| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Copyright (C) 2009-2011 Red Hat, Inc. |
| * |
| * Author: Mikulas Patocka <mpatocka@redhat.com> |
| * |
| * This file is released under the GPL. |
| */ |
| |
| #include <linux/dm-bufio.h> |
| |
| #include <linux/device-mapper.h> |
| #include <linux/dm-io.h> |
| #include <linux/slab.h> |
| #include <linux/sched/mm.h> |
| #include <linux/jiffies.h> |
| #include <linux/vmalloc.h> |
| #include <linux/shrinker.h> |
| #include <linux/module.h> |
| #include <linux/rbtree.h> |
| #include <linux/stacktrace.h> |
| #include <linux/jump_label.h> |
| |
| #include "dm.h" |
| |
| #define DM_MSG_PREFIX "bufio" |
| |
| /* |
| * Memory management policy: |
| * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory |
| * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower). |
| * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers. |
| * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT |
| * dirty buffers. |
| */ |
| #define DM_BUFIO_MIN_BUFFERS 8 |
| |
| #define DM_BUFIO_MEMORY_PERCENT 2 |
| #define DM_BUFIO_VMALLOC_PERCENT 25 |
| #define DM_BUFIO_WRITEBACK_RATIO 3 |
| #define DM_BUFIO_LOW_WATERMARK_RATIO 16 |
| |
| /* |
| * Check buffer ages in this interval (seconds) |
| */ |
| #define DM_BUFIO_WORK_TIMER_SECS 30 |
| |
| /* |
| * Free buffers when they are older than this (seconds) |
| */ |
| #define DM_BUFIO_DEFAULT_AGE_SECS 300 |
| |
| /* |
| * The nr of bytes of cached data to keep around. |
| */ |
| #define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024) |
| |
| /* |
| * Align buffer writes to this boundary. |
| * Tests show that SSDs have the highest IOPS when using 4k writes. |
| */ |
| #define DM_BUFIO_WRITE_ALIGN 4096 |
| |
| /* |
| * dm_buffer->list_mode |
| */ |
| #define LIST_CLEAN 0 |
| #define LIST_DIRTY 1 |
| #define LIST_SIZE 2 |
| |
| /*--------------------------------------------------------------*/ |
| |
| /* |
| * Rather than use an LRU list, we use a clock algorithm where entries |
| * are held in a circular list. When an entry is 'hit' a reference bit |
| * is set. The least recently used entry is approximated by running a |
| * cursor around the list selecting unreferenced entries. Referenced |
| * entries have their reference bit cleared as the cursor passes them. |
| */ |
| struct lru_entry { |
| struct list_head list; |
| atomic_t referenced; |
| }; |
| |
| struct lru_iter { |
| struct lru *lru; |
| struct list_head list; |
| struct lru_entry *stop; |
| struct lru_entry *e; |
| }; |
| |
| struct lru { |
| struct list_head *cursor; |
| unsigned long count; |
| |
| struct list_head iterators; |
| }; |
| |
| /*--------------*/ |
| |
| static void lru_init(struct lru *lru) |
| { |
| lru->cursor = NULL; |
| lru->count = 0; |
| INIT_LIST_HEAD(&lru->iterators); |
| } |
| |
| static void lru_destroy(struct lru *lru) |
| { |
| WARN_ON_ONCE(lru->cursor); |
| WARN_ON_ONCE(!list_empty(&lru->iterators)); |
| } |
| |
| /* |
| * Insert a new entry into the lru. |
| */ |
| static void lru_insert(struct lru *lru, struct lru_entry *le) |
| { |
| /* |
| * Don't be tempted to set to 1, makes the lru aspect |
| * perform poorly. |
| */ |
| atomic_set(&le->referenced, 0); |
| |
| if (lru->cursor) { |
| list_add_tail(&le->list, lru->cursor); |
| } else { |
| INIT_LIST_HEAD(&le->list); |
| lru->cursor = &le->list; |
| } |
| lru->count++; |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Convert a list_head pointer to an lru_entry pointer. |
| */ |
| static inline struct lru_entry *to_le(struct list_head *l) |
| { |
| return container_of(l, struct lru_entry, list); |
| } |
| |
| /* |
| * Initialize an lru_iter and add it to the list of cursors in the lru. |
| */ |
| static void lru_iter_begin(struct lru *lru, struct lru_iter *it) |
| { |
| it->lru = lru; |
| it->stop = lru->cursor ? to_le(lru->cursor->prev) : NULL; |
| it->e = lru->cursor ? to_le(lru->cursor) : NULL; |
| list_add(&it->list, &lru->iterators); |
| } |
| |
| /* |
| * Remove an lru_iter from the list of cursors in the lru. |
| */ |
| static inline void lru_iter_end(struct lru_iter *it) |
| { |
| list_del(&it->list); |
| } |
| |
| /* Predicate function type to be used with lru_iter_next */ |
| typedef bool (*iter_predicate)(struct lru_entry *le, void *context); |
| |
| /* |
| * Advance the cursor to the next entry that passes the |
| * predicate, and return that entry. Returns NULL if the |
| * iteration is complete. |
| */ |
| static struct lru_entry *lru_iter_next(struct lru_iter *it, |
| iter_predicate pred, void *context) |
| { |
| struct lru_entry *e; |
| |
| while (it->e) { |
| e = it->e; |
| |
| /* advance the cursor */ |
| if (it->e == it->stop) |
| it->e = NULL; |
| else |
| it->e = to_le(it->e->list.next); |
| |
| if (pred(e, context)) |
| return e; |
| } |
| |
| return NULL; |
| } |
| |
| /* |
| * Invalidate a specific lru_entry and update all cursors in |
| * the lru accordingly. |
| */ |
| static void lru_iter_invalidate(struct lru *lru, struct lru_entry *e) |
| { |
| struct lru_iter *it; |
| |
| list_for_each_entry(it, &lru->iterators, list) { |
| /* Move c->e forwards if necc. */ |
| if (it->e == e) { |
| it->e = to_le(it->e->list.next); |
| if (it->e == e) |
| it->e = NULL; |
| } |
| |
| /* Move it->stop backwards if necc. */ |
| if (it->stop == e) { |
| it->stop = to_le(it->stop->list.prev); |
| if (it->stop == e) |
| it->stop = NULL; |
| } |
| } |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Remove a specific entry from the lru. |
| */ |
| static void lru_remove(struct lru *lru, struct lru_entry *le) |
| { |
| lru_iter_invalidate(lru, le); |
| if (lru->count == 1) { |
| lru->cursor = NULL; |
| } else { |
| if (lru->cursor == &le->list) |
| lru->cursor = lru->cursor->next; |
| list_del(&le->list); |
| } |
| lru->count--; |
| } |
| |
| /* |
| * Mark as referenced. |
| */ |
| static inline void lru_reference(struct lru_entry *le) |
| { |
| atomic_set(&le->referenced, 1); |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Remove the least recently used entry (approx), that passes the predicate. |
| * Returns NULL on failure. |
| */ |
| enum evict_result { |
| ER_EVICT, |
| ER_DONT_EVICT, |
| ER_STOP, /* stop looking for something to evict */ |
| }; |
| |
| typedef enum evict_result (*le_predicate)(struct lru_entry *le, void *context); |
| |
| static struct lru_entry *lru_evict(struct lru *lru, le_predicate pred, void *context) |
| { |
| unsigned long tested = 0; |
| struct list_head *h = lru->cursor; |
| struct lru_entry *le; |
| |
| if (!h) |
| return NULL; |
| /* |
| * In the worst case we have to loop around twice. Once to clear |
| * the reference flags, and then again to discover the predicate |
| * fails for all entries. |
| */ |
| while (tested < lru->count) { |
| le = container_of(h, struct lru_entry, list); |
| |
| if (atomic_read(&le->referenced)) { |
| atomic_set(&le->referenced, 0); |
| } else { |
| tested++; |
| switch (pred(le, context)) { |
| case ER_EVICT: |
| /* |
| * Adjust the cursor, so we start the next |
| * search from here. |
| */ |
| lru->cursor = le->list.next; |
| lru_remove(lru, le); |
| return le; |
| |
| case ER_DONT_EVICT: |
| break; |
| |
| case ER_STOP: |
| lru->cursor = le->list.next; |
| return NULL; |
| } |
| } |
| |
| h = h->next; |
| |
| cond_resched(); |
| } |
| |
| return NULL; |
| } |
| |
| /*--------------------------------------------------------------*/ |
| |
| /* |
| * Buffer state bits. |
| */ |
| #define B_READING 0 |
| #define B_WRITING 1 |
| #define B_DIRTY 2 |
| |
| /* |
| * Describes how the block was allocated: |
| * kmem_cache_alloc(), __get_free_pages() or vmalloc(). |
| * See the comment at alloc_buffer_data. |
| */ |
| enum data_mode { |
| DATA_MODE_SLAB = 0, |
| DATA_MODE_GET_FREE_PAGES = 1, |
| DATA_MODE_VMALLOC = 2, |
| DATA_MODE_LIMIT = 3 |
| }; |
| |
| struct dm_buffer { |
| /* protected by the locks in dm_buffer_cache */ |
| struct rb_node node; |
| |
| /* immutable, so don't need protecting */ |
| sector_t block; |
| void *data; |
| unsigned char data_mode; /* DATA_MODE_* */ |
| |
| /* |
| * 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 int dirty_start; |
