1 files changed, 390 insertions, 0 deletions

diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c
new file mode 100644
index 000000000000..f565512f6fac
--- /dev/null
+++ b/drivers/md/bcache/io.c
@@ -0,0 +1,390 @@
+/*
+ * 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"
+
+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;
+        }
+
+        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.
+ *
+ * If bch_bio_split() is running under generic_make_request(), it's not safe to
+ * allocate more than one bio from the same bio set. Therefore, if it is running
+ * under generic_make_request() it masks out __GFP_WAIT when doing the
+ * allocation. The caller must check for failure if there's any possibility of
+ * it being called from under generic_make_request(); it is then the caller's
+ * responsibility to retry from a safe context (by e.g. punting to workqueue).
+ */
+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 we're being called from underneath generic_make_request() and we
+         * already allocated any bios from this bio set, we risk deadlock if we
+         * use the mempool. So instead, we possibly fail and let the caller punt
+         * to workqueue or somesuch and retry in a safe context.
+         */
+        if (current->bio_list)
+                gfp &= ~__GFP_WAIT;
+
+        if (sectors >= bio_sectors(bio))
+                return bio;
+
+        if (bio->bi_rw & REQ_DISCARD) {
+                ret = bio_alloc_bioset(gfp, 1, bs);
+                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);
+        struct bio_vec *bv, *end = bio_iovec(bio) +
+                min_t(int, bio_segments(bio), queue_max_segments(q));
+
+        struct bvec_merge_data bvm = {
+                .bi_bdev        = bio->bi_bdev,
+                .bi_sector      = bio->bi_sector,
+                .bi_size        = 0,
+                .bi_rw          = bio->bi_rw,
+        };
+
+        if (bio->bi_rw & REQ_DISCARD)
+                return min(ret, q->limits.max_discard_sectors);
+
+        if (bio_segments(bio) > queue_max_segments(q) ||
+            q->merge_bvec_fn) {
+                ret = 0;
+
+                for (bv = bio_iovec(bio); bv < end; bv++) {
+                        if (q->merge_bvec_fn &&
+                            q->merge_bvec_fn(q, &bvm, bv) < (int) bv->bv_len)
+                                break;
+
+                        ret             += bv->bv_len >> 9;
+                        bvm.bi_size     += bv->bv_len;
+                }
+
+                if (ret >= (BIO_MAX_PAGES * PAGE_SIZE) >> 9)
+                        return (BIO_MAX_PAGES * PAGE_SIZE) >> 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);
+}
+
+static void __bch_bio_submit_split(struct closure *cl)
+{
+        struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
+        struct bio *bio = s->bio, *n;
+
+        do {
+                n = bch_bio_split(bio, bch_bio_max_sectors(bio),
+                                  GFP_NOIO, s->p->bio_split);
+                if (!n)
+                        continue_at(cl, __bch_bio_submit_split, system_wq);
+
+                n->bi_end_io    = bch_bio_submit_split_endio;
+                n->bi_private   = cl;
+
+                closure_get(cl);
+                bch_generic_make_request_hack(n);
+        } while (n != bio);
+
+        continue_at(cl, bch_bio_submit_split_done, NULL);
+}
+
+void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p)
+{
+        struct bio_split_hook *s;
+
+        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);
+
+        s->bio          = bio;
+        s->p            = p;
+        s->bi_end_io    = bio->bi_end_io;
+        s->bi_private   = bio->bi_private;
+        bio_get(bio);
+
+        closure_call(&s->cl, __bch_bio_submit_split, NULL, NULL);
+        return;
+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);
+}