Revision a358505d8af3ab43763e1b49549619528783d2bf authored by Linus Torvalds on 28 June 2020, 16:42:47 UTC, committed by Linus Torvalds on 28 June 2020, 16:42:47 UTC
Pull x86 entry fixes from Borislav Petkov: "This is the x86/entry urgent pile which has accumulated since the merge window. It is not the smallest but considering the almost complete entry core rewrite, the amount of fixes to follow is somewhat higher than usual, which is to be expected. Peter Zijlstra says: 'These patches address a number of instrumentation issues that were found after the x86/entry overhaul. When combined with rcu/urgent and objtool/urgent, these patches make UBSAN/KASAN/KCSAN happy again. Part of making this all work is bumping the minimum GCC version for KASAN builds to gcc-8.3, the reason for this is that the __no_sanitize_address function attribute is broken in GCC releases before that. No known GCC version has a working __no_sanitize_undefined, however because the only noinstr violation that results from this happens when an UB is found, we treat it like WARN. That is, we allow it to violate the noinstr rules in order to get the warning out'" * tag 'x86_entry_for_5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/entry: Fix #UD vs WARN more x86/entry: Increase entry_stack size to a full page x86/entry: Fixup bad_iret vs noinstr objtool: Don't consider vmlinux a C-file kasan: Fix required compiler version compiler_attributes.h: Support no_sanitize_undefined check with GCC 4 x86/entry, bug: Comment the instrumentation_begin() usage for WARN() x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*() x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline() compiler_types.h: Add __no_sanitize_{address,undefined} to noinstr kasan: Bump required compiler version x86, kcsan: Add __no_kcsan to noinstr kcsan: Remove __no_kcsan_or_inline x86, kcsan: Remove __no_kcsan_or_inline usage
bio.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/blk-cgroup.h>
#include <linux/highmem.h>
#include <linux/sched/sysctl.h>
#include <linux/blk-crypto.h>
#include <trace/events/block.h>
#include "blk.h"
#include "blk-rq-qos.h"
/*
* Test patch to inline a certain number of bi_io_vec's inside the bio
* itself, to shrink a bio data allocation from two mempool calls to one
*/
#define BIO_INLINE_VECS 4
/*
* if you change this list, also change bvec_alloc or things will
* break badly! cannot be bigger than what you can fit into an
* unsigned short
*/
#define BV(x, n) { .nr_vecs = x, .name = "biovec-"#n }
static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = {
BV(1, 1), BV(4, 4), BV(16, 16), BV(64, 64), BV(128, 128), BV(BIO_MAX_PAGES, max),
};
#undef BV
/*
* fs_bio_set is the bio_set containing bio and iovec memory pools used by
* IO code that does not need private memory pools.
*/
struct bio_set fs_bio_set;
EXPORT_SYMBOL(fs_bio_set);
/*
* Our slab pool management
*/
struct bio_slab {
struct kmem_cache *slab;
unsigned int slab_ref;
unsigned int slab_size;
char name[8];
};
static DEFINE_MUTEX(bio_slab_lock);
static struct bio_slab *bio_slabs;
static unsigned int bio_slab_nr, bio_slab_max;
static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
{
unsigned int sz = sizeof(struct bio) + extra_size;
struct kmem_cache *slab = NULL;
struct bio_slab *bslab, *new_bio_slabs;
unsigned int new_bio_slab_max;
unsigned int i, entry = -1;
mutex_lock(&bio_slab_lock);
i = 0;
while (i < bio_slab_nr) {
bslab = &bio_slabs[i];
if (!bslab->slab && entry == -1)
entry = i;
else if (bslab->slab_size == sz) {
slab = bslab->slab;
bslab->slab_ref++;
break;
}
i++;
}
if (slab)
goto out_unlock;
if (bio_slab_nr == bio_slab_max && entry == -1) {
new_bio_slab_max = bio_slab_max << 1;
new_bio_slabs = krealloc(bio_slabs,
new_bio_slab_max * sizeof(struct bio_slab),
GFP_KERNEL);
if (!new_bio_slabs)
goto out_unlock;
bio_slab_max = new_bio_slab_max;
bio_slabs = new_bio_slabs;
}
if (entry == -1)
entry = bio_slab_nr++;
bslab = &bio_slabs[entry];
snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
slab = kmem_cache_create(bslab->name, sz, ARCH_KMALLOC_MINALIGN,
SLAB_HWCACHE_ALIGN, NULL);
if (!slab)
goto out_unlock;
bslab->slab = slab;
bslab->slab_ref = 1;
bslab->slab_size = sz;
out_unlock:
mutex_unlock(&bio_slab_lock);
return slab;
}
static void bio_put_slab(struct bio_set *bs)
{
struct bio_slab *bslab = NULL;
unsigned int i;
mutex_lock(&bio_slab_lock);
for (i = 0; i < bio_slab_nr; i++) {
if (bs->bio_slab == bio_slabs[i].slab) {
bslab = &bio_slabs[i];
break;
}
}
if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
goto out;
WARN_ON(!bslab->slab_ref);
if (--bslab->slab_ref)
goto out;
kmem_cache_destroy(bslab->slab);
bslab->slab = NULL;
out:
mutex_unlock(&bio_slab_lock);
}
unsigned int bvec_nr_vecs(unsigned short idx)
{
return bvec_slabs[--idx].nr_vecs;
}
void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
{
if (!idx)
return;
idx--;
BIO_BUG_ON(idx >= BVEC_POOL_NR);
if (idx == BVEC_POOL_MAX) {
mempool_free(bv, pool);
} else {
struct biovec_slab *bvs = bvec_slabs + idx;
kmem_cache_free(bvs->slab, bv);
}
}
struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
mempool_t *pool)
{
struct bio_vec *bvl;
/*
* see comment near bvec_array define!