| unsigned int dirty_end; |
| unsigned int write_start; |
| unsigned int write_end; |
| 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 |
| }; |
| |
| /*--------------------------------------------------------------*/ |
| |
| /* |
| * The buffer cache manages buffers, particularly: |
| * - inc/dec of holder count |
| * - setting the last_accessed field |
| * - maintains clean/dirty state along with lru |
| * - selecting buffers that match predicates |
| * |
| * It does *not* handle: |
| * - allocation/freeing of buffers. |
| * - IO |
| * - Eviction or cache sizing. |
| * |
| * cache_get() and cache_put() are threadsafe, you do not need to |
| * protect these calls with a surrounding mutex. All the other |
| * methods are not threadsafe; they do use locking primitives, but |
| * only enough to ensure get/put are threadsafe. |
| */ |
| |
| struct buffer_tree { |
| struct rw_semaphore lock; |
| struct rb_root root; |
| } ____cacheline_aligned_in_smp; |
| |
| struct dm_buffer_cache { |
| struct lru lru[LIST_SIZE]; |
| /* |
| * We spread entries across multiple trees to reduce contention |
| * on the locks. |
| */ |
| unsigned int num_locks; |
| struct buffer_tree trees[]; |
| }; |
| |
| static inline unsigned int cache_index(sector_t block, unsigned int num_locks) |
| { |
| return dm_hash_locks_index(block, num_locks); |
| } |
| |
| static inline void cache_read_lock(struct dm_buffer_cache *bc, sector_t block) |
| { |
| down_read(&bc->trees[cache_index(block, bc->num_locks)].lock); |
| } |
| |
| static inline void cache_read_unlock(struct dm_buffer_cache *bc, sector_t block) |
| { |
| up_read(&bc->trees[cache_index(block, bc->num_locks)].lock); |
| } |
| |
| static inline void cache_write_lock(struct dm_buffer_cache *bc, sector_t block) |
| { |
| down_write(&bc->trees[cache_index(block, bc->num_locks)].lock); |
| } |
| |
| static inline void cache_write_unlock(struct dm_buffer_cache *bc, sector_t block) |
| { |
| up_write(&bc->trees[cache_index(block, bc->num_locks)].lock); |
| } |
| |
| /* |
| * Sometimes we want to repeatedly get and drop locks as part of an iteration. |
| * This struct helps avoid redundant drop and gets of the same lock. |
| */ |
| struct lock_history { |
| struct dm_buffer_cache *cache; |
| bool write; |
| unsigned int previous; |
| unsigned int no_previous; |
| }; |
| |
| static void lh_init(struct lock_history *lh, struct dm_buffer_cache *cache, bool write) |
| { |
| lh->cache = cache; |
| lh->write = write; |
| lh->no_previous = cache->num_locks; |
| lh->previous = lh->no_previous; |
| } |
| |
| static void __lh_lock(struct lock_history *lh, unsigned int index) |
| { |
| if (lh->write) |
| down_write(&lh->cache->trees[index].lock); |
| else |
| down_read(&lh->cache->trees[index].lock); |
| } |
| |
| static void __lh_unlock(struct lock_history *lh, unsigned int index) |
| { |
| if (lh->write) |
| up_write(&lh->cache->trees[index].lock); |
| else |
| up_read(&lh->cache->trees[index].lock); |
| } |
| |
| /* |
| * Make sure you call this since it will unlock the final lock. |
| */ |
| static void lh_exit(struct lock_history *lh) |
| { |
| if (lh->previous != lh->no_previous) { |
| __lh_unlock(lh, lh->previous); |
| lh->previous = lh->no_previous; |
| } |
| } |
| |
| /* |
| * Named 'next' because there is no corresponding |
| * 'up/unlock' call since it's done automatically. |
| */ |
| static void lh_next(struct lock_history *lh, sector_t b) |
| { |
| unsigned int index = cache_index(b, lh->no_previous); /* no_previous is num_locks */ |
| |
| if (lh->previous != lh->no_previous) { |
| if (lh->previous != index) { |
| __lh_unlock(lh, lh->previous); |
| __lh_lock(lh, index); |
| lh->previous = index; |
| } |
| } else { |
| __lh_lock(lh, index); |
| lh->previous = index; |
| } |
| } |
| |
| static inline struct dm_buffer *le_to_buffer(struct lru_entry *le) |
| { |
| return container_of(le, struct dm_buffer, lru); |
| } |
| |
| static struct dm_buffer *list_to_buffer(struct list_head *l) |
| { |
| struct lru_entry *le = list_entry(l, struct lru_entry, list); |
| |
| if (!le) |
| return NULL; |
| |
| return le_to_buffer(le); |
| } |
| |
| static void cache_init(struct dm_buffer_cache *bc, unsigned int num_locks) |
| { |
| unsigned int i; |
| |
| bc->num_locks = num_locks; |
| |
| for (i = 0; i < bc->num_locks; i++) { |
| init_rwsem(&bc->trees[i].lock); |
| bc->trees[i].root = RB_ROOT; |
| } |
| |
| lru_init(&bc->lru[LIST_CLEAN]); |
| lru_init(&bc->lru[LIST_DIRTY]); |
| } |
| |
| static void cache_destroy(struct dm_buffer_cache *bc) |
| { |
| unsigned int i; |
| |
| for (i = 0; i < bc->num_locks; i++) |
| WARN_ON_ONCE(!RB_EMPTY_ROOT(&bc->trees[i].root)); |
| |
| lru_destroy(&bc->lru[LIST_CLEAN]); |
| lru_destroy(&bc->lru[LIST_DIRTY]); |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * not threadsafe, or racey depending how you look at it |
| */ |
| static inline unsigned long cache_count(struct dm_buffer_cache *bc, int list_mode) |
| { |
| return bc->lru[list_mode].count; |
| } |
| |
| static inline unsigned long cache_total(struct dm_buffer_cache *bc) |
| { |
| return cache_count(bc, LIST_CLEAN) + cache_count(bc, LIST_DIRTY); |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Gets a specific buffer, indexed by block. |
| * If the buffer is found then its holder count will be incremented and |
| * lru_reference will be called. |
| * |
| * threadsafe |
| */ |
| static struct dm_buffer *__cache_get(const struct rb_root *root, sector_t block) |
| { |
| struct rb_node *n = root->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 void __cache_inc_buffer(struct dm_buffer *b) |
| { |
| atomic_inc(&b->hold_count); |
| WRITE_ONCE(b->last_accessed, jiffies); |
| } |
| |
| static struct dm_buffer *cache_get(struct dm_buffer_cache *bc, sector_t block) |
| { |
| struct dm_buffer *b; |
| |
| cache_read_lock(bc, block); |
| b = __cache_get(&bc->trees[cache_index(block, bc->num_locks)].root, block); |
| if (b) { |
| lru_reference(&b->lru); |
| __cache_inc_buffer(b); |
| } |
| cache_read_unlock(bc, block); |
| |
| return b; |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Returns true if the hold count hits zero. |
| * threadsafe |
| */ |
| static bool cache_put(struct dm_buffer_cache *bc, struct dm_buffer *b) |
| { |
| bool r; |
| |
| cache_read_lock(bc, b->block); |
| BUG_ON(!atomic_read(&b->hold_count)); |
| r = atomic_dec_and_test(&b->hold_count); |
| cache_read_unlock(bc, b->block); |
| |
| return r; |
| } |
| |
| /*--------------*/ |
| |
| typedef enum evict_result (*b_predicate)(struct dm_buffer *, void *); |
| |
| /* |
| * Evicts a buffer based on a predicate. The oldest buffer that |
| * matches the predicate will be selected. In addition to the |
| * predicate the hold_count of the selected buffer will be zero. |
| */ |
| struct evict_wrapper { |
| struct lock_history *lh; |
| b_predicate pred; |
| void *context; |
| }; |
| |
| /* |
| * Wraps the buffer predicate turning it into an lru predicate. Adds |
| * extra test for hold_count. |
| */ |
| static enum evict_result __evict_pred(struct lru_entry *le, void *context) |
| { |
| struct evict_wrapper *w = context; |
| struct dm_buffer *b = le_to_buffer(le); |
| |
| lh_next(w->lh, b->block); |
| |
| if (atomic_read(&b->hold_count)) |
| return ER_DONT_EVICT; |
| |
| return w->pred(b, w->context); |
| } |
| |
| static struct dm_buffer *__cache_evict(struct dm_buffer_cache *bc, int list_mode, |
| b_predicate pred, void *context, |
| struct lock_history *lh) |
| { |
| struct evict_wrapper w = {.lh = lh, .pred = pred, .context = context}; |
| struct lru_entry *le; |
| struct dm_buffer *b; |
| |
| le = lru_evict(&bc->lru[list_mode], __evict_pred, &w); |
| if (!le) |
| return NULL; |
| |
| b = le_to_buffer(le); |
| /* __evict_pred will have locked the appropriate tree. */ |
| rb_erase(&b->node, &bc->trees[cache_index(b->block, bc->num_locks)].root); |
| |
| return b; |
| } |
| |
| static struct dm_buffer *cache_evict(struct dm_buffer_cache *bc, int list_mode, |
| b_predicate pred, void *context) |
| { |
| struct dm_buffer *b; |
| struct lock_history lh; |
