linux/block/bio.c
Mel Gorman d0164adc89 mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00

2056 lines
48 KiB
C

/*
* Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public Licens
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
*
*/
#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 <trace/events/block.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) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
};
#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)
{
BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
if (idx == BIOVEC_MAX_IDX)
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 == BIOVEC_MAX_IDX) {
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 = BIOVEC_MAX_IDX;
goto fallback;
}
}
return bvl;
}
static void __bio_free(struct bio *bio)
{
bio_disassociate_task(bio);
if (bio_integrity(bio))
bio_integrity_free(bio);
}
static void bio_free(struct bio *bio)
{
struct bio_set *bs = bio->bi_pool;
void *p;
__bio_free(bio);
if (bs) {
if (bio_flagged(bio, BIO_OWNS_VEC))
bvec_free(bs->bvec_pool, bio->bi_io_vec, BIO_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);
}
}
void bio_init(struct bio *bio)
{
memset(bio, 0, sizeof(*bio));
atomic_set(&bio->__bi_remaining, 1);
atomic_set(&bio->__bi_cnt, 1);
}
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_free(bio);
memset(bio, 0, BIO_RESET_BYTES);
bio->bi_flags = flags;
atomic_set(&bio->__bi_remaining, 1);
}
EXPORT_SYMBOL(bio_reset);
static void bio_chain_endio(struct bio *bio)
{
struct bio *parent = bio->bi_private;
parent->bi_error = bio->bi_error;
bio_endio(parent);
bio_put(bio);
}
/*
* Increment chain count for the bio. Make sure the CHAIN flag update
* is visible before the raised count.
*/
static inline void bio_inc_remaining(struct bio *bio)
{
bio_set_flag(bio, BIO_CHAIN);
smp_mb__before_atomic();
atomic_inc(&bio->__bi_remaining);
}
/**
* 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;
/*
* 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)))
bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
*current->bio_list = 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, int nr_iovecs, struct bio_set *bs)
{
gfp_t saved_gfp = gfp_mask;
unsigned front_pad;
unsigned inline_vecs;
unsigned long idx = BIO_POOL_NONE;
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(!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(current->bio_list))
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);
if (nr_iovecs > inline_vecs) {
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_set_flag(bio, BIO_OWNS_VEC);
} else if (nr_iovecs) {
bvl = bio->bi_inline_vecs;
}
bio->bi_pool = bs;
bio->bi_flags |= idx << BIO_POOL_OFFSET;
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(struct bio *bio)
{
unsigned long flags;
struct bio_vec bv;
struct bvec_iter iter;
bio_for_each_segment(bv, bio, iter) {
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);
/**
* 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);
inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
{
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
blk_recount_segments(q, bio);
return bio->bi_phys_segments;
}
EXPORT_SYMBOL(bio_phys_segments);
/**
* __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 && BIO_POOL_IDX(bio) != BIO_POOL_NONE);
/*
* most users will be overriding ->bi_bdev with a new target,
* so we don't set nor calculate new physical/hw segment counts here
*/
bio->bi_bdev = bio_src->bi_bdev;
bio_set_flag(bio, BIO_CLONED);
bio->bi_rw = bio_src->bi_rw;
bio->bi_iter = bio_src->bi_iter;
bio->bi_io_vec = bio_src->bi_io_vec;
}
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);
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);
/**
* bio_clone_bioset - clone a bio
* @bio_src: bio to clone
* @gfp_mask: allocation priority
* @bs: bio_set to allocate from
*
* Clone bio. Caller will own the returned bio, but not the actual data it
* points to. Reference count of returned bio will be one.
*/
struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
struct bio_set *bs)
{
struct bvec_iter iter;
struct bio_vec bv;
struct bio *bio;
/*
* Pre immutable biovecs, __bio_clone() used to just do a memcpy from
* bio_src->bi_io_vec to bio->bi_io_vec.