*/
switch (nr) {
case 1:
*idx = 0;
break;
case 2 ... 4:
*idx = 1;
break;
case 5 ... 16:
*idx = 2;
break;
case 17 ... 64:
*idx = 3;
break;
case 65 ... 128:
*idx = 4;
break;
case 129 ... BIO_MAX_PAGES:
*idx = 5;
break;
default:
return NULL;
}
/*
* idx now points to the pool we want to allocate from. only the
* 1-vec entry pool is mempool backed.
*/
if (*idx == BVEC_POOL_MAX) {
fallback:
bvl = mempool_alloc(pool, gfp_mask);
} else {
struct biovec_slab *bvs = bvec_slabs + *idx;
gfp_t __gfp_mask = gfp_mask & ~(__GFP_DIRECT_RECLAIM | __GFP_IO);
/*
* Make this allocation restricted and don't dump info on
* allocation failures, since we'll fallback to the mempool
* in case of failure.
*/
__gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
/*
* Try a slab allocation. If this fails and __GFP_DIRECT_RECLAIM
* is set, retry with the 1-entry mempool
*/
bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
if (unlikely(!bvl && (gfp_mask & __GFP_DIRECT_RECLAIM))) {
*idx = BVEC_POOL_MAX;
goto fallback;
}
}
(*idx)++;
return bvl;
}
void bio_uninit(struct bio *bio)
{
bio_disassociate_blkg(bio);
if (bio_integrity(bio))
bio_integrity_free(bio);
bio_crypt_free_ctx(bio);
}
EXPORT_SYMBOL(bio_uninit);
static void bio_free(struct bio *bio)
{
struct bio_set *bs = bio->bi_pool;
void *p;
bio_uninit(bio);
if (bs) {
bvec_free(&bs->bvec_pool, bio->bi_io_vec, BVEC_POOL_IDX(bio));
/*
* If we have front padding, adjust the bio pointer before freeing
*/
p = bio;
p -= bs->front_pad;
mempool_free(p, &bs->bio_pool);
} else {
/* Bio was allocated by bio_kmalloc() */
kfree(bio);
}
}
/*
* Users of this function have their own bio allocation. Subsequently,
* they must remember to pair any call to bio_init() with bio_uninit()
* when IO has completed, or when the bio is released.
*/
void bio_init(struct bio *bio, struct bio_vec *table,
unsigned short max_vecs)
{
memset(bio, 0, sizeof(*bio));
atomic_set(&bio->__bi_remaining, 1);
atomic_set(&bio->__bi_cnt, 1);
bio->bi_io_vec = table;
bio->bi_max_vecs = max_vecs;
}
EXPORT_SYMBOL(bio_init);
/**
* bio_reset - reinitialize a bio
* @bio: bio to reset
*
* Description:
* After calling bio_reset(), @bio will be in the same state as a freshly
* allocated bio returned bio bio_alloc_bioset() - the only fields that are
* preserved are the ones that are initialized by bio_alloc_bioset(). See
* comment in struct bio.
*/
void bio_reset(struct bio *bio)
{
unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
bio_uninit(bio);
memset(bio, 0, BIO_RESET_BYTES);
bio->bi_flags = flags;
atomic_set(&bio->__bi_remaining, 1);
}
EXPORT_SYMBOL(bio_reset);
static struct bio *__bio_chain_endio(struct bio *bio)
{
struct bio *parent = bio->bi_private;
if (!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 @bio's parent bio
*
* The caller won't have a bi_end_io called when @bio completes - instead,
* @parent's bi_end_io won't be called until both @parent and @bio have
* completed; the chained bio will also be freed when it completes.
*
* The caller must not set bi_private or bi_end_io in @bio.
*/
void bio_chain(struct bio *bio, struct bio *parent)
{
BUG_ON(bio->bi_private || bio->bi_end_io);
bio->bi_private = parent;
bio->bi_end_io = bio_chain_endio;
bio_inc_remaining(parent);
}
EXPORT_SYMBOL(bio_chain);
static void bio_alloc_rescue(struct work_struct *work)
{
struct bio_set *bs = container_of(work, struct bio_set, rescue_work);
struct bio *bio;
while (1) {
spin_lock(&bs->rescue_lock);
bio = bio_list_pop(&bs->rescue_list);
spin_unlock(&bs->rescue_lock);
if (!bio)
break;
generic_make_request(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);
}
/**
* bio_alloc_bioset - allocate a bio for I/O
* @gfp_mask: the GFP_* mask given to the slab allocator
* @nr_iovecs: number of iovecs to pre-allocate
* @bs: the bio_set to allocate from.
*
* Description:
* If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is
* backed by the @bs's mempool.
*
* When @bs is not NULL, if %__GFP_DIRECT_RECLAIM is set then bio_alloc will
* always be able to allocate a bio. This is due to the mempool guarantees.
* To make this work, callers must never allocate more than 1 bio at a time
* from this pool. Callers that need to allocate more than 1 bio must always
* submit the previously allocated bio for IO before attempting to allocate
* a new one. Failure to do so can cause deadlocks under memory pressure.
*
* Note that when running under generic_make_request() (i.e. any block
* driver), bios are not submitted until after you return - see the code in
* generic_make_request() that converts recursion into iteration, to prevent
* stack overflows.
*
* This would normally mean allocating multiple bios under
* generic_make_request() 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
* generic_make_request() should be avoided - instead, use bio_set's front_pad
* for per bio allocations.
*
* RETURNS:
* Pointer to new bio on success, NULL on failure.