| |
| lh_init(&lh, bc, true); |
| b = __cache_evict(bc, list_mode, pred, context, &lh); |
| lh_exit(&lh); |
| |
| return b; |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Mark a buffer as clean or dirty. Not threadsafe. |
| */ |
| static void cache_mark(struct dm_buffer_cache *bc, struct dm_buffer *b, int list_mode) |
| { |
| cache_write_lock(bc, b->block); |
| if (list_mode != b->list_mode) { |
| lru_remove(&bc->lru[b->list_mode], &b->lru); |
| b->list_mode = list_mode; |
| lru_insert(&bc->lru[b->list_mode], &b->lru); |
| } |
| cache_write_unlock(bc, b->block); |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Runs through the lru associated with 'old_mode', if the predicate matches then |
| * it moves them to 'new_mode'. Not threadsafe. |
| */ |
| static void __cache_mark_many(struct dm_buffer_cache *bc, int old_mode, int new_mode, |
| b_predicate pred, void *context, struct lock_history *lh) |
| { |
| struct lru_entry *le; |
| struct dm_buffer *b; |
| struct evict_wrapper w = {.lh = lh, .pred = pred, .context = context}; |
| |
| while (true) { |
| le = lru_evict(&bc->lru[old_mode], __evict_pred, &w); |
| if (!le) |
| break; |
| |
| b = le_to_buffer(le); |
| b->list_mode = new_mode; |
| lru_insert(&bc->lru[b->list_mode], &b->lru); |
| } |
| } |
| |
| static void cache_mark_many(struct dm_buffer_cache *bc, int old_mode, int new_mode, |
| b_predicate pred, void *context) |
| { |
| struct lock_history lh; |
| |
| lh_init(&lh, bc, true); |
| __cache_mark_many(bc, old_mode, new_mode, pred, context, &lh); |
| lh_exit(&lh); |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Iterates through all clean or dirty entries calling a function for each |
| * entry. The callback may terminate the iteration early. Not threadsafe. |
| */ |
| |
| /* |
| * Iterator functions should return one of these actions to indicate |
| * how the iteration should proceed. |
| */ |
| enum it_action { |
| IT_NEXT, |
| IT_COMPLETE, |
| }; |
| |
| typedef enum it_action (*iter_fn)(struct dm_buffer *b, void *context); |
| |
| static void __cache_iterate(struct dm_buffer_cache *bc, int list_mode, |
| iter_fn fn, void *context, struct lock_history *lh) |
| { |
| struct lru *lru = &bc->lru[list_mode]; |
| struct lru_entry *le, *first; |
| |
| if (!lru->cursor) |
| return; |
| |
| first = le = to_le(lru->cursor); |
| do { |
| struct dm_buffer *b = le_to_buffer(le); |
| |
| lh_next(lh, b->block); |
| |
| switch (fn(b, context)) { |
| case IT_NEXT: |
| break; |
| |
| case IT_COMPLETE: |
| return; |
| } |
| cond_resched(); |
| |
| le = to_le(le->list.next); |
| } while (le != first); |
| } |
| |
| static void cache_iterate(struct dm_buffer_cache *bc, int list_mode, |
| iter_fn fn, void *context) |
| { |
| struct lock_history lh; |
| |
| lh_init(&lh, bc, false); |
| __cache_iterate(bc, list_mode, fn, context, &lh); |
| lh_exit(&lh); |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Passes ownership of the buffer to the cache. Returns false if the |
| * buffer was already present (in which case ownership does not pass). |
| * eg, a race with another thread. |
| * |
| * Holder count should be 1 on insertion. |
| * |
| * Not threadsafe. |
| */ |
| static bool __cache_insert(struct rb_root *root, struct dm_buffer *b) |
| { |
| struct rb_node **new = &root->rb_node, *parent = NULL; |
| struct dm_buffer *found; |
| |
| while (*new) { |
| found = container_of(*new, struct dm_buffer, node); |
| |
| if (found->block == b->block) |
| return false; |
| |
| 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, root); |
| |
| return true; |
| } |
| |
| static bool cache_insert(struct dm_buffer_cache *bc, struct dm_buffer *b) |
| { |
| bool r; |
| |
| if (WARN_ON_ONCE(b->list_mode >= LIST_SIZE)) |
| return false; |
| |
| cache_write_lock(bc, b->block); |
| BUG_ON(atomic_read(&b->hold_count) != 1); |
| r = __cache_insert(&bc->trees[cache_index(b->block, bc->num_locks)].root, b); |
| if (r) |
| lru_insert(&bc->lru[b->list_mode], &b->lru); |
| cache_write_unlock(bc, b->block); |
| |
| return r; |
| } |
| |
| /*--------------*/ |
| |
| /* |
| * Removes buffer from cache, ownership of the buffer passes back to the caller. |
| * Fails if the hold_count is not one (ie. the caller holds the only reference). |
| * |
| * Not threadsafe. |
| */ |
| static bool cache_remove(struct dm_buffer_cache *bc, struct dm_buffer *b) |
| { |
| bool r; |
| |
| cache_write_lock(bc, b->block); |
| |
| if (atomic_read(&b->hold_count) != 1) { |
| r = false; |
| } else { |
| r = true; |
| rb_erase(&b->node, &bc->trees[cache_index(b->block, bc->num_locks)].root); |
| lru_remove(&bc->lru[b->list_mode], &b->lru); |
| } |
| |
| cache_write_unlock(bc, b->block); |
| |
| return r; |
| } |
| |
| /*--------------*/ |
| |
| typedef void (*b_release)(struct dm_buffer *); |
| |
| static struct dm_buffer *__find_next(struct rb_root *root, sector_t block) |
| { |
| struct rb_node *n = root->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 __remove_range(struct dm_buffer_cache *bc, |
| struct rb_root *root, |
| sector_t begin, sector_t end, |
| b_predicate pred, b_release release) |
| { |
| struct dm_buffer *b; |
| |
| while (true) { |
| cond_resched(); |
| |
| b = __find_next(root, begin); |
| if (!b || (b->block >= end)) |
| break; |
| |
| begin = b->block + 1; |
| |
| if (atomic_read(&b->hold_count)) |
| continue; |
| |
| if (pred(b, NULL) == ER_EVICT) { |
| rb_erase(&b->node, root); |
| lru_remove(&bc->lru[b->list_mode], &b->lru); |
| release(b); |
| } |
| } |
| } |
| |
| static void cache_remove_range(struct dm_buffer_cache *bc, |
| sector_t begin, sector_t end, |
| b_predicate pred, b_release release) |
| { |
| unsigned int i; |
| |
| for (i = 0; i < bc->num_locks; i++) { |
| down_write(&bc->trees[i].lock); |
| __remove_range(bc, &bc->trees[i].root, begin, end, pred, release); |
| up_write(&bc->trees[i].lock); |
| } |
| } |
| |
| /*----------------------------------------------------------------*/ |
| |
| /* |
| * Linking of buffers: |
| * 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. |
| * |
| * Dirty and clean buffers that are being written are linked to |
| * lru[LIST_DIRTY] with their lru_list field. When the write |
| * finishes, the buffer cannot be relinked immediately (because we |
| * are in an interrupt context and relinking requires process |
| * context), so some clean-not-writing buffers can be held on |
| * dirty_lru too. They are later added to lru in the process |
| * context. |
| */ |
| struct dm_bufio_client { |
| struct block_device *bdev; |
| unsigned int block_size; |
| s8 sectors_per_block_bits; |
| |
| bool no_sleep; |
| struct mutex lock; |
| spinlock_t spinlock; |
| |
| int async_write_error; |
| |
| void (*alloc_callback)(struct dm_buffer *buf); |
| void (*write_callback)(struct dm_buffer *buf); |
| struct kmem_cache *slab_buffer; |
| struct kmem_cache *slab_cache; |
| struct dm_io_client *dm_io; |
| |
| struct list_head reserved_buffers; |
| unsigned int need_reserved_buffers; |
| |
| unsigned int minimum_buffers; |
| |
| sector_t start; |
| |
| struct shrinker shrinker; |
| struct work_struct shrink_work; |
| atomic_long_t need_shrink; |
| |
| wait_queue_head_t free_buffer_wait; |
| |
| struct list_head client_list; |
| |
| /* |
| * Used by global_cleanup to sort the clients list. |
| */ |
| unsigned long oldest_buffer; |
| |
| struct dm_buffer_cache cache; /* must be last member */ |
| }; |
| |
| static DEFINE_STATIC_KEY_FALSE(no_sleep_enabled); |
| |
| /*----------------------------------------------------------------*/ |
| |
| #define dm_bufio_in_request() (!!current->bio_list) |
| |
| static void dm_bufio_lock(struct dm_bufio_client *c) |
| { |
| if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep) |
| spin_lock_bh(&c->spinlock); |
| else |
| mutex_lock_nested(&c->lock, dm_bufio_in_request()); |
| } |
| |
| static void dm_bufio_unlock(struct dm_bufio_client *c) |
| { |
| if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep) |
| spin_unlock_bh(&c->spinlock); |
| else |
| mutex_unlock(&c->lock); |
| } |
| |
| /*----------------------------------------------------------------*/ |