*
* We can't do that anymore, because:
*
* - The point of cloning the biovec is to produce a bio with a biovec
* the caller can modify: bi_idx and bi_bvec_done should be 0.
*
* - The original bio could've had more than BIO_MAX_PAGES biovecs; if
* we tried to clone the whole thing bio_alloc_bioset() would fail.
* But the clone should succeed as long as the number of biovecs we
* actually need to allocate is fewer than BIO_MAX_PAGES.
*
* - Lastly, bi_vcnt should not be looked at or relied upon by code
* that does not own the bio - reason being drivers don't use it for
* iterating over the biovec anymore, so expecting it to be kept up
* to date (i.e. for clones that share the parent biovec) is just
* asking for trouble and would force extra work on
* __bio_clone_fast() anyways.
*/
bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
if (!bio)
return NULL;
bio->bi_bdev = bio_src->bi_bdev;
bio->bi_rw = bio_src->bi_rw;
bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
if (bio->bi_rw & REQ_DISCARD)
goto integrity_clone;
if (bio->bi_rw & REQ_WRITE_SAME) {
bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
goto integrity_clone;
}
bio_for_each_segment(bv, bio_src, iter)
bio->bi_io_vec[bio->bi_vcnt++] = bv;
integrity_clone:
if (bio_integrity(bio_src)) {
int ret;
ret = bio_integrity_clone(bio, bio_src, gfp_mask);
if (ret < 0) {
bio_put(bio);
return NULL;
}
}
return bio;
}
EXPORT_SYMBOL(bio_clone_bioset);
/**
* bio_add_pc_page - attempt to add page to 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 REQ_PC bios.
*/
int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page
*page, unsigned int len, unsigned int offset)
{
int retried_segments = 0;
struct bio_vec *bvec;
/*
* cloned bio must not modify vec list
*/
if (unlikely(bio_flagged(bio, BIO_CLONED)))
return 0;
if (((bio->bi_iter.bi_size + len) >> 9) > queue_max_hw_sectors(q))
return 0;
/*
* For filesystems with a blocksize smaller than the pagesize
* we will often be called with the same page as last time and
* a consecutive offset. Optimize this special case.
*/
if (bio->bi_vcnt > 0) {
struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (page == prev->bv_page &&
offset == prev->bv_offset + prev->bv_len) {
prev->bv_len += len;
bio->bi_iter.bi_size += len;
goto done;
}
/*
* If the queue doesn't support SG gaps and adding this
* offset would create a gap, disallow it.
*/
if (bvec_gap_to_prev(q, prev, offset))
return 0;
}
if (bio->bi_vcnt >= bio->bi_max_vecs)
return 0;
/*
* setup the new entry, we might clear it again later if we
* cannot add the page
*/
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_phys_segments++;
bio->bi_iter.bi_size += len;
/*
* Perform a recount if the number of segments is greater
* than queue_max_segments(q).
*/
while (bio->bi_phys_segments > queue_max_segments(q)) {
if (retried_segments)
goto failed;
retried_segments = 1;
blk_recount_segments(q, bio);
}
/* If we may be able to merge these biovecs, force a recount */
if (bio->bi_vcnt > 1 && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
bio_clear_flag(bio, BIO_SEG_VALID);
done:
return len;
failed:
bvec->bv_page = NULL;
bvec->bv_len = 0;
bvec->bv_offset = 0;
bio->bi_vcnt--;
bio->bi_iter.bi_size -= len;
blk_recount_segments(q, bio);
return 0;
}
EXPORT_SYMBOL(bio_add_pc_page);
/**
* bio_add_page - attempt to add page to 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. 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)
{
struct bio_vec *bv;
/*
* cloned bio must not modify vec list
*/
if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
return 0;
/*
* For filesystems with a blocksize smaller than the pagesize
* we will often be called with the same page as last time and
* a consecutive offset. Optimize this special case.