*/
struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
struct bio_set *bs)
{
gfp_t saved_gfp = gfp_mask;
unsigned front_pad;
unsigned inline_vecs;
struct bio_vec *bvl = NULL;
struct bio *bio;
void *p;
if (!bs) {
if (nr_iovecs > UIO_MAXIOV)
return NULL;
p = kmalloc(sizeof(struct bio) +
nr_iovecs * sizeof(struct bio_vec),
gfp_mask);
front_pad = 0;
inline_vecs = nr_iovecs;
} else {
/* should not use nobvec bioset for nr_iovecs > 0 */
if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) &&
nr_iovecs > 0))
return NULL;
/*
* generic_make_request() 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 generic_make_request(). 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);
}
front_pad = bs->front_pad;
inline_vecs = BIO_INLINE_VECS;
}
if (unlikely(!p))
return NULL;
bio = p + front_pad;
bio_init(bio, NULL, 0);
if (nr_iovecs > inline_vecs) {
unsigned long idx = 0;
bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool);
if (!bvl && gfp_mask != saved_gfp) {
punt_bios_to_rescuer(bs);
gfp_mask = saved_gfp;
bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool);
}
if (unlikely(!bvl))
goto err_free;
bio->bi_flags |= idx << BVEC_POOL_OFFSET;
} else if (nr_iovecs) {
bvl = bio->bi_inline_vecs;
}
bio->bi_pool = bs;
bio->bi_max_vecs = nr_iovecs;
bio->bi_io_vec = bvl;
return bio;
err_free:
mempool_free(p, &bs->bio_pool);
return NULL;
}
EXPORT_SYMBOL(bio_alloc_bioset);
void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
{
unsigned long flags;
struct bio_vec bv;
struct bvec_iter iter;
__bio_for_each_segment(bv, bio, iter, start) {
char *data = bvec_kmap_irq(&bv, &flags);
memset(data, 0, bv.bv_len);
flush_dcache_page(bv.bv_page);
bvec_kunmap_irq(data, &flags);
}
}
EXPORT_SYMBOL(zero_fill_bio_iter);
/**
* bio_truncate - truncate the bio to small size of @new_size
* @bio: the bio to be truncated
* @new_size: new size for truncating the bio
*
* Description:
* Truncate the bio to new size of @new_size. If bio_op(bio) is
* REQ_OP_READ, zero the truncated part. This function should only
* be used for handling corner cases, such as bio eod.
*/
void bio_truncate(struct bio *bio, unsigned new_size)
{
struct bio_vec bv;
struct bvec_iter iter;
unsigned int done = 0;
bool truncated = false;
if (new_size >= bio->bi_iter.bi_size)
return;
if (bio_op(bio) != REQ_OP_READ)
goto exit;
bio_for_each_segment(bv, bio, iter) {
if (done + bv.bv_len > new_size) {
unsigned offset;
if (!truncated)
offset = new_size - done;
else
offset = 0;
zero_user(bv.bv_page, offset, bv.bv_len - offset);
truncated = true;
}
done += bv.bv_len;
}
exit:
/*
* Don't touch bvec table here and make it really immutable, since
* fs bio user has to retrieve all pages via bio_for_each_segment_all
* in its .end_bio() callback.
*
* It is enough to truncate bio by updating .bi_size since we can make
* correct bvec with the updated .bi_size for drivers.
*/
bio->bi_iter.bi_size = new_size;
}
/**
* guard_bio_eod - truncate a BIO to fit the block device
* @bio: bio to truncate
*
* This allows us to do IO even on the odd last sectors of a device, even if the
* block size is some multiple of the physical sector size.
*
* We'll just truncate the bio to the size of the device, and clear the end of
* the buffer head manually. Truly out-of-range accesses will turn into actual
* I/O errors, this only handles the "we need to be able to do I/O at the final
* sector" case.
*/
void guard_bio_eod(struct bio *bio)
{
sector_t maxsector;
struct hd_struct *part;
rcu_read_lock();
part = __disk_get_part(bio->bi_disk, bio->bi_partno);
if (part)
maxsector = part_nr_sects_read(part);
else
maxsector = get_capacity(bio->bi_disk);
rcu_read_unlock();
if (!maxsector)
return;
/*
* If the *whole* IO is past the end of the device,
* let it through, and the IO layer will turn it into
* an EIO.
*/
if (unlikely(bio->bi_iter.bi_sector >= maxsector))
return;
maxsector -= bio->bi_iter.bi_sector;
if (likely((bio->bi_iter.bi_size >> 9) <= maxsector))
return;
bio_truncate(bio, maxsector << 9);
}
/**
* bio_put - release a reference to a bio
* @bio: bio to release reference to
*
* Description:
* Put a reference to a &struct bio, either one you have gotten with
* bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it.
**/
void bio_put(struct bio *bio)
{
if (!bio_flagged(bio, BIO_REFFED))
bio_free(bio);
else {
BIO_BUG_ON(!atomic_read(&bio->__bi_cnt));
/*
* last put frees it
*/
if (atomic_dec_and_test(&bio->__bi_cnt))
bio_free(bio);
}
}
EXPORT_SYMBOL(bio_put);
/**
* __bio_clone_fast - clone a bio that shares the original bio's biovec
* @bio: destination bio
* @bio_src: bio to clone
*
* Clone a &bio. Caller will own the returned bio, but not
* the actual data it points to. Reference count of returned
* bio will be one.
*
* Caller must ensure that @bio_src is not freed before @bio.
*/
void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
{
BUG_ON(bio->bi_pool && BVEC_POOL_IDX(bio));
/*
* most users will be overriding ->bi_disk with a new target,
* so we don't set nor calculate new physical/hw segment counts here
*/
bio->bi_disk = bio_src->bi_disk;
bio->bi_partno = bio_src->bi_partno;
bio_set_flag(bio, BIO_CLONED);
if (bio_flagged(bio_src, BIO_THROTTLED))
bio_set_flag(bio, BIO_THROTTLED);
bio->bi_opf = bio_src->bi_opf;
bio->bi_ioprio = bio_src->bi_ioprio;
bio->bi_write_hint = bio_src->bi_write_hint;
bio->bi_iter = bio_src->bi_iter;
bio->bi_io_vec = bio_src->bi_io_vec;
bio_clone_blkg_association(bio, bio_src);
blkcg_bio_issue_init(bio);
}
EXPORT_SYMBOL(__bio_clone_fast);
/**
* bio_clone_fast - clone a bio that shares the original bio's biovec
* @bio: bio to clone
* @gfp_mask: allocation priority
* @bs: bio_set to allocate from
*
* Like __bio_clone_fast, only also allocates the returned bio
*/
struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
{
struct bio *b;
b = bio_alloc_bioset(gfp_mask, 0, bs);
if (!b)
return NULL;
__bio_clone_fast(b, bio);
bio_crypt_clone(b, bio, gfp_mask);
if (bio_integrity(bio)) {
int ret;
ret = bio_integrity_clone(b, bio, gfp_mask);
if (ret < 0) {
bio_put(b);
return NULL;
}
}
return b;
}
EXPORT_SYMBOL(bio_clone_fast);
const char *bio_devname(struct bio *bio, char *buf)
{
return disk_name(bio->bi_disk, bio->bi_partno, buf);
}
EXPORT_SYMBOL(bio_devname);
static inline bool page_is_mergeable(const struct bio_vec *bv,
struct page *page, unsigned int len, unsigned int off,
bool *same_page)
{
phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) +
bv->bv_offset + bv->bv_len - 1;
phys_addr_t page_addr = page_to_phys(page);
if (vec_end_addr + 1 != page_addr + off)
return false;
if (xen_domain() && !xen_biovec_phys_mergeable(bv, page))
return false;
*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
if (!*same_page && pfn_to_page(PFN_DOWN(vec_end_addr)) + 1 != page)
return false;
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.