| |
| /* |
| * Default cache size: available memory divided by the ratio. |
| */ |
| static unsigned long dm_bufio_default_cache_size; |
| |
| /* |
| * Total cache size set by the user. |
| */ |
| static unsigned long dm_bufio_cache_size; |
| |
| /* |
| * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change |
| * at any time. If it disagrees, the user has changed cache size. |
| */ |
| static unsigned long dm_bufio_cache_size_latch; |
| |
| static DEFINE_SPINLOCK(global_spinlock); |
| |
| /* |
| * Buffers are freed after this timeout |
| */ |
| static unsigned int dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS; |
| static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES; |
| |
| static unsigned long dm_bufio_peak_allocated; |
| static unsigned long dm_bufio_allocated_kmem_cache; |
| static unsigned long dm_bufio_allocated_get_free_pages; |
| static unsigned long dm_bufio_allocated_vmalloc; |
| static unsigned long dm_bufio_current_allocated; |
| |
| /*----------------------------------------------------------------*/ |
| |
| /* |
| * The current number of clients. |
| */ |
| static int dm_bufio_client_count; |
| |
| /* |
| * The list of all clients. |
| */ |
| static LIST_HEAD(dm_bufio_all_clients); |
| |
| /* |
| * This mutex protects dm_bufio_cache_size_latch and dm_bufio_client_count |
| */ |
| static DEFINE_MUTEX(dm_bufio_clients_lock); |
| |
| static struct workqueue_struct *dm_bufio_wq; |
| static struct delayed_work dm_bufio_cleanup_old_work; |
| static struct work_struct dm_bufio_replacement_work; |
| |
| |
| #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| static void buffer_record_stack(struct dm_buffer *b) |
| { |
| b->stack_len = stack_trace_save(b->stack_entries, MAX_STACK, 2); |
| } |
| #endif |
| |
| /*----------------------------------------------------------------*/ |
| |
| static void adjust_total_allocated(struct dm_buffer *b, bool unlink) |
| { |
| unsigned char data_mode; |
| long diff; |
| |
| static unsigned long * const class_ptr[DATA_MODE_LIMIT] = { |
| &dm_bufio_allocated_kmem_cache, |
| &dm_bufio_allocated_get_free_pages, |
| &dm_bufio_allocated_vmalloc, |
| }; |
| |
| data_mode = b->data_mode; |
| diff = (long)b->c->block_size; |
| if (unlink) |
| diff = -diff; |
| |
| spin_lock(&global_spinlock); |
| |
| *class_ptr[data_mode] += diff; |
| |
| dm_bufio_current_allocated += diff; |
| |
| if (dm_bufio_current_allocated > dm_bufio_peak_allocated) |
| dm_bufio_peak_allocated = dm_bufio_current_allocated; |
| |
| if (!unlink) { |
| if (dm_bufio_current_allocated > dm_bufio_cache_size) |
| queue_work(dm_bufio_wq, &dm_bufio_replacement_work); |
| } |
| |
| spin_unlock(&global_spinlock); |
| } |
| |
| /* |
| * Change the number of clients and recalculate per-client limit. |
| */ |
| static void __cache_size_refresh(void) |
| { |
| if (WARN_ON(!mutex_is_locked(&dm_bufio_clients_lock))) |
| return; |
| if (WARN_ON(dm_bufio_client_count < 0)) |
| return; |
| |
| dm_bufio_cache_size_latch = READ_ONCE(dm_bufio_cache_size); |
| |
| /* |
| * Use default if set to 0 and report the actual cache size used. |
| */ |
| if (!dm_bufio_cache_size_latch) { |
| (void)cmpxchg(&dm_bufio_cache_size, 0, |
| dm_bufio_default_cache_size); |
| dm_bufio_cache_size_latch = dm_bufio_default_cache_size; |
| } |
| } |
| |
| /* |
| * Allocating buffer data. |
| * |
| * Small buffers are allocated with kmem_cache, to use space optimally. |
| * |
| * For large buffers, we choose between get_free_pages and vmalloc. |
| * Each has advantages and disadvantages. |
| * |
| * __get_free_pages can randomly fail if the memory is fragmented. |
| * __vmalloc won't randomly fail, but vmalloc space is limited (it may be |
| * as low as 128M) so using it for caching is not appropriate. |
| * |
| * If the allocation may fail we use __get_free_pages. Memory fragmentation |
| * won't have a fatal effect here, but it just causes flushes of some other |
| * buffers and more I/O will be performed. Don't use __get_free_pages if it |
| * always fails (i.e. order > MAX_ORDER). |
| * |
| * If the allocation shouldn't fail we use __vmalloc. This is only for the |
| * initial reserve allocation, so there's no risk of wasting all vmalloc |
| * space. |
| */ |
| static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, |
| unsigned char *data_mode) |
| { |
| if (unlikely(c->slab_cache != NULL)) { |
| *data_mode = DATA_MODE_SLAB; |
| return kmem_cache_alloc(c->slab_cache, gfp_mask); |
| } |
| |
| if (c->block_size <= KMALLOC_MAX_SIZE && |
| gfp_mask & __GFP_NORETRY) { |
| *data_mode = DATA_MODE_GET_FREE_PAGES; |
| return (void *)__get_free_pages(gfp_mask, |
| c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT)); |
| } |
| |
| *data_mode = DATA_MODE_VMALLOC; |
| |
| /* |
| * __vmalloc allocates the data pages and auxiliary structures with |
| * gfp_flags that were specified, but pagetables are always allocated |
| * with GFP_KERNEL, no matter what was specified as gfp_mask. |
| * |
| * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that |
| * all allocations done by this process (including pagetables) are done |
| * as if GFP_NOIO was specified. |
| */ |
| if (gfp_mask & __GFP_NORETRY) { |
| unsigned int noio_flag = memalloc_noio_save(); |
| void *ptr = __vmalloc(c->block_size, gfp_mask); |
| |
| memalloc_noio_restore(noio_flag); |
| return ptr; |
| } |
| |
| return __vmalloc(c->block_size, gfp_mask); |
| } |
| |
| /* |
| * Free buffer's data. |
| */ |
| static void free_buffer_data(struct dm_bufio_client *c, |
| void *data, unsigned char data_mode) |
| { |
| switch (data_mode) { |
| case DATA_MODE_SLAB: |
| kmem_cache_free(c->slab_cache, data); |
| break; |
| |
| case DATA_MODE_GET_FREE_PAGES: |
| free_pages((unsigned long)data, |
| c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT)); |
| break; |
| |
| case DATA_MODE_VMALLOC: |
| vfree(data); |
| break; |
| |
| default: |
| DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d", |
| data_mode); |
| BUG(); |
| } |
| } |
| |
| /* |
| * Allocate buffer and its data. |
| */ |
| static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask) |
| { |
| struct dm_buffer *b = kmem_cache_alloc(c->slab_buffer, gfp_mask); |
| |
| if (!b) |
| return NULL; |
| |
| b->c = c; |
| |
| b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode); |
| if (!b->data) { |
| 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; |
| #endif |
| return b; |
| } |
| |
| /* |
| * Free buffer and its data. |
| */ |
| 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); |
| } |
| |
| /* |
| *-------------------------------------------------------------------------- |
| * Submit I/O on the buffer. |
| * |
| * Bio interface is faster but it has some problems: |
| * the vector list is limited (increasing this limit increases |
| * memory-consumption per buffer, so it is not viable); |
| * |
| * the memory must be direct-mapped, not vmalloced; |
| * |
| * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and |
| * it is not vmalloced, try using the bio interface. |
| * |
| * If the buffer is big, if it is vmalloced or if the underlying device |
| * rejects the bio because it is too large, use dm-io layer to do the I/O. |
| * The dm-io layer splits the I/O into multiple requests, avoiding the above |
| * shortcomings. |
| *-------------------------------------------------------------------------- |
| */ |
| |
| /* |
| * dm-io completion routine. It just calls b->bio.bi_end_io, pretending |
| * that the request was handled directly with bio interface. |
| */ |
| static void dmio_complete(unsigned long error, void *context) |
| { |
| struct dm_buffer *b = context; |
| |
| b->end_io(b, unlikely(error != 0) ? BLK_STS_IOERR : 0); |
| } |
| |
| static void use_dmio(struct dm_buffer *b, enum req_op op, sector_t sector, |
| unsigned int n_sectors, unsigned int offset) |
| { |
| int r; |
| struct dm_io_request io_req = { |
| .bi_opf = op, |
| .notify.fn = dmio_complete, |
| .notify.context = b, |
| .client = b->c->dm_io, |
| }; |
| struct dm_io_region region = { |
| .bdev = b->c->bdev, |
| .sector = sector, |
