Re: [PATCH v1 09/10] bcache: add io_disable to struct cache_set

Hannes Reinecke
2018-01-08T07:30:31Z

On 01/03/2018 03:03 PM, Coly Li wrote:
> When too many I/Os failed on cache device, bch_cache_set_error() is called
> in the error handling code path to retire whole problematic cache set. If
> new I/O requests continue to come and take refcount dc->count, the cache
> set won't be retired immediately, this is a problem.
>
> Further more, there are several kernel thread and self-armed kernel work
> may still running after bch_cache_set_error() is called. It needs to wait
> quite a while for them to stop, or they won't stop at all. They also
> prevent the cache set from being retired.
>
> The solution in this patch is, to add per cache set flag to disable I/O
> request on this cache and all attached backing devices. Then new coming I/O
> requests can be rejected in *_make_request() before taking refcount, kernel
> threads and self-armed kernel worker can stop very fast when io_disable is
> true.
>
> Because bcache also do internal I/Os for writeback, garbage collection,
> bucket allocation, journaling, this kind of I/O should be disabled after
> bch_cache_set_error() is called. So closure_bio_submit() is modified to
> check whether cache_set->io_disable is true. If cache_set->io_disable is
> true, closure_bio_submit() will set bio->bi_status to BLK_STS_IOERR and
> return, generic_make_request() won't be called.
>
> A sysfs interface is also added for cache_set->io_disable, to read and set
> io_disable value for debugging. It is helpful to trigger more corner case
> issues for failed cache device.
>
> Signed-off-by: Coly Li <colyli@suse.de>
> ---
> drivers/md/bcache/alloc.c | 2 +-
> drivers/md/bcache/bcache.h | 14 ++++++++++++++
> drivers/md/bcache/btree.c | 6 ++++--
> drivers/md/bcache/io.c | 2 +-
> drivers/md/bcache/journal.c | 4 ++--
> drivers/md/bcache/request.c | 26 +++++++++++++++++++-------
> drivers/md/bcache/super.c | 7 ++++++-
> drivers/md/bcache/sysfs.c | 4 ++++
> drivers/md/bcache/util.h | 6 ------
> drivers/md/bcache/writeback.c | 34 ++++++++++++++++++++++------------
> 10 files changed, 73 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
> index 48c002faf08d..3be737582f27 100644
> --- a/drivers/md/bcache/alloc.c
> +++ b/drivers/md/bcache/alloc.c
> @@ -286,7 +286,7 @@ do { \
> break; \
> \
> mutex_unlock(&(ca)->set->bucket_lock); \
> - if (kthread_should_stop()) \
> + if (kthread_should_stop() || ca->set->io_disable) \
> return 0; \
> \
> set_current_state(TASK_INTERRUPTIBLE); \
> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> index c53f312b2216..9c7f9b1cb791 100644
> --- a/drivers/md/bcache/bcache.h
> +++ b/drivers/md/bcache/bcache.h
> @@ -481,6 +481,7 @@ struct cache_set {
> struct cache_accounting accounting;
>
> unsigned long flags;
> + bool io_disable;
>
> struct cache_sb sb;
>
> @@ -853,6 +854,19 @@ static inline void wake_up_allocators(struct cache_set *c)
> wake_up_process(ca->alloc_thread);
> }
>
> +static inline void closure_bio_submit(struct cache_set *c,
> + struct bio *bio,
> + struct closure *cl)
> +{
> + closure_get(cl);
> + if (unlikely(c->io_disable)) {
> + bio->bi_status = BLK_STS_IOERR;
> + bio_endio(bio);
> + return;
> + }
> + generic_make_request(bio);
> +}
> +
> /* Forward declarations */
>
> void bch_count_io_errors(struct cache *, blk_status_t, int, const char *);
> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> index bf0d7978bc3d..75470cce1177 100644
> --- a/drivers/md/bcache/btree.c
> +++ b/drivers/md/bcache/btree.c
> @@ -1788,9 +1788,11 @@ static int bch_gc_thread(void *arg)
>
> while (1) {
> wait_event_interruptible(c->gc_wait,
> - kthread_should_stop() || gc_should_run(c));
> + kthread_should_stop() ||
> + c->io_disable ||
> + gc_should_run(c));
>
> - if (kthread_should_stop())
> + if (kthread_should_stop() || c->io_disable)
> break;
>
> set_gc_sectors(c);
> diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c
> index a783c5a41ff1..8013ecbcdbda 100644
> --- a/drivers/md/bcache/io.c
> +++ b/drivers/md/bcache/io.c
> @@ -38,7 +38,7 @@ void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
> bio_set_dev(bio, PTR_CACHE(c, &b->key, 0)->bdev);
>
> b->submit_time_us = local_clock_us();
> - closure_bio_submit(bio, bio->bi_private);