*/
static bool bio_try_merge_hw_seg(struct request_queue *q, struct bio *bio,
struct page *page, unsigned len,
unsigned offset, bool *same_page)
{
struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
unsigned long mask = queue_segment_boundary(q);
phys_addr_t addr1 = page_to_phys(bv->bv_page) + bv->bv_offset;
phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
if ((addr1 | mask) != (addr2 | mask))
return false;
if (bv->bv_len + len > queue_max_segment_size(q))
return false;
return __bio_try_merge_page(bio, page, len, offset, same_page);
}
/**
* bio_add_hw_page - attempt to add a page to a bio with hw constraints
* @q: the target queue
* @bio: destination bio
* @page: page to add
* @len: vec entry length
* @offset: vec entry offset
* @max_sectors: maximum number of sectors that can be added
* @same_page: return if the segment has been merged inside the same page
*
* Add a page to a bio while respecting the hardware max_sectors, max_segment
* and gap limitations.
*/
int bio_add_hw_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset,
unsigned int max_sectors, bool *same_page)
{
struct bio_vec *bvec;
if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
return 0;
if (((bio->bi_iter.bi_size + len) >> 9) > max_sectors)
return 0;
if (bio->bi_vcnt > 0) {
if (bio_try_merge_hw_seg(q, bio, page, len, offset, same_page))
return len;
/*
* If the queue doesn't support SG gaps and adding this segment
* would create a gap, disallow it.
*/
bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (bvec_gap_to_prev(q, bvec, offset))
return 0;
}
if (bio_full(bio, len))
return 0;
if (bio->bi_vcnt >= queue_max_segments(q))
return 0;
bvec = &bio->bi_io_vec[bio->bi_vcnt];
bvec->bv_page = page;
bvec->bv_len = len;
bvec->bv_offset = offset;
bio->bi_vcnt++;
bio->bi_iter.bi_size += len;
return len;
}
/**
* bio_add_pc_page - attempt to add page to passthrough bio
* @q: the target queue
* @bio: destination bio
* @page: page to add
* @len: vec entry length
* @offset: vec entry offset
*
* Attempt to add a page to the bio_vec maplist. This can fail for a
* number of reasons, such as the bio being full or target block device
* limitations. The target block device must allow bio's up to PAGE_SIZE,
* so it is always possible to add a single page to an empty bio.
*
* This should only be used by passthrough bios.
*/
int bio_add_pc_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset)
{
bool same_page = false;
return bio_add_hw_page(q, bio, page, len, offset,
queue_max_hw_sectors(q), &same_page);
}
EXPORT_SYMBOL(bio_add_pc_page);
/**
* __bio_try_merge_page - try appending data to an existing bvec.
* @bio: destination bio
* @page: start page to add
* @len: length of the data to add
* @off: offset of the data relative to @page
* @same_page: return if the segment has been merged inside the same page
*
* Try to add the data at @page + @off to the last bvec of @bio. This is a
* a useful optimisation for file systems with a block size smaller than the
* page size.
*
* Warn if (@len, @off) crosses pages in case that @same_page is true.
*
* Return %true on success or %false on failure.
*/
bool __bio_try_merge_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int off, bool *same_page)
{
if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
return false;
if (bio->bi_vcnt > 0) {
struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (page_is_mergeable(bv, page, len, off, same_page)) {
if (bio->bi_iter.bi_size > UINT_MAX - len)
return false;
bv->bv_len += len;
bio->bi_iter.bi_size += len;
return true;
}
}
return false;
}
EXPORT_SYMBOL_GPL(__bio_try_merge_page);
/**
* __bio_add_page - add page(s) to a bio in a new segment
* @bio: destination bio
* @page: start page to add
* @len: length of the data to add, may cross pages
* @off: offset of the data relative to @page, may cross pages
*
* Add the data at @page + @off to @bio as a new bvec. The caller must ensure
* that @bio has space for another bvec.
*/
void __bio_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int off)
{
struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt];
WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
WARN_ON_ONCE(bio_full(bio, len));
bv->bv_page = page;
bv->bv_offset = off;
bv->bv_len = len;
bio->bi_iter.bi_size += len;
bio->bi_vcnt++;
if (!bio_flagged(bio, BIO_WORKINGSET) && unlikely(PageWorkingset(page)))
bio_set_flag(bio, BIO_WORKINGSET);
}
EXPORT_SYMBOL_GPL(__bio_add_page);
/**
* bio_add_page - attempt to add page(s) to bio
* @bio: destination bio
* @page: start page to add
* @len: vec entry length, may cross pages
* @offset: vec entry offset relative to @page, may cross pages
*
* Attempt to add page(s) to the bio_vec maplist. This will only fail
* if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio.