| .count = n_sectors, |
| }; |
| |
| if (b->data_mode != DATA_MODE_VMALLOC) { |
| io_req.mem.type = DM_IO_KMEM; |
| io_req.mem.ptr.addr = (char *)b->data + offset; |
| } else { |
| io_req.mem.type = DM_IO_VMA; |
| io_req.mem.ptr.vma = (char *)b->data + offset; |
| } |
| |
| r = dm_io(&io_req, 1, ®ion, NULL); |
| if (unlikely(r)) |
| b->end_io(b, errno_to_blk_status(r)); |
| } |
| |
| static void bio_complete(struct bio *bio) |
| { |
| struct dm_buffer *b = bio->bi_private; |
| blk_status_t status = bio->bi_status; |
| |
| bio_uninit(bio); |
| kfree(bio); |
| b->end_io(b, status); |
| } |
| |
| static void use_bio(struct dm_buffer *b, enum req_op op, sector_t sector, |
| unsigned int n_sectors, unsigned int offset) |
| { |
| struct bio *bio; |
| char *ptr; |
| unsigned int len; |
| |
| bio = bio_kmalloc(1, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN); |
| if (!bio) { |
| use_dmio(b, op, sector, n_sectors, offset); |
| return; |
| } |
| bio_init(bio, b->c->bdev, bio->bi_inline_vecs, 1, op); |
| bio->bi_iter.bi_sector = sector; |
| bio->bi_end_io = bio_complete; |
| bio->bi_private = b; |
| |
| ptr = (char *)b->data + offset; |
| len = n_sectors << SECTOR_SHIFT; |
| |
| __bio_add_page(bio, virt_to_page(ptr), len, offset_in_page(ptr)); |
| |
| submit_bio(bio); |
| } |
| |
| static inline sector_t block_to_sector(struct dm_bufio_client *c, sector_t block) |
| { |
| sector_t sector; |
| |
| if (likely(c->sectors_per_block_bits >= 0)) |
| sector = block << c->sectors_per_block_bits; |
| else |
| sector = block * (c->block_size >> SECTOR_SHIFT); |
| sector += c->start; |
| |
| return sector; |
| } |
| |
| static void submit_io(struct dm_buffer *b, enum req_op op, |
| void (*end_io)(struct dm_buffer *, blk_status_t)) |
| { |
| unsigned int n_sectors; |
| sector_t sector; |
| unsigned int offset, end; |
| |
| b->end_io = end_io; |
| |
| sector = block_to_sector(b->c, b->block); |
| |
| if (op != REQ_OP_WRITE) { |
| n_sectors = b->c->block_size >> SECTOR_SHIFT; |
| offset = 0; |
| } else { |
| if (b->c->write_callback) |
| b->c->write_callback(b); |
| offset = b->write_start; |
| end = b->write_end; |
| offset &= -DM_BUFIO_WRITE_ALIGN; |
| end += DM_BUFIO_WRITE_ALIGN - 1; |
| end &= -DM_BUFIO_WRITE_ALIGN; |
| if (unlikely(end > b->c->block_size)) |
| end = b->c->block_size; |
| |
| sector += offset >> SECTOR_SHIFT; |
| n_sectors = (end - offset) >> SECTOR_SHIFT; |
| } |
| |
| if (b->data_mode != DATA_MODE_VMALLOC) |
| use_bio(b, op, sector, n_sectors, offset); |
| else |
| use_dmio(b, op, sector, n_sectors, offset); |
| } |
| |
| /* |
| *-------------------------------------------------------------- |
| * Writing dirty buffers |
| *-------------------------------------------------------------- |
| */ |
| |
| /* |
| * The endio routine for write. |
| * |
| * Set the error, clear B_WRITING bit and wake anyone who was waiting on |
| * it. |
| */ |
| static void write_endio(struct dm_buffer *b, blk_status_t status) |
| { |
| b->write_error = status; |
| if (unlikely(status)) { |
| struct dm_bufio_client *c = b->c; |
| |
| (void)cmpxchg(&c->async_write_error, 0, |
| blk_status_to_errno(status)); |
| } |
| |
| BUG_ON(!test_bit(B_WRITING, &b->state)); |
| |
| smp_mb__before_atomic(); |
| clear_bit(B_WRITING, &b->state); |
| smp_mb__after_atomic(); |
| |
| wake_up_bit(&b->state, B_WRITING); |
| } |
| |
| /* |
| * Initiate a write on a dirty buffer, but don't wait for it. |
| * |
| * - If the buffer is not dirty, exit. |
| * - If there some previous write going on, wait for it to finish (we can't |
| * have two writes on the same buffer simultaneously). |
| * - Submit our write and don't wait on it. We set B_WRITING indicating |
| * that there is a write in progress. |
| */ |
| static void __write_dirty_buffer(struct dm_buffer *b, |
| struct list_head *write_list) |
| { |
| if (!test_bit(B_DIRTY, &b->state)) |
| return; |
| |
| clear_bit(B_DIRTY, &b->state); |
| wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); |
| |
| b->write_start = b->dirty_start; |
| b->write_end = b->dirty_end; |
| |
| if (!write_list) |
| submit_io(b, REQ_OP_WRITE, write_endio); |
| else |
| list_add_tail(&b->write_list, write_list); |
| } |
| |
| static void __flush_write_list(struct list_head *write_list) |
| { |
| struct blk_plug plug; |
| |
| blk_start_plug(&plug); |
| while (!list_empty(write_list)) { |
| struct dm_buffer *b = |
| list_entry(write_list->next, struct dm_buffer, write_list); |
| list_del(&b->write_list); |
| submit_io(b, REQ_OP_WRITE, write_endio); |
| cond_resched(); |
| } |
| blk_finish_plug(&plug); |
| } |
| |
| /* |
| * Wait until any activity on the buffer finishes. Possibly write the |
| * buffer if it is dirty. When this function finishes, there is no I/O |
| * running on the buffer and the buffer is not dirty. |
| */ |
| static void __make_buffer_clean(struct dm_buffer *b) |
| { |
| 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 */ |
| return; |
| |
| wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); |
| __write_dirty_buffer(b, NULL); |
| 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. |
| */ |
| static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) |
| { |
| struct dm_buffer *b; |
| |
| 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; |
| |
| b = cache_evict(&c->cache, LIST_DIRTY, is_dirty, NULL); |
| if (b) { |
| __make_buffer_clean(b); |
| return b; |
| } |
| |
| return NULL; |
| } |
| |
| /* |
| * Wait until some other threads free some buffer or release hold count on |
| * some buffer. |
| * |
| * This function is entered with c->lock held, drops it and regains it |
| * before exiting. |
| */ |
| static void __wait_for_free_buffer(struct dm_bufio_client *c) |
| { |
| DECLARE_WAITQUEUE(wait, current); |
| |
| add_wait_queue(&c->free_buffer_wait, &wait); |
| set_current_state(TASK_UNINTERRUPTIBLE); |
| dm_bufio_unlock(c); |
| |
| /* |
| * 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); |
| |
| dm_bufio_lock(c); |
| } |
| |
| enum new_flag { |
| NF_FRESH = 0, |
| NF_READ = 1, |
| NF_GET = 2, |
| NF_PREFETCH = 3 |
| }; |
| |
| /* |
| * Allocate a new buffer. If the allocation is not possible, wait until |
| * some other thread frees a buffer. |
| * |
| * May drop the lock and regain it. |
| */ |
| static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) |
| { |
| struct dm_buffer *b; |
| bool tried_noio_alloc = false; |
| |
| /* |
| * dm-bufio is resistant to allocation failures (it just keeps |
| * one buffer reserved in cases all the allocations fail). |
| * So set flags to not try too hard: |
| * GFP_NOWAIT: don't wait; if we need to sleep we'll release our |
| * mutex and wait ourselves. |
| * __GFP_NORETRY: don't retry and rather return failure |
| * __GFP_NOMEMALLOC: don't use emergency reserves |
| * __GFP_NOWARN: don't print a warning in case of failure |
| * |
| * For debugging, if we set the cache size to 1, no new buffers will |
| * be allocated. |
| */ |
| while (1) { |
| if (dm_bufio_cache_size_latch != 1) { |
| b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); |
| if (b) |
| return b; |
| } |
| |
| if (nf == NF_PREFETCH) |
| return NULL; |
| |
| if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) { |
| dm_bufio_unlock(c); |
| b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); |
| dm_bufio_lock(c); |
| if (b) |
| return b; |
| tried_noio_alloc = true; |
| } |
| |
| if (!list_empty(&c->reserved_buffers)) { |
| b = list_to_buffer(c->reserved_buffers.next); |
| list_del(&b->lru.list); |
| c->need_reserved_buffers++; |
| |
| return b; |
| } |
| |
| b = __get_unclaimed_buffer(c); |
| if (b) |
| return b; |
| |
| __wait_for_free_buffer(c); |
| } |
| } |
| |
| static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf) |
| { |
| struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf); |
| |
| if (!b) |
| return NULL; |
| |
| if (c->alloc_callback) |
| c->alloc_callback(b); |
| |
| return b; |
| } |
| |
| /* |
| * Free a buffer and wake other threads waiting for free buffers. |
| */ |
| 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); |
| c->need_reserved_buffers--; |
