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-rw-r--r--block/bio.c1809
1 files changed, 1809 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c
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index 0000000000..5eba53ca95
--- /dev/null
+++ b/block/bio.c
@@ -0,0 +1,1809 @@
+// 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"
+
+#define ALLOC_CACHE_THRESHOLD 16
+#define ALLOC_CACHE_MAX 256
+
+struct bio_alloc_cache {
+ struct bio *free_list;
+ struct bio *free_list_irq;
+ unsigned int nr;
+ unsigned int nr_irq;
+};
+
+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 void bio_alloc_irq_cache_splice(struct bio_alloc_cache *cache)
+{
+ unsigned long flags;
+
+ /* cache->free_list must be empty */
+ if (WARN_ON_ONCE(cache->free_list))
+ return;
+
+ local_irq_save(flags);
+ cache->free_list = cache->free_list_irq;
+ cache->free_list_irq = NULL;
+ cache->nr += cache->nr_irq;
+ cache->nr_irq = 0;
+ local_irq_restore(flags);
+}
+
+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) {
+ if (READ_ONCE(cache->nr_irq) >= ALLOC_CACHE_THRESHOLD)
+ bio_alloc_irq_cache_splice(cache);
+ 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.
+ *
+ * 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;
+ if (!mempool_is_saturated(&bs->bio_pool))
+ opf &= ~REQ_ALLOC_CACHE;
+
+ 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_iter(struct bio *bio, struct bvec_iter start)
+{
+ struct bio_vec bv;
+ struct bvec_iter iter;
+
+ __bio_for_each_segment(bv, bio, iter, start)
+ memzero_bvec(&bv);
+}
+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.
+ */
+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);
+}
+
+static int __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;
+ }
+ return i;
+}
+
+static void bio_alloc_cache_prune(struct bio_alloc_cache *cache,
+ unsigned int nr)
+{
+ nr -= __bio_alloc_cache_prune(cache, nr);
+ if (!READ_ONCE(cache->free_list)) {
+ bio_alloc_irq_cache_splice(cache);
+ __bio_alloc_cache_prune(cache, nr);
+ }
+}
+
+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;
+}
+
+static inline void bio_put_percpu_cache(struct bio *bio)
+{
+ struct bio_alloc_cache *cache;
+
+ cache = per_cpu_ptr(bio->bi_pool->cache, get_cpu());
+ if (READ_ONCE(cache->nr_irq) + cache->nr > ALLOC_CACHE_MAX) {
+ put_cpu();
+ bio_free(bio);
+ return;
+ }
+
+ bio_uninit(bio);
+
+ if ((bio->bi_opf & REQ_POLLED) && !WARN_ON_ONCE(in_interrupt())) {
+ bio->bi_next = cache->free_list;
+ bio->bi_bdev = NULL;
+ cache->free_list = bio;
+ cache->nr++;
+ } else {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ bio->bi_next = cache->free_list_irq;
+ cache->free_list_irq = bio;
+ cache->nr_irq++;
+ local_irq_restore(flags);
+ }
+ put_cpu();
+}
+
+/**
+ * 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)
+ bio_put_percpu_cache(bio);
+ 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 bool bvec_try_merge_page(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;
+ if (!zone_device_pages_have_same_pgmap(bv->bv_page, page))
+ return false;
+
+ *same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
+ if (!*same_page) {
+ if (IS_ENABLED(CONFIG_KMSAN))
+ return false;
+ if (bv->bv_page + bv_end / PAGE_SIZE != page + off / PAGE_SIZE)
+ return false;
+ }
+
+ bv->bv_len += len;
+ return true;
+}
+
+/*
+ * 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.
+ */
+bool bvec_try_merge_hw_page(struct request_queue *q, struct bio_vec *bv,
+ struct page *page, unsigned len, unsigned offset,
+ bool *same_page)
+{
+ 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 bvec_try_merge_page(bv, 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)
+{
+ if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
+ return 0;
+
+ if (((bio->bi_iter.bi_size + len) >> SECTOR_SHIFT) > max_sectors)
+ return 0;
+
+ if (bio->bi_vcnt > 0) {
+ struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
+
+ if (bvec_try_merge_hw_page(q, bv, page, len, offset,
+ same_page)) {
+ bio->bi_iter.bi_size += len;
+ return len;
+ }
+
+ if (bio->bi_vcnt >=
+ min(bio->bi_max_vecs, queue_max_segments(q)))
+ return 0;
+
+ /*
+ * If the queue doesn't support SG gaps and adding this segment
+ * would create a gap, disallow it.