*/
if (bio->bi_vcnt > 0) {
bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (page == bv->bv_page &&
offset == bv->bv_offset + bv->bv_len) {
bv->bv_len += len;
goto done;
}
}
if (bio->bi_vcnt >= bio->bi_max_vecs)
return 0;
bv = &bio->bi_io_vec[bio->bi_vcnt];
bv->bv_page = page;
bv->bv_len = len;
bv->bv_offset = offset;
bio->bi_vcnt++;
done:
bio->bi_iter.bi_size += len;
return len;
}
EXPORT_SYMBOL(bio_add_page);
struct submit_bio_ret {
struct completion event;
int error;
};
static void submit_bio_wait_endio(struct bio *bio)
{
struct submit_bio_ret *ret = bio->bi_private;
ret->error = bio->bi_error;
complete(&ret->event);
}
/**
* submit_bio_wait - submit a bio, and wait until it completes
* @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
* @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.
*/
int submit_bio_wait(int rw, struct bio *bio)
{
struct submit_bio_ret ret;
rw |= REQ_SYNC;
init_completion(&ret.event);
bio->bi_private = &ret;
bio->bi_end_io = submit_bio_wait_endio;
submit_bio(rw, bio);
wait_for_completion(&ret.event);
return ret.error;
}
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_advance_iter(bio, &bio->bi_iter, bytes);
}
EXPORT_SYMBOL(bio_advance);
/**
* bio_alloc_pages - allocates a single page for each bvec in a bio
* @bio: bio to allocate pages for
* @gfp_mask: flags for allocation
*
* Allocates pages up to @bio->bi_vcnt.
*
* Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
* freed.
*/
int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
{
int i;
struct bio_vec *bv;
bio_for_each_segment_all(bv, bio, i) {
bv->bv_page = alloc_page(gfp_mask);
if (!bv->bv_page) {
while (--bv >= bio->bi_io_vec)
__free_page(bv->bv_page);
return -ENOMEM;
}
}
return 0;
}
EXPORT_SYMBOL(bio_alloc_pages);
/**
* bio_copy_data - copy contents of data buffers from one chain of bios to
* another
* @src: source bio list
* @dst: destination bio list
*
* If @src and @dst are single bios, bi_next must be NULL - otherwise, treats
* @src and @dst as linked lists of bios.
*
* 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, dst_iter;
struct bio_vec src_bv, dst_bv;
void *src_p, *dst_p;
unsigned bytes;
src_iter = src->bi_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;
}
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);
bio_advance_iter(src, &src_iter, bytes);
bio_advance_iter(dst, &dst_iter, bytes);
}
}
EXPORT_SYMBOL(bio_copy_data);
struct bio_map_data {
int is_our_pages;
struct iov_iter iter;
struct iovec iov[];
};
static struct bio_map_data *bio_alloc_map_data(unsigned int iov_count,
gfp_t gfp_mask)
{
if (iov_count > UIO_MAXIOV)
return NULL;
return kmalloc(sizeof(struct bio_map_data) +
sizeof(struct iovec) * iov_count, gfp_mask);
}
/**
* bio_copy_from_iter - copy all pages from iov_iter to bio
* @bio: The &struct bio which describes the I/O as destination
* @iter: iov_iter as source
*
* Copy all pages from iov_iter to bio.
* Returns 0 on success, or error on failure.
*/
static int bio_copy_from_iter(struct bio *bio, struct iov_iter iter)
{
int i;
struct bio_vec *bvec;
bio_for_each_segment_all(bvec, bio, i) {
ssize_t ret;
ret = copy_page_from_iter(bvec->bv_page,
bvec->bv_offset,
bvec->bv_len,
&iter);
if (!iov_iter_count(&iter))
break;
if (ret < bvec->bv_len)
return -EFAULT;
}
return 0;
}
/**
* bio_copy_to_iter - copy all pages from bio to iov_iter
* @bio: The &struct bio which describes the I/O as source
* @iter: iov_iter as destination
*
* Copy all pages from bio to iov_iter.
* Returns 0 on success, or error on failure.