| } |
| |
| /* |
| * We hold the bufio lock here, so no one can add entries to the |
| * wait queue anyway. |
| */ |
| if (unlikely(waitqueue_active(&c->free_buffer_wait))) |
| wake_up(&c->free_buffer_wait); |
| } |
| |
| static enum evict_result cleaned(struct dm_buffer *b, void *context) |
| { |
| if (WARN_ON_ONCE(test_bit(B_READING, &b->state))) |
| return ER_DONT_EVICT; /* should never happen */ |
| |
| if (test_bit(B_DIRTY, &b->state) || test_bit(B_WRITING, &b->state)) |
| return ER_DONT_EVICT; |
| else |
| return ER_EVICT; |
| } |
| |
| static void __move_clean_buffers(struct dm_bufio_client *c) |
| { |
| cache_mark_many(&c->cache, LIST_DIRTY, LIST_CLEAN, cleaned, NULL); |
| } |
| |
| struct write_context { |
| int no_wait; |
| struct list_head *write_list; |
| }; |
| |
| 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); |
| } |
| |
| /* |
| * Check if we're over watermark. |
| * If we are over threshold_buffers, start freeing buffers. |
| * If we're over "limit_buffers", block until we get under the limit. |
| */ |
| static void __check_watermark(struct dm_bufio_client *c, |
| struct list_head *write_list) |
| { |
| 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); |
| } |
| |
| /* |
| *-------------------------------------------------------------- |
| * Getting a buffer |
| *-------------------------------------------------------------- |
| */ |
| |
| 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) |
| { |
| struct dm_buffer *b, *new_b = NULL; |
| |
| *need_submit = 0; |
| |
| /* This can't be called with NF_GET */ |
| if (WARN_ON_ONCE(nf == NF_GET)) |
| return NULL; |
| |
| new_b = __alloc_buffer_wait(c, nf); |
| if (!new_b) |
| return NULL; |
| |
| /* |
| * We've had a period where the mutex was unlocked, so need to |
| * recheck the buffer tree. |
| */ |
| b = cache_get(&c->cache, block); |
| if (b) { |
| __free_buffer_wake(new_b); |
| goto found_buffer; |
| } |
| |
| __check_watermark(c, write_list); |
| |
| b = new_b; |
| atomic_set(&b->hold_count, 1); |
| WRITE_ONCE(b->last_accessed, jiffies); |
| b->block = block; |
| b->read_error = 0; |
| b->write_error = 0; |
| b->list_mode = LIST_CLEAN; |
| |
| if (nf == NF_FRESH) |
| b->state = 0; |
| else { |
| 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) { |
| 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; |
| } |
| |
| return b; |
| } |
| |
| /* |
| * The endio routine for reading: set the error, clear the bit and wake up |
| * anyone waiting on the buffer. |
| */ |
| static void read_endio(struct dm_buffer *b, blk_status_t status) |
| { |
| b->read_error = status; |
| |
| BUG_ON(!test_bit(B_READING, &b->state)); |
| |
| smp_mb__before_atomic(); |
| clear_bit(B_READING, &b->state); |
| smp_mb__after_atomic(); |
| |
| wake_up_bit(&b->state, B_READING); |
| } |
| |
| /* |
| * A common routine for dm_bufio_new and dm_bufio_read. Operation of these |
| * functions is similar except that dm_bufio_new doesn't read the |
| * buffer from the disk (assuming that the caller overwrites all the data |
| * and uses dm_bufio_mark_buffer_dirty to write new data back). |
| */ |
| static void *new_read(struct dm_bufio_client *c, sector_t block, |
| enum new_flag nf, struct dm_buffer **bp) |
| { |
| int need_submit = 0; |
| struct dm_buffer *b; |
| |
| LIST_HEAD(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 && (atomic_read(&b->hold_count) == 1)) |
| buffer_record_stack(b); |
| #endif |
| |
| __flush_write_list(&write_list); |
| |
| if (!b) |
| return NULL; |
| |
| if (need_submit) |
| submit_io(b, REQ_OP_READ, read_endio); |
| |
| wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); |
| |
| if (b->read_error) { |
| int error = blk_status_to_errno(b->read_error); |
| |
| dm_bufio_release(b); |
| |
| return ERR_PTR(error); |
| } |
| |
| *bp = b; |
| |
| return b->data; |
| } |
| |
| void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, |
| struct dm_buffer **bp) |
| { |
| return new_read(c, block, NF_GET, bp); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get); |
| |
| void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, |
| struct dm_buffer **bp) |
| { |
| if (WARN_ON_ONCE(dm_bufio_in_request())) |
| return ERR_PTR(-EINVAL); |
| |
| return new_read(c, block, NF_READ, bp); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_read); |
| |
| void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, |
| struct dm_buffer **bp) |
| { |
| if (WARN_ON_ONCE(dm_bufio_in_request())) |
| return ERR_PTR(-EINVAL); |
| |
| return new_read(c, block, NF_FRESH, bp); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_new); |
| |
| void dm_bufio_prefetch(struct dm_bufio_client *c, |
| sector_t block, unsigned int n_blocks) |
| { |
| struct blk_plug plug; |
| |
| LIST_HEAD(write_list); |
| |
| if (WARN_ON_ONCE(dm_bufio_in_request())) |
| return; /* should never happen */ |
| |
| blk_start_plug(&plug); |
| |
| 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))) { |
| dm_bufio_unlock(c); |
| blk_finish_plug(&plug); |
| __flush_write_list(&write_list); |
| blk_start_plug(&plug); |
| dm_bufio_lock(c); |
| } |
| if (unlikely(b != NULL)) { |
| dm_bufio_unlock(c); |
| |
| if (need_submit) |
| submit_io(b, REQ_OP_READ, read_endio); |
| dm_bufio_release(b); |
| |
| cond_resched(); |
| |
| if (!n_blocks) |
| goto flush_plug; |
| dm_bufio_lock(c); |
| } |
| dm_bufio_unlock(c); |
| } |
| |
| flush_plug: |
| blk_finish_plug(&plug); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_prefetch); |
| |
| void dm_bufio_release(struct dm_buffer *b) |
| { |
| struct dm_bufio_client *c = b->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)) { |
| dm_bufio_lock(c); |
| |
| /* 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); |
| } |
| |
| cache_put_and_wake(c, b); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_release); |
| |
| void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, |
| unsigned int start, unsigned int end) |
| { |
| struct dm_bufio_client *c = b->c; |
| |
| BUG_ON(start >= end); |
| BUG_ON(end > b->c->block_size); |
| |
| dm_bufio_lock(c); |
| |
| BUG_ON(test_bit(B_READING, &b->state)); |
| |
| if (!test_and_set_bit(B_DIRTY, &b->state)) { |
| b->dirty_start = start; |
| b->dirty_end = end; |
| cache_mark(&c->cache, b, LIST_DIRTY); |
| } else { |
| if (start < b->dirty_start) |
| b->dirty_start = start; |
| if (end > b->dirty_end) |
| b->dirty_end = end; |
| } |
| |
| dm_bufio_unlock(c); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty); |
| |
| void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) |
| { |
| dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty); |
| |
| void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) |
| { |
| LIST_HEAD(write_list); |
| |
| if (WARN_ON_ONCE(dm_bufio_in_request())) |
| return; /* should never happen */ |
| |
| dm_bufio_lock(c); |
| __write_dirty_buffers_async(c, 0, &write_list); |
| dm_bufio_unlock(c); |
| __flush_write_list(&write_list); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async); |
| |
| /* |
| * For performance, it is essential that the buffers are written asynchronously |
| * and simultaneously (so that the block layer can merge the writes) and then |
| * waited upon. |
| * |
| * 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 nr_buffers; |
| struct lru_entry *e; |
| struct lru_iter it; |
| |
| LIST_HEAD(write_list); |
| |
| dm_bufio_lock(c); |
| __write_dirty_buffers_async(c, 0, &write_list); |
| dm_bufio_unlock(c); |
| __flush_write_list(&write_list); |
| dm_bufio_lock(c); |
| |
| 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 (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)) |
| cache_mark(&c->cache, b, LIST_CLEAN); |
| |
| cache_put_and_wake(c, b); |
| |
| cond_resched(); |
| } |
| lru_iter_end(&it); |
| |
| wake_up(&c->free_buffer_wait); |
| dm_bufio_unlock(c); |
| |
| a = xchg(&c->async_write_error, 0); |
| f = dm_bufio_issue_flush(c); |
| if (a) |
| return a; |
| |
| return f; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers); |
| |
| /* |
| * Use dm-io to send an empty barrier to flush the device. |
| */ |
