1925 строки
46 KiB
C
1925 строки
46 KiB
C
/*
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* Copyright (C) 2009-2011 Red Hat, Inc.
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*
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* Author: Mikulas Patocka <mpatocka@redhat.com>
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*
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* This file is released under the GPL.
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*/
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#include "dm-bufio.h"
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#include <linux/device-mapper.h>
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#include <linux/dm-io.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/shrinker.h>
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#include <linux/module.h>
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#include <linux/rbtree.h>
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#define DM_MSG_PREFIX "bufio"
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/*
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* Memory management policy:
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* Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory
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* or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower).
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* Always allocate at least DM_BUFIO_MIN_BUFFERS buffers.
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* Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT
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* dirty buffers.
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*/
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#define DM_BUFIO_MIN_BUFFERS 8
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#define DM_BUFIO_MEMORY_PERCENT 2
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#define DM_BUFIO_VMALLOC_PERCENT 25
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#define DM_BUFIO_WRITEBACK_PERCENT 75
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/*
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* Check buffer ages in this interval (seconds)
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*/
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#define DM_BUFIO_WORK_TIMER_SECS 30
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/*
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* Free buffers when they are older than this (seconds)
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*/
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#define DM_BUFIO_DEFAULT_AGE_SECS 300
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/*
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* The nr of bytes of cached data to keep around.
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*/
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#define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
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/*
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* The number of bvec entries that are embedded directly in the buffer.
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* If the chunk size is larger, dm-io is used to do the io.
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*/
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#define DM_BUFIO_INLINE_VECS 16
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/*
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* Don't try to use kmem_cache_alloc for blocks larger than this.
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* For explanation, see alloc_buffer_data below.
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*/
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#define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT (PAGE_SIZE >> 1)
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#define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1))
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/*
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* dm_buffer->list_mode
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*/
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#define LIST_CLEAN 0
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#define LIST_DIRTY 1
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#define LIST_SIZE 2
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/*
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* Linking of buffers:
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* All buffers are linked to cache_hash with their hash_list field.
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*
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* Clean buffers that are not being written (B_WRITING not set)
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* are linked to lru[LIST_CLEAN] with their lru_list field.
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*
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* Dirty and clean buffers that are being written are linked to
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* lru[LIST_DIRTY] with their lru_list field. When the write
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* finishes, the buffer cannot be relinked immediately (because we
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* are in an interrupt context and relinking requires process
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* context), so some clean-not-writing buffers can be held on
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* dirty_lru too. They are later added to lru in the process
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* context.
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*/
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struct dm_bufio_client {
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struct mutex lock;
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struct list_head lru[LIST_SIZE];
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unsigned long n_buffers[LIST_SIZE];
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struct block_device *bdev;
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unsigned block_size;
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unsigned char sectors_per_block_bits;
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unsigned char pages_per_block_bits;
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unsigned char blocks_per_page_bits;
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unsigned aux_size;
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void (*alloc_callback)(struct dm_buffer *);
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void (*write_callback)(struct dm_buffer *);
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struct dm_io_client *dm_io;
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struct list_head reserved_buffers;
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unsigned need_reserved_buffers;
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unsigned minimum_buffers;
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struct rb_root buffer_tree;
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wait_queue_head_t free_buffer_wait;
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int async_write_error;
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struct list_head client_list;
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struct shrinker shrinker;
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};
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/*
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* Buffer state bits.
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*/
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#define B_READING 0
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#define B_WRITING 1
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#define B_DIRTY 2
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/*
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* Describes how the block was allocated:
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* kmem_cache_alloc(), __get_free_pages() or vmalloc().
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* See the comment at alloc_buffer_data.
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*/
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enum data_mode {
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DATA_MODE_SLAB = 0,
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DATA_MODE_GET_FREE_PAGES = 1,
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DATA_MODE_VMALLOC = 2,
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DATA_MODE_LIMIT = 3
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};
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struct dm_buffer {
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struct rb_node node;
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struct list_head lru_list;
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sector_t block;
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void *data;
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enum data_mode data_mode;
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unsigned char list_mode; /* LIST_* */
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unsigned hold_count;
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int read_error;
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int write_error;
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unsigned long state;
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unsigned long last_accessed;
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struct dm_bufio_client *c;
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struct list_head write_list;
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struct bio bio;
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struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
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};
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/*----------------------------------------------------------------*/
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static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
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static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
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static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
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{
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unsigned ret = c->blocks_per_page_bits - 1;
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BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
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return ret;
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}
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#define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)])
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#define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)])
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#define dm_bufio_in_request() (!!current->bio_list)
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static void dm_bufio_lock(struct dm_bufio_client *c)
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{
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mutex_lock_nested(&c->lock, dm_bufio_in_request());
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}
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static int dm_bufio_trylock(struct dm_bufio_client *c)
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{
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return mutex_trylock(&c->lock);
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}
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static void dm_bufio_unlock(struct dm_bufio_client *c)
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{
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mutex_unlock(&c->lock);
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}
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/*
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* FIXME Move to sched.h?