*/
static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter)
{
int i;
struct bio_vec *bvec;
bio_for_each_segment_all(bvec, bio, i) {
ssize_t ret;
ret = copy_page_to_iter(bvec->bv_page,
bvec->bv_offset,
bvec->bv_len,
&iter);
if (!iov_iter_count(&iter))
break;
if (ret < bvec->bv_len)
return -EFAULT;
}
return 0;
}
static void bio_free_pages(struct bio *bio)
{
struct bio_vec *bvec;
int i;
bio_for_each_segment_all(bvec, bio, i)
__free_page(bvec->bv_page);
}
/**
* bio_uncopy_user - finish previously mapped bio
* @bio: bio being terminated
*
* Free pages allocated from bio_copy_user_iov() and write back data
* to user space in case of a read.
*/
int bio_uncopy_user(struct bio *bio)
{
struct bio_map_data *bmd = bio->bi_private;
int ret = 0;
if (!bio_flagged(bio, BIO_NULL_MAPPED)) {
/*
* if we're in a workqueue, the request is orphaned, so
* don't copy into a random user address space, just free.
*/
if (current->mm && bio_data_dir(bio) == READ)
ret = bio_copy_to_iter(bio, bmd->iter);
if (bmd->is_our_pages)
bio_free_pages(bio);
}
kfree(bmd);
bio_put(bio);
return ret;
}
EXPORT_SYMBOL(bio_uncopy_user);
/**
* bio_copy_user_iov - copy user data to bio
* @q: destination block queue
* @map_data: pointer to the rq_map_data holding pages (if necessary)
* @iter: iovec iterator
* @gfp_mask: memory allocation flags
*
* Prepares and returns a bio for indirect user io, bouncing data
* to/from kernel pages as necessary. Must be paired with
* call bio_uncopy_user() on io completion.
*/
struct bio *bio_copy_user_iov(struct request_queue *q,
struct rq_map_data *map_data,
const struct iov_iter *iter,
gfp_t gfp_mask)
{
struct bio_map_data *bmd;
struct page *page;
struct bio *bio;
int i, ret;
int nr_pages = 0;
unsigned int len = iter->count;
unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
for (i = 0; i < iter->nr_segs; i++) {
unsigned long uaddr;
unsigned long end;
unsigned long start;
uaddr = (unsigned long) iter->iov[i].iov_base;
end = (uaddr + iter->iov[i].iov_len + PAGE_SIZE - 1)
>> PAGE_SHIFT;
start = uaddr >> PAGE_SHIFT;
/*
* Overflow, abort
*/
if (end < start)
return ERR_PTR(-EINVAL);
nr_pages += end - start;
}
if (offset)
nr_pages++;
bmd = bio_alloc_map_data(iter->nr_segs, gfp_mask);
if (!bmd)
return ERR_PTR(-ENOMEM);
/*
* We need to do a deep copy of the iov_iter including the iovecs.
* The caller provided iov might point to an on-stack or otherwise
* shortlived one.