| int dm_bufio_issue_flush(struct dm_bufio_client *c) |
| { |
| struct dm_io_request io_req = { |
| .bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC, |
| .mem.type = DM_IO_KMEM, |
| .mem.ptr.addr = NULL, |
| .client = c->dm_io, |
| }; |
| struct dm_io_region io_reg = { |
| .bdev = c->bdev, |
| .sector = 0, |
| .count = 0, |
| }; |
| |
| if (WARN_ON_ONCE(dm_bufio_in_request())) |
| return -EINVAL; |
| |
| return dm_io(&io_req, 1, &io_reg, NULL); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_issue_flush); |
| |
| /* |
| * Use dm-io to send a discard request to flush the device. |
| */ |
| int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count) |
| { |
| struct dm_io_request io_req = { |
| .bi_opf = REQ_OP_DISCARD | REQ_SYNC, |
| .mem.type = DM_IO_KMEM, |
| .mem.ptr.addr = NULL, |
| .client = c->dm_io, |
| }; |
| struct dm_io_region io_reg = { |
| .bdev = c->bdev, |
| .sector = block_to_sector(c, block), |
| .count = block_to_sector(c, count), |
| }; |
| |
| if (WARN_ON_ONCE(dm_bufio_in_request())) |
| return -EINVAL; /* discards are optional */ |
| |
| return dm_io(&io_req, 1, &io_reg, NULL); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_issue_discard); |
| |
| static bool forget_buffer(struct dm_bufio_client *c, sector_t block) |
| { |
| 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; |
| } |
| |
| /* |
| * Free the given buffer. |
| * |
| * This is just a hint, if the buffer is in use or dirty, this function |
| * does nothing. |
| */ |
| void dm_bufio_forget(struct dm_bufio_client *c, sector_t block) |
| { |
| dm_bufio_lock(c); |
| forget_buffer(c, block); |
| dm_bufio_unlock(c); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_forget); |
| |
| static enum evict_result idle(struct dm_buffer *b, void *context) |
| { |
| 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); |
| |
| void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n) |
| { |
| c->minimum_buffers = n; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_set_minimum_buffers); |
| |
| unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c) |
| { |
| return c->block_size; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get_block_size); |
| |
| sector_t dm_bufio_get_device_size(struct dm_bufio_client *c) |
| { |
| sector_t s = bdev_nr_sectors(c->bdev); |
| |
| if (s >= c->start) |
| s -= c->start; |
| else |
| s = 0; |
| if (likely(c->sectors_per_block_bits >= 0)) |
| s >>= c->sectors_per_block_bits; |
| else |
| sector_div(s, c->block_size >> SECTOR_SHIFT); |
| return s; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get_device_size); |
| |
| struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c) |
| { |
| return c->dm_io; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get_dm_io_client); |
| |
| sector_t dm_bufio_get_block_number(struct dm_buffer *b) |
| { |
| return b->block; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get_block_number); |
| |
| void *dm_bufio_get_block_data(struct dm_buffer *b) |
| { |
| return b->data; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get_block_data); |
| |
| void *dm_bufio_get_aux_data(struct dm_buffer *b) |
| { |
| return b + 1; |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data); |
| |
| struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b) |
| { |
| return b->c; |
| } |
| 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) |
| { |
| int i; |
| struct dm_buffer *b; |
| |
| if (WARN_ON(dm_bufio_in_request())) |
| return; /* should never happen */ |
| |
| /* |
| * An optimization so that the buffers are not written one-by-one. |
| */ |
| dm_bufio_write_dirty_buffers_async(c); |
| |
| dm_bufio_lock(c); |
| |
| while ((b = __get_unclaimed_buffer(c))) |
| __free_buffer_wake(b); |
| |
| 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))) |
| __free_buffer_wake(b); |
| #endif |
| |
| for (i = 0; i < LIST_SIZE; i++) |
| WARN_ON(cache_count(&c->cache, i)); |
| |
| dm_bufio_unlock(c); |
| } |
| |
| static unsigned long get_retain_buffers(struct dm_bufio_client *c) |
| { |
| unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes); |
| |
| if (likely(c->sectors_per_block_bits >= 0)) |
| retain_bytes >>= c->sectors_per_block_bits + SECTOR_SHIFT; |
| else |
| retain_bytes /= c->block_size; |
| |
| return retain_bytes; |
| } |
| |
| static void __scan(struct dm_bufio_client *c) |
| { |
| int l; |
| struct dm_buffer *b; |
| unsigned long freed = 0; |
| unsigned long retain_target = get_retain_buffers(c); |
| unsigned long count = cache_total(&c->cache); |
| |
| for (l = 0; l < LIST_SIZE; l++) { |
| while (true) { |
| if (count - freed <= retain_target) |
| atomic_long_set(&c->need_shrink, 0); |
| if (!atomic_long_read(&c->need_shrink)) |
| 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(); |
| } |
| } |
| } |
| |
| static void shrink_work(struct work_struct *w) |
| { |
| struct dm_bufio_client *c = container_of(w, struct dm_bufio_client, shrink_work); |
| |
| dm_bufio_lock(c); |
| __scan(c); |
| dm_bufio_unlock(c); |
| } |
| |
| static unsigned long dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) |
| { |
| struct dm_bufio_client *c; |
| |
| c = container_of(shrink, struct dm_bufio_client, shrinker); |
| atomic_long_add(sc->nr_to_scan, &c->need_shrink); |
| queue_work(dm_bufio_wq, &c->shrink_work); |
| |
| return sc->nr_to_scan; |
| } |
| |
| 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 = cache_total(&c->cache); |
| unsigned long retain_target = get_retain_buffers(c); |
| unsigned long queued_for_cleanup = atomic_long_read(&c->need_shrink); |
| |
| if (unlikely(count < retain_target)) |
| count = 0; |
| else |
| count -= retain_target; |
| |
| if (unlikely(count < queued_for_cleanup)) |
| count = 0; |
| else |
| count -= queued_for_cleanup; |
| |
| return count; |
| } |
| |
| /* |
| * Create the buffering interface |
| */ |
| struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned int block_size, |
| unsigned int reserved_buffers, unsigned int aux_size, |
| void (*alloc_callback)(struct dm_buffer *), |
| void (*write_callback)(struct dm_buffer *), |
| unsigned int flags) |
| { |
| int r; |
| unsigned int num_locks; |
| struct dm_bufio_client *c; |
| char slab_name[27]; |
| |
| if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) { |
| DMERR("%s: block size not specified or is not multiple of 512b", __func__); |
| r = -EINVAL; |
| goto bad_client; |
| } |
| |
| num_locks = dm_num_hash_locks(); |
| c = kzalloc(sizeof(*c) + (num_locks * sizeof(struct buffer_tree)), GFP_KERNEL); |
| if (!c) { |
| r = -ENOMEM; |
| goto bad_client; |
| } |
| cache_init(&c->cache, num_locks); |
| |
| c->bdev = bdev; |
| c->block_size = block_size; |
| if (is_power_of_2(block_size)) |
| c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT; |
| else |
| c->sectors_per_block_bits = -1; |
| |
| c->alloc_callback = alloc_callback; |
| c->write_callback = write_callback; |
| |
| if (flags & DM_BUFIO_CLIENT_NO_SLEEP) { |
| c->no_sleep = true; |
| static_branch_inc(&no_sleep_enabled); |
| } |
| |
| mutex_init(&c->lock); |
| spin_lock_init(&c->spinlock); |
| INIT_LIST_HEAD(&c->reserved_buffers); |
| c->need_reserved_buffers = reserved_buffers; |
| |
| dm_bufio_set_minimum_buffers(c, DM_BUFIO_MIN_BUFFERS); |
| |
| init_waitqueue_head(&c->free_buffer_wait); |
| c->async_write_error = 0; |
| |
| c->dm_io = dm_io_client_create(); |
| if (IS_ERR(c->dm_io)) { |
| r = PTR_ERR(c->dm_io); |
| goto bad_dm_io; |
| } |
| |
| if (block_size <= KMALLOC_MAX_SIZE && |
| (block_size < PAGE_SIZE || !is_power_of_2(block_size))) { |
| unsigned int align = min(1U << __ffs(block_size), (unsigned int)PAGE_SIZE); |
| |
| snprintf(slab_name, sizeof(slab_name), "dm_bufio_cache-%u", block_size); |
| c->slab_cache = kmem_cache_create(slab_name, block_size, align, |
| SLAB_RECLAIM_ACCOUNT, NULL); |
| if (!c->slab_cache) { |
| r = -ENOMEM; |
| goto bad; |
| } |
| } |
| if (aux_size) |
| snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer-%u", aux_size); |
| else |
| snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer"); |
| c->slab_buffer = kmem_cache_create(slab_name, sizeof(struct dm_buffer) + aux_size, |
