| /* |
| * Copyright (C) 2009-2011 Red Hat, Inc. |
| * |
| * Author: Mikulas Patocka <mpatocka@redhat.com> |
| * |
| * This file is released under the GPL. |
| */ |
| |
| #include "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_PERCENT 75 |
| |
| /* |
| * 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) |
| |
| /* |
| * The number of bvec entries that are embedded directly in the buffer. |
| * If the chunk size is larger, dm-io is used to do the io. |
| */ |
| #define DM_BUFIO_INLINE_VECS 16 |
| |
| /* |
| * Don't try to use kmem_cache_alloc for blocks larger than this. |
| * For explanation, see alloc_buffer_data below. |
| */ |
| #define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT (PAGE_SIZE >> 1) |
| #define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1)) |
| |
| /* |
| * 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 cache_hash with their hash_list 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; |
| unsigned char sectors_per_block_bits; |
| unsigned char pages_per_block_bits; |
| unsigned char blocks_per_page_bits; |
| unsigned aux_size; |
| void (*alloc_callback)(struct dm_buffer *); |
| void (*write_callback)(struct dm_buffer *); |
| |
| 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; |
| sector_t block; |
| void *data; |
| enum data_mode data_mode; |
| unsigned char list_mode; /* LIST_* */ |
| unsigned hold_count; |
| blk_status_t read_error; |
| blk_status_t write_error; |
| 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; |
| struct bio bio; |
| struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS]; |
| #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| #define MAX_STACK 10 |
| struct stack_trace stack_trace; |
| unsigned long stack_entries[MAX_STACK]; |
| #endif |
| }; |
| |
| /*----------------------------------------------------------------*/ |
| |
| static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT]; |
| static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT]; |
| |
| static inline int dm_bufio_cache_index(struct dm_bufio_client *c) |
| { |
| unsigned ret = c->blocks_per_page_bits - 1; |
| |
| BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches)); |
| |
| return ret; |
| } |
| |
| #define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)]) |
| #define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)]) |
| |
| #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(param_spinlock); |
| |
| /* |
| * 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; |
| |
| /*----------------------------------------------------------------*/ |
| |
| /* |
| * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count |
| */ |
| static unsigned long dm_bufio_cache_size_per_client; |
| |
| /* |
| * 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, |
| * dm_bufio_cache_size_per_client and dm_bufio_client_count |
| */ |
| static DEFINE_MUTEX(dm_bufio_clients_lock); |
| |
| #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| static void buffer_record_stack(struct dm_buffer *b) |
| { |
| b->stack_trace.nr_entries = 0; |
| b->stack_trace.max_entries = MAX_STACK; |
| b->stack_trace.entries = b->stack_entries; |
| b->stack_trace.skip = 2; |
| save_stack_trace(&b->stack_trace); |
| } |
| #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(enum data_mode 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, |
| }; |
| |
| spin_lock(¶m_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; |
| |
| spin_unlock(¶m_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; |
| } |
| |
| dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch / |
| (dm_bufio_client_count ? : 1); |
| } |
| |
| /* |
| * 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, |
| enum data_mode *data_mode) |
| { |
| unsigned noio_flag; |
| void *ptr; |
| |
| if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) { |
| *data_mode = DATA_MODE_SLAB; |
| return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask); |
| } |
| |
| if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT && |
| gfp_mask & __GFP_NORETRY) { |
| *data_mode = DATA_MODE_GET_FREE_PAGES; |
| return (void *)__get_free_pages(gfp_mask, |
| c->pages_per_block_bits); |
| } |
| |
| *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) |
| noio_flag = memalloc_noio_save(); |
| |
| ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); |
| |
| if (gfp_mask & __GFP_NORETRY) |
| memalloc_noio_restore(noio_flag); |
| |
| return ptr; |
| } |
| |
| /* |
| * Free buffer's data. |
| */ |
| static void free_buffer_data(struct dm_bufio_client *c, |