*/
bmd->is_our_pages = map_data ? 0 : 1;
memcpy(bmd->iov, iter->iov, sizeof(struct iovec) * iter->nr_segs);
iov_iter_init(&bmd->iter, iter->type, bmd->iov,
iter->nr_segs, iter->count);
ret = -ENOMEM;
bio = bio_kmalloc(gfp_mask, nr_pages);
if (!bio)
goto out_bmd;
if (iter->type & WRITE)
bio->bi_rw |= REQ_WRITE;
ret = 0;
if (map_data) {
nr_pages = 1 << map_data->page_order;
i = map_data->offset / PAGE_SIZE;
}
while (len) {
unsigned int bytes = PAGE_SIZE;
bytes -= offset;
if (bytes > len)
bytes = len;
if (map_data) {
if (i == map_data->nr_entries * nr_pages) {
ret = -ENOMEM;
break;
}
page = map_data->pages[i / nr_pages];
page += (i % nr_pages);
i++;
} else {
page = alloc_page(q->bounce_gfp | gfp_mask);
if (!page) {
ret = -ENOMEM;
break;
}
}
if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
break;
len -= bytes;
offset = 0;
}
if (ret)
goto cleanup;
/*
* success
*/
if (((iter->type & WRITE) && (!map_data || !map_data->null_mapped)) ||
(map_data && map_data->from_user)) {
ret = bio_copy_from_iter(bio, *iter);
if (ret)
goto cleanup;
}
bio->bi_private = bmd;
return bio;
cleanup:
if (!map_data)
bio_free_pages(bio);
bio_put(bio);
out_bmd:
kfree(bmd);
return ERR_PTR(ret);
}
/**
* bio_map_user_iov - map user iovec into bio
* @q: the struct request_queue for the bio
* @iter: iovec iterator
* @gfp_mask: memory allocation flags
*
* Map the user space address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
struct bio *bio_map_user_iov(struct request_queue *q,
const struct iov_iter *iter,
gfp_t gfp_mask)
{
int j;
int nr_pages = 0;
struct page **pages;
struct bio *bio;
int cur_page = 0;
int ret, offset;
struct iov_iter i;
struct iovec iov;
iov_for_each(iov, i, *iter) {
unsigned long uaddr = (unsigned long) iov.iov_base;
unsigned long len = iov.iov_len;
unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = uaddr >> PAGE_SHIFT;
/*
* Overflow, abort
*/
if (end < start)
return ERR_PTR(-EINVAL);
nr_pages += end - start;
/*
* buffer must be aligned to at least hardsector size for now
*/
if (uaddr & queue_dma_alignment(q))
return ERR_PTR(-EINVAL);
}
if (!nr_pages)
return ERR_PTR(-EINVAL);
bio = bio_kmalloc(gfp_mask, nr_pages);
if (!bio)
return ERR_PTR(-ENOMEM);
ret = -ENOMEM;
pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
if (!pages)
goto out;
iov_for_each(iov, i, *iter) {
unsigned long uaddr = (unsigned long) iov.iov_base;
unsigned long len = iov.iov_len;
unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = uaddr >> PAGE_SHIFT;
const int local_nr_pages = end - start;
const int page_limit = cur_page + local_nr_pages;
ret = get_user_pages_fast(uaddr, local_nr_pages,
(iter->type & WRITE) != WRITE,
&pages[cur_page]);
if (ret < local_nr_pages) {
ret = -EFAULT;
goto out_unmap;
}
offset = uaddr & ~PAGE_MASK;
for (j = cur_page; j < page_limit; j++) {
unsigned int bytes = PAGE_SIZE - offset;
if (len <= 0)
break;
if (bytes > len)
bytes = len;
/*
* sorry...
*/
if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
bytes)
break;
len -= bytes;
offset = 0;
}
cur_page = j;
/*
* release the pages we didn't map into the bio, if any
*/
while (j < page_limit)
page_cache_release(pages[j++]);
}
kfree(pages);
/*
* set data direction, and check if mapped pages need bouncing
*/
if (iter->type & WRITE)
bio->bi_rw |= REQ_WRITE;
bio_set_flag(bio, BIO_USER_MAPPED);
/*
* subtle -- if __bio_map_user() ended up bouncing a bio,
* it would normally disappear when its bi_end_io is run.
* however, we need it for the unmap, so grab an extra
* reference to it
*/
bio_get(bio);
return bio;
out_unmap:
for (j = 0; j < nr_pages; j++) {
if (!pages[j])
break;
page_cache_release(pages[j]);
}
out:
kfree(pages);
bio_put(bio);
return ERR_PTR(ret);
}
static void __bio_unmap_user(struct bio *bio)
{
struct bio_vec *bvec;
int i;
/*
* make sure we dirty pages we wrote to
*/
bio_for_each_segment_all(bvec, bio, i) {
if (bio_data_dir(bio) == READ)
set_page_dirty_lock(bvec->bv_page);
page_cache_release(bvec->bv_page);
}
bio_put(bio);
}
/**
* bio_unmap_user - unmap a bio
* @bio: the bio being unmapped
*
* Unmap a bio previously mapped by bio_map_user(). Must be called with
* a process context.