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*/
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#ifdef CONFIG_PREEMPT_VOLUNTARY
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# define dm_bufio_cond_resched() \
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do { \
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if (unlikely(need_resched())) \
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_cond_resched(); \
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} while (0)
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#else
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# define dm_bufio_cond_resched() do { } while (0)
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#endif
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/*----------------------------------------------------------------*/
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/*
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* Default cache size: available memory divided by the ratio.
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*/
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static unsigned long dm_bufio_default_cache_size;
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/*
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* Total cache size set by the user.
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*/
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static unsigned long dm_bufio_cache_size;
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/*
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* A copy of dm_bufio_cache_size because dm_bufio_cache_size can change
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* at any time. If it disagrees, the user has changed cache size.
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*/
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static unsigned long dm_bufio_cache_size_latch;
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static DEFINE_SPINLOCK(param_spinlock);
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/*
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* Buffers are freed after this timeout
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*/
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static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
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static unsigned dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
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static unsigned long dm_bufio_peak_allocated;
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static unsigned long dm_bufio_allocated_kmem_cache;
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static unsigned long dm_bufio_allocated_get_free_pages;
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static unsigned long dm_bufio_allocated_vmalloc;
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static unsigned long dm_bufio_current_allocated;
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/*----------------------------------------------------------------*/
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/*
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* Per-client cache: dm_bufio_cache_size / dm_bufio_client_count
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*/
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static unsigned long dm_bufio_cache_size_per_client;
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/*
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* The current number of clients.
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*/
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static int dm_bufio_client_count;
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/*
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* The list of all clients.
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*/
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static LIST_HEAD(dm_bufio_all_clients);
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/*
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* This mutex protects dm_bufio_cache_size_latch,
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* dm_bufio_cache_size_per_client and dm_bufio_client_count
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*/
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static DEFINE_MUTEX(dm_bufio_clients_lock);
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/*----------------------------------------------------------------
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* A red/black tree acts as an index for all the buffers.
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*--------------------------------------------------------------*/
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static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
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{
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struct rb_node *n = c->buffer_tree.rb_node;
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struct dm_buffer *b;
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while (n) {
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b = container_of(n, struct dm_buffer, node);
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if (b->block == block)
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return b;
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n = (b->block < block) ? n->rb_left : n->rb_right;
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}
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return NULL;
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}
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static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
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{
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struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
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struct dm_buffer *found;
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while (*new) {
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found = container_of(*new, struct dm_buffer, node);
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if (found->block == b->block) {
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BUG_ON(found != b);
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return;
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}
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parent = *new;
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new = (found->block < b->block) ?
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&((*new)->rb_left) : &((*new)->rb_right);
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}
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rb_link_node(&b->node, parent, new);
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rb_insert_color(&b->node, &c->buffer_tree);
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}
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static void __remove(struct dm_bufio_client *c, struct dm_buffer *b)
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{
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rb_erase(&b->node, &c->buffer_tree);
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}
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/*----------------------------------------------------------------*/
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static void adjust_total_allocated(enum data_mode data_mode, long diff)
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{
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static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
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&dm_bufio_allocated_kmem_cache,
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&dm_bufio_allocated_get_free_pages,
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&dm_bufio_allocated_vmalloc,
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};
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spin_lock(¶m_spinlock);
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*class_ptr[data_mode] += diff;
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dm_bufio_current_allocated += diff;
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if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
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dm_bufio_peak_allocated = dm_bufio_current_allocated;
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spin_unlock(¶m_spinlock);
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}
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/*
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* Change the number of clients and recalculate per-client limit.
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*/
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static void __cache_size_refresh(void)
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{
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BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
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BUG_ON(dm_bufio_client_count < 0);
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dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
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/*
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* Use default if set to 0 and report the actual cache size used.
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*/
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if (!dm_bufio_cache_size_latch) {
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(void)cmpxchg(&dm_bufio_cache_size, 0,
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dm_bufio_default_cache_size);
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dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
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}
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dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch /
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(dm_bufio_client_count ? : 1);
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}
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/*
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* Allocating buffer data.
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*
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* Small buffers are allocated with kmem_cache, to use space optimally.
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*
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* For large buffers, we choose between get_free_pages and vmalloc.
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* Each has advantages and disadvantages.
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*
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* __get_free_pages can randomly fail if the memory is fragmented.
