linux/drivers/md/bcache/io.c
Kent Overstreet 8e51e414a3 bcache: Use standard utility code
Some of bcache's utility code has made it into the rest of the kernel,
so drop the bcache versions.

Bcache used to have a workaround for allocating from a bio set under
generic_make_request() (if you allocated more than once, the bios you
already allocated would get stuck on current->bio_list when you
submitted, and you'd risk deadlock) - bcache would mask out __GFP_WAIT
when allocating bios under generic_make_request() so that allocation
could fail and it could retry from workqueue. But bio_alloc_bioset() has
a workaround now, so we can drop this hack and the associated error
handling.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
2013-07-01 14:43:53 -07:00

382 lines
8.6 KiB
C

/*
* Some low level IO code, and hacks for various block layer limitations
*
* Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
* Copyright 2012 Google, Inc.
*/
#include "bcache.h"
#include "bset.h"
#include "debug.h"
#include <linux/blkdev.h>
static void bch_bi_idx_hack_endio(struct bio *bio, int error)
{
struct bio *p = bio->bi_private;
bio_endio(p, error);
bio_put(bio);
}
static void bch_generic_make_request_hack(struct bio *bio)
{
if (bio->bi_idx) {
struct bio *clone = bio_alloc(GFP_NOIO, bio_segments(bio));
memcpy(clone->bi_io_vec,
bio_iovec(bio),
bio_segments(bio) * sizeof(struct bio_vec));
clone->bi_sector = bio->bi_sector;
clone->bi_bdev = bio->bi_bdev;
clone->bi_rw = bio->bi_rw;
clone->bi_vcnt = bio_segments(bio);
clone->bi_size = bio->bi_size;
clone->bi_private = bio;
clone->bi_end_io = bch_bi_idx_hack_endio;
bio = clone;
}
/*
* Hack, since drivers that clone bios clone up to bi_max_vecs, but our
* bios might have had more than that (before we split them per device
* limitations).
*
* To be taken out once immutable bvec stuff is in.
*/
bio->bi_max_vecs = bio->bi_vcnt;
generic_make_request(bio);
}
/**
* bch_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.
*
* If bio_sectors(@bio) was less than or equal to @sectors, returns @bio
* unchanged.
*
* The newly allocated bio will point to @bio's bi_io_vec, if the split was on a
* bvec boundry; it is the caller's responsibility to ensure that @bio is not
* freed before the split.
*/
struct bio *bch_bio_split(struct bio *bio, int sectors,
gfp_t gfp, struct bio_set *bs)
{
unsigned idx = bio->bi_idx, vcnt = 0, nbytes = sectors << 9;
struct bio_vec *bv;
struct bio *ret = NULL;
BUG_ON(sectors <= 0);
if (sectors >= bio_sectors(bio))
return bio;
if (bio->bi_rw & REQ_DISCARD) {
ret = bio_alloc_bioset(gfp, 1, bs);
if (!ret)
return NULL;
idx = 0;
goto out;
}
bio_for_each_segment(bv, bio, idx) {
vcnt = idx - bio->bi_idx;
if (!nbytes) {
ret = bio_alloc_bioset(gfp, vcnt, bs);
if (!ret)
return NULL;
memcpy(ret->bi_io_vec, bio_iovec(bio),
sizeof(struct bio_vec) * vcnt);
break;
} else if (nbytes < bv->bv_len) {
ret = bio_alloc_bioset(gfp, ++vcnt, bs);
if (!ret)
return NULL;
memcpy(ret->bi_io_vec, bio_iovec(bio),
sizeof(struct bio_vec) * vcnt);
ret->bi_io_vec[vcnt - 1].bv_len = nbytes;
bv->bv_offset += nbytes;
bv->bv_len -= nbytes;
break;
}
nbytes -= bv->bv_len;
}
out:
ret->bi_bdev = bio->bi_bdev;
ret->bi_sector = bio->bi_sector;
ret->bi_size = sectors << 9;
ret->bi_rw = bio->bi_rw;
ret->bi_vcnt = vcnt;
ret->bi_max_vecs = vcnt;
bio->bi_sector += sectors;
bio->bi_size -= sectors << 9;
bio->bi_idx = idx;
if (bio_integrity(bio)) {
if (bio_integrity_clone(ret, bio, gfp)) {
bio_put(ret);
return NULL;
}
bio_integrity_trim(ret, 0, bio_sectors(ret));
bio_integrity_trim(bio, bio_sectors(ret), bio_sectors(bio));
}
return ret;
}
static unsigned bch_bio_max_sectors(struct bio *bio)
{
unsigned ret = bio_sectors(bio);
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
unsigned max_segments = min_t(unsigned, BIO_MAX_PAGES,
queue_max_segments(q));
if (bio->bi_rw & REQ_DISCARD)
return min(ret, q->limits.max_discard_sectors);
if (bio_segments(bio) > max_segments ||
q->merge_bvec_fn) {
struct bio_vec *bv;
int i, seg = 0;
ret = 0;
bio_for_each_segment(bv, bio, i) {
struct bvec_merge_data bvm = {
.bi_bdev = bio->bi_bdev,
.bi_sector = bio->bi_sector,
.bi_size = ret << 9,
.bi_rw = bio->bi_rw,
};
if (seg == max_segments)
break;
if (q->merge_bvec_fn &&
q->merge_bvec_fn(q, &bvm, bv) < (int) bv->bv_len)
break;
seg++;
ret += bv->bv_len >> 9;
}
}