| 0, SLAB_RECLAIM_ACCOUNT, NULL); |
| if (!c->slab_buffer) { |
| r = -ENOMEM; |
| goto bad; |
| } |
| |
| while (c->need_reserved_buffers) { |
| struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); |
| |
| if (!b) { |
| r = -ENOMEM; |
| goto bad; |
| } |
| __free_buffer_wake(b); |
| } |
| |
| INIT_WORK(&c->shrink_work, shrink_work); |
| atomic_long_set(&c->need_shrink, 0); |
| |
| c->shrinker.count_objects = dm_bufio_shrink_count; |
| c->shrinker.scan_objects = dm_bufio_shrink_scan; |
| c->shrinker.seeks = 1; |
| c->shrinker.batch = 0; |
| r = register_shrinker(&c->shrinker, "dm-bufio:(%u:%u)", |
| MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev)); |
| if (r) |
| goto bad; |
| |
| mutex_lock(&dm_bufio_clients_lock); |
| dm_bufio_client_count++; |
| list_add(&c->client_list, &dm_bufio_all_clients); |
| __cache_size_refresh(); |
| mutex_unlock(&dm_bufio_clients_lock); |
| |
| return c; |
| |
| bad: |
| while (!list_empty(&c->reserved_buffers)) { |
| 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); |
| kmem_cache_destroy(c->slab_buffer); |
| dm_io_client_destroy(c->dm_io); |
| bad_dm_io: |
| mutex_destroy(&c->lock); |
| if (c->no_sleep) |
| static_branch_dec(&no_sleep_enabled); |
| kfree(c); |
| bad_client: |
| return ERR_PTR(r); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_client_create); |
| |
| /* |
| * Free the buffering interface. |
| * It is required that there are no references on any buffers. |
| */ |
| void dm_bufio_client_destroy(struct dm_bufio_client *c) |
| { |
| unsigned int i; |
| |
| drop_buffers(c); |
| |
| unregister_shrinker(&c->shrinker); |
| flush_work(&c->shrink_work); |
| |
| mutex_lock(&dm_bufio_clients_lock); |
| |
| list_del(&c->client_list); |
| dm_bufio_client_count--; |
| __cache_size_refresh(); |
| |
| mutex_unlock(&dm_bufio_clients_lock); |
| |
| WARN_ON(c->need_reserved_buffers); |
| |
| while (!list_empty(&c->reserved_buffers)) { |
| 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 (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(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); |
| mutex_destroy(&c->lock); |
| if (c->no_sleep) |
| static_branch_dec(&no_sleep_enabled); |
| kfree(c); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_client_destroy); |
| |
| void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start) |
| { |
| c->start = 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); |
| |
| if (max_age > UINT_MAX / HZ) |
| max_age = UINT_MAX / HZ; |
| |
| return max_age * HZ; |
| } |
| |
| static bool older_than(struct dm_buffer *b, unsigned long age_hz) |
| { |
| return time_after_eq(jiffies, READ_ONCE(b->last_accessed) + 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) |
| { |
| 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); |
| |
| dm_bufio_lock(c); |
| |
| __check_watermark(c, &write_list); |
| if (unlikely(!list_empty(&write_list))) { |
| dm_bufio_unlock(c); |
| __flush_write_list(&write_list); |
| dm_bufio_lock(c); |
| } |
| |
| count = cache_total(&c->cache); |
| if (count > retain) |
| __evict_many(c, ¶ms, LIST_CLEAN, count - retain); |
| |
| dm_bufio_unlock(c); |
| } |
| |
| static void cleanup_old_buffers(void) |
| { |
| unsigned long max_age_hz = get_max_age_hz(); |
| struct dm_bufio_client *c; |
| |
| mutex_lock(&dm_bufio_clients_lock); |
| |
| __cache_size_refresh(); |
| |
| list_for_each_entry(c, &dm_bufio_all_clients, client_list) |
| evict_old_buffers(c, max_age_hz); |
| |
| mutex_unlock(&dm_bufio_clients_lock); |
| } |
| |
| static void work_fn(struct work_struct *w) |
| { |
| cleanup_old_buffers(); |
| |
| queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work, |
| DM_BUFIO_WORK_TIMER_SECS * HZ); |
| } |
| |
| /*--------------------------------------------------------------*/ |
| |
| /* |
| * 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 (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; |
| } |
| |
| list_add_tail(&new_client->client_list, h); |
| } |
| |
| 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 |
| }; |
| |
| 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 check_watermarks(void) |
| { |
| 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); |
| |
| __flush_write_list(&write_list); |
| } |
| |
| 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 do_global_cleanup(struct work_struct *w) |
| { |
| check_watermarks(); |
| evict_old(); |
| } |
| |
| /* |
| *-------------------------------------------------------------- |
| * Module setup |
| *-------------------------------------------------------------- |
| */ |
| |
| /* |
| * This is called only once for the whole dm_bufio module. |
| * It initializes memory limit. |
| */ |
| static int __init dm_bufio_init(void) |
| { |
| __u64 mem; |
| |
| dm_bufio_allocated_kmem_cache = 0; |
| dm_bufio_allocated_get_free_pages = 0; |
| dm_bufio_allocated_vmalloc = 0; |
| dm_bufio_current_allocated = 0; |
| |
| mem = (__u64)mult_frac(totalram_pages() - totalhigh_pages(), |
| DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT; |
| |
| if (mem > ULONG_MAX) |
| mem = ULONG_MAX; |
| |
| #ifdef CONFIG_MMU |
| if (mem > mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100)) |
| mem = mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100); |
| #endif |
| |
| dm_bufio_default_cache_size = mem; |
| |
| mutex_lock(&dm_bufio_clients_lock); |
| __cache_size_refresh(); |
| mutex_unlock(&dm_bufio_clients_lock); |
| |
| dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0); |
| if (!dm_bufio_wq) |
| return -ENOMEM; |
| |
| INIT_DELAYED_WORK(&dm_bufio_cleanup_old_work, work_fn); |
| INIT_WORK(&dm_bufio_replacement_work, do_global_cleanup); |
| queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work, |
| DM_BUFIO_WORK_TIMER_SECS * HZ); |
| |
| return 0; |
| } |
| |
| /* |
| * This is called once when unloading the dm_bufio module. |
| */ |
| static void __exit dm_bufio_exit(void) |
| { |
| int bug = 0; |
| |
| cancel_delayed_work_sync(&dm_bufio_cleanup_old_work); |
| destroy_workqueue(dm_bufio_wq); |
| |
| if (dm_bufio_client_count) { |
| DMCRIT("%s: dm_bufio_client_count leaked: %d", |
| __func__, dm_bufio_client_count); |
| bug = 1; |
| } |
| |
| if (dm_bufio_current_allocated) { |
| DMCRIT("%s: dm_bufio_current_allocated leaked: %lu", |
| __func__, dm_bufio_current_allocated); |
| bug = 1; |
| } |
| |
| if (dm_bufio_allocated_get_free_pages) { |
| DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu", |
| __func__, dm_bufio_allocated_get_free_pages); |
| bug = 1; |
| } |
| |
| if (dm_bufio_allocated_vmalloc) { |
| DMCRIT("%s: dm_bufio_vmalloc leaked: %lu", |
| __func__, dm_bufio_allocated_vmalloc); |
| bug = 1; |
| } |
| |
| WARN_ON(bug); /* leaks are not worth crashing the system */ |
| } |
| |
| module_init(dm_bufio_init) |
| module_exit(dm_bufio_exit) |
| |
| module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, 0644); |
| MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache"); |
| |
| module_param_named(max_age_seconds, dm_bufio_max_age, uint, 0644); |
| MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds"); |
| |
| module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, 0644); |
| MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory"); |
| |
| module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, 0644); |
| MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory"); |
| |
| module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, 0444); |
| MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc"); |
| |
| module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, 0444); |
| MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages"); |
| |
| module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, 0444); |
| MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc"); |
| |
| module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, 0444); |
| MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache"); |
| |
| MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>"); |
| MODULE_DESCRIPTION(DM_NAME " buffered I/O library"); |
| MODULE_LICENSE("GPL"); |