![Coly Li](/assets/img/avatar_default.png)
When md raid device (e.g. raid456) is used as backing device, read-ahead requests on a degrading and recovering md raid device might be failured immediately by md raid code, but indeed this md raid array can still be read or write for normal I/O requests. Therefore such failed read-ahead request are not real hardware failure. Further more, after degrading and recovering accomplished, read-ahead requests will be handled by md raid array again. For such condition, I/O failures of read-ahead requests don't indicate real health status (because normal I/O still be served), they should not be counted into I/O error counter dc->io_errors. Since there is no simple way to detect whether the backing divice is a md raid device, this patch simply ignores I/O failures for read-ahead bios on backing device, to avoid bogus backing device failure on a degrading md raid array. Suggested-and-tested-by: Thorsten Knabe <linux@thorsten-knabe.de> Signed-off-by: Coly Li <colyli@suse.de> Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
175 lines
4.2 KiB
C
175 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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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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/* 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, bio->bi_inline_vecs, bucket_pages(c));
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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_iter.bi_sector = PTR_OFFSET(&b->key, 0);
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bio_set_dev(bio, 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(c, bio, bio->bi_private);
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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 int 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_backing_io_errors(struct cached_dev *dc, struct bio *bio)
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{
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unsigned int errors;
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WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
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/*
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* Read-ahead requests on a degrading and recovering md raid
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* (e.g. raid6) device might be failured immediately by md
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* raid code, which is not a real hardware media failure. So
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* we shouldn't count failed REQ_RAHEAD bio to dc->io_errors.
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*/
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if (bio->bi_opf & REQ_RAHEAD) {
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pr_warn_ratelimited("%s: Read-ahead I/O failed on backing device, ignore",
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dc->backing_dev_name);
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return;
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}
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errors = atomic_add_return(1, &dc->io_errors);
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if (errors < dc->error_limit)
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pr_err("%s: IO error on backing device, unrecoverable",
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dc->backing_dev_name);
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else
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bch_cached_dev_error(dc);
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}
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void bch_count_io_errors(struct cache *ca,
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blk_status_t error,
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int is_read,
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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 int count = atomic_inc_return(&ca->io_count);
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while (count > ca->set->error_decay) {
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unsigned int errors;
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unsigned int old = count;
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unsigned int 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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* successfully 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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unsigned int 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%s",
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ca->cache_dev_name, m,
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is_read ? ", recovering." : ".");
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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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ca->cache_dev_name, 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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blk_status_t 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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int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
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unsigned int threshold = op_is_write(bio_op(bio))
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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 int 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, is_read, m);
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}
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void bch_bbio_endio(struct cache_set *c, struct bio *bio,
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blk_status_t 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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