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- /*
- * 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>
- #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
- /*
- * Linking of buffers:
- * All buffers are linked to buffer_tree 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 mutex lock;
- struct list_head lru[LIST_SIZE];
- unsigned long n_buffers[LIST_SIZE];
- struct block_device *bdev;
- unsigned block_size;
- s8 sectors_per_block_bits;
- void (*alloc_callback)(struct dm_buffer *);
- void (*write_callback)(struct dm_buffer *);
- struct kmem_cache *slab_buffer;
- struct kmem_cache *slab_cache;
- struct dm_io_client *dm_io;
- struct list_head reserved_buffers;
- unsigned need_reserved_buffers;
- unsigned minimum_buffers;
- struct rb_root buffer_tree;
- wait_queue_head_t free_buffer_wait;
- sector_t start;
- int async_write_error;
- struct list_head client_list;
- struct shrinker shrinker;
- };
- /*
- * 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 {
- struct rb_node node;
- struct list_head lru_list;
- struct list_head global_list;
- sector_t block;
- void *data;
- unsigned char data_mode; /* DATA_MODE_* */
- unsigned char list_mode; /* LIST_* */
- blk_status_t read_error;
- blk_status_t write_error;
- unsigned accessed;
- unsigned hold_count;
- unsigned long state;
- unsigned long last_accessed;
- unsigned dirty_start;
- unsigned dirty_end;
- unsigned write_start;
- unsigned write_end;
- struct dm_bufio_client *c;
- struct list_head write_list;
- void (*end_io)(struct dm_buffer *, blk_status_t);
- #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
- #define MAX_STACK 10
- unsigned int stack_len;
- unsigned long stack_entries[MAX_STACK];
- #endif
- };
- /*----------------------------------------------------------------*/
- #define dm_bufio_in_request() (!!current->bio_list)
- 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)
- {
- return mutex_trylock(&c->lock);
- }
- static void dm_bufio_unlock(struct dm_bufio_client *c)
- {
- 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);
- static LIST_HEAD(global_queue);
- static unsigned long global_num = 0;
- /*
- * Buffers are freed after this timeout
- */
- static unsigned 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
- /*----------------------------------------------------------------
- * 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 = (b->block < block) ? n->rb_left : n->rb_right;
- }
- return NULL;
- }
- 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 = (found->block < b->block) ?
- &((*new)->rb_left) : &((*new)->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)
- {
- 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;
- 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);
- }
- /*
- * Change the number of clients and recalculate per-client limit.
- */
- static void __cache_size_refresh(void)
- {
- BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
- BUG_ON(dm_bufio_client_count < 0);
- 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 noio_flag = memalloc_noio_save();
- void *ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL);
- memalloc_noio_restore(noio_flag);
- return ptr;
- }
- return __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL);
- }
- /*
- * 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;
- }
- #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;
- 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.
- *
- * 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, int rw, sector_t sector,
- unsigned n_sectors, unsigned offset)
- {
- int r;
- struct dm_io_request io_req = {
- .bi_op = rw,
- .bi_op_flags = 0,
- .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_put(bio);
- b->end_io(b, status);
- }
- static void use_bio(struct dm_buffer *b, int rw, sector_t sector,
- unsigned n_sectors, unsigned offset)
- {
- struct bio *bio;
- char *ptr;
- unsigned vec_size, len;
- vec_size = b->c->block_size >> PAGE_SHIFT;
- if (unlikely(b->c->sectors_per_block_bits < PAGE_SHIFT - SECTOR_SHIFT))
- vec_size += 2;
- bio = bio_kmalloc(GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN, vec_size);
- if (!bio) {
- dmio:
- use_dmio(b, rw, sector, n_sectors, offset);
- return;
- }
- bio->bi_iter.bi_sector = sector;
- bio_set_dev(bio, b->c->bdev);
- bio_set_op_attrs(bio, rw, 0);
- bio->bi_end_io = bio_complete;
- bio->bi_private = b;
- ptr = (char *)b->data + offset;
