIOV)
+		return NULL;
+	return kmalloc(struct_size(bio, bi_inline_vecs, nr_vecs), gfp_mask);
+}
+EXPORT_SYMBOL(bio_kmalloc);
+
+void zero_fill_bio(struct bio *bio)
+{
+	struct bio_vec bv;
+	struct bvec_iter iter;
+
+	bio_for_each_segment(bv, bio, iter)
+		memzero_bvec(&bv);
+}
+EXPORT_SYMBOL(zero_fill_bio);
+
+/**
+ * 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.
+ */
+static 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 = bdev_nr_sectors(bio->bi_bdev);
+
+	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);
+}
+
+#define ALLOC_CACHE_MAX		512
+#define ALLOC_CACHE_SLACK	 64
+
+static void bio_alloc_cache_prune(struct bio_alloc_cache *cache,
+				  unsigned int nr)
+{
+	unsigned int i = 0;
+	struct bio *bio;
+
+	while ((bio = cache->free_list) != NULL) {
+		cache->free_list = bio->bi_next;
+		cache->nr--;
+		bio_free(bio);
+		if (++i == nr)
+			break;
+	}
+}
+
+static int bio_cpu_dead(unsigned int cpu, struct hlist_node *node)
+{
+	struct bio_set *bs;
+
+	bs = hlist_entry_safe(node, struct bio_set, cpuhp_dead);
+	if (bs->cache) {
+		struct bio_alloc_cache *cache = per_cpu_ptr(bs->cache, cpu);
+
+		bio_alloc_cache_prune(cache, -1U);
+	}
+	return 0;
+}
+
+static void bio_alloc_cache_destroy(struct bio_set *bs)
+{
+	int cpu;
+
+	if (!bs->cache)
+		return;
+
+	cpuhp_state_remove_instance_nocalls(CPUHP_BIO_DEAD, &bs->cpuhp_dead);
+	for_each_possible_cpu(cpu) {
+		struct bio_alloc_cache *cache;
+
+		cache = per_cpu_ptr(bs->cache, cpu);
+		bio_alloc_cache_prune(cache, -1U);
+	}
+	free_percpu(bs->cache);
+	bs->cache = NULL;
+}
+
+/**
+ * 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 (unlikely(bio_flagged(bio, BIO_REFFED))) {
+		BUG_ON(!atomic_read(&bio->__bi_cnt));
+		if (!atomic_dec_and_test(&bio->__bi_cnt))
+			return;
+	}
+
+	if ((bio->bi_opf & REQ_ALLOC_CACHE) && !WARN_ON_ONCE(in_interrupt())) {
+		struct bio_alloc_cache *cache;
+
+		bio_uninit(bio);
+		cache = per_cpu_ptr(bio->bi_pool->cache, get_cpu());
+		bio->bi_next = cache->free_list;
+		bio->bi_bdev = NULL;
+		cache->free_list = bio;
+		if (++cache->nr > ALLOC_CACHE_MAX + ALLOC_CACHE_SLACK)
+			bio_alloc_cache_prune(cache, ALLOC_CACHE_SLACK);
+		put_cpu();
+	} else {
+		bio_free(bio);
+	}
+}
+EXPORT_SYMBOL(bio_put);
+
+static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp)
+{
+	bio_set_flag(bio, BIO_CLONED);
+	bio->bi_ioprio = bio_src->bi_ioprio;
+	bio->bi_iter = bio_src->bi_iter;
+
+	if (bio->bi_bdev) {
+		if (bio->bi_bdev == bio_src->bi_bdev &&
+		    bio_flagged(bio_src, BIO_REMAPPED))
+			bio_set_flag(bio, BIO_REMAPPED);
+		bio_clone_blkg_association(bio, bio_src);
+	}
+
+	if (bio_crypt_clone(bio, bio_src, gfp) < 0)
+		return -ENOMEM;
+	if (bio_integrity(bio_src) &&
+	    bio_integrity_clone(bio, bio_src, gfp) < 0)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * bio_alloc_clone - clone a bio that shares the original bio's biovec
+ * @bdev: block_device to clone onto
+ * @bio_src: bio to clone from
+ * @gfp: allocation priority
+ * @bs: bio_set to allocate from
+ *
+ * Allocate a new bio that is a clone of @bio_src. The caller owns the returned
+ * bio, but not the actual data it points to.
