diff options
| -rw-r--r-- | drivers/md/dm-bufio.c | 941 |
1 files changed, 478 insertions, 463 deletions
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index 9daff9b77cee..1e000ec73bd6 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -321,37 +321,42 @@ enum data_mode { }; struct dm_buffer { + /* protected by the locks in dm_buffer_cache */ struct rb_node node; - struct list_head lru_list; - struct list_head global_list; + /* immutable, so don't need protecting */ sector_t block; void *data; unsigned char data_mode; /* DATA_MODE_* */ - unsigned int accessed; - unsigned int __hold_count; + /* + * These two fields are used in isolation, so do not need + * a surrounding lock. + */ + atomic_t hold_count; unsigned long last_accessed; + /* + * Everything else is protected by the mutex in + * dm_bufio_client + */ + unsigned long state; + struct lru_entry lru; unsigned char list_mode; /* LIST_* */ blk_status_t read_error; blk_status_t write_error; - unsigned long state; unsigned int dirty_start; unsigned int dirty_end; unsigned int write_start; unsigned int write_end; - struct dm_bufio_client *c; struct list_head write_list; + struct dm_bufio_client *c; void (*end_io)(struct dm_buffer *b, blk_status_t bs); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING #define MAX_STACK 10 unsigned int stack_len; unsigned long stack_entries[MAX_STACK]; #endif - /* Temp members to allow dm_buffer_cache code to compile */ - atomic_t hold_count; - struct lru_entry lru; }; /*--------------------------------------------------------------*/ @@ -814,7 +819,7 @@ static void cache_remove_range(struct dm_buffer_cache *bc, /* * Linking of buffers: - * All buffers are linked to buffer_tree with their node field. + * All buffers are linked to buffer_cache with their node field. * * Clean buffers that are not being written (B_WRITING not set) * are linked to lru[LIST_CLEAN] with their lru_list field. @@ -832,9 +837,6 @@ struct dm_bufio_client { spinlock_t spinlock; bool no_sleep; - struct list_head lru[LIST_SIZE]; - unsigned long n_buffers[LIST_SIZE]; - struct block_device *bdev; unsigned int block_size; s8 sectors_per_block_bits; @@ -849,7 +851,7 @@ struct dm_bufio_client { unsigned int minimum_buffers; - struct rb_root buffer_tree; + struct dm_buffer_cache cache; wait_queue_head_t free_buffer_wait; sector_t start; @@ -861,6 +863,11 @@ struct dm_bufio_client { struct shrinker shrinker; struct work_struct shrink_work; atomic_long_t need_shrink; + + /* + * Used by global_cleanup to sort the clients list. + */ + unsigned long oldest_buffer; }; static DEFINE_STATIC_KEY_FALSE(no_sleep_enabled); @@ -877,14 +884,6 @@ static void dm_bufio_lock(struct dm_bufio_client *c) mutex_lock_nested(&c->lock, dm_bufio_in_request()); } -static int dm_bufio_trylock(struct dm_bufio_client *c) -{ - if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep) - return spin_trylock_bh(&c->spinlock); - else - return mutex_trylock(&c->lock); -} - static void dm_bufio_unlock(struct dm_bufio_client *c) { if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep) @@ -913,10 +912,6 @@ static unsigned long dm_bufio_cache_size_latch; static DEFINE_SPINLOCK(global_spinlock); -static LIST_HEAD(global_queue); - -static unsigned long global_num; - /* * Buffers are freed after this timeout */ @@ -958,78 +953,6 @@ static void buffer_record_stack(struct dm_buffer *b) } #endif -/* - *---------------------------------------------------------------- - * A red/black tree acts as an index for all the buffers. - *---------------------------------------------------------------- - */ -static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block) -{ - struct rb_node *n = c->buffer_tree.rb_node; - struct dm_buffer *b; - - while (n) { - b = container_of(n, struct dm_buffer, node); - - if (b->block == block) - return b; - - n = block < b->block ? n->rb_left : n->rb_right; - } - - return NULL; -} - -static struct dm_buffer *__find_next_old(struct dm_bufio_client *c, sector_t block) -{ - struct rb_node *n = c->buffer_tree.rb_node; - struct dm_buffer *b; - struct dm_buffer *best = NULL; - - while (n) { - b = container_of(n, struct dm_buffer, node); - - if (b->block == block) - return b; - - if (block <= b->block) { - n = n->rb_left; - best = b; - } else { - n = n->rb_right; - } - } - - return best; -} - -static void __insert(struct dm_bufio_client *c, struct dm_buffer *b) -{ - struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL; - struct dm_buffer *found; - - while (*new) { - found = container_of(*new, struct dm_buffer, node); - - if (found->block == b->block) { - BUG_ON(found != b); - return; - } - - parent = *new; - new = b->block < found->block ? - &found->node.rb_left : &found->node.rb_right; - } - - rb_link_node(&b->node, parent, new); - rb_insert_color(&b->node, &c->buffer_tree); -} - -static void __remove(struct dm_bufio_client *c, struct dm_buffer *b) -{ - rb_erase(&b->node, &c->buffer_tree); -} - /*----------------------------------------------------------------*/ static void adjust_total_allocated(struct dm_buffer *b, bool unlink) @@ -1057,16 +980,9 @@ static void adjust_total_allocated(struct dm_buffer *b, bool unlink) if (dm_bufio_current_allocated > dm_bufio_peak_allocated) dm_bufio_peak_allocated = dm_bufio_current_allocated; - b->accessed = 1; - if (!unlink) { - list_add(&b->global_list, &global_queue); - global_num++; if (dm_bufio_current_allocated > dm_bufio_cache_size) queue_work(dm_bufio_wq, &dm_bufio_replacement_work); - } else { - list_del(&b->global_list); - global_num--; } spin_unlock(&global_spinlock); @@ -1196,6 +1112,7 @@ static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask) kmem_cache_free(c->slab_buffer, b); return NULL; } + adjust_total_allocated(b, false); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING b->stack_len = 0; @@ -1210,62 +1127,12 @@ static void free_buffer(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; + adjust_total_allocated(b, true); free_buffer_data(c, b->data, b->data_mode); kmem_cache_free(c->slab_buffer, b); } /* - * Link buffer to the buffer tree and clean or dirty queue. - */ -static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty) -{ - struct dm_bufio_client *c = b->c; - - c->n_buffers[dirty]++; - b->block = block; - b->list_mode = dirty; - list_add(&b->lru_list, &c->lru[dirty]); - __insert(b->c, b); - b->last_accessed = jiffies; - - adjust_total_allocated(b, false); -} - -/* - * Unlink buffer from the buffer tree and dirty or clean queue. - */ -static void __unlink_buffer(struct dm_buffer *b) -{ - struct dm_bufio_client *c = b->c; - - BUG_ON(!c->n_buffers[b->list_mode]); - - c->n_buffers[b->list_mode]--; - __remove(b->c, b); - list_del(&b->lru_list); - - adjust_total_allocated(b, true); -} - -/* - * Place the buffer to the head of dirty or clean LRU queue. - */ -static void __relink_lru(struct dm_buffer *b, int dirty) -{ - struct dm_bufio_client *c = b->c; - - b->accessed = 1; - - BUG_ON(!c->n_buffers[b->list_mode]); - - c->n_buffers[b->list_mode]--; - c->n_buffers[dirty]++; - b->list_mode = dirty; - list_move(&b->lru_list, &c->lru[dirty]); - b->last_accessed = jiffies; -} - -/* *-------------------------------------------------------------------------- * Submit I/O on the buffer. * @@ -1504,7 +1371,7 @@ static void __flush_write_list(struct list_head *write_list) */ static void __make_buffer_clean(struct dm_buffer *b) { - BUG_ON(b->__hold_count); + BUG_ON(atomic_read(&b->hold_count)); /* smp_load_acquire() pairs with read_endio()'s smp_mb__before_atomic() */ if (!smp_load_acquire(&b->state)) /* fast case */ @@ -1515,6 +1382,36 @@ static void __make_buffer_clean(struct dm_buffer *b) wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); } +static enum evict_result is_clean(struct dm_buffer *b, void *context) +{ + struct dm_bufio_client *c = context; + + /* These should never happen */ + if (WARN_ON_ONCE(test_bit(B_WRITING, &b->state))) + return ER_DONT_EVICT; + if (WARN_ON_ONCE(test_bit(B_DIRTY, &b->state))) + return ER_DONT_EVICT; + if (WARN_ON_ONCE(b->list_mode != LIST_CLEAN)) + return ER_DONT_EVICT; + + if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep && + unlikely(test_bit(B_READING, &b->state))) + return ER_DONT_EVICT; + + return ER_EVICT; +} + +static enum evict_result is_dirty(struct dm_buffer *b, void *context) +{ + /* These should never happen */ + if (WARN_ON_ONCE(test_bit(B_READING, &b->state))) + return ER_DONT_EVICT; + if (WARN_ON_ONCE(b->list_mode != LIST_DIRTY)) + return ER_DONT_EVICT; + + return ER_EVICT; +} + /* * Find some buffer that is not held by anybody, clean it, unlink it and * return it. @@ -1523,34 +1420,20 @@ static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) { struct dm_buffer *b; - list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) { - BUG_ON(test_bit(B_WRITING, &b->state)); - BUG_ON(test_bit(B_DIRTY, &b->state)); - - if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep && - unlikely(test_bit_acquire(B_READING, &b->state))) - continue; - - if (!b->__hold_count) { - __make_buffer_clean(b); - __unlink_buffer(b); - return b; - } - cond_resched(); + b = cache_evict(&c->cache, LIST_CLEAN, is_clean, c); + if (b) { + /* this also waits for pending reads */ + __make_buffer_clean(b); + return b; } if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep) return