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linux-next/drivers/md/raid5-log.h
Song Liu 70d466f760 md/r5cache: gracefully handle journal device errors for writeback mode
For the raid456 with writeback cache, when journal device failed during
normal operation, it is still possible to persist all data, as all
pending data is still in stripe cache. However, it is necessary to handle
journal failure gracefully.

During journal failures, the following logic handles the graceful shutdown
of journal:
1. raid5_error() marks the device as Faulty and schedules async work
   log->disable_writeback_work;
2. In disable_writeback_work (r5c_disable_writeback_async), the mddev is
   suspended, set to write through, and then resumed. mddev_suspend()
   flushes all cached stripes;
3. All cached stripes need to be flushed carefully to the RAID array.

This patch fixes issues within the process above:
1. In r5c_update_on_rdev_error() schedule disable_writeback_work for
   journal failures;
2. In r5c_disable_writeback_async(), wait for MD_SB_CHANGE_PENDING,
   since raid5_error() updates superblock.
3. In handle_stripe(), allow stripes with data in journal (s.injournal > 0)
   to make progress during log_failed;
4. In delay_towrite(), if log failed only process data in the cache (skip
   new writes in dev->towrite);
5. In __get_priority_stripe(), process loprio_list during journal device
   failures.
6. In raid5_remove_disk(), wait for all cached stripes are flushed before
   calling log_exit().

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
2017-05-11 22:11:11 -07:00

117 lines
3.7 KiB
C

#ifndef _RAID5_LOG_H
#define _RAID5_LOG_H
extern int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev);
extern void r5l_exit_log(struct r5conf *conf);
extern int r5l_write_stripe(struct r5l_log *log, struct stripe_head *head_sh);
extern void r5l_write_stripe_run(struct r5l_log *log);
extern void r5l_flush_stripe_to_raid(struct r5l_log *log);
extern void r5l_stripe_write_finished(struct stripe_head *sh);
extern int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio);
extern void r5l_quiesce(struct r5l_log *log, int state);
extern bool r5l_log_disk_error(struct r5conf *conf);
extern bool r5c_is_writeback(struct r5l_log *log);
extern int
r5c_try_caching_write(struct r5conf *conf, struct stripe_head *sh,
struct stripe_head_state *s, int disks);
extern void
r5c_finish_stripe_write_out(struct r5conf *conf, struct stripe_head *sh,
struct stripe_head_state *s);
extern void r5c_release_extra_page(struct stripe_head *sh);
extern void r5c_use_extra_page(struct stripe_head *sh);
extern void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
extern void r5c_handle_cached_data_endio(struct r5conf *conf,
struct stripe_head *sh, int disks);
extern int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh);
extern void r5c_make_stripe_write_out(struct stripe_head *sh);
extern void r5c_flush_cache(struct r5conf *conf, int num);
extern void r5c_check_stripe_cache_usage(struct r5conf *conf);
extern void r5c_check_cached_full_stripe(struct r5conf *conf);
extern struct md_sysfs_entry r5c_journal_mode;
extern void r5c_update_on_rdev_error(struct mddev *mddev,
struct md_rdev *rdev);
extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
extern struct dma_async_tx_descriptor *
ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
struct dma_async_tx_descriptor *tx);
extern int ppl_init_log(struct r5conf *conf);
extern void ppl_exit_log(struct r5conf *conf);
extern int ppl_write_stripe(struct r5conf *conf, struct stripe_head *sh);
extern void ppl_write_stripe_run(struct r5conf *conf);
extern void ppl_stripe_write_finished(struct stripe_head *sh);
extern int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add);
static inline bool raid5_has_ppl(struct r5conf *conf)
{
return test_bit(MD_HAS_PPL, &conf->mddev->flags);
}
static inline int log_stripe(struct stripe_head *sh, struct stripe_head_state *s)
{
struct r5conf *conf = sh->raid_conf;
if (conf->log) {
if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
/* writing out phase */
if (s->waiting_extra_page)
return 0;
return r5l_write_stripe(conf->log, sh);
} else if (test_bit(STRIPE_LOG_TRAPPED, &sh->state)) {
/* caching phase */
return r5c_cache_data(conf->log, sh);
}
} else if (raid5_has_ppl(conf)) {
return ppl_write_stripe(conf, sh);
}
return -EAGAIN;
}
static inline void log_stripe_write_finished(struct stripe_head *sh)
{
struct r5conf *conf = sh->raid_conf;
if (conf->log)
r5l_stripe_write_finished(sh);
else if (raid5_has_ppl(conf))
ppl_stripe_write_finished(sh);
}
static inline void log_write_stripe_run(struct r5conf *conf)
{
if (conf->log)
r5l_write_stripe_run(conf->log);
else if (raid5_has_ppl(conf))
ppl_write_stripe_run(conf);
}
static inline void log_exit(struct r5conf *conf)
{
if (conf->log)
r5l_exit_log(conf);
else if (raid5_has_ppl(conf))
ppl_exit_log(conf);
}
static inline int log_init(struct r5conf *conf, struct md_rdev *journal_dev,
bool ppl)
{
if (journal_dev)
return r5l_init_log(conf, journal_dev);
else if (ppl)
return ppl_init_log(conf);
return 0;
}
static inline int log_modify(struct r5conf *conf, struct md_rdev *rdev, bool add)
{
if (raid5_has_ppl(conf))
return ppl_modify_log(conf, rdev, add);
return 0;
}
#endif