*/
int bio_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int offset)
{
bool same_page = false;
if (!__bio_try_merge_page(bio, page, len, offset, &same_page)) {
if (bio_full(bio, len))
return 0;
__bio_add_page(bio, page, len, offset);
}
return len;
}
EXPORT_SYMBOL(bio_add_page);
void bio_release_pages(struct bio *bio, bool mark_dirty)
{
struct bvec_iter_all iter_all;
struct bio_vec *bvec;
if (bio_flagged(bio, BIO_NO_PAGE_REF))
return;
bio_for_each_segment_all(bvec, bio, iter_all) {
if (mark_dirty && !PageCompound(bvec->bv_page))
set_page_dirty_lock(bvec->bv_page);
put_page(bvec->bv_page);
}
}
EXPORT_SYMBOL_GPL(bio_release_pages);
static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter)
{
const struct bio_vec *bv = iter->bvec;
unsigned int len;
size_t size;
if (WARN_ON_ONCE(iter->iov_offset > bv->bv_len))
return -EINVAL;
len = min_t(size_t, bv->bv_len - iter->iov_offset, iter->count);
size = bio_add_page(bio, bv->bv_page, len,
bv->bv_offset + iter->iov_offset);
if (unlikely(size != len))
return -EINVAL;
iov_iter_advance(iter, size);
return 0;
}
#define PAGE_PTRS_PER_BVEC (sizeof(struct bio_vec) / sizeof(struct page *))
/**
* __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
* @bio: bio to add pages to
* @iter: iov iterator describing the region to be mapped
*
* Pins pages from *iter and appends them to @bio's bvec array. The
* pages will have to be released using put_page() when done.
* For multi-segment *iter, this function only adds pages from the
* the next non-empty segment of the iov iterator.
*/
static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
{
unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
struct page **pages = (struct page **)bv;
bool same_page = false;
ssize_t size, left;
unsigned len, i;
size_t offset;
/*
* Move page array up in the allocated memory for the bio vecs as far as
* possible so that we can start filling biovecs from the beginning
* without overwriting the temporary page array.
*/
BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
if (unlikely(size <= 0))
return size ? size : -EFAULT;
for (left = size, i = 0; left > 0; left -= len, i++) {
struct page *page = pages[i];
len = min_t(size_t, PAGE_SIZE - offset, left);
if (__bio_try_merge_page(bio, page, len, offset, &same_page)) {
if (same_page)
put_page(page);
} else {
if (WARN_ON_ONCE(bio_full(bio, len)))
return -EINVAL;
__bio_add_page(bio, page, len, offset);
}
offset = 0;
}
iov_iter_advance(iter, size);
return 0;
}
static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
{
unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
struct request_queue *q = bio->bi_disk->queue;
unsigned int max_append_sectors = queue_max_zone_append_sectors(q);
struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
struct page **pages = (struct page **)bv;
ssize_t size, left;
unsigned len, i;
size_t offset;
if (WARN_ON_ONCE(!max_append_sectors))
return 0;
/*
* Move page array up in the allocated memory for the bio vecs as far as
* possible so that we can start filling biovecs from the beginning
* without overwriting the temporary page array.
*/
BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
if (unlikely(size <= 0))
return size ? size : -EFAULT;
for (left = size, i = 0; left > 0; left -= len, i++) {
struct page *page = pages[i];
bool same_page = false;
len = min_t(size_t, PAGE_SIZE - offset, left);
if (bio_add_hw_page(q, bio, page, len, offset,
max_append_sectors, &same_page) != len)
return -EINVAL;
if (same_page)
put_page(page);
offset = 0;
}
iov_iter_advance(iter, size);
return 0;
}
/**
* bio_iov_iter_get_pages - add user or kernel pages to a bio
* @bio: bio to add pages to
* @iter: iov iterator describing the region to be added
*
* This takes either an iterator pointing to user memory, or one pointing to
* kernel pages (BVEC iterator). If we're adding user pages, we pin them and
* map them into the kernel. On IO completion, the caller should put those
* pages. If we're adding kernel pages, and the caller told us it's safe to
* do so, we just have to add the pages to the bio directly. We don't grab an
* extra reference to those pages (the user should already have that), and we
* don't put the page on IO completion. The caller needs to check if the bio is
* flagged BIO_NO_PAGE_REF on IO completion. If it isn't, then pages should be
* released.
*
* The function tries, but does not guarantee, to pin as many pages as
* fit into the bio, or are requested in *iter, whatever is smaller. If
* MM encounters an error pinning the requested pages, it stops. Error
* is returned only if 0 pages could be pinned.
*/
int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
{
const bool is_bvec = iov_iter_is_bvec(iter);
int ret;
if (WARN_ON_ONCE(bio->bi_vcnt))
return -EINVAL;
do {
if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
if (WARN_ON_ONCE(is_bvec))
return -EINVAL;
ret = __bio_iov_append_get_pages(bio, iter);
} else {
if (is_bvec)
ret = __bio_iov_bvec_add_pages(bio, iter);
else
ret = __bio_iov_iter_get_pages(bio, iter);
}
} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
if (is_bvec)
bio_set_flag(bio, BIO_NO_PAGE_REF);
return bio->bi_vcnt ? 0 : ret;
}
EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
static void submit_bio_wait_endio(struct bio *bio)
{
complete(bio->bi_private);
}
/**
* submit_bio_wait - submit a bio, and wait until it completes
* @bio: The &struct bio which describes the I/O
*
* Simple wrapper around submit_bio(). Returns 0 on success, or the error from
* bio_endio() on failure.
*
* WARNING: Unlike to how submit_bio() is usually used, this function does not
* result in bio reference to be consumed. The caller must drop the reference
* on his own.