*
* bio_unmap_user() may sleep.
*/
void bio_unmap_user(struct bio *bio)
{
__bio_unmap_user(bio);
bio_put(bio);
}
EXPORT_SYMBOL(bio_unmap_user);
static void bio_map_kern_endio(struct bio *bio)
{
bio_put(bio);
}
/**
* bio_map_kern - map kernel address into bio
* @q: the struct request_queue for the bio
* @data: pointer to buffer to map
* @len: length in bytes
* @gfp_mask: allocation flags for bio allocation
*
* Map the kernel address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
gfp_t gfp_mask)
{
unsigned long kaddr = (unsigned long)data;
unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = kaddr >> PAGE_SHIFT;
const int nr_pages = end - start;
int offset, i;
struct bio *bio;
bio = bio_kmalloc(gfp_mask, nr_pages);
if (!bio)
return ERR_PTR(-ENOMEM);
offset = offset_in_page(kaddr);
for (i = 0; i < nr_pages; i++) {
unsigned int bytes = PAGE_SIZE - offset;
if (len <= 0)
break;
if (bytes > len)
bytes = len;
if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
offset) < bytes) {
/* we don't support partial mappings */
bio_put(bio);
return ERR_PTR(-EINVAL);
}
data += bytes;
len -= bytes;
offset = 0;
}
bio->bi_end_io = bio_map_kern_endio;
return bio;
}
EXPORT_SYMBOL(bio_map_kern);
static void bio_copy_kern_endio(struct bio *bio)
{
bio_free_pages(bio);
bio_put(bio);
}
static void bio_copy_kern_endio_read(struct bio *bio)
{
char *p = bio->bi_private;
struct bio_vec *bvec;
int i;
bio_for_each_segment_all(bvec, bio, i) {
memcpy(p, page_address(bvec->bv_page), bvec->bv_len);
p += bvec->bv_len;
}
bio_copy_kern_endio(bio);
}
/**
* bio_copy_kern - copy kernel address into bio
* @q: the struct request_queue for the bio
* @data: pointer to buffer to copy
* @len: length in bytes
* @gfp_mask: allocation flags for bio and page allocation
* @reading: data direction is READ
*
* copy the kernel address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
gfp_t gfp_mask, int reading)
{
unsigned long kaddr = (unsigned long)data;
unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = kaddr >> PAGE_SHIFT;
struct bio *bio;
void *p = data;
int nr_pages = 0;
/*
* Overflow, abort
*/
if (end < start)
return ERR_PTR(-EINVAL);
nr_pages = end - start;
bio = bio_kmalloc(gfp_mask, nr_pages);
if (!bio)
return ERR_PTR(-ENOMEM);
while (len) {
struct page *page;
unsigned int bytes = PAGE_SIZE;
if (bytes > len)
bytes = len;
page = alloc_page(q->bounce_gfp | gfp_mask);
if (!page)
goto cleanup;
if (!reading)
memcpy(page_address(page), p, bytes);
if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
break;
len -= bytes;
p += bytes;
}
if (reading) {
bio->bi_end_io = bio_copy_kern_endio_read;
bio->bi_private = data;
} else {
bio->bi_end_io = bio_copy_kern_endio;
bio->bi_rw |= REQ_WRITE;
}
return bio;
cleanup:
bio_free_pages(bio);
bio_put(bio);
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(bio_copy_kern);
/*
* 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;
int i;
bio_for_each_segment_all(bvec, bio, i) {
struct page *page = bvec->bv_page;
if (page && !PageCompound(page))
set_page_dirty_lock(page);
}
}
static void bio_release_pages(struct bio *bio)
{
struct bio_vec *bvec;
int i;
bio_for_each_segment_all(bvec, bio, i) {