+ *
+ * The caller must ensure that the return bio is not freed before @bio_src.
+ */
+struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
+		gfp_t gfp, struct bio_set *bs)
+{
+	struct bio *bio;
+
+	bio = bio_alloc_bioset(bdev, 0, bio_src->bi_opf, gfp, bs);
+	if (!bio)
+		return NULL;
+
+	if (__bio_clone(bio, bio_src, gfp) < 0) {
+		bio_put(bio);
+		return NULL;
+	}
+	bio->bi_io_vec = bio_src->bi_io_vec;
+
+	return bio;
+}
+EXPORT_SYMBOL(bio_alloc_clone);
+
+/**
+ * bio_init_clone - clone a bio that shares the original bio's biovec
+ * @bdev: block_device to clone onto
+ * @bio: bio to clone into
+ * @bio_src: bio to clone from
+ * @gfp: allocation priority
+ *
+ * Initialize a new bio in caller provided memory that is a clone of @bio_src.
+ * The caller owns the returned bio, but not the actual data it points to.
+ *
+ * The caller must ensure that @bio_src is not freed before @bio.
+ */
+int bio_init_clone(struct block_device *bdev, struct bio *bio,
+		struct bio *bio_src, gfp_t gfp)
+{
+	int ret;
+
+	bio_init(bio, bdev, bio_src->bi_io_vec, 0, bio_src->bi_opf);
+	ret = __bio_clone(bio, bio_src, gfp);
+	if (ret)
+		bio_uninit(bio);
+	return ret;
+}
+EXPORT_SYMBOL(bio_init_clone);
+
+/**
+ * bio_full - check if the bio is full
+ * @bio:	bio to check
+ * @len:	length of one segment to be added
+ *
+ * Return true if @bio is full and one segment with @len bytes can't be
+ * added to the bio, otherwise return false
+ */
+static inline bool bio_full(struct bio *bio, unsigned len)
+{
+	if (bio->bi_vcnt >= bio->bi_max_vecs)
+		return true;
+	if (bio->bi_iter.bi_size > UINT_MAX - len)
+		return true;
+	return false;
+}
+
+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;
+	else if (IS_ENABLED(CONFIG_KMSAN))
+		return false;
+	return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE);
+}
+
+/**
+ * __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.
+ */
+static 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;
+}
+
+/*
+ * 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->limits, bvec, offset))
+			return 0;
+	}
+
+	if (bio_full(bio, len))
+		return 0;
+
+	if (bio->bi_vcnt >= queue_max_segments(q))
+		return 0;
+
+	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, 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_add_zone_append_page - attempt to add page to zone-append 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 of a bio that will be submitted
+ * for a zone-append request. This can fail for a number of reasons, such as the
+ * bio being full or the target block device is not a zoned block device or
+ * other limitations of the target block device. 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.
+ *
+ * Returns: number of bytes added to the bio, or 0 in case of a failure.
+ */
+int bio_add_zone_append_page(struct bio *bio, struct page *page,
+			     unsigned int len, unsigned int offset)
+{
+	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+	bool same_page = false;
+
+	if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_ZONE_APPEND))
+		return 0;
+
+	if (WARN_ON_ONCE(!bdev_is_zoned(bio->bi_bdev)))
+		return 0;
+
+	return bio_add_hw_page(q, bio, page, len, offset,
+			       queue_max_zone_append_sectors(q), &same_page);
+}
+EXPORT_SYMBOL_GPL(bio_add_zone_append_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)
+{
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+	WARN_ON_ONCE(bio_full(bio, len));
+
+	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, off);
+	bio->bi_iter.bi_size += len;
+	bio->bi_vcnt++;
+}
+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);
+
+/**
+ * bio_add_folio - Attempt to add part of a folio to a bio.
+ * @bio: BIO to add to.
+ * @folio: Folio to add.
+ * @len: How many bytes from the folio to add.
+ * @off: First byte in this folio to add.
+ *
+ * Filesystems that use folios can call this function instead of calling
+ * bio_add_page() for each page in the folio.  If @off is bigger than
+ * PAGE_SIZE, this function can create a bio_vec that starts in a page
+ * after the bv_page.  BIOs do not support folios that are 4GiB or larger.