NULL; - list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) { - BUG_ON(test_bit(B_READING, &b->state)); - - if (!b->__hold_count) { - __make_buffer_clean(b); - __unlink_buffer(b); - return b; - } - cond_resched(); + b = cache_evict(&c->cache, LIST_DIRTY, is_dirty, NULL); + if (b) { + __make_buffer_clean(b); + return b; } return NULL; @@ -1571,7 +1454,12 @@ static void __wait_for_free_buffer(struct dm_bufio_client *c) set_current_state(TASK_UNINTERRUPTIBLE); dm_bufio_unlock(c); - io_schedule(); + /* + * It's possible to miss a wake up event since we don't always + * hold c->lock when wake_up is called. So we have a timeout here, + * just in case. + */ + io_schedule_timeout(5 * HZ); remove_wait_queue(&c->free_buffer_wait, &wait); @@ -1629,9 +1517,8 @@ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client } if (!list_empty(&c->reserved_buffers)) { - b = list_entry(c->reserved_buffers.next, - struct dm_buffer, lru_list); - list_del(&b->lru_list); + b = list_to_buffer(c->reserved_buffers.next); + list_del(&b->lru.list); c->need_reserved_buffers++; return b; @@ -1665,36 +1552,56 @@ static void __free_buffer_wake(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; + b->block = -1; if (!c->need_reserved_buffers) free_buffer(b); else { - list_add(&b->lru_list, &c->reserved_buffers); + list_add(&b->lru.list, &c->reserved_buffers); c->need_reserved_buffers--; } wake_up(&c->free_buffer_wait); } -static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait, - struct list_head *write_list) +static enum evict_result cleaned(struct dm_buffer *b, void *context) { - struct dm_buffer *b, *tmp; + if (WARN_ON_ONCE(test_bit(B_READING, &b->state))) + return ER_DONT_EVICT; /* should never happen */ - list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { - BUG_ON(test_bit(B_READING, &b->state)); + if (test_bit(B_DIRTY, &b->state) || test_bit(B_WRITING, &b->state)) + return ER_DONT_EVICT; + else + return ER_EVICT; +} - if (!test_bit(B_DIRTY, &b->state) && - !test_bit(B_WRITING, &b->state)) { - __relink_lru(b, LIST_CLEAN); - continue; - } +static void __move_clean_buffers(struct dm_bufio_client *c) +{ + cache_mark_many(&c->cache, LIST_DIRTY, LIST_CLEAN, cleaned, NULL); +} - if (no_wait && test_bit(B_WRITING, &b->state)) - return; +struct write_context { + int no_wait; + struct list_head *write_list; +}; - __write_dirty_buffer(b, write_list); - cond_resched(); - } +static enum it_action write_one(struct dm_buffer *b, void *context) +{ + struct write_context *wc = context; + + if (wc->no_wait && test_bit(B_WRITING, &b->state)) + return IT_COMPLETE; + + __write_dirty_buffer(b, wc->write_list); + return IT_NEXT; +} + +static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait, + struct list_head *write_list) +{ + struct write_context wc = {.no_wait = no_wait, .write_list = write_list}; + + __move_clean_buffers(c); + cache_iterate(&c->cache, LIST_DIRTY, write_one, &wc); } /* @@ -1705,7 +1612,8 @@ static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait, static void __check_watermark(struct dm_bufio_client *c, struct list_head *write_list) { - if (c->n_buffers[LIST_DIRTY] > c->n_buffers[LIST_CLEAN] * DM_BUFIO_WRITEBACK_RATIO) + if (cache_count(&c->cache, LIST_DIRTY) > + cache_count(&c->cache, LIST_CLEAN) * DM_BUFIO_WRITEBACK_RATIO) __write_dirty_buffers_async(c, 1, write_list); } @@ -1715,6 +1623,21 @@ static void __check_watermark(struct dm_bufio_client *c, *-------------------------------------------------------------- */ +static void cache_put_and_wake(struct dm_bufio_client *c, struct dm_buffer *b) +{ + /* + * Relying on waitqueue_active() is racey, but we sleep + * with schedule_timeout anyway. + */ + if (cache_put(&c->cache, b) && + unlikely(waitqueue_active(&c->free_buffer_wait))) + wake_up(&c->free_buffer_wait); +} + +/* + * This assumes you have already checked the cache to see if the buffer + * is already present (it will recheck after dropping the lock for allocation). + */ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, enum new_flag nf, int *need_submit, struct list_head *write_list) @@ -1723,11 +1646,8 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, *need_submit = 0; - b = __find(c, block); - if (b) - goto found_buffer; - - if (nf == NF_GET) + /* This can't be called with NF_GET */ + if (WARN_ON_ONCE(nf == NF_GET)) return NULL; new_b = __alloc_buffer_wait(c, nf); @@ -1738,7 +1658,7 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, * We've had a period where the mutex was unlocked, so need to * recheck the buffer tree. */ - b = __find(c, block); + b = cache_get(&c->cache, block); if (b) { __free_buffer_wake(new_b); goto found_buffer; @@ -1747,24 +1667,35 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, __check_watermark(c, write_list); b = new_b; - b->__hold_count = 1; + atomic_set(&b->hold_count, 1); + WRITE_ONCE(b->last_accessed, jiffies); + b->block = block; b->read_error = 0; b->write_error = 0; - __link_buffer(b, block, LIST_CLEAN); + b->list_mode = LIST_CLEAN; - if (nf == NF_FRESH) { + if (nf == NF_FRESH) b->state = 0; - return b; + else { + b->state = 1 << B_READING; + *need_submit = 1; } - b->state = 1 << B_READING; - *need_submit = 1; + /* + * We mustn't insert into the cache until the B_READING state + * is set. Otherwise another thread could get it and use + * it before it had been read. + */ + cache_insert(&c->cache, b); return b; found_buffer: - if (nf == NF_PREFETCH) + if (nf == NF_PREFETCH) { + cache_put_and_wake(c, b); return NULL; + } + /* * Note: it is essential that we don't wait for the buffer to be * read if dm_bufio_get function is used. Both dm_bufio_get and @@ -1772,12 +1703,11 @@ found_buffer: * If the user called both dm_bufio_prefetch and dm_bufio_get on * the same buffer, it would deadlock if we waited. */ - if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state))) + if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state))) { + cache_put_and_wake(c, b); return NULL; + } - b->__hold_count++; - __relink_lru(b, test_bit(B_DIRTY, &b->state) || - test_bit(B_WRITING, &b->state)); return b; } @@ -1807,18 +1737,50 @@ static void read_endio(struct dm_buffer *b, blk_status_t status) static void *new_read(struct dm_bufio_client *c, sector_t block, enum new_flag nf, struct dm_buffer **bp) { - int need_submit; + int need_submit = 0; struct dm_buffer *b; LIST_HEAD(write_list); - dm_bufio_lock(c); - b = __bufio_new(c, block, nf, &need_submit, &write_list); + *bp = NULL; + + /* + * Fast path, hopefully the block is already in the cache. No need + * to get the client lock for this. + */ + b = cache_get(&c->cache, block); + if (b) { + if (nf == NF_PREFETCH) { + cache_put_and_wake(c, b); + return NULL; + } + + /* + * Note: it is essential that we don't wait for the buffer to be + * read if dm_bufio_get function is used. Both dm_bufio_get and + * dm_bufio_prefetch can be used in the driver request routine. + * If the user called both dm_bufio_prefetch and dm_bufio_get on + * the same buffer, it would deadlock if we waited. + */ + if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state))) { + cache_put_and_wake(c, b); + return NULL; + } + } + + if (!b) { + if (nf == NF_GET) + return NULL; + + dm_bufio_lock(c); + b = __bufio_new(c, block, nf, &need_submit, &write_list); + dm_bufio_unlock(c); + } + #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING - if (b && b->hold_count == 1) + if (b && (atomic_read(&b->hold_count) == 1)) buffer_record_stack(b); #endif - dm_bufio_unlock(c); __flush_write_list(&write_list); @@ -1881,12 +1843,19 @@ void dm_bufio_prefetch(struct dm_bufio_client *c, return; /* should never happen */ blk_start_plug(&plug); - dm_bufio_lock(c); for (; n_blocks--; block++) { int need_submit; struct dm_buffer *b; + b = cache_get(&c->cache, block); + if (b) { + /* already in cache */ + cache_put_and_wake(c, b); + continue; + } + + dm_bufio_lock(c); b = __bufio_new(c, block, NF_PREFETCH, &need_submit, &write_list); if (unlikely(!list_empty(&write_list))) { @@ -1909,10 +1878,9 @@ void dm_bufio_prefetch(struct dm_bufio_client *c, goto flush_plug; dm_bufio_lock(c); } + dm_bufio_unlock(c); } - dm_bufio_unlock(c); - flush_plug: blk_finish_plug(&plug); } @@ -1922,29 +1890,28 @@ void dm_bufio_release(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; - dm_bufio_lock(c); - - BUG_ON(!b->__hold_count); - - b->__hold_count--; - if (!b->__hold_count) { - wake_up(&c->free_buffer_wait); + /* + * If there were errors on the buffer, and the buffer is not + * to be written, free the buffer. There is no point in caching + * invalid buffer. + */ + if ((b->read_error || b->write_error) && + !test_bit_acquire(B_READING, &b->state) && + !test_bit(B_WRITING, &b->state) && + !test_bit(B_DIRTY, &b->state)) { + dm_bufio_lock(c); - /* - * If there were errors on the buffer, and the buffer is not - * to be written, free the buffer. There is no point in caching - * invalid buffer. - */ - if ((b->read_error || b->write_error) && - !test_bit_acquire(B_READING, &b->state) && - !test_bit(B_WRITING, &b->state) && - !test_bit(B_DIRTY, &b->state)) { - __unlink_buffer(b); + /* cache remove can fail if there are other holders */ + if (cache_remove(&c->cache, b)) { __free_buffer_wake(b); + dm_bufio_unlock(c); + return; } + + dm_bufio_unlock(c); } - dm_bufio_unlock(c); + cache_put_and_wake(c, b); } EXPORT_SYMBOL_GPL(dm_bufio_release); @@ -1963,7 +1930,7 @@ void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, if (!test_and_set_bit(B_DIRTY, &b->state)) { b->dirty_start = start; b->dirty_end = end; - __relink_lru(b, LIST_DIRTY); + cache_mark(&c->cache, b, LIST_DIRTY); } else { if (start < b->dirty_start) b->dirty_start = start; @@ -2002,11 +1969,19 @@ EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async); * * Finally, we flush hardware disk cache. */ +static bool is_writing(struct lru_entry *e, void *context) +{ + struct dm_buffer *b = le_to_buffer(e); + + return test_bit(B_WRITING, &b->state); +} + int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) { int a, f; - unsigned long buffers_processed = 0; - struct dm_buffer *b, *tmp; + unsigned long nr_buffers; + struct lru_entry *e; + struct lru_iter it; LIST_HEAD(write_list); @@ -2016,52 +1991,32 @@ int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) __flush_write_list(&write_list); dm_bufio_lock(c); -again: - list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { - int dropped_lock = 0; - - if (buffers_processed < c->n_buffers[LIST_DIRTY]) - buffers_processed++; + nr_buffers = cache_count(&c->cache, LIST_DIRTY); + lru_iter_begin(&c->cache.lru[LIST_DIRTY], &it); + while ((e = lru_iter_next(&it, is_writing, c))) { + struct dm_buffer *b = le_to_buffer(e); + __cache_inc_buffer(b); BUG_ON(test_bit(B_READING, &b->state)); - if (test_bit(B_WRITING, &b->state)) { - if (buffers_processed < c->n_buffers[LIST_DIRTY]) { - dropped_lock = 1; - b->__hold_count++; - dm_bufio_unlock(c); - wait_on_bit_io(&b->state, B_WRITING, - TASK_UNINTERRUPTIBLE); - dm_bufio_lock(c); - b->__hold_count--; - } else - wait_on_bit_io(&b->state, B_WRITING, - TASK_UNINTERRUPTIBLE); + if (nr_buffers) { + nr_buffers--; + dm_bufio_unlock(c); + wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); + dm_bufio_lock(c); + } else { + wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); } - if (!test_bit(B_DIRTY, &b->state) && - !test_bit(B_WRITING, &b->state)) - __relink_lru(b, LIST_CLEAN); + if (!test_bit(B_DIRTY, &b->state) && !test_bit(B_WRITING, &b->state)) + cache_mark(&c->cache, b, LIST_CLEAN); - cond_resched(); + cache_put_and_wake(c, b); - /* - * If we dropped the lock, the list is no longer consistent, - * so we must restart the search. - * - * In the most common case, the buffer just processed is - * relinked to the clean list, so we won't loop scanning the - * same buffer again and again. - * - * This may livelock if there is another thread simultaneously - * dirtying buffers, so we count the number of buffers walked - * and if it exceeds the total number of buffers, it means that - * someone is doing some writes simultaneously with us. In - * this case, stop, dropping the lock. - */ - if (dropped_lock) - goto again; + cond_resched(); } + lru_iter_end(&it); + wake_up(&c->free_buffer_wait); dm_bufio_unlock(c); @@ -2122,12 +2077,23 @@ int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t c } EXPORT_SYMBOL_GPL(dm_bufio_issue_discard); -static void forget_buffer_locked(struct dm_buffer *b) +static bool forget_buffer(struct dm_bufio_client *c, sector_t block) { - if (likely(!b->__hold_count) && likely(!smp_load_acquire(&b->state))) { - __unlink_buffer(b); - __free_buffer_wake(b); + struct dm_buffer *b; + + b = cache_get(&c->cache, block); + if (b) { + if (likely(!smp_load_acquire(&b->state))) { + if (cache_remove(&c->cache, b)) + __free_buffer_wake(b); + else + cache_put_and_wake(c, b); + } else { + cache_put_and_wake(c, b); + } } + + return b ? true : false; } /* @@ -2138,38 +2104,22 @@ static void forget_buffer_locked(struct dm_buffer *b) */ void dm_bufio_forget(struct dm_bufio_client *c, sector_t block) { - struct dm_buffer *b; - dm_bufio_lock(c); - - b = __find(c, block); - if (b) - forget_buffer_locked(b); - + forget_buffer(c, block); dm_bufio_unlock(c); } EXPORT_SYMBOL_GPL(dm_bufio_forget); -void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks) +static enum evict_result idle(struct dm_buffer *b, void *context) { - struct dm_buffer *b; - sector_t end_block = block + n_blocks; - - while (block < end_block) { - dm_bufio_lock(c); - - b = __find_next_old(c, block); - if (b) { - block = b->block + 1; - forget_buffer_locked(b); - } - - dm_bufio_unlock(c); - - if (!b) - break; - } + return b->state ? ER_DONT_EVICT : ER_EVICT; +} +void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks) +{ + dm_bufio_lock(c); + cache_remove_range(&c->cache, block, block + n_blocks, idle, __free_buffer_wake); + dm_bufio_unlock(c); } EXPORT_SYMBOL_GPL(dm_bufio_forget_buffers); @@ -2231,11 +2181,26 @@ struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b) } EXPORT_SYMBOL_GPL(dm_bufio_get_client); +static enum it_action warn_leak(struct dm_buffer *b, void *context) +{ + bool *warned = context; + + WARN_ON(!