struct page *page = bvec->bv_page;
if (page)
put_page(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 the offending pages 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 page_cache_release() 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)
{
unsigned long flags;
struct bio *bio;
spin_lock_irqsave(&bio_dirty_lock, flags);
bio = bio_dirty_list;
bio_dirty_list = NULL;
spin_unlock_irqrestore(&bio_dirty_lock, flags);
while (bio) {
struct bio *next = bio->bi_private;
bio_set_pages_dirty(bio);
bio_release_pages(bio);
bio_put(bio);
bio = next;
}
}
void bio_check_pages_dirty(struct bio *bio)
{
struct bio_vec *bvec;
int nr_clean_pages = 0;
int i;
bio_for_each_segment_all(bvec, bio, i) {
struct page *page = bvec->bv_page;
if (PageDirty(page) || PageCompound(page)) {
page_cache_release(page);
bvec->bv_page = NULL;
} else {
nr_clean_pages++;
}
}
if (nr_clean_pages) {
unsigned long flags;
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);
} else {
bio_put(bio);
}
}
void generic_start_io_acct(int rw, unsigned long sectors,
struct hd_struct *part)
{
int cpu = part_stat_lock();
part_round_stats(cpu, part);
part_stat_inc(cpu, part, ios[rw]);
part_stat_add(cpu, part, sectors[rw], sectors);
part_inc_in_flight(part, rw);
part_stat_unlock();
}
EXPORT_SYMBOL(generic_start_io_acct);
void generic_end_io_acct(int rw, struct hd_struct *part,
unsigned long start_time)
{
unsigned long duration = jiffies - start_time;
int cpu = part_stat_lock();
part_stat_add(cpu, part, ticks[rw], duration);
part_round_stats(cpu, part);
part_dec_in_flight(part, rw);
part_stat_unlock();
}
EXPORT_SYMBOL(generic_end_io_acct);
#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
void bio_flush_dcache_pages(struct bio *bi)
{
struct bio_vec bvec;
struct bvec_iter iter;
bio_for_each_segment(bvec, bi, iter)
flush_dcache_page(bvec.bv_page);
}
EXPORT_SYMBOL(bio_flush_dcache_pages);
#endif
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.
**/
void bio_endio(struct bio *bio)
{
while (bio) {
if (unlikely(!bio_remaining_done(bio)))
break;
/*
* 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) {
struct bio *parent = bio->bi_private;
parent->bi_error = bio->bi_error;
bio_put(bio);
bio = parent;
} else {
if (bio->bi_end_io)
bio->bi_end_io(bio);
bio = NULL;
}
}
}
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
* @bio is not freed before the split.
*/
struct bio *bio_split(struct bio *bio, int sectors,
gfp_t gfp, struct bio_set *bs)
{
struct bio *split = NULL;
BUG_ON(sectors <= 0);
BUG_ON(sectors >= bio_sectors(bio));
/*
* Discards need a mutable bio_vec to accommodate the payload
* required by the DSM TRIM and UNMAP commands.
*/
if (bio->bi_rw & REQ_DISCARD)
split = bio_clone_bioset(bio, gfp, bs);
else
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, 0, sectors);
bio_advance(bio, split->bi_iter.bi_size);
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_clear_flag(bio, BIO_SEG_VALID);
bio_advance(bio, offset << 9);
bio->bi_iter.bi_size = size;
}
EXPORT_SYMBOL_GPL(bio_trim);
/*
* create memory pools for biovec's in a bio_set.
* use the global biovec slabs created for general use.