*/
int submit_bio_wait(struct bio *bio)
{
DECLARE_COMPLETION_ONSTACK_MAP(done, bio->bi_disk->lockdep_map);
unsigned long hang_check;
bio->bi_private = &done;
bio->bi_end_io = submit_bio_wait_endio;
bio->bi_opf |= REQ_SYNC;
submit_bio(bio);
/* Prevent hang_check timer from firing at us during very long I/O */
hang_check = sysctl_hung_task_timeout_secs;
if (hang_check)
while (!wait_for_completion_io_timeout(&done,
hang_check * (HZ/2)))
;
else
wait_for_completion_io(&done);
return blk_status_to_errno(bio->bi_status);
}
EXPORT_SYMBOL(submit_bio_wait);
/**
* bio_advance - increment/complete a bio by some number of bytes
* @bio: bio to advance
* @bytes: number of bytes to complete
*
* This updates bi_sector, bi_size and bi_idx; if the number of bytes to
* complete doesn't align with a bvec boundary, then bv_len and bv_offset will
* be updated on the last bvec as well.
*
* @bio will then represent the remaining, uncompleted portion of the io.
*/
void bio_advance(struct bio *bio, unsigned bytes)
{
if (bio_integrity(bio))
bio_integrity_advance(bio, bytes);
bio_crypt_advance(bio, bytes);
bio_advance_iter(bio, &bio->bi_iter, bytes);
}
EXPORT_SYMBOL(bio_advance);
void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
struct bio *src, struct bvec_iter *src_iter)
{
struct bio_vec src_bv, dst_bv;
void *src_p, *dst_p;
unsigned bytes;
while (src_iter->bi_size && dst_iter->bi_size) {
src_bv = bio_iter_iovec(src, *src_iter);
dst_bv = bio_iter_iovec(dst, *dst_iter);
bytes = min(src_bv.bv_len, dst_bv.bv_len);
src_p = kmap_atomic(src_bv.bv_page);
dst_p = kmap_atomic(dst_bv.bv_page);
memcpy(dst_p + dst_bv.bv_offset,
src_p + src_bv.bv_offset,
bytes);
kunmap_atomic(dst_p);
kunmap_atomic(src_p);
flush_dcache_page(dst_bv.bv_page);
bio_advance_iter(src, src_iter, bytes);
bio_advance_iter(dst, dst_iter, bytes);
}
}
EXPORT_SYMBOL(bio_copy_data_iter);
/**
* bio_copy_data - copy contents of data buffers from one bio to another
* @src: source bio
* @dst: destination bio
*
* Stops when it reaches the end of either @src or @dst - that is, copies
* min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
*/
void bio_copy_data(struct bio *dst, struct bio *src)
{
struct bvec_iter src_iter = src->bi_iter;
struct bvec_iter dst_iter = dst->bi_iter;
bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
}
EXPORT_SYMBOL(bio_copy_data);
/**
* bio_list_copy_data - copy contents of data buffers from one chain of bios to
* another
* @src: source bio list
* @dst: destination bio list
*
* Stops when it reaches the end of either the @src list or @dst list - that is,
* copies min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of
* bios).
*/
void bio_list_copy_data(struct bio *dst, struct bio *src)
{
struct bvec_iter src_iter = src->bi_iter;
struct bvec_iter dst_iter = dst->bi_iter;
while (1) {
if (!src_iter.bi_size) {
src = src->bi_next;
if (!src)
break;
src_iter = src->bi_iter;
}
if (!dst_iter.bi_size) {
dst = dst->bi_next;
if (!dst)
break;
dst_iter = dst->bi_iter;
}
bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
}
}
EXPORT_SYMBOL(bio_list_copy_data);
void bio_free_pages(struct bio *bio)
{
struct bio_vec *bvec;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bvec, bio, iter_all)
__free_page(bvec->bv_page);
}
EXPORT_SYMBOL(bio_free_pages);
/*
* bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
* for performing direct-IO in BIOs.
*
* The problem is that we cannot run set_page_dirty() from interrupt context
* because the required locks are not interrupt-safe. So what we can do is to
* mark the pages dirty _before_ performing IO. And in interrupt context,
* check that the pages are still dirty. If so, fine. If not, redirty them
* in process context.
*
* We special-case compound pages here: normally this means reads into hugetlb
* pages. The logic in here doesn't really work right for compound pages
* because the VM does not uniformly chase down the head page in all cases.
* But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
* handle them at all. So we skip compound pages here at an early stage.
*
* Note that this code is very hard to test under normal circumstances because
* direct-io pins the pages with get_user_pages(). This makes
* is_page_cache_freeable return false, and the VM will not clean the pages.
* But other code (eg, flusher threads) could clean the pages if they are mapped
* pagecache.
*
* Simply disabling the call to bio_set_pages_dirty() is a good way to test the
* deferred bio dirtying paths.
*/
/*
* bio_set_pages_dirty() will mark all the bio's pages as dirty.
*/
void bio_set_pages_dirty(struct bio *bio)
{
struct bio_vec *bvec;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bvec, bio, iter_all) {
if (!PageCompound(bvec->bv_page))
set_page_dirty_lock(bvec->bv_page);
}
}
/*
* bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
* If they are, then fine. If, however, some pages are clean then they must
* have been written out during the direct-IO read. So we take another ref on
* the BIO and re-dirty the pages in process context.
*
* It is expected that bio_check_pages_dirty() will wholly own the BIO from
* here on. It will run one put_page() against each page and will run one
* bio_put() against the BIO.
*/
static void bio_dirty_fn(struct work_struct *work);
static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
static DEFINE_SPINLOCK(bio_dirty_lock);
static struct bio *bio_dirty_list;
/*
* This runs in process context
*/
static void bio_dirty_fn(struct work_struct *work)
{
struct bio *bio, *next;
spin_lock_irq(&bio_dirty_lock);
next = bio_dirty_list;
bio_dirty_list = NULL;
spin_unlock_irq(&bio_dirty_lock);
while ((bio = next) != NULL) {
next = bio->bi_private;
bio_release_pages(bio, true);
bio_put(bio);
}
}
void bio_check_pages_dirty(struct bio *bio)
{
struct bio_vec *bvec;
unsigned long flags;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bvec, bio, iter_all) {
if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page))
goto defer;
}
bio_release_pages(bio, false);
bio_put(bio);
return;
defer:
spin_lock_irqsave(&bio_dirty_lock, flags);
bio->bi_private = bio_dirty_list;
bio_dirty_list = bio;
spin_unlock_irqrestore(&bio_dirty_lock, flags);
schedule_work(&bio_dirty_work);
}
static inline bool bio_remaining_done(struct bio *bio)
{
/*
* If we're not chaining, then ->__bi_remaining is always 1 and
* we always end io on the first invocation.
