diff options
| -rw-r--r-- | drivers/md/raid5-cache.c | 171 | ||||
| -rw-r--r-- | drivers/md/raid5.c | 20 | ||||
| -rw-r--r-- | drivers/md/raid5.h | 1 |
3 files changed, 168 insertions, 24 deletions
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index 302dea3296ba..76c0e5063f1b 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -20,6 +20,7 @@ #include <linux/crc32c.h> #include <linux/random.h> #include <linux/kthread.h> +#include <linux/types.h> #include "md.h" #include "raid5.h" #include "bitmap.h" @@ -164,9 +165,60 @@ struct r5l_log { struct work_struct deferred_io_work; /* to disable write back during in degraded mode */ struct work_struct disable_writeback_work; + + /* to for chunk_aligned_read in writeback mode, details below */ + spinlock_t tree_lock; + struct radix_tree_root big_stripe_tree; }; /* + * Enable chunk_aligned_read() with write back cache. + * + * Each chunk may contain more than one stripe (for example, a 256kB + * chunk contains 64 4kB-page, so this chunk contain 64 stripes). For + * chunk_aligned_read, these stripes are grouped into one "big_stripe". + * For each big_stripe, we count how many stripes of this big_stripe + * are in the write back cache. These data are tracked in a radix tree + * (big_stripe_tree). We use radix_tree item pointer as the counter. + * r5c_tree_index() is used to calculate keys for the radix tree. + * + * chunk_aligned_read() calls r5c_big_stripe_cached() to look up + * big_stripe of each chunk in the tree. If this big_stripe is in the + * tree, chunk_aligned_read() aborts. This look up is protected by + * rcu_read_lock(). + * + * It is necessary to remember whether a stripe is counted in + * big_stripe_tree. Instead of adding new flag, we reuses existing flags: + * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE. If either of these + * two flags are set, the stripe is counted in big_stripe_tree. This + * requires moving set_bit(STRIPE_R5C_PARTIAL_STRIPE) to + * r5c_try_caching_write(); and moving clear_bit of + * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE to + * r5c_finish_stripe_write_out(). + */ + +/* + * radix tree requests lowest 2 bits of data pointer to be 2b'00. + * So it is necessary to left shift the counter by 2 bits before using it + * as data pointer of the tree. + */ +#define R5C_RADIX_COUNT_SHIFT 2 + +/* + * calculate key for big_stripe_tree + * + * sect: align_bi->bi_iter.bi_sector or sh->sector + */ +static inline sector_t r5c_tree_index(struct r5conf *conf, + sector_t sect) +{ + sector_t offset; + + offset = sector_div(sect, conf->chunk_sectors); + return sect; +} + +/* * an IO range starts from a meta data block and end at the next meta data * block. The io unit's the meta data block tracks data/parity followed it. io * unit is written to log disk with normal write, as we always flush log disk @@ -412,16 +464,6 @@ void r5c_make_stripe_write_out(struct stripe_head *sh) if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) atomic_inc(&conf->preread_active_stripes); - - if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) { - BUG_ON(atomic_read(&conf->r5c_cached_partial_stripes) == 0); - atomic_dec(&conf->r5c_cached_partial_stripes); - } - - if (test_and_clear_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) { - BUG_ON(atomic_read(&conf->r5c_cached_full_stripes) == 0); - atomic_dec(&conf->r5c_cached_full_stripes); - } } static void r5c_handle_data_cached(struct stripe_head *sh) @@ -2320,6 +2362,10 @@ int r5c_try_caching_write(struct r5conf *conf, int i; struct r5dev *dev; int to_cache = 0; + void **pslot; + sector_t tree_index; + int ret; + uintptr_t refcount; BUG_ON(!r5c_is_writeback(log)); @@ -2364,6 +2410,44 @@ int r5c_try_caching_write(struct r5conf *conf, } } + /* if the stripe is not counted in big_stripe_tree, add it now */ + if (!test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) && + !test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) { + tree_index = r5c_tree_index(conf, sh->sector); + spin_lock(&log->tree_lock); + pslot = radix_tree_lookup_slot(&log->big_stripe_tree, + tree_index); + if (pslot) { + refcount = (uintptr_t)radix_tree_deref_slot_protected( + pslot, &log->tree_lock) >> + R5C_RADIX_COUNT_SHIFT; + radix_tree_replace_slot( + &log->big_stripe_tree, pslot, + (void *)((refcount + 1) << R5C_RADIX_COUNT_SHIFT)); + } else { + /* + * this radix_tree_insert can fail safely, so no + * need to call radix_tree_preload() + */ + ret = radix_tree_insert( + &log->big_stripe_tree, tree_index, + (void *)(1 << R5C_RADIX_COUNT_SHIFT)); + if (ret) { + spin_unlock(&log->tree_lock); + r5c_make_stripe_write_out(sh); + return -EAGAIN; + } + } + spin_unlock(&log->tree_lock); + + /* + * set STRIPE_R5C_PARTIAL_STRIPE, this shows the stripe is + * counted in the radix tree + */ + set_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state); + atomic_inc(&conf->r5c_cached_partial_stripes); + } + for (i = disks; i--; ) { dev = &sh->dev[i]; if (dev->towrite) { @@ -2438,17 +2522,20 @@ void r5c_finish_stripe_write_out(struct r5conf *conf, struct stripe_head *sh, struct stripe_head_state *s) { + struct r5l_log *log = conf->log; int i; int do_wakeup = 0; + sector_t tree_index; + void **pslot; + uintptr_t refcount; - if (!conf->log || - !test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags)) + if (!log || !test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags)) return; WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state)); clear_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags); - if (conf->log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) + if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) return; for (i = sh->disks; i--; ) { @@ -2470,12 +2557,43 @@ void r5c_finish_stripe_write_out(struct r5conf *conf, if (do_wakeup) wake_up(&conf->wait_for_overlap); - spin_lock_irq(&conf->log->stripe_in_journal_lock); + spin_lock_irq(&log->stripe_in_journal_lock); list_del_init(&sh->r5c); - spin_unlock_irq(&conf->log->stripe_in_journal_lock); + spin_unlock_irq(&log->stripe_in_journal_lock); sh->log_start = MaxSector; - atomic_dec(&conf->log->stripe_in_journal_count); - r5c_update_log_state(conf->log); + + atomic_dec(&log->stripe_in_journal_count); + r5c_update_log_state(log); + + /* stop counting this stripe in big_stripe_tree */ + if (test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) || + test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) { + tree_index = r5c_tree_index(conf, sh->sector); + spin_lock(&log->tree_lock); + pslot = radix_tree_lookup_slot(&log->big_stripe_tree, + tree_index); + BUG_ON(pslot == NULL); + refcount = (uintptr_t)radix_tree_deref_slot_protected( + pslot, &log->tree_lock) >> + R5C_RADIX_COUNT_SHIFT; + if (refcount == 1) + radix_tree_delete(&log->big_stripe_tree, tree_index); + else + radix_tree_replace_slot( + &log->big_stripe_tree, pslot, + (void *)((refcount - 1) << R5C_RADIX_COUNT_SHIFT)); + spin_unlock(&log->tree_lock); + } + + if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) { + BUG_ON(atomic_read(&conf->r5c_cached_partial_stripes) == 0); + atomic_dec(&conf->r5c_cached_partial_stripes); + } + + if (test_and_clear_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) { + BUG_ON(atomic_read(&conf->r5c_cached_full_stripes) == 0); + atomic_dec(&conf->r5c_cached_full_stripes); + } } int @@ -2535,6 +2653,22 @@ r5c_cache_data(struct r5l_log *log, struct stripe_head *sh, return 0; } +/* check whether this big stripe is in write back cache. */ +bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect) +{ + struct r5l_log *log = conf->log; + sector_t tree_index; + void *slot; + + if (!log) + return false; + + WARN_ON_ONCE(!rcu_read_lock_held()); + tree_index = r5c_tree_index(conf, sect); + slot = radix_tree_lookup(&log->big_stripe_tree, tree_index); + return slot != NULL; +} + static int r5l_load_log(struct r5l_log *log) { struct md_rdev *rdev = log->rdev; @@ -2681,6 +2815,9 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev) if (!log->meta_pool) goto out_mempool; + spin_lock_init(&log->tree_lock); + INIT_RADIX_TREE(&log->big_stripe_tree, GFP_NOWAIT | __GFP_NOWARN); + log->reclaim_thread = md_register_thread(r5l_reclaim_thread, log->rdev->mddev, "reclaim"); if (!log->reclaim_thread) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 9d744a8961d1..b62f671a93ab 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -281,13 +281,13 @@ static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh, atomic_dec(&conf->r5c_cached_partial_stripes); list_add_tail(&sh->lru, &conf->r5c_full_stripe_list); r5c_check_cached_full_stripe(conf); - } else { - /* partial stripe */ - if (!test_and_set_bit(STRIPE_R5C_PARTIAL_STRIPE, - &sh->state)) - atomic_inc(&conf->r5c_cached_partial_stripes); + } else + /* + * STRIPE_R5C_PARTIAL_STRIPE is set in + * r5c_try_caching_write(). No need to + * set it again. + */ list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list); - } } } } @@ -5062,6 +5062,13 @@ static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio) rdev->recovery_offset >= end_sector))) rdev = NULL; } + + if (r5c_big_stripe_cached(conf, align_bi->bi_iter.bi_sector)) { + rcu_read_unlock(); + bio_put(align_bi); + return 0; + } + if (rdev) { sector_t first_bad; int bad_sectors; @@ -5418,7 +5425,6 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) * data on failed drives. */ if (rw == READ && mddev->degraded == 0 && - !r5c_is_writeback(conf->log) && mddev->reshape_position == MaxSector) { bi = chunk_aligned_read(mddev, bi); if (!bi) diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index ebb89bda88f1..c0687df5ba06 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -792,4 +792,5 @@ 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); +extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect); #endif |