(*warned)); + *warned = true; + DMERR("leaked buffer %llx, hold count %u, list %d", + (unsigned long long)b->block, atomic_read(&b->hold_count), b->list_mode); +#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING + stack_trace_print(b->stack_entries, b->stack_len, 1); + /* mark unclaimed to avoid WARN_ON at end of drop_buffers() */ + atomic_set(&b->hold_count, 0); +#endif + return IT_NEXT; +} + static void drop_buffers(struct dm_bufio_client *c) { - struct dm_buffer *b; int i; - bool warned = false; + struct dm_buffer *b; if (WARN_ON(dm_bufio_in_request())) return; /* should never happen */ @@ -2250,18 +2215,11 @@ static void drop_buffers(struct dm_bufio_client *c) while ((b = __get_unclaimed_buffer(c))) __free_buffer_wake(b); - for (i = 0; i < LIST_SIZE; i++) - list_for_each_entry(b, &c->lru[i], lru_list) { - WARN_ON(!warned); - warned = true; - DMERR("leaked buffer %llx, hold count %u, list %d", - (unsigned long long)b->block, b->__hold_count, i); -#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING - stack_trace_print(b->stack_entries, b->stack_len, 1); - /* mark unclaimed to avoid WARN_ON below */ - b->hold_count = 0; -#endif - } + for (i = 0; i < LIST_SIZE; i++) { + bool warned = false; + + cache_iterate(&c->cache, i, warn_leak, &warned); + } #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING while ((b = __get_unclaimed_buffer(c))) @@ -2269,39 +2227,11 @@ static void drop_buffers(struct dm_bufio_client *c) #endif for (i = 0; i < LIST_SIZE; i++) - WARN_ON(!list_empty(&c->lru[i])); + WARN_ON(cache_count(&c->cache, i)); dm_bufio_unlock(c); } -/* - * We may not be able to evict this buffer if IO pending or the client - * is still using it. Caller is expected to know buffer is too old. - * - * And if GFP_NOFS is used, we must not do any I/O because we hold - * dm_bufio_clients_lock and we would risk deadlock if the I/O gets - * rerouted to different bufio client. - */ -static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp) -{ - if (!(gfp & __GFP_FS) || - (static_branch_unlikely(&no_sleep_enabled) && b->c->no_sleep)) { - if (test_bit_acquire(B_READING, &b->state) || - test_bit(B_WRITING, &b->state) || - test_bit(B_DIRTY, &b->state)) - return false; - } - - if (b->__hold_count) - return false; - - __make_buffer_clean(b); - __unlink_buffer(b); - __free_buffer_wake(b); - - return true; -} - static unsigned long get_retain_buffers(struct dm_bufio_client *c) { unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes); @@ -2317,22 +2247,28 @@ static unsigned long get_retain_buffers(struct dm_bufio_client *c) static void __scan(struct dm_bufio_client *c) { int l; - struct dm_buffer *b, *tmp; + struct dm_buffer *b; unsigned long freed = 0; - unsigned long count = c->n_buffers[LIST_CLEAN] + - c->n_buffers[LIST_DIRTY]; unsigned long retain_target = get_retain_buffers(c); + unsigned long count = cache_total(&c->cache); for (l = 0; l < LIST_SIZE; l++) { - list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) { + while (true) { if (count - freed <= retain_target) atomic_long_set(&c->need_shrink, 0); if (!atomic_long_read(&c->need_shrink)) - return; - if (__try_evict_buffer(b, GFP_KERNEL)) { - atomic_long_dec(&c->need_shrink); - freed++; - } + break; + + b = cache_evict(&c->cache, l, + l == LIST_CLEAN ? is_clean : is_dirty, c); + if (!b) + break; + + __make_buffer_clean(b); + __free_buffer_wake(b); + + atomic_long_dec(&c->need_shrink); + freed++; cond_resched(); } } @@ -2361,8 +2297,7 @@ static unsigned long dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink static unsigned long dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker); - unsigned long count = READ_ONCE(c->n_buffers[LIST_CLEAN]) + - READ_ONCE(c->n_buffers[LIST_DIRTY]); + unsigned long count = cache_total(&c->cache); unsigned long retain_target = get_retain_buffers(c); unsigned long queued_for_cleanup = atomic_long_read(&c->need_shrink); @@ -2390,7 +2325,6 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign { int r; struct dm_bufio_client *c; - unsigned int i; char slab_name[27]; if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) { @@ -2404,7 +2338,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign r = -ENOMEM; goto bad_client; } - c->buffer_tree = RB_ROOT; + cache_init(&c->cache); c->bdev = bdev; c->block_size = block_size; @@ -2421,11 +2355,6 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign static_branch_inc(&no_sleep_enabled); } - for (i = 0; i < LIST_SIZE; i++) { - INIT_LIST_HEAD(&c->lru[i]); - c->n_buffers[i] = 0; - } - mutex_init(&c->lock); spin_lock_init(&c->spinlock); INIT_LIST_HEAD(&c->reserved_buffers); @@ -2497,9 +2426,9 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign bad: while (!list_empty(&c->reserved_buffers)) { - struct dm_buffer *b = list_entry(c->reserved_buffers.next, - struct dm_buffer, lru_list); - list_del(&b->lru_list); + struct dm_buffer *b = list_to_buffer(c->reserved_buffers.next); + + list_del(&b->lru.list); free_buffer(b); } kmem_cache_destroy(c->slab_cache); @@ -2536,23 +2465,23 @@ void dm_bufio_client_destroy(struct dm_bufio_client *c) mutex_unlock(&dm_bufio_clients_lock); - WARN_ON(!RB_EMPTY_ROOT(&c->buffer_tree)); WARN_ON(c->need_reserved_buffers); while (!list_empty(&c->reserved_buffers)) { - struct dm_buffer *b = list_entry(c->reserved_buffers.next, - struct dm_buffer, lru_list); - list_del(&b->lru_list); + struct dm_buffer *b = list_to_buffer(c->reserved_buffers.next); + + list_del(&b->lru.list); free_buffer(b); } for (i = 0; i < LIST_SIZE; i++) - if (c->n_buffers[i]) - DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]); + if (cache_count(&c->cache, i)) + DMERR("leaked buffer count %d: %lu", i, cache_count(&c->cache, i)); for (i = 0; i < LIST_SIZE; i++) - WARN_ON(c->n_buffers[i]); + WARN_ON(cache_count(&c->cache, i)); + cache_destroy(&c->cache); kmem_cache_destroy(c->slab_cache); kmem_cache_destroy(c->slab_buffer); dm_io_client_destroy(c->dm_io); @@ -2569,6 +2498,8 @@ void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start) } EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset); +/*--------------------------------------------------------------*/ + static unsigned int get_max_age_hz(void) { unsigned int max_age = READ_ONCE(dm_bufio_max_age); @@ -2581,13 +2512,74 @@ static unsigned int get_max_age_hz(void) static bool older_than(struct dm_buffer *b, unsigned long age_hz) { - return time_after_eq(jiffies, b->last_accessed + age_hz); + return time_after_eq(jiffies, READ_ONCE(b->last_accessed) + age_hz); } -static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) +struct evict_params { + gfp_t gfp; + unsigned long age_hz; + + /* + * This gets updated with the largest last_accessed (ie. most + * recently used) of the evicted buffers. It will not be reinitialised + * by __evict_many(), so you can use it across multiple invocations. + */ + unsigned long last_accessed; +}; + +/* + * We may not be able to evict this buffer if IO pending or the client + * is still using it. + * + * And if GFP_NOFS is used, we must not do any I/O because we hold + * dm_bufio_clients_lock and we would risk deadlock if the I/O gets + * rerouted to different bufio client. + */ +static enum evict_result select_for_evict(struct dm_buffer *b, void *context) +{ + struct evict_params *params = context; + + if (!(params->gfp & __GFP_FS) || + (static_branch_unlikely(&no_sleep_enabled) && b->c->no_sleep)) { + if (test_bit_acquire(B_READING, &b->state) || + test_bit(B_WRITING, &b->state) || + test_bit(B_DIRTY, &b->state)) + return ER_DONT_EVICT; + } + + return older_than(b, params->age_hz) ? ER_EVICT : ER_STOP; +} + +static unsigned long __evict_many(struct dm_bufio_client *c, + struct evict_params *params, + int list_mode, unsigned long max_count) { - struct dm_buffer *b, *tmp; - unsigned long retain_target = get_retain_buffers(c); + unsigned long count; + unsigned long last_accessed; + struct dm_buffer *b; + + for (count = 0; count < max_count; count++) { + b = cache_evict(&c->cache, list_mode, select_for_evict, params); + if (!b) + break; + + last_accessed = READ_ONCE(b->last_accessed); + if (time_after_eq(params->last_accessed, last_accessed)) + params->last_accessed = last_accessed; + + __make_buffer_clean(b); + __free_buffer_wake(b); + + cond_resched(); + } + + return count; +} + +static void evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) +{ + struct evict_params params = {.gfp = 0, .age_hz = age_hz, .last_accessed = 0}; + unsigned long retain = get_retain_buffers(c); unsigned long count; LIST_HEAD(write_list); @@ -2600,112 +2592,135 @@ static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) dm_bufio_lock(c); } - count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; - list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) { - if (count <= retain_target) - break; - - if (!older_than(b, age_hz)) - break; - - if (__try_evict_buffer(b, 0)) - count--; - - cond_resched(); - } + count = cache_total(&c->cache); + if (count > retain) + __evict_many(c, ¶ms, LIST_CLEAN, count - retain); dm_bufio_unlock(c); } -static void do_global_cleanup(struct work_struct *w) +static void cleanup_old_buffers(void) { - struct