*/
if (!bio_flagged(bio, BIO_CHAIN))
return true;
BUG_ON(atomic_read(&bio->__bi_remaining) <= 0);
if (atomic_dec_and_test(&bio->__bi_remaining)) {
bio_clear_flag(bio, BIO_CHAIN);
return true;
}
return false;
}
/**
* bio_endio - end I/O on a bio
* @bio: bio
*
* Description:
* bio_endio() will end I/O on the whole bio. bio_endio() is the preferred
* way to end I/O on a bio. No one should call bi_end_io() directly on a
* bio unless they own it and thus know that it has an end_io function.
*
* bio_endio() can be called several times on a bio that has been chained
* using bio_chain(). The ->bi_end_io() function will only be called the
* last time. At this point the BLK_TA_COMPLETE tracing event will be
* generated if BIO_TRACE_COMPLETION is set.
**/
void bio_endio(struct bio *bio)
{
again:
if (!bio_remaining_done(bio))
return;
if (!bio_integrity_endio(bio))
return;
if (bio->bi_disk)
rq_qos_done_bio(bio->bi_disk->queue, bio);
/*
* Need to have a real endio function for chained bios, otherwise
* various corner cases will break (like stacking block devices that
* save/restore bi_end_io) - however, we want to avoid unbounded
* recursion and blowing the stack. Tail call optimization would
* handle this, but compiling with frame pointers also disables
* gcc's sibling call optimization.
*/
if (bio->bi_end_io == bio_chain_endio) {
bio = __bio_chain_endio(bio);
goto again;
}
if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
trace_block_bio_complete(bio->bi_disk->queue, bio);
bio_clear_flag(bio, BIO_TRACE_COMPLETION);
}
blk_throtl_bio_endio(bio);
/* release cgroup info */
bio_uninit(bio);
if (bio->bi_end_io)
bio->bi_end_io(bio);
}
EXPORT_SYMBOL(bio_endio);
/**
* bio_split - split a bio
* @bio: bio to split
* @sectors: number of sectors to split from the front of @bio
* @gfp: gfp mask
* @bs: bio set to allocate from
*
* Allocates and returns a new bio which represents @sectors from the start of
* @bio, and updates @bio to represent the remaining sectors.
*
* Unless this is a discard request the newly allocated bio will point
* to @bio's bi_io_vec. It is the caller's responsibility to ensure that
* neither @bio nor @bs are freed before the split bio.
*/
struct bio *bio_split(struct bio *bio, int sectors,
gfp_t gfp, struct bio_set *bs)
{
struct bio *split;
BUG_ON(sectors <= 0);
BUG_ON(sectors >= bio_sectors(bio));
/* Zone append commands cannot be split */
if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND))
return NULL;
split = bio_clone_fast(bio, gfp, bs);
if (!split)
return NULL;
split->bi_iter.bi_size = sectors << 9;
if (bio_integrity(split))
bio_integrity_trim(split);
bio_advance(bio, split->bi_iter.bi_size);
if (bio_flagged(bio, BIO_TRACE_COMPLETION))
bio_set_flag(split, BIO_TRACE_COMPLETION);
return split;
}
EXPORT_SYMBOL(bio_split);
/**
* bio_trim - trim a bio
* @bio: bio to trim
* @offset: number of sectors to trim from the front of @bio
* @size: size we want to trim @bio to, in sectors
*/
void bio_trim(struct bio *bio, int offset, int size)
{
/* 'bio' is a cloned bio which we need to trim to match
* the given offset and size.
*/
size <<= 9;
if (offset == 0 && size == bio->bi_iter.bi_size)
return;
bio_advance(bio, offset << 9);
bio->bi_iter.bi_size = size;
if (bio_integrity(bio))
bio_integrity_trim(bio);
}
EXPORT_SYMBOL_GPL(bio_trim);
/*
* create memory pools for biovec's in a bio_set.
* use the global biovec slabs created for general use.
*/
int biovec_init_pool(mempool_t *pool, int pool_entries)
{
struct biovec_slab *bp = bvec_slabs + BVEC_POOL_MAX;
return mempool_init_slab_pool(pool, pool_entries, bp->slab);
}
/*
* bioset_exit - exit a bioset initialized with bioset_init()
*
* May be called on a zeroed but uninitialized bioset (i.e. allocated with
* kzalloc()).
*/
void bioset_exit(struct bio_set *bs)
{
if (bs->rescue_workqueue)
destroy_workqueue(bs->rescue_workqueue);
bs->rescue_workqueue = NULL;
mempool_exit(&bs->bio_pool);
mempool_exit(&bs->bvec_pool);
bioset_integrity_free(bs);
if (bs->bio_slab)
bio_put_slab(bs);
bs->bio_slab = NULL;
}
EXPORT_SYMBOL(bioset_exit);
/**
* bioset_init - Initialize a bio_set
* @bs: pool to initialize
* @pool_size: Number of bio and bio_vecs to cache in the mempool
* @front_pad: Number of bytes to allocate in front of the returned bio
* @flags: Flags to modify behavior, currently %BIOSET_NEED_BVECS
* and %BIOSET_NEED_RESCUER
*
* Description:
* Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
* to ask for a number of bytes to be allocated in front of the bio.
* Front pad allocation is useful for embedding the bio inside
* another structure, to avoid allocating extra data to go with the bio.
* Note that the bio must be embedded at the END of that structure always,
* or things will break badly.
* If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated
* for allocating iovecs. This pool is not needed e.g. for bio_clone_fast().
* If %BIOSET_NEED_RESCUER is set, a workqueue is created which can be used to
* dispatch queued requests when the mempool runs out of space.