> + closure_bio_submit(c, bio, bio->bi_private);
> }
>
> void bch_submit_bbio(struct bio *bio, struct cache_set *c,
> diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
> index a87165c1d8e5..979873641030 100644
> --- a/drivers/md/bcache/journal.c
> +++ b/drivers/md/bcache/journal.c
> @@ -62,7 +62,7 @@ reread: left = ca->sb.bucket_size - offset;
> bio_set_op_attrs(bio, REQ_OP_READ, 0);
> bch_bio_map(bio, data);
>
> - closure_bio_submit(bio, &cl);
> + closure_bio_submit(ca->set, bio, &cl);
> closure_sync(&cl);
>
> /* This function could be simpler now since we no longer write
> @@ -653,7 +653,7 @@ static void journal_write_unlocked(struct closure *cl)
> spin_unlock(&c->journal.lock);
>
> while ((bio = bio_list_pop(&list)))
> - closure_bio_submit(bio, cl);
> + closure_bio_submit(c, bio, cl);
>
> continue_at(cl, journal_write_done, NULL);
> }
> diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
> index 643c3021624f..a85d6a605a8e 100644
> --- a/drivers/md/bcache/request.c
> +++ b/drivers/md/bcache/request.c
> @@ -725,7 +725,7 @@ static void cached_dev_read_error(struct closure *cl)
>
> /* XXX: invalidate cache */
>
> - closure_bio_submit(bio, cl);
> + closure_bio_submit(s->iop.c, bio, cl);
> }
>
> continue_at(cl, cached_dev_cache_miss_done, NULL);
> @@ -850,7 +850,7 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
> s->cache_miss = miss;
> s->iop.bio = cache_bio;
> bio_get(cache_bio);
> - closure_bio_submit(cache_bio, &s->cl);
> + closure_bio_submit(s->iop.c, cache_bio, &s->cl);
>
> return ret;
> out_put:
> @@ -858,7 +858,7 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
> out_submit:
> miss->bi_end_io = request_endio;
> miss->bi_private = &s->cl;
> - closure_bio_submit(miss, &s->cl);
> + closure_bio_submit(s->iop.c, miss, &s->cl);
> return ret;
> }
>
> @@ -923,7 +923,7 @@ static void cached_dev_write(struct cached_dev *dc, struct search *s)
>
> if ((bio_op(bio) != REQ_OP_DISCARD) ||
> blk_queue_discard(bdev_get_queue(dc->bdev)))
> - closure_bio_submit(bio, cl);
> + closure_bio_submit(s->iop.c, bio, cl);
> } else if (s->iop.writeback) {
> bch_writeback_add(dc);
> s->iop.bio = bio;
> @@ -938,12 +938,12 @@ static void cached_dev_write(struct cached_dev *dc, struct search *s)
> flush->bi_private = cl;
> flush->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
>
> - closure_bio_submit(flush, cl);
> + closure_bio_submit(s->iop.c, flush, cl);
> }
> } else {
> s->iop.bio = bio_clone_fast(bio, GFP_NOIO, dc->disk.bio_split);
>
> - closure_bio_submit(bio, cl);
> + closure_bio_submit(s->iop.c, bio, cl);
> }
>
> closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
> @@ -959,7 +959,7 @@ static void cached_dev_nodata(struct closure *cl)
> bch_journal_meta(s->iop.c, cl);
>
> /* If it's a flush, we send the flush to the backing device too */
> - closure_bio_submit(bio, cl);
> + closure_bio_submit(s->iop.c, bio, cl);
>
> continue_at(cl, cached_dev_bio_complete, NULL);
> }
> @@ -974,6 +974,12 @@ static blk_qc_t cached_dev_make_request(struct request_queue *q,
> struct cached_dev *dc = container_of(d, struct cached_dev, disk);
> int rw = bio_data_dir(bio);
>
> + if (unlikely(d->c && d->c->io_disable)) {
> + bio->bi_status = BLK_STS_IOERR;
> + bio_endio(bio);
> + return BLK_QC_T_NONE;
> + }
> +
> generic_start_io_acct(q, rw, bio_sectors(bio), &d->disk->part0);
>
> bio_set_dev(bio, dc->bdev);
> @@ -1089,6 +1095,12 @@ static blk_qc_t flash_dev_make_request(struct request_queue *q,
> struct bcache_device *d = bio->bi_disk->private_data;
> int rw = bio_data_dir(bio);
>
> + if (unlikely(d->c->io_disable)) {
> + bio->bi_status = BLK_STS_IOERR;
> + bio_endio(bio);
> + return BLK_QC_T_NONE;
> + }
> +
> generic_start_io_acct(q, rw, bio_sectors(bio), &d->disk->part0);
>
> s = search_alloc(bio, d);
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index bbe911847eea..7aa76c3e3556 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -521,7 +521,7 @@ static void prio_io(struct cache *ca, uint64_t bucket, int op,
> bio_set_op_attrs(bio, op, REQ_SYNC|REQ_META|op_flags);
> bch_bio_map(bio, ca->disk_buckets);
>
> - closure_bio_submit(bio, &ca->prio);
> + closure_bio_submit(ca->set, bio, &ca->prio);
> closure_sync(cl);
> }
>
> @@ -1333,6 +1333,10 @@ bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...)