dm_bufio_client *locked_client = NULL; - struct dm_bufio_client *current_client; - struct dm_buffer *b; - unsigned int spinlock_hold_count; - unsigned long threshold = dm_bufio_cache_size - - dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO; - unsigned long loops = global_num * 2; + unsigned long max_age_hz = get_max_age_hz(); + struct dm_bufio_client *c; mutex_lock(&dm_bufio_clients_lock); - while (1) { - cond_resched(); + __cache_size_refresh(); - spin_lock(&global_spinlock); - if (unlikely(dm_bufio_current_allocated <= threshold)) - break; + list_for_each_entry(c, &dm_bufio_all_clients, client_list) + evict_old_buffers(c, max_age_hz); - spinlock_hold_count = 0; -get_next: - if (!loops--) - break; - if (unlikely(list_empty(&global_queue))) - break; - b = list_entry(global_queue.prev, struct dm_buffer, global_list); - - if (b->accessed) { - b->accessed = 0; - list_move(&b->global_list, &global_queue); - if (likely(++spinlock_hold_count < 16)) - goto get_next; - spin_unlock(&global_spinlock); - continue; - } + mutex_unlock(&dm_bufio_clients_lock); +} - current_client = b->c; - if (unlikely(current_client != locked_client)) { - if (locked_client) - dm_bufio_unlock(locked_client); +static void work_fn(struct work_struct *w) +{ + cleanup_old_buffers(); - if (!dm_bufio_trylock(current_client)) { - spin_unlock(&global_spinlock); - dm_bufio_lock(current_client); - locked_client = current_client; - continue; - } + queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work, + DM_BUFIO_WORK_TIMER_SECS * HZ); +} - locked_client = current_client; - } +/*--------------------------------------------------------------*/ - spin_unlock(&global_spinlock); +/* + * Global cleanup tries to evict the oldest buffers from across _all_ + * the clients. It does this by repeatedly evicting a few buffers from + * the client that holds the oldest buffer. It's approximate, but hopefully + * good enough. + */ +static struct dm_bufio_client *__pop_client(void) +{ + struct list_head *h; - if (unlikely(!__try_evict_buffer(b, GFP_KERNEL))) { - spin_lock(&global_spinlock); - list_move(&b->global_list, &global_queue); - spin_unlock(&global_spinlock); - } + if (list_empty(&dm_bufio_all_clients)) + return NULL; + + h = dm_bufio_all_clients.next; + list_del(h); + return container_of(h, struct dm_bufio_client, client_list); +} + +/* + * Inserts the client in the global client list based on its + * 'oldest_buffer' field. + */ +static void __insert_client(struct dm_bufio_client *new_client) +{ + struct dm_bufio_client *c; + struct list_head *h = dm_bufio_all_clients.next; + + while (h != &dm_bufio_all_clients) { + c = container_of(h, struct dm_bufio_client, client_list); + if (time_after_eq(c->oldest_buffer, new_client->oldest_buffer)) + break; + h = h->next; } - spin_unlock(&global_spinlock); + list_add_tail(&new_client->client_list, h); +} - if (locked_client) - dm_bufio_unlock(locked_client); +static unsigned long __evict_a_few(unsigned long nr_buffers) +{ + unsigned long count; + struct dm_bufio_client *c; + struct evict_params params = { + .gfp = GFP_KERNEL, + .age_hz = 0, + /* set to jiffies in case there are no buffers in this client */ + .last_accessed = jiffies + }; - mutex_unlock(&dm_bufio_clients_lock); + c = __pop_client(); + if (!c) + return 0; + + dm_bufio_lock(c); + count = __evict_many(c, ¶ms, LIST_CLEAN, nr_buffers); + dm_bufio_unlock(c); + + if (count) + c->oldest_buffer = params.last_accessed; + __insert_client(c); + + return count; } -static void cleanup_old_buffers(void) +static void check_watermarks(void) { - unsigned long max_age_hz = get_max_age_hz(); + LIST_HEAD(write_list); struct dm_bufio_client *c; mutex_lock(&dm_bufio_clients_lock); + list_for_each_entry(c, &dm_bufio_all_clients, client_list) { + dm_bufio_lock(c); + __check_watermark(c, &write_list); + dm_bufio_unlock(c); + } + mutex_unlock(&dm_bufio_clients_lock); - __cache_size_refresh(); + __flush_write_list(&write_list); +} - list_for_each_entry(c, &dm_bufio_all_clients, client_list) - __evict_old_buffers(c, max_age_hz); +static void evict_old(void) +{ + unsigned long threshold = dm_bufio_cache_size - + dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO; + mutex_lock(&dm_bufio_clients_lock); + while (dm_bufio_current_allocated > threshold) { + if (!__evict_a_few(64)) + break; + cond_resched(); + } mutex_unlock(&dm_bufio_clients_lock); } -static void work_fn(struct work_struct *w) +static void do_global_cleanup(struct work_struct *w) { - cleanup_old_buffers(); - - queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work, - DM_BUFIO_WORK_TIMER_SECS * HZ); + check_watermarks(); + evict_old(); } /* |