+ */
+ if (bvec_gap_to_prev(&q->limits, bv, offset))
+ 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 (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
+ return 0;
+ if (bio->bi_iter.bi_size > UINT_MAX - len)
+ return 0;
+
+ if (bio->bi_vcnt > 0 &&
+ bvec_try_merge_page(&bio->bi_io_vec[bio->bi_vcnt - 1],
+ page, len, offset, &same_page)) {
+ bio->bi_iter.bi_size += len;
+ return len;
+ }
+
+ if (bio->bi_vcnt >= bio->bi_max_vecs)
+ return 0;
+ __bio_add_page(bio, page, len, offset);
+ return len;
+}
+EXPORT_SYMBOL(bio_add_page);
+
+void bio_add_folio_nofail(struct bio *bio, struct folio *folio, size_t len,
+ size_t off)
+{
+ WARN_ON_ONCE(len > UINT_MAX);
+ WARN_ON_ONCE(off > UINT_MAX);
+ __bio_add_page(bio, &folio->page, len, off);
+}
+
+/**
+ * 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;
+}
+EXPORT_SYMBOL(bio_add_folio);
+
+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 {
+ bio_release_page(bio, page++);
+ 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_CLONED);
+}
+
+static int bio_iov_add_page(struct bio *bio, struct page *page,
+ unsigned int len, unsigned int offset)
+{
+ bool same_page = false;
+
+ if (WARN_ON_ONCE(bio->bi_iter.bi_size > UINT_MAX - len))
+ return -EIO;
+
+ if (bio->bi_vcnt > 0 &&
+ bvec_try_merge_page(&bio->bi_io_vec[bio->bi_vcnt - 1],
+ page, len, offset, &same_page)) {
+ bio->bi_iter.bi_size += len;
+ if (same_page)
+ bio_release_page(bio, page);
+ return 0;
+ }
+ __bio_add_page(bio, page, len, offset);
+ 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)
+ bio_release_page(bio, 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
+ *
+ * Extracts pages from *iter and appends them to @bio's bvec array. The pages
+ * will have to be cleaned up in the way indicated by the BIO_PAGE_PINNED flag.
+ * For a 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)
+{
+ iov_iter_extraction_t extraction_flags = 0;
+ 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;
+ 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);
+
+ if (bio->bi_bdev && blk_queue_pci_p2pdma(bio->bi_bdev->bd_disk->queue))
+ extraction_flags |= ITER_ALLOW_P2PDMA;
+
+ /*
+ * 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_extract_pages(iter, &pages,
+ UINT_MAX - bio->bi_iter.bi_size,
+ nr_pages, extraction_flags, &offset);
+ if (unlikely(size <= 0))
+ return size ? size : -EFAULT;
+
+ nr_pages = DIV_ROUND_UP(offset + size, PAGE_SIZE);
+
+ if (bio->bi_bdev) {
+ size_t 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)
+ bio_release_page(bio, 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 (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
+ return -EIO;
+
+ if (iov_iter_is_bvec(iter)) {
+ bio_iov_bvec_set(bio, iter);
+ iov_iter_advance(iter, bio->bi_iter.bi_size);
+ return 0;
+ }
+
+ if (iov_iter_extract_will_pin(iter))
+ bio_set_flag(bio, BIO_PAGE_PINNED);
+ 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 folio_mark_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.
+ *
+ * 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);
+ }
+}
+EXPORT_SYMBOL_GPL(bio_set_pages_dirty);
+
+/*
+ * 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 unpin 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);
+}
+EXPORT_SYMBOL_GPL(bio_check_pages_dirty);
+
+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;
+
+ BUILD_BUG_ON(BIO_FLAG_LAST > 8 * sizeof_field(struct bio, bi_flags));
+
+ 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);