- len = n_sectors << SECTOR_SHIFT;
- do {
- unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len);
- if (!bio_add_page(bio, virt_to_page(ptr), this_step,
- offset_in_page(ptr))) {
- bio_put(bio);
- goto dmio;
- }
- len -= this_step;
- ptr += this_step;
- } while (len > 0);
- submit_bio(bio);
- }
- static void submit_io(struct dm_buffer *b, int rw, void (*end_io)(struct dm_buffer *, blk_status_t))
- {
- unsigned n_sectors;
- sector_t sector;
- unsigned offset, end;
- b->end_io = end_io;
- if (likely(b->c->sectors_per_block_bits >= 0))
- sector = b->block << b->c->sectors_per_block_bits;
- else
- sector = b->block * (b->c->block_size >> SECTOR_SHIFT);
- sector += b->c->start;
- if (rw != 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, rw, sector, n_sectors, offset);
- else
- use_dmio(b, rw, 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(b->hold_count);
- if (!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);
- }
- /*
- * 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;
- 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 (!b->hold_count) {
- __make_buffer_clean(b);
- __unlink_buffer(b);
- return b;
- }
- cond_resched();
- }
- 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();
- }
- 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);
- io_schedule();
- 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_entry(c->reserved_buffers.next,
- struct dm_buffer, lru_list);
- 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;
- if (!c->need_reserved_buffers)
- free_buffer(b);
- else {
- 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)
- {
- struct dm_buffer *b, *tmp;
- 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)) {
- __relink_lru(b, LIST_CLEAN);
- continue;
- }
- if (no_wait && test_bit(B_WRITING, &b->state))
- return;
- __write_dirty_buffer(b, write_list);
- cond_resched();
- }
- }
- /*
- * 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 (c->n_buffers[LIST_DIRTY] > c->n_buffers[LIST_CLEAN] * DM_BUFIO_WRITEBACK_RATIO)
- __write_dirty_buffers_async(c, 1, write_list);
- }
- /*----------------------------------------------------------------
- * Getting a buffer
- *--------------------------------------------------------------*/
- 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;
- b = __find(c, block);
- if (b)
- goto found_buffer;
- if (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 = __find(c, block);
- if (b) {
- __free_buffer_wake(new_b);
- goto found_buffer;
- }
- __check_watermark(c, write_list);
- b = new_b;
- b->hold_count = 1;
- b->read_error = 0;
- b->write_error = 0;
- __link_buffer(b, block, LIST_CLEAN);
- if (nf == NF_FRESH) {
- b->state = 0;
- return b;
- }
- b->state = 1 << B_READING;
- *need_submit = 1;
- return b;
- found_buffer:
- if (nf == NF_PREFETCH)
- 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(B_READING, &b->state)))
- return NULL;
- b->hold_count++;
- __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
- test_bit(B_WRITING, &b->state));
- 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;
- struct dm_buffer *b;
- LIST_HEAD(write_list);
- dm_bufio_lock(c);
- b = __bufio_new(c, block, nf, &need_submit, &write_list);
- #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
- if (b && b->hold_count == 1)
- buffer_record_stack(b);
- #endif
- dm_bufio_unlock(c);
- __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)
- {
- BUG_ON(dm_bufio_in_request());
- 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)
- {
- BUG_ON(dm_bufio_in_request());
- 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 n_blocks)
- {
- struct blk_plug plug;
- LIST_HEAD(write_list);
- BUG_ON(dm_bufio_in_request());
- blk_start_plug(&plug);
- dm_bufio_lock(c);
- for (; n_blocks--; block++) {
- int need_submit;
- struct dm_buffer *b;
- 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;
- 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(B_READING, &b->state) &&
- !test_bit(B_WRITING, &b->state) &&
- !test_bit(B_DIRTY, &b->state)) {
- __unlink_buffer(b);
- __free_buffer_wake(b);
- }
- }
- dm_bufio_unlock(c);
- }
- EXPORT_SYMBOL_GPL(dm_bufio_release);
- void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
- unsigned start, unsigned 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;
- __relink_lru(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);
- BUG_ON(dm_bufio_in_request());
- 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.
