// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2001 Jens Axboe <[email protected]>
*/
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/bio-integrity.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/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_write_hint = 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);
/**
* bio_chain_and_submit - submit a bio after chaining it to another one
* @prev: bio to chain and submit
* @new: bio to chain to
*
* If @prev is non-NULL, chain it to @new and submit it.
*
* Return: @new.
*/
struct bio *bio_chain_and_submit(struct bio *prev, struct bio *new)
{
if (prev) {
bio_chain(prev, new);
submit_bio(prev);
}
return new;
}
struct bio *blk_next_bio(struct bio *bio, struct block_device *bdev,
unsigned int nr_pages, blk_opf_t opf, gfp_t gfp)
{
return bio_chain_and_submit(bio, bio_alloc(bdev, nr_pages, opf, gfp));
}
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(¤t->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(¤t->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(¤t->bio_list[0]) ||
!bio_list_empty(¤t->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)
goto out_free;
if (in_task()) {
bio_uninit(bio);
bio->bi_next = cache->free_list;
/* Not necessary but helps not to iopoll already freed bios */
bio->bi_bdev = NULL;
cache->free_list = bio;
cache->nr++;
} else if (in_hardirq()) {
lockdep_assert_irqs_disabled();
bio_uninit(bio);
bio->bi_next = cache->free_list_irq;
cache->free_list_irq = bio;
cache->nr_irq++;
} else {
goto out_free;
}
put_cpu();
return;
out_free:
put_cpu();
bio_free(bio);
}
/**
* bio_put - release a reference to a bio
* @bio: bio to release reference to
*
* Description:
* Put a reference to a &struct bio, either one you have gotten with
* bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it.
**/
void bio_put(struct bio *bio)
{
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_write_hint = bio_src->bi_write_hint;
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 + off) &
PAGE_MASK));
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 = bvec_phys(bv);
phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
if ((addr1 | mask) != (addr2 | mask))
return false;
if (len > queue_max_segment_size(q) - bv->bv_len)
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)
{
unsigned int max_size = max_sectors << SECTOR_SHIFT;
if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
return 0;
len = min3(len, max_size, queue_max_segment_size(q));
if (len > max_size - bio->bi_iter.bi_size)
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_hw_folio - attempt to add a folio to a bio with hw constraints
* @q: the target queue
* @bio: destination bio
* @folio: folio to add
* @len: vec entry length
* @offset: vec entry offset in the folio
* @max_sectors: maximum number of sectors that can be added
* @same_page: return if the segment has been merged inside the same folio
*
* Add a folio to a bio while respecting the hardware max_sectors, max_segment
* and gap limitations.
*/
int bio_add_hw_folio(struct request_queue *q, struct bio *bio,
struct folio *folio, size_t len, size_t offset,
unsigned int max_sectors, bool *same_page)
{
if (len > UINT_MAX || offset > UINT_MAX)
return 0;
return bio_add_hw_page(q, bio, folio_page(folio, 0), len, offset,
max_sectors, same_page);
}
/**
* 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);
}
EXPORT_SYMBOL_GPL(bio_add_folio_nofail);
/**
* 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) {
size_t nr_pages;
if (mark_dirty) {
folio_lock(fi.folio);
folio_mark_dirty(fi.folio);
folio_unlock(fi.folio);
}
nr_pages = (fi.offset + fi.length - 1) / PAGE_SIZE -
fi.offset / PAGE_SIZE + 1;
unpin_user_folio(fi.folio, nr_pages);
}
}
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_folio(struct bio *bio, struct folio *folio, size_t len,
size_t 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],
folio_page(folio, 0), len, offset,
&same_page)) {
bio->bi_iter.bi_size += len;
if (same_page && bio_flagged(bio, BIO_PAGE_PINNED))
unpin_user_folio(folio, 1);
return 0;
}
bio_add_folio_nofail(bio, folio, len, offset);
return 0;
}
static int bio_iov_add_zone_append_folio(struct bio *bio, struct folio *folio,
size_t len, size_t offset)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
bool same_page = false;
if (bio_add_hw_folio(q, bio, folio, len, offset,
queue_max_zone_append_sectors(q), &same_page) != len)
return -EINVAL;
if (same_page && bio_flagged(bio, BIO_PAGE_PINNED))
unpin_user_folio(folio, 1);
return 0;
}
static unsigned int get_contig_folio_len(unsigned int *num_pages,
struct page **pages, unsigned int i,
struct folio *folio, size_t left,
size_t offset)
{
size_t bytes = left;
size_t contig_sz = min_t(size_t, PAGE_SIZE - offset, bytes);
unsigned int j;
/*
* We might COW a single page in the middle of
* a large folio, so we have to check that all
* pages belong to the same folio.
*/
bytes -= contig_sz;
for (j = i + 1; j < i + *num_pages; j++) {
size_t next = min_t(size_t, PAGE_SIZE, bytes);
if (page_folio(pages[j]) != folio ||
pages[j] != pages[j - 1] + 1) {
break;
}
contig_sz += next;
bytes -= next;
}
*num_pages = j - i;
return contig_sz;
}
#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;
unsigned int num_pages, i = 0;
size_t offset, folio_offset, left, len;
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 += num_pages) {
struct page *page = pages[i];
struct folio *folio = page_folio(page);
folio_offset = ((size_t)folio_page_idx(folio, page) <<
PAGE_SHIFT) + offset;
len = min(folio_size(folio) - folio_offset, left);
num_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE);
if (num_pages > 1)
len = get_contig_folio_len(&num_pages, pages, i,
folio, left, offset);
if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
ret = bio_iov_add_zone_append_folio(bio, folio, len,
folio_offset);
if (ret)
break;
} else
bio_iov_add_folio(bio, folio, len, folio_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);
bio->bi_private = &done;
bio->bi_end_io = submit_bio_wait_endio;
bio->bi_opf |= REQ_SYNC;
submit_bio(bio);
blk_wait_io(&done);
return blk_status_to_errno(bio->bi_status);
}
EXPORT_SYMBOL(submit_bio_wait);
static void bio_wait_end_io(struct bio *bio)
{
complete(bio->bi_private);
bio_put(bio);
}
/*
* bio_await_chain - ends @bio and waits for every chained bio to complete
*/
void bio_await_chain(struct bio *bio)
{
DECLARE_COMPLETION_ONSTACK_MAP(done,
bio->bi_bdev->bd_disk->lockdep_map);
bio->bi_private = &done;
bio->bi_end_io = bio_wait_end_io;
bio_endio(bio);
blk_wait_io(&done);
}
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;
blk_zone_bio_endio(bio);
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;
}
#ifdef CONFIG_BLK_CGROUP
/*
* Release cgroup info. We shouldn't have to do this here, but quite
* a few callers of bio_init fail to call bio_uninit, so we cover up
* for that here at least for now.
*/
if (bio->bi_blkg) {
blkg_put(bio->bi_blkg);
bio->bi_blkg = NULL;
}
#endif
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);
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