> acquire_console_sem();
> */
>
> + c->io_disable = true;
> + /* make others know io_disable is true earlier */
> + smp_mb();
> +
> printk(KERN_ERR "bcache: error on %pU: ", c->sb.set_uuid);
>
> va_start(args, fmt);
> @@ -1564,6 +1568,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
> c->congested_read_threshold_us = 2000;
> c->congested_write_threshold_us = 20000;
> c->error_limit = DEFAULT_IO_ERROR_LIMIT;
> + c->io_disable = false;
>
> return c;
> err:
> diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
> index d7ce9a05b304..acce7c82e111 100644
> --- a/drivers/md/bcache/sysfs.c
> +++ b/drivers/md/bcache/sysfs.c
> @@ -92,6 +92,7 @@ read_attribute(partial_stripes_expensive);
>
> rw_attribute(synchronous);
> rw_attribute(journal_delay_ms);
> +rw_attribute(io_disable);
> rw_attribute(discard);
> rw_attribute(running);
> rw_attribute(label);
> @@ -573,6 +574,7 @@ SHOW(__bch_cache_set)
> sysfs_printf(gc_always_rewrite, "%i", c->gc_always_rewrite);
> sysfs_printf(btree_shrinker_disabled, "%i", c->shrinker_disabled);
> sysfs_printf(copy_gc_enabled, "%i", c->copy_gc_enabled);
> + sysfs_printf(io_disable, "%i", c->io_disable);
>
> if (attr == &sysfs_bset_tree_stats)
> return bch_bset_print_stats(c, buf);
> @@ -663,6 +665,7 @@ STORE(__bch_cache_set)
> c->error_decay = strtoul_or_return(buf) / 88;
>
> sysfs_strtoul(journal_delay_ms, c->journal_delay_ms);
> + sysfs_strtoul_clamp(io_disable, c->io_disable, 0, 1);
> sysfs_strtoul(verify, c->verify);
> sysfs_strtoul(key_merging_disabled, c->key_merging_disabled);
> sysfs_strtoul(expensive_debug_checks, c->expensive_debug_checks);
> @@ -744,6 +747,7 @@ static struct attribute *bch_cache_set_internal_files[] = {
> &sysfs_gc_always_rewrite,
> &sysfs_btree_shrinker_disabled,
> &sysfs_copy_gc_enabled,
> + &sysfs_io_disable,
> NULL
> };
> KTYPE(bch_cache_set_internal);
> diff --git a/drivers/md/bcache/util.h b/drivers/md/bcache/util.h
> index ed5e8a412eb8..03e533631798 100644
> --- a/drivers/md/bcache/util.h
> +++ b/drivers/md/bcache/util.h
> @@ -564,12 +564,6 @@ static inline sector_t bdev_sectors(struct block_device *bdev)
> return bdev->bd_inode->i_size >> 9;
> }
>
> -#define closure_bio_submit(bio, cl) \
> -do { \
> - closure_get(cl); \
> - generic_make_request(bio); \
> -} while (0)
> -
> uint64_t bch_crc64_update(uint64_t, const void *, size_t);
> uint64_t bch_crc64(const void *, size_t);
>
> diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
> index e58f9be5ae43..54add41d2569 100644
> --- a/drivers/md/bcache/writeback.c
> +++ b/drivers/md/bcache/writeback.c
> @@ -93,8 +93,11 @@ static void update_writeback_rate(struct work_struct *work)
> writeback_rate_update);
> struct cache_set *c = dc->disk.c;
>
> - /* quit directly if cache set is stopping */
> - if (test_bit(CACHE_SET_STOPPING, &c->flags))
> + /*
> + * quit directly if cache set is stopping. c->io_disable
> + * can be set via sysfs, check it here too.