| void *data, enum data_mode data_mode) |
| { |
| switch (data_mode) { |
| case DATA_MODE_SLAB: |
| kmem_cache_free(DM_BUFIO_CACHE(c), data); |
| break; |
| |
| case DATA_MODE_GET_FREE_PAGES: |
| free_pages((unsigned long)data, c->pages_per_block_bits); |
| 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 = kmalloc(sizeof(struct dm_buffer) + c->aux_size, |
| gfp_mask); |
| |
| if (!b) |
| return NULL; |
| |
| b->c = c; |
| |
| b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode); |
| if (!b->data) { |
| kfree(b); |
| return NULL; |
| } |
| |
| adjust_total_allocated(b->data_mode, (long)c->block_size); |
| |
| #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
| memset(&b->stack_trace, 0, sizeof(b->stack_trace)); |
| #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->data_mode, -(long)c->block_size); |
| |
| free_buffer_data(c, b->data, b->data_mode); |
| kfree(b); |
| } |
| |
| /* |
| * Link buffer to the hash list 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; |
| } |
| |
| /* |
| * Unlink buffer from the hash list 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); |
| } |
| |
| /* |
| * 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; |
| |
| 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; |
| * |
| * the I/O driver can reject requests spuriously if it thinks that |
| * the requests are too big for the device or if they cross a |
| * controller-defined memory boundary. |
| * |
| * 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->bio.bi_status = error ? BLK_STS_IOERR : 0; |
| b->bio.bi_end_io(&b->bio); |
| } |
| |
| static void use_dmio(struct dm_buffer *b, int rw, sector_t sector, |
| unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) |
| { |
| 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; |
| } |
| |
| b->bio.bi_end_io = end_io; |
| |
| r = dm_io(&io_req, 1, ®ion, NULL); |
| if (r) { |
| b->bio.bi_status = errno_to_blk_status(r); |
| end_io(&b->bio); |
| } |
| } |
| |
| static void inline_endio(struct bio *bio) |
| { |
| bio_end_io_t *end_fn = bio->bi_private; |
| blk_status_t status = bio->bi_status; |
| |
| /* |
| * Reset the bio to free any attached resources |
| * (e.g. bio integrity profiles). |
| */ |
| bio_reset(bio); |
| |
| bio->bi_status = status; |
| end_fn(bio); |
| } |
| |
| static void use_inline_bio(struct dm_buffer *b, int rw, sector_t sector, |
| unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) |
| { |
| char *ptr; |
| unsigned len; |
| |
| bio_init(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS); |
| b->bio.bi_iter.bi_sector = sector; |
| bio_set_dev(&b->bio, b->c->bdev); |
| b->bio.bi_end_io = inline_endio; |
| /* |
| * Use of .bi_private isn't a problem here because |
| * the dm_buffer's inline bio is local to bufio. |
| */ |
| b->bio.bi_private = end_io; |
| bio_set_op_attrs(&b->bio, rw, 0); |
| |
| 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(&b->bio, virt_to_page(ptr), this_step, |
| offset_in_page(ptr))) { |
| BUG_ON(b->c->block_size <= PAGE_SIZE); |
| use_dmio(b, rw, sector, n_sectors, offset, end_io); |
| return; |
| } |
| |
| len -= this_step; |
| ptr += this_step; |
| } while (len > 0); |
| |
| submit_bio(&b->bio); |
| } |
| |
| static void submit_io(struct dm_buffer *b, int rw, bio_end_io_t *end_io) |
| { |
| unsigned n_sectors; |
| sector_t sector; |
| unsigned offset, end; |
| |
| sector = (b->block << b->c->sectors_per_block_bits) + b->c->start; |
| |
| if (rw != REQ_OP_WRITE) { |
| n_sectors = 1 << b->c->sectors_per_block_bits; |
| 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 (n_sectors <= ((DM_BUFIO_INLINE_VECS * PAGE_SIZE) >> SECTOR_SHIFT) && |
| b->data_mode != DATA_MODE_VMALLOC) |
| use_inline_bio(b, rw, sector, n_sectors, offset, end_io); |
| else |
| use_dmio(b, rw, sector, n_sectors, offset, end_io); |
| } |
| |
| /*---------------------------------------------------------------- |
| * 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 bio *bio) |
| { |
| struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); |
| |
| b->write_error = bio->bi_status; |
| if (unlikely(bio->bi_status)) { |
| struct dm_bufio_client *c = b->c; |
| |
| (void)cmpxchg(&c->async_write_error, 0, |
| blk_status_to_errno(bio->bi_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(); |
| } |
| } |
| |
| /* |
| * Get writeback threshold and buffer limit for a given client. |
| */ |
| static void __get_memory_limit(struct dm_bufio_client *c, |
| unsigned long *threshold_buffers, |
| unsigned long *limit_buffers) |
| { |
| unsigned long buffers; |
| |