+ *
+ * Return: Whether the addition was successful.
+ */
+bool bio_add_folio(struct bio *bio, struct folio *folio, size_t len,
+		   size_t off)
+{
+	if (len > UINT_MAX || off > UINT_MAX)
+		return false;
+	return bio_add_page(bio, &folio->page, len, off) > 0;
+}
+
+void __bio_release_pages(struct bio *bio, bool mark_dirty)
+{
+	struct folio_iter fi;
+
+	bio_for_each_folio_all(fi, bio) {
+		struct page *page;
+		size_t done = 0;
+
+		if (mark_dirty) {
+			folio_lock(fi.folio);
+			folio_mark_dirty(fi.folio);
+			folio_unlock(fi.folio);
+		}
+		page = folio_page(fi.folio, fi.offset / PAGE_SIZE);
+		do {
+			folio_put(fi.folio);
+			done += PAGE_SIZE;
+		} while (done < fi.length);
+	}
+}
+EXPORT_SYMBOL_GPL(__bio_release_pages);
+
+void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter)
+{
+	size_t size = iov_iter_count(iter);
+
+	WARN_ON_ONCE(bio->bi_max_vecs);
+
+	if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
+		struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+		size_t max_sectors = queue_max_zone_append_sectors(q);
+
+		size = min(size, max_sectors << SECTOR_SHIFT);
+	}
+
+	bio->bi_vcnt = iter->nr_segs;
+	bio->bi_io_vec = (struct bio_vec *)iter->bvec;
+	bio->bi_iter.bi_bvec_done = iter->iov_offset;
+	bio->bi_iter.bi_size = size;
+	bio_set_flag(bio, BIO_NO_PAGE_REF);
+	bio_set_flag(bio, BIO_CLONED);
+}
+
+static int bio_iov_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)) {
+		__bio_add_page(bio, page, len, offset);
+		return 0;
+	}
+
+	if (same_page)
+		put_page(page);
+	return 0;
+}
+
+static int bio_iov_add_zone_append_page(struct bio *bio, struct page *page,
+		unsigned int len, unsigned int offset)
+{
+	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+	bool same_page = false;
+
+	if (bio_add_hw_page(q, bio, page, len, offset,
+			queue_max_zone_append_sectors(q), &same_page) != len)
+		return -EINVAL;
+	if (same_page)
+		put_page(page);
+	return 0;
+}
+
+#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;
+	ssize_t size, left;
+	unsigned len, i = 0;
+	size_t offset, trim;
+	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);
+
+	/*
+	 * Each segment in the iov is required to be a block size multiple.
+	 * However, we may not be able to get the entire segment if it spans
+	 * more pages than bi_max_vecs allows, so we have to ALIGN_DOWN the
+	 * result to ensure the bio's total size is correct. The remainder of
+	 * the iov data will be picked up in the next bio iteration.
+	 */
+	size = iov_iter_get_pages2(iter, pages, UINT_MAX - bio->bi_iter.bi_size,
+				  nr_pages, &offset);
+	if (unlikely(size <= 0))
+		return size ? size : -EFAULT;
+
+	nr_pages = DIV_ROUND_UP(offset + size, PAGE_SIZE);
+
+	trim = size & (bdev_logical_block_size(bio->bi_bdev) - 1);
+	iov_iter_revert(iter, trim);
+
+	size -= trim;
+	if (unlikely(!size)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	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_op(bio) == REQ_OP_ZONE_APPEND) {
+			ret = bio_iov_add_zone_append_page(bio, page, len,
+					offset);
+			if (ret)
+				break;
+		} else
+			bio_iov_add_page(bio, page, len, offset);
+
+		offset = 0;
+	}
+
+	iov_iter_revert(iter, left);
+out:
+	while (i < nr_pages)
+		put_page(pages[i++]);
+
+	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. For bvec based iterators bio_iov_iter_get_pages() uses the provided
+ * bvecs rather than copying them. Hence anyone issuing kiocb based IO needs
+ * to ensure the bvecs and pages stay referenced until the submitted I/O is
+ * completed by a call to ->ki_complete() or returns with an error other than
+ * -EIOCBQUEUED. 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)
+{
+	int ret = 0;
+
+	if (iov_iter_is_bvec(iter)) {
+		bio_iov_bvec_set(bio, iter);
+		iov_iter_advance(iter, bio->bi_iter.bi_size);