*
*/
int bioset_init(struct bio_set *bs,
unsigned int pool_size,
unsigned int front_pad,
int flags)
{
unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
bs->front_pad = front_pad;
spin_lock_init(&bs->rescue_lock);
bio_list_init(&bs->rescue_list);
INIT_WORK(&bs->rescue_work, bio_alloc_rescue);
bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
if (!bs->bio_slab)
return -ENOMEM;
if (mempool_init_slab_pool(&bs->bio_pool, pool_size, bs->bio_slab))
goto bad;
if ((flags & BIOSET_NEED_BVECS) &&
biovec_init_pool(&bs->bvec_pool, pool_size))
goto bad;
if (!(flags & BIOSET_NEED_RESCUER))
return 0;
bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
if (!bs->rescue_workqueue)
goto bad;
return 0;
bad:
bioset_exit(bs);
return -ENOMEM;
}
EXPORT_SYMBOL(bioset_init);
/*
* Initialize and setup a new bio_set, based on the settings from
* another bio_set.
*/
int bioset_init_from_src(struct bio_set *bs, struct bio_set *src)
{
int flags;
flags = 0;
if (src->bvec_pool.min_nr)
flags |= BIOSET_NEED_BVECS;
if (src->rescue_workqueue)
flags |= BIOSET_NEED_RESCUER;
return bioset_init(bs, src->bio_pool.min_nr, src->front_pad, flags);
}
EXPORT_SYMBOL(bioset_init_from_src);
#ifdef CONFIG_BLK_CGROUP
/**
* bio_disassociate_blkg - puts back the blkg reference if associated
* @bio: target bio
*
* Helper to disassociate the blkg from @bio if a blkg is associated.
*/
void bio_disassociate_blkg(struct bio *bio)
{
if (bio->bi_blkg) {
blkg_put(bio->bi_blkg);
bio->bi_blkg = NULL;
}
}
EXPORT_SYMBOL_GPL(bio_disassociate_blkg);
/**
* __bio_associate_blkg - associate a bio with the a blkg
* @bio: target bio
* @blkg: the blkg to associate
*
* This tries to associate @bio with the specified @blkg. Association failure
* is handled by walking up the blkg tree. Therefore, the blkg associated can
* be anything between @blkg and the root_blkg. This situation only happens
* when a cgroup is dying and then the remaining bios will spill to the closest
* alive blkg.
*
* A reference will be taken on the @blkg and will be released when @bio is
* freed.
*/
static void __bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
{
bio_disassociate_blkg(bio);
bio->bi_blkg = blkg_tryget_closest(blkg);
}
/**
* bio_associate_blkg_from_css - associate a bio with a specified css
* @bio: target bio
* @css: target css
*
* Associate @bio with the blkg found by combining the css's blkg and the
* request_queue of the @bio. This falls back to the queue's root_blkg if
* the association fails with the css.
*/
void bio_associate_blkg_from_css(struct bio *bio,
struct cgroup_subsys_state *css)
{
struct request_queue *q = bio->bi_disk->queue;
struct blkcg_gq *blkg;
rcu_read_lock();
if (!css || !css->parent)
blkg = q->root_blkg;
else
blkg = blkg_lookup_create(css_to_blkcg(css), q);
__bio_associate_blkg(bio, blkg);
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css);
#ifdef CONFIG_MEMCG
/**
* bio_associate_blkg_from_page - associate a bio with the page's blkg
* @bio: target bio
* @page: the page to lookup the blkcg from
*
* Associate @bio with the blkg from @page's owning memcg and the respective
* request_queue. If cgroup_e_css returns %NULL, fall back to the queue's
* root_blkg.
*/
void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
{
struct cgroup_subsys_state *css;
if (!page->mem_cgroup)
return;
rcu_read_lock();
css = cgroup_e_css(page->mem_cgroup->css.cgroup, &io_cgrp_subsys);
bio_associate_blkg_from_css(bio, css);
rcu_read_unlock();
}
#endif /* CONFIG_MEMCG */
/**
* bio_associate_blkg - associate a bio with a blkg
* @bio: target bio
*
* Associate @bio with the blkg found from the bio's css and request_queue.
* If one is not found, bio_lookup_blkg() creates the blkg. If a blkg is
* already associated, the css is reused and association redone as the
* request_queue may have changed.
*/
void bio_associate_blkg(struct bio *bio)
{
struct cgroup_subsys_state *css;
rcu_read_lock();
if (bio->bi_blkg)
css = &bio_blkcg(bio)->css;
else
css = blkcg_css();
bio_associate_blkg_from_css(bio, css);
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(bio_associate_blkg);
/**
* bio_clone_blkg_association - clone blkg association from src to dst bio
* @dst: destination bio
* @src: source bio
*/
void bio_clone_blkg_association(struct bio *dst, struct bio *src)
{
rcu_read_lock();
if (src->bi_blkg)
__bio_associate_blkg(dst, src->bi_blkg);
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(bio_clone_blkg_association);
#endif /* CONFIG_BLK_CGROUP */
static void __init biovec_init_slabs(void)
{
int i;
for (i = 0; i < BVEC_POOL_NR; i++) {
int size;
struct biovec_slab *bvs = bvec_slabs + i;
if (bvs->nr_vecs <= BIO_INLINE_VECS) {
bvs->slab = NULL;
continue;
}
size = bvs->nr_vecs * sizeof(struct bio_vec);
bvs->slab = kmem_cache_create(bvs->name, size, 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
}
}
static int __init init_bio(void)
{
bio_slab_max = 2;
bio_slab_nr = 0;
bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab),
GFP_KERNEL);
BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);
if (!bio_slabs)
panic("bio: can't allocate bios\n");
bio_integrity_init();
biovec_init_slabs();
if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS))
panic("bio: can't allocate bios\n");
if (bioset_integrity_create(&fs_bio_set, BIO_POOL_SIZE))
panic("bio: can't create integrity pool\n");
return 0;
}
subsys_initcall(init_bio);
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