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