*/
mempool_t *biovec_create_pool(int pool_entries)
{
struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
return mempool_create_slab_pool(pool_entries, bp->slab);
}
void bioset_free(struct bio_set *bs)
{
if (bs->rescue_workqueue)
destroy_workqueue(bs->rescue_workqueue);
if (bs->bio_pool)
mempool_destroy(bs->bio_pool);
if (bs->bvec_pool)
mempool_destroy(bs->bvec_pool);
bioset_integrity_free(bs);
bio_put_slab(bs);
kfree(bs);
}
EXPORT_SYMBOL(bioset_free);
static struct bio_set *__bioset_create(unsigned int pool_size,
unsigned int front_pad,
bool create_bvec_pool)
{
unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
struct bio_set *bs;
bs = kzalloc(sizeof(*bs), GFP_KERNEL);
if (!bs)
return NULL;
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) {
kfree(bs);
return NULL;
}
bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
if (!bs->bio_pool)
goto bad;
if (create_bvec_pool) {
bs->bvec_pool = biovec_create_pool(pool_size);
if (!bs->bvec_pool)
goto bad;
}
bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
if (!bs->rescue_workqueue)
goto bad;
return bs;
bad:
bioset_free(bs);
return NULL;
}
/**
* bioset_create - Create a bio_set
* @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
*
* 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.
*/
struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
{
return __bioset_create(pool_size, front_pad, true);
}
EXPORT_SYMBOL(bioset_create);
/**
* bioset_create_nobvec - Create a bio_set without bio_vec mempool
* @pool_size: Number of bio to cache in the mempool
* @front_pad: Number of bytes to allocate in front of the returned bio
*
* Description:
* Same functionality as bioset_create() except that mempool is not
* created for bio_vecs. Saving some memory for bio_clone_fast() users.
*/
struct bio_set *bioset_create_nobvec(unsigned int pool_size, unsigned int front_pad)
{
return __bioset_create(pool_size, front_pad, false);
}
EXPORT_SYMBOL(bioset_create_nobvec);
#ifdef CONFIG_BLK_CGROUP
/**
* bio_associate_blkcg - associate a bio with the specified blkcg
* @bio: target bio
* @blkcg_css: css of the blkcg to associate
*
* Associate @bio with the blkcg specified by @blkcg_css. Block layer will
* treat @bio as if it were issued by a task which belongs to the blkcg.
*
* This function takes an extra reference of @blkcg_css which will be put
* when @bio is released. The caller must own @bio and is responsible for
* synchronizing calls to this function.
*/
int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css)
{
if (unlikely(bio->bi_css))
return -EBUSY;
css_get(blkcg_css);
bio->bi_css = blkcg_css;
return 0;
}
EXPORT_SYMBOL_GPL(bio_associate_blkcg);
/**
* bio_associate_current - associate a bio with %current
* @bio: target bio
*
* Associate @bio with %current if it hasn't been associated yet. Block
* layer will treat @bio as if it were issued by %current no matter which
* task actually issues it.
*
* This function takes an extra reference of @task's io_context and blkcg
* which will be put when @bio is released. The caller must own @bio,
* ensure %current->io_context exists, and is responsible for synchronizing
* calls to this function.
*/
int bio_associate_current(struct bio *bio)
{
struct io_context *ioc;
if (bio->bi_css)
return -EBUSY;
ioc = current->io_context;
if (!ioc)
return -ENOENT;
get_io_context_active(ioc);
bio->bi_ioc = ioc;
bio->bi_css = task_get_css(current, io_cgrp_id);
return 0;
}
EXPORT_SYMBOL_GPL(bio_associate_current);
/**
* bio_disassociate_task - undo bio_associate_current()
* @bio: target bio
*/
void bio_disassociate_task(struct bio *bio)
{
if (bio->bi_ioc) {
put_io_context(bio->bi_ioc);
bio->bi_ioc = NULL;
}
if (bio->bi_css) {
css_put(bio->bi_css);
bio->bi_css = NULL;
}
}
#endif /* CONFIG_BLK_CGROUP */
static void __init biovec_init_slabs(void)
{
int i;
for (i = 0; i < BIOVEC_NR_POOLS; 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 = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
if (!bio_slabs)
panic("bio: can't allocate bios\n");
bio_integrity_init();
biovec_init_slabs();
fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
if (!fs_bio_set)
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);