- */
- int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
- {
- int a, f;
- unsigned long buffers_processed = 0;
- struct dm_buffer *b, *tmp;
- 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);
- 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++;
- 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 (!test_bit(B_DIRTY, &b->state) &&
- !test_bit(B_WRITING, &b->state))
- __relink_lru(b, LIST_CLEAN);
- cond_resched();
- /*
- * 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;
- }
- 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_op = REQ_OP_WRITE,
- .bi_op_flags = 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,
- };
- BUG_ON(dm_bufio_in_request());
- return dm_io(&io_req, 1, &io_reg, NULL);
- }
- EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
- /*
- * We first delete any other buffer that may be at that new location.
- *
- * Then, we write the buffer to the original location if it was dirty.
- *
- * Then, if we are the only one who is holding the buffer, relink the buffer
- * in the buffer tree for the new location.
- *
- * If there was someone else holding the buffer, we write it to the new
- * location but not relink it, because that other user needs to have the buffer
- * at the same place.
- */
- void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
- {
- struct dm_bufio_client *c = b->c;
- struct dm_buffer *new;
- BUG_ON(dm_bufio_in_request());
- dm_bufio_lock(c);
- retry:
- new = __find(c, new_block);
- if (new) {
- if (new->hold_count) {
- __wait_for_free_buffer(c);
- goto retry;
- }
- /*
- * FIXME: Is there any point waiting for a write that's going
- * to be overwritten in a bit?
- */
- __make_buffer_clean(new);
- __unlink_buffer(new);
- __free_buffer_wake(new);
- }
- BUG_ON(!b->hold_count);
- BUG_ON(test_bit(B_READING, &b->state));
- __write_dirty_buffer(b, NULL);
- if (b->hold_count == 1) {
- wait_on_bit_io(&b->state, B_WRITING,
- TASK_UNINTERRUPTIBLE);
- set_bit(B_DIRTY, &b->state);
- b->dirty_start = 0;
- b->dirty_end = c->block_size;
- __unlink_buffer(b);
- __link_buffer(b, new_block, LIST_DIRTY);
- } else {
- sector_t old_block;
- wait_on_bit_lock_io(&b->state, B_WRITING,
- TASK_UNINTERRUPTIBLE);
- /*
- * Relink buffer to "new_block" so that write_callback
- * sees "new_block" as a block number.
- * After the write, link the buffer back to old_block.
- * All this must be done in bufio lock, so that block number
- * change isn't visible to other threads.
- */
- old_block = b->block;
- __unlink_buffer(b);
- __link_buffer(b, new_block, b->list_mode);
- submit_io(b, REQ_OP_WRITE, write_endio);
- wait_on_bit_io(&b->state, B_WRITING,
- TASK_UNINTERRUPTIBLE);
- __unlink_buffer(b);
- __link_buffer(b, old_block, b->list_mode);
- }
- dm_bufio_unlock(c);
- dm_bufio_release(b);
- }
- EXPORT_SYMBOL_GPL(dm_bufio_release_move);
- /*
- * 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)
- {
- struct dm_buffer *b;
- dm_bufio_lock(c);
- b = __find(c, block);
- if (b && likely(!b->hold_count) && likely(!b->state)) {
- __unlink_buffer(b);
- __free_buffer_wake(b);
- }
- dm_bufio_unlock(c);
- }
- EXPORT_SYMBOL_GPL(dm_bufio_forget);
- void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
- {
- c->minimum_buffers = n;
- }
- EXPORT_SYMBOL_GPL(dm_bufio_set_minimum_buffers);
- unsigned 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 = i_size_read(c->bdev->bd_inode) >> SECTOR_SHIFT;
- 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 void drop_buffers(struct dm_bufio_client *c)
- {
- struct dm_buffer *b;
- int i;
- bool warned = false;
- BUG_ON(dm_bufio_in_request());
- /*
- * 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++)
- 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 BUG_ON below */
- b->hold_count = 0;
- #endif
- }
- #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++)
- BUG_ON(!list_empty(&c->lru[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)) {
- if (test_bit(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);
- 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 unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
- gfp_t gfp_mask)
- {
- int l;
- struct dm_buffer *b, *tmp;
- 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);
- for (l = 0; l < LIST_SIZE; l++) {
- list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
- if (__try_evict_buffer(b, gfp_mask))
- freed++;
- if (!--nr_to_scan || ((count - freed) <= retain_target))
- return freed;
- cond_resched();
- }
- }
- return freed;
- }
- static unsigned long
- dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
- {
- struct dm_bufio_client *c;
- unsigned long freed;
- c = container_of(shrink, struct dm_bufio_client, shrinker);
- if (sc->gfp_mask & __GFP_FS)
- dm_bufio_lock(c);
- else if (!dm_bufio_trylock(c))