ret = min(ret, queue_max_sectors(q));
WARN_ON(!ret);
ret = max_t(int, ret, bio_iovec(bio)->bv_len >> 9);
return ret;
}
static void bch_bio_submit_split_done(struct closure *cl)
{
struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
s->bio->bi_end_io = s->bi_end_io;
s->bio->bi_private = s->bi_private;
bio_endio(s->bio, 0);
closure_debug_destroy(&s->cl);
mempool_free(s, s->p->bio_split_hook);
}
static void bch_bio_submit_split_endio(struct bio *bio, int error)
{
struct closure *cl = bio->bi_private;
struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
if (error)
clear_bit(BIO_UPTODATE, &s->bio->bi_flags);
bio_put(bio);
closure_put(cl);
}
void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p)
{
struct bio_split_hook *s;
struct bio *n;
if (!bio_has_data(bio) && !(bio->bi_rw & REQ_DISCARD))
goto submit;
if (bio_sectors(bio) <= bch_bio_max_sectors(bio))
goto submit;
s = mempool_alloc(p->bio_split_hook, GFP_NOIO);
closure_init(&s->cl, NULL);
s->bio = bio;
s->p = p;
s->bi_end_io = bio->bi_end_io;
s->bi_private = bio->bi_private;
bio_get(bio);
do {
n = bch_bio_split(bio, bch_bio_max_sectors(bio),
GFP_NOIO, s->p->bio_split);
n->bi_end_io = bch_bio_submit_split_endio;
n->bi_private = &s->cl;
closure_get(&s->cl);
bch_generic_make_request_hack(n);
} while (n != bio);
continue_at(&s->cl, bch_bio_submit_split_done, NULL);
submit:
bch_generic_make_request_hack(bio);
}
/* Bios with headers */
void bch_bbio_free(struct bio *bio, struct cache_set *c)
{
struct bbio *b = container_of(bio, struct bbio, bio);
mempool_free(b, c->bio_meta);
}
struct bio *bch_bbio_alloc(struct cache_set *c)
{
struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO);
struct bio *bio = &b->bio;
bio_init(bio);
bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET;
bio->bi_max_vecs = bucket_pages(c);
bio->bi_io_vec = bio->bi_inline_vecs;
return bio;
}
void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
{
struct bbio *b = container_of(bio, struct bbio, bio);
bio->bi_sector = PTR_OFFSET(&b->key, 0);
bio->bi_bdev = PTR_CACHE(c, &b->key, 0)->bdev;
b->submit_time_us = local_clock_us();
closure_bio_submit(bio, bio->bi_private, PTR_CACHE(c, &b->key, 0));
}
void bch_submit_bbio(struct bio *bio, struct cache_set *c,
struct bkey *k, unsigned ptr)
{
struct bbio *b = container_of(bio, struct bbio, bio);
bch_bkey_copy_single_ptr(&b->key, k, ptr);
__bch_submit_bbio(bio, c);
}
/* IO errors */
void bch_count_io_errors(struct cache *ca, int error, const char *m)
{
/*
* The halflife of an error is:
* log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
*/
if (ca->set->error_decay) {
unsigned count = atomic_inc_return(&ca->io_count);
while (count > ca->set->error_decay) {
unsigned errors;
unsigned old = count;
unsigned new = count - ca->set->error_decay;
/*
* First we subtract refresh from count; each time we
* succesfully do so, we rescale the errors once:
*/
count = atomic_cmpxchg(&ca->io_count, old, new);
if (count == old) {
count = new;
errors = atomic_read(&ca->io_errors);
do {
old = errors;
new = ((uint64_t) errors * 127) / 128;
errors = atomic_cmpxchg(&ca->io_errors,
old, new);
} while (old != errors);
}
}
}
if (error) {
char buf[BDEVNAME_SIZE];
unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
&ca->io_errors);
errors >>= IO_ERROR_SHIFT;
if (errors < ca->set->error_limit)
pr_err("%s: IO error on %s, recovering",
bdevname(ca->bdev, buf), m);
else
bch_cache_set_error(ca->set,
"%s: too many IO errors %s",
bdevname(ca->bdev, buf), m);
}
}
void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
int error, const char *m)
{
struct bbio *b = container_of(bio, struct bbio, bio);
struct cache *ca = PTR_CACHE(c, &b->key, 0);
unsigned threshold = bio->bi_rw & REQ_WRITE
? c->congested_write_threshold_us
: c->congested_read_threshold_us;
if (threshold) {
unsigned t = local_clock_us();
int us = t - b->submit_time_us;
int congested = atomic_read(&c->congested);
if (us > (int) threshold) {
int ms = us / 1024;
c->congested_last_us = t;
ms = min(ms, CONGESTED_MAX + congested);
atomic_sub(ms, &c->congested);
} else if (congested < 0)
atomic_inc(&c->congested);
}
bch_count_io_errors(ca, error, m);
}
void bch_bbio_endio(struct cache_set *c, struct bio *bio,
int error, const char *m)
{
struct closure *cl = bio->bi_private;
bch_bbio_count_io_errors(c, bio, error, m);
bio_put(bio);
closure_put(cl);
}