// SPDX-License-Identifier: GPL-2.0
/*
 * 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>

/* 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_inline(bio, NULL, meta_bucket_pages(&c->cache->sb), 0);

        return bio;
}

void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
{
        struct bbio *b = container_of(bio, struct bbio, bio);

        bio->bi_iter.bi_sector  = PTR_OFFSET(&b->key, 0);
        bio_set_dev(bio, c->cache->bdev);

        b->submit_time_us = local_clock_us();
        closure_bio_submit(c, bio, bio->bi_private);
}

void bch_submit_bbio(struct bio *bio, struct cache_set *c,
                     struct bkey *k, unsigned int 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_backing_io_errors(struct cached_dev *dc, struct bio *bio)
{
        unsigned int errors;

        WARN_ONCE(!dc, "NULL pointer of struct cached_dev");

        /*
         * Read-ahead requests on a degrading and recovering md raid
         * (e.g. raid6) device might be failured immediately by md
         * raid code, which is not a real hardware media failure. So
         * we shouldn't count failed REQ_RAHEAD bio to dc->io_errors.
         */
        if (bio->bi_opf & REQ_RAHEAD) {
                pr_warn_ratelimited("%pg: Read-ahead I/O failed on backing device, ignore\n",
                                    dc->bdev);
                return;
        }

        errors = atomic_add_return(1, &dc->io_errors);
        if (errors < dc->error_limit)
                pr_err("%pg: IO error on backing device, unrecoverable\n",
                        dc->bdev);
        else
                bch_cached_dev_error(dc);
}

void bch_count_io_errors(struct cache *ca,
                         blk_status_t error,
                         int is_read,
                         const char *m)
{
        /*
         * The halflife of an error is:
         * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
         */

        if (ca->set->error_decay) {
                unsigned int count = atomic_inc_return(&ca->io_count);

                while (count > ca->set->error_decay) {
                        unsigned int errors;
                        unsigned int old = count;
                        unsigned int new = count - ca->set->error_decay;

                        /*
                         * First we subtract refresh from count; each time we
                         * successfully 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) {
                unsigned int errors = atomic_add_return(1 << IO_ERROR_SHIFT,
                                                    &ca->io_errors);
                errors >>= IO_ERROR_SHIFT;

                if (errors < ca->set->error_limit)
                        pr_err("%pg: IO error on %s%s\n",
                               ca->bdev, m,
                               is_read ? ", recovering." : ".");
                else
                        bch_cache_set_error(ca->set,
                                            "%pg: too many IO errors %s\n",
                                            ca->bdev, m);
        }
}

void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
                              blk_status_t error, const char *m)
{
        struct bbio *b = container_of(bio, struct bbio, bio);
        struct cache *ca = c->cache;
        int is_read = (bio_data_dir(bio) == READ ? 1 : 0);

        unsigned int threshold = op_is_write(bio_op(bio))
                ? c->congested_write_threshold_us
                : c->congested_read_threshold_us;

        if (threshold) {
                unsigned int 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, is_read, m);
}

void bch_bbio_endio(struct cache_set *c, struct bio *bio,
                    blk_status_t 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);
}