+		return 0;
+	}
+
+	do {
+		ret = __bio_iov_iter_get_pages(bio, iter);
+	} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
+
+	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_bdev->bd_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);
+
+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)
+{
+	while (src_iter->bi_size && dst_iter->bi_size) {
+		struct bio_vec src_bv = bio_iter_iovec(src, *src_iter);
+		struct bio_vec dst_bv = bio_iter_iovec(dst, *dst_iter);
+		unsigned int bytes = min(src_bv.bv_len, dst_bv.bv_len);
+		void *src_buf = bvec_kmap_local(&src_bv);
+		void *dst_buf = bvec_kmap_local(&dst_bv);
+
+		memcpy(dst_buf, src_buf, bytes);
+
+		kunmap_local(dst_buf);
+		kunmap_local(src_buf);
+
+		bio_advance_iter_single(src, src_iter, bytes);
+		bio_advance_iter_single(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);
+
+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 folio_iter fi;
+
+	bio_for_each_folio_all(fi, bio) {
+		folio_lock(fi.folio);
+		folio_mark_dirty(fi.folio);
+		folio_unlock(fi.folio);
+	}
+}
+
+/*
+ * 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 folio_iter fi;
+	unsigned long flags;
+
+	bio_for_each_folio_all(fi, bio) {
+		if (!folio_test_dirty(fi.folio))
+			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.
+ **/
+void bio_endio(struct bio *bio)
+{
+again:
+	if (!bio_remaining_done(bio))
+		return;
+	if (!bio_integrity_endio(bio))
+		return;
+
+	rq_qos_done_bio(bio);
+
+	if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
+		trace_block_bio_complete(bdev_get_queue(bio->bi_bdev), bio);
+		bio_clear_flag(bio, BIO_TRACE_COMPLETION);
+	}
+
+	/*
+	 * 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;
+	}
+
+	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_alloc_clone(bio->bi_bdev, 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
+ *
+ * This function is typically used for bios that are cloned and submitted
+ * to the underlying device in parts.
+ */
+void bio_trim(struct bio *bio, sector_t offset, sector_t size)
+{
+	if (WARN_ON_ONCE(offset > BIO_MAX_SECTORS || size > BIO_MAX_SECTORS ||
+			 offset + size > bio_sectors(bio)))
+		return;
+
+	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 + ARRAY_SIZE(bvec_slabs) - 1;
+
+	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)
+{
+	bio_alloc_cache_destroy(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_init_clone().
+ *    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)
+{
+	bs->front_pad = front_pad;
+	if (flags & BIOSET_NEED_BVECS)
+		bs->back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
+	else
+		bs->back_pad = 0;
+
+	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(bs);
+	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) {
+		bs->rescue_workqueue = alloc_workqueue("bioset",
+							WQ_MEM_RECLAIM, 0);
+		if (!bs->rescue_workqueue)
+			goto bad;
+	}
+	if (flags & BIOSET_PERCPU_CACHE) {
+		bs->cache = alloc_percpu(struct bio_alloc_cache);
+		if (!bs->cache)
+			goto bad;
+		cpuhp_state_add_instance_nocalls(CPUHP_BIO_DEAD, &bs->cpuhp_dead);
+	}
+
+	return 0;
+bad:
+	bioset_exit(bs);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL(bioset_init);
+
+static int __init init_bio(void)
+{
+	int i;
+
+	bio_integrity_init();
+
+	for (i = 0; i < ARRAY_SIZE(bvec_slabs); i++) {
+		struct biovec_slab *bvs = bvec_slabs + i;
+
+		bvs->slab = kmem_cache_create(bvs->name,
+				bvs->nr_vecs * sizeof(struct bio_vec), 0,
+				SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
+	}
+
+	cpuhp_setup_state_multi(CPUHP_BIO_DEAD, "block/bio:dead", NULL,
+					bio_cpu_dead);
+
+	if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0,
+			BIOSET_NEED_BVECS | BIOSET_PERCPU_CACHE))
+		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);