| if (unlikely(READ_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch)) { |
| if (mutex_trylock(&dm_bufio_clients_lock)) { |
| __cache_size_refresh(); |
| mutex_unlock(&dm_bufio_clients_lock); |
| } |
| } |
| |
| buffers = dm_bufio_cache_size_per_client >> |
| (c->sectors_per_block_bits + SECTOR_SHIFT); |
| |
| if (buffers < c->minimum_buffers) |
| buffers = c->minimum_buffers; |
| |
| *limit_buffers = buffers; |
| *threshold_buffers = mult_frac(buffers, |
| DM_BUFIO_WRITEBACK_PERCENT, 100); |
| } |
| |
| /* |
| * 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) |
| { |
| unsigned long threshold_buffers, limit_buffers; |
| |
| __get_memory_limit(c, &threshold_buffers, &limit_buffers); |
| |
| while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] > |
| limit_buffers) { |
| |
| struct dm_buffer *b = __get_unclaimed_buffer(c); |
| |
| if (!b) |
| return; |
| |
| __free_buffer_wake(b); |
| cond_resched(); |
| } |
| |
| if (c->n_buffers[LIST_DIRTY] > threshold_buffers) |
| __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 hash table. |
| */ |
| 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 bio *bio) |
| { |
| struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); |
| |
| b->read_error = bio->bi_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 and empty barrier 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 hash queue 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(dm_bufio_forget); |
| |
| void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n) |
| { |
| c->minimum_buffers = n; |
| } |
| EXPORT_SYMBOL(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) |
| { |
| return i_size_read(c->bdev->bd_inode) >> |
| (SECTOR_SHIFT + c->sectors_per_block_bits); |
| } |
| EXPORT_SYMBOL_GPL(dm_bufio_get_device_size); |
| |
| 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 |
| print_stack_trace(&b->stack_trace, 1); |
| b->hold_count = 0; /* mark unclaimed to avoid BUG_ON below */ |
| #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); |
| return retain_bytes >> (c->sectors_per_block_bits + SECTOR_SHIFT); |
| } |
| |
| 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; |
| |
| BUG_ON(block_size < 1 << SECTOR_SHIFT || |
| (block_size & (block_size - 1))); |
| |
| 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; |
| c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT; |
| c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ? |
| __ffs(block_size) - PAGE_SHIFT : 0; |
| c->blocks_per_page_bits = (__ffs(block_size) < PAGE_SHIFT ? |
| PAGE_SHIFT - __ffs(block_size) : 0); |
| |
| c->aux_size = aux_size; |
| 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; |
| |
| c->minimum_buffers = 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; |
| } |
| |
| mutex_lock(&dm_bufio_clients_lock); |
| if (c->blocks_per_page_bits) { |
| if (!DM_BUFIO_CACHE_NAME(c)) { |
| DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size); |
| if (!DM_BUFIO_CACHE_NAME(c)) { |
| r = -ENOMEM; |
| mutex_unlock(&dm_bufio_clients_lock); |
| goto bad; |
| } |
| } |
| |
| if (!DM_BUFIO_CACHE(c)) { |
| DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c), |
| c->block_size, |
| c->block_size, 0, NULL); |
| if (!DM_BUFIO_CACHE(c)) { |
| r = -ENOMEM; |
| mutex_unlock(&dm_bufio_clients_lock); |
| goto bad; |
| } |
| } |
| } |
| mutex_unlock(&dm_bufio_clients_lock); |
| |
| 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); |
| } |
| 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]); |
| |
| 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 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 struct workqueue_struct *dm_bufio_wq; |
| static struct delayed_work dm_bufio_work; |
| |
| static void work_fn(struct work_struct *w) |
| { |
| cleanup_old_buffers(); |
| |
| queue_delayed_work(dm_bufio_wq, &dm_bufio_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; |
| |
| memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches); |
| memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names); |
| |
| 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_work, work_fn); |
| queue_delayed_work(dm_bufio_wq, &dm_bufio_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; |
| int i; |
| |
| cancel_delayed_work_sync(&dm_bufio_work); |
| destroy_workqueue(dm_bufio_wq); |
| |
| for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) |
| kmem_cache_destroy(dm_bufio_caches[i]); |
| |
| for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++) |
| kfree(dm_bufio_cache_names[i]); |
| |
| 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"); |