> + */
> + if (test_bit(CACHE_SET_STOPPING, &c->flags) || c->io_disable)
> return;
>
> down_read(&dc->writeback_lock);
> @@ -105,8 +108,11 @@ static void update_writeback_rate(struct work_struct *work)
>
> up_read(&dc->writeback_lock);
>
> - /* do not schedule delayed work if cache set is stopping */
> - if (test_bit(CACHE_SET_STOPPING, &c->flags))
> + /*
> + * do not schedule delayed work if cache set is stopping,
> + * c->io_disable can be set via sysfs, check it here too.
> + */
> + if (test_bit(CACHE_SET_STOPPING, &c->flags) || c->io_disable)
> return;
>
> schedule_delayed_work(&dc->writeback_rate_update,
> @@ -217,7 +223,7 @@ static void write_dirty(struct closure *cl)
> bio_set_dev(&io->bio, io->dc->bdev);
> io->bio.bi_end_io = dirty_endio;
>
> - closure_bio_submit(&io->bio, cl);
> + closure_bio_submit(io->dc->disk.c, &io->bio, cl);
> }
>
> continue_at(cl, write_dirty_finish, io->dc->writeback_write_wq);
> @@ -240,7 +246,7 @@ static void read_dirty_submit(struct closure *cl)
> {
> struct dirty_io *io = container_of(cl, struct dirty_io, cl);
>
> - closure_bio_submit(&io->bio, cl);
> + closure_bio_submit(io->dc->disk.c, &io->bio, cl);
>
> continue_at(cl, write_dirty, io->dc->writeback_write_wq);
> }
> @@ -259,7 +265,7 @@ static void read_dirty(struct cached_dev *dc)
> * mempools.
> */
>
> - while (!kthread_should_stop()) {
> + while (!(kthread_should_stop() || dc->disk.c->io_disable)) {
>
> w = bch_keybuf_next(&dc->writeback_keys);
> if (!w)
> @@ -269,7 +275,9 @@ static void read_dirty(struct cached_dev *dc)
>
> if (KEY_START(&w->key) != dc->last_read ||
> jiffies_to_msecs(delay) > 50)
> - while (!kthread_should_stop() && delay)
> + while (!kthread_should_stop() &&
> + !dc->disk.c->io_disable &&
> + delay)
> delay = schedule_timeout_interruptible(delay);
>
> dc->last_read = KEY_OFFSET(&w->key);
> @@ -450,18 +458,19 @@ static bool refill_dirty(struct cached_dev *dc)
> static int bch_writeback_thread(void *arg)
> {
> struct cached_dev *dc = arg;
> + struct cache_set *c = dc->disk.c;
> bool searched_full_index;
>
> bch_ratelimit_reset(&dc->writeback_rate);
>
> - while (!kthread_should_stop()) {
> + while (!(kthread_should_stop() || c->io_disable)) {
> down_write(&dc->writeback_lock);
> if (!atomic_read(&dc->has_dirty) ||
> (!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) &&
> !dc->writeback_running)) {
> up_write(&dc->writeback_lock);
>
> - if (kthread_should_stop())
> + if (kthread_should_stop() || c->io_disable)
> break;
>
> set_current_state(TASK_INTERRUPTIBLE);
> @@ -485,8 +494,8 @@ static int bch_writeback_thread(void *arg)
> if (searched_full_index) {
> unsigned delay = dc->writeback_delay * HZ;
>
> - while (delay &&
> - !kthread_should_stop() &&
> + while (delay && !kthread_should_stop() &&
> + !c->io_disable &&
> !test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
> delay = schedule_timeout_interruptible(delay);
>
> @@ -494,6 +503,7 @@ static int bch_writeback_thread(void *arg)
> }
> }
>
> + dc->writeback_thread = NULL;
> cached_dev_put(dc);
>
> return 0;
>
The last hunk actually belong to the previous patch; please move it to
there.

Otherwise:

Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)