linux/block/bio.c
Damien Le Moal dd291d77cc block: Introduce zone write plugging
Zone write plugging implements a per-zone "plug" for write operations
to control the submission and execution order of write operations to
sequential write required zones of a zoned block device. Per-zone
plugging guarantees that at any time there is at most only one write
request per zone being executed. This mechanism is intended to replace
zone write locking which implements a similar per-zone write throttling
at the scheduler level, but is implemented only by mq-deadline.

Unlike zone write locking which operates on requests, zone write
plugging operates on BIOs. A zone write plug is simply a BIO list that
is atomically manipulated using a spinlock and a kblockd submission
work. A write BIO to a zone is "plugged" to delay its execution if a
write BIO for the same zone was already issued, that is, if a write
request for the same zone is being executed. The next plugged BIO is
unplugged and issued once the write request completes.

This mechanism allows to:
 - Untangle zone write ordering from block IO schedulers. This allows
   removing the restriction on using mq-deadline for writing to zoned
   block devices. Any block IO scheduler, including "none" can be used.
 - Zone write plugging operates on BIOs instead of requests. Plugged
   BIOs waiting for execution thus do not hold scheduling tags and thus
   are not preventing other BIOs from executing (reads or writes to
   other zones). Depending on the workload, this can significantly
   improve the device use (higher queue depth operation) and
   performance.
 - Both blk-mq (request based) zoned devices and BIO-based zoned devices
   (e.g.  device mapper) can use zone write plugging. It is mandatory
   for the former but optional for the latter. BIO-based drivers can
   use zone write plugging to implement write ordering guarantees, or
   the drivers can implement their own if needed.
 - The code is less invasive in the block layer and is mostly limited to
   blk-zoned.c with some small changes in blk-mq.c, blk-merge.c and
   bio.c.

Zone write plugging is implemented using struct blk_zone_wplug. This
structure includes a spinlock, a BIO list and a work structure to
handle the submission of plugged BIOs. Zone write plugs structures are
managed using a per-disk hash table.

Plugging of zone write BIOs is done using the function
blk_zone_write_plug_bio() which returns false if a BIO execution does
not need to be delayed and true otherwise. This function is called
from blk_mq_submit_bio() after a BIO is split to avoid large BIOs
spanning multiple zones which would cause mishandling of zone write
plugs. This ichange enables by default zone write plugging for any mq
request-based block device. BIO-based device drivers can also use zone
write plugging by expliclty calling blk_zone_write_plug_bio() in their
->submit_bio method. For such devices, the driver must ensure that a
BIO passed to blk_zone_write_plug_bio() is already split and not
straddling zone boundaries.

Only write and write zeroes BIOs are plugged. Zone write plugging does
not introduce any significant overhead for other operations. A BIO that
is being handled through zone write plugging is flagged using the new
BIO flag BIO_ZONE_WRITE_PLUGGING. A request handling a BIO flagged with
this new flag is flagged with the new RQF_ZONE_WRITE_PLUGGING flag.
The completion of BIOs and requests flagged trigger respectively calls
to the functions blk_zone_write_bio_endio() and
blk_zone_write_complete_request(). The latter function is used to
trigger submission of the next plugged BIO using the zone plug work.
blk_zone_write_bio_endio() does the same for BIO-based devices.
This ensures that at any time, at most one request (blk-mq devices) or
one BIO (BIO-based devices) is being executed for any zone. The
handling of zone write plugs using a per-zone plug spinlock maximizes
parallelism and device usage by allowing multiple zones to be writen
simultaneously without lock contention.

Zone write plugging ignores flush BIOs without data. Hovever, any flush
BIO that has data is always plugged so that the write part of the flush
sequence is serialized with other regular writes.

Given that any BIO handled through zone write plugging will be the only
BIO in flight for the target zone when it is executed, the unplugging
and submission of a BIO will have no chance of successfully merging with
plugged requests or requests in the scheduler. To overcome this
potential performance degradation, blk_mq_submit_bio() calls the
function blk_zone_write_plug_attempt_merge() to try to merge other
plugged BIOs with the one just unplugged and submitted. Successful
merging is signaled using blk_zone_write_plug_bio_merged(), called from
bio_attempt_back_merge(). Furthermore, to avoid recalculating the number
of segments of plugged BIOs to attempt merging, the number of segments
of a plugged BIO is saved using the new struct bio field
__bi_nr_segments. To avoid growing the size of struct bio, this field is
added as a union with the bio_cookie field. This is safe to do as
polling is always disabled for plugged BIOs.

When BIOs are plugged in a zone write plug, the device request queue
usage counter is always incremented. This reference is kept and reused
for blk-mq devices when the plugged BIO is unplugged and submitted
again using submit_bio_noacct_nocheck(). For this case, the unplugged
BIO is already flagged with BIO_ZONE_WRITE_PLUGGING and
blk_mq_submit_bio() proceeds directly to allocating a new request for
the BIO, re-using the usage reference count taken when the BIO was
plugged. This extra reference count is dropped in
blk_zone_write_plug_attempt_merge() for any plugged BIO that is
successfully merged. Given that BIO-based devices will not take this
path, the extra reference is dropped after a plugged BIO is unplugged
and submitted.

Zone write plugs are dynamically allocated and managed using a hash
table (an array of struct hlist_head) with RCU protection.
A zone write plug is allocated when a write BIO is received for the
zone and not freed until the zone is fully written, reset or finished.
To detect when a zone write plug can be freed, the write state of each
zone is tracked using a write pointer offset which corresponds to the
offset of a zone write pointer relative to the zone start. Write
operations always increment this write pointer offset. Zone reset
operations set it to 0 and zone finish operations set it to the zone
size.

If a write error happens, the wp_offset value of a zone write plug may
become incorrect and out of sync with the device managed write pointer.
This is handled using the zone write plug flag BLK_ZONE_WPLUG_ERROR.
The function blk_zone_wplug_handle_error() is called from the new disk
zone write plug work when this flag is set. This function executes a
report zone to update the zone write pointer offset to the current
value as indicated by the device. The disk zone write plug work is
scheduled whenever a BIO flagged with BIO_ZONE_WRITE_PLUGGING completes
with an error or when bio_zone_wplug_prepare_bio() detects an unaligned
write. Once scheduled, the disk zone write plugs work keeps running
until all zone errors are handled.

To match the new data structures used for zoned disks, the function
disk_free_zone_bitmaps() is renamed to the more generic
disk_free_zone_resources(). The function disk_init_zone_resources() is
also introduced to initialize zone write plugs resources when a gendisk
is allocated.

In order to guarantee that the user can simultaneously write up to a
number of zones equal to a device max active zone limit or max open zone
limit, zone write plugs are allocated using a mempool sized to the
maximum of these 2 device limits. For a device that does not have
active and open zone limits, 128 is used as the default mempool size.

If a change to the device active and open zone limits is detected, the
disk mempool is resized when blk_revalidate_disk_zones() is executed.

This commit contains contributions from Christoph Hellwig <hch@lst.de>.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240408014128.205141-8-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-17 08:44:03 -06:00

1810 lines
48 KiB
C

// 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/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);
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)
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);
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 (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_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 nr_pages;
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);
nr_pages = (fi.offset + fi.length - 1) / PAGE_SIZE -
fi.offset / PAGE_SIZE + 1;
do {
bio_release_page(bio, page++);
} while (--nr_pages != 0);
}
}
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);
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);
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;
}
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);