- return SHRINK_STOP;
- freed = __scan(c, sc->nr_to_scan, sc->gfp_mask);
- dm_bufio_unlock(c);
- return freed;
- }
- 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 retain_target = get_retain_buffers(c);
- return (count < retain_target) ? 0 : (count - retain_target);
- }
- /*
- * Create the buffering interface
- */
- struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
- unsigned reserved_buffers, unsigned aux_size,
- void (*alloc_callback)(struct dm_buffer *),
- void (*write_callback)(struct dm_buffer *))
- {
- int r;
- struct dm_bufio_client *c;
- unsigned i;
- 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;
- }
- c = kzalloc(sizeof(*c), GFP_KERNEL);
- if (!c) {
- r = -ENOMEM;
- goto bad_client;
- }
- c->buffer_tree = RB_ROOT;
- 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;
- for (i = 0; i < LIST_SIZE; i++) {
- INIT_LIST_HEAD(&c->lru[i]);
- c->n_buffers[i] = 0;
- }
- mutex_init(&c->lock);
- 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 align = min(1U << __ffs(block_size), (unsigned)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);
- }
- 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);
- 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_entry(c->reserved_buffers.next,
- struct dm_buffer, lru_list);
- 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);
- 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 i;
- drop_buffers(c);
- unregister_shrinker(&c->shrinker);
- mutex_lock(&dm_bufio_clients_lock);
- list_del(&c->client_list);
- dm_bufio_client_count--;
- __cache_size_refresh();
- mutex_unlock(&dm_bufio_clients_lock);
- BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree));
- BUG_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);
- 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]);
- for (i = 0; i < LIST_SIZE; i++)
- BUG_ON(c->n_buffers[i]);
- kmem_cache_destroy(c->slab_cache);
- kmem_cache_destroy(c->slab_buffer);
- dm_io_client_destroy(c->dm_io);
- mutex_destroy(&c->lock);
- 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 get_max_age_hz(void)
- {
- unsigned 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, b->last_accessed + age_hz);
- }
- static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
- {
- struct dm_buffer *b, *tmp;
- unsigned long retain_target = 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 = 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();
- }
- dm_bufio_unlock(c);
- }
- static void do_global_cleanup(struct work_struct *w)
- {
- struct dm_bufio_client *locked_client = NULL;
- struct dm_bufio_client *current_client;
- struct dm_buffer *b;
- unsigned 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;
- mutex_lock(&dm_bufio_clients_lock);
- while (1) {
- cond_resched();
- spin_lock(&global_spinlock);
- if (unlikely(dm_bufio_current_allocated <= threshold))
- break;
- 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;
- }
- current_client = b->c;
- if (unlikely(current_client != locked_client)) {
- if (locked_client)
- dm_bufio_unlock(locked_client);
- if (!dm_bufio_trylock(current_client)) {
- spin_unlock(&global_spinlock);
- dm_bufio_lock(current_client);
- locked_client = current_client;
- continue;
- }
- locked_client = current_client;
- }
- spin_unlock(&global_spinlock);
- if (unlikely(!__try_evict_buffer(b, GFP_KERNEL))) {
- spin_lock(&global_spinlock);
- list_move(&b->global_list, &global_queue);
- spin_unlock(&global_spinlock);
- }
- }
- spin_unlock(&global_spinlock);
- if (locked_client)
- dm_bufio_unlock(locked_client);
- mutex_unlock(&dm_bufio_clients_lock);
- }
- 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);
- }
- /*----------------------------------------------------------------
- * 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);
- flush_workqueue(dm_bufio_wq);
- 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;
- }
- BUG_ON(bug);
- }
- module_init(dm_bufio_init)
- module_exit(dm_bufio_exit)
- module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
- MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
- module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
- MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
- module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, S_IRUGO | S_IWUSR);
- 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, S_IRUGO | S_IWUSR);
- MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
- module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
- 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, S_IRUGO);
- 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, S_IRUGO);
- MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
- module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
- 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");
|