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* __vmalloc won't randomly fail, but vmalloc space is limited (it may be
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* as low as 128M) so using it for caching is not appropriate.
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*
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* If the allocation may fail we use __get_free_pages. Memory fragmentation
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* won't have a fatal effect here, but it just causes flushes of some other
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* buffers and more I/O will be performed. Don't use __get_free_pages if it
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* always fails (i.e. order >= MAX_ORDER).
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*
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* If the allocation shouldn't fail we use __vmalloc. This is only for the
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* initial reserve allocation, so there's no risk of wasting all vmalloc
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* space.
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*/
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static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
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enum data_mode *data_mode)
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{
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unsigned noio_flag;
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void *ptr;
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if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
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*data_mode = DATA_MODE_SLAB;
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return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
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}
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if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
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gfp_mask & __GFP_NORETRY) {
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*data_mode = DATA_MODE_GET_FREE_PAGES;
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return (void *)__get_free_pages(gfp_mask,
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c->pages_per_block_bits);
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}
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*data_mode = DATA_MODE_VMALLOC;
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/*
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* __vmalloc allocates the data pages and auxiliary structures with
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* gfp_flags that were specified, but pagetables are always allocated
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* with GFP_KERNEL, no matter what was specified as gfp_mask.
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*
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* Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
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* all allocations done by this process (including pagetables) are done
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* as if GFP_NOIO was specified.
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*/
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if (gfp_mask & __GFP_NORETRY)
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noio_flag = memalloc_noio_save();
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ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
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if (gfp_mask & __GFP_NORETRY)
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memalloc_noio_restore(noio_flag);
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return ptr;
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}
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/*
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* Free buffer's data.
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*/
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static void free_buffer_data(struct dm_bufio_client *c,
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void *data, enum data_mode data_mode)
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{
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switch (data_mode) {
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case DATA_MODE_SLAB:
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kmem_cache_free(DM_BUFIO_CACHE(c), data);
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break;
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case DATA_MODE_GET_FREE_PAGES:
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free_pages((unsigned long)data, c->pages_per_block_bits);
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break;
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case DATA_MODE_VMALLOC:
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vfree(data);
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break;
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default:
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DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
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data_mode);
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BUG();
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}
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}
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/*
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* Allocate buffer and its data.
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*/
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static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
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{
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struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size,
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gfp_mask);
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if (!b)
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return NULL;
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b->c = c;
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b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
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if (!b->data) {
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kfree(b);
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return NULL;
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}
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adjust_total_allocated(b->data_mode, (long)c->block_size);
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return b;
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}
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/*
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* Free buffer and its data.
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*/
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static void free_buffer(struct dm_buffer *b)
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{
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struct dm_bufio_client *c = b->c;
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adjust_total_allocated(b->data_mode, -(long)c->block_size);
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free_buffer_data(c, b->data, b->data_mode);
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kfree(b);
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}
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/*
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* Link buffer to the hash list and clean or dirty queue.
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*/
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static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
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{
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struct dm_bufio_client *c = b->c;
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c->n_buffers[dirty]++;
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b->block = block;
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b->list_mode = dirty;
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list_add(&b->lru_list, &c->lru[dirty]);
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__insert(b->c, b);
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b->last_accessed = jiffies;
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}
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/*
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* Unlink buffer from the hash list and dirty or clean queue.
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*/
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static void __unlink_buffer(struct dm_buffer *b)
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{
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struct dm_bufio_client *c = b->c;
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BUG_ON(!c->n_buffers[b->list_mode]);
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c->n_buffers[b->list_mode]--;
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__remove(b->c, b);
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list_del(&b->lru_list);
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}
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/*
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* Place the buffer to the head of dirty or clean LRU queue.
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*/
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static void __relink_lru(struct dm_buffer *b, int dirty)
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{
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struct dm_bufio_client *c = b->c;
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BUG_ON(!c->n_buffers[b->list_mode]);
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c->n_buffers[b->list_mode]--;
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c->n_buffers[dirty]++;
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b->list_mode = dirty;
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list_move(&b->lru_list, &c->lru[dirty]);
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b->last_accessed = jiffies;
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}
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/*----------------------------------------------------------------
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* Submit I/O on the buffer.
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*
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* Bio interface is faster but it has some problems:
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* the vector list is limited (increasing this limit increases
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* memory-consumption per buffer, so it is not viable);
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*
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* the memory must be direct-mapped, not vmalloced;
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*
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* the I/O driver can reject requests spuriously if it thinks that
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* the requests are too big for the device or if they cross a
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* controller-defined memory boundary.
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*
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* If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
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* it is not vmalloced, try using the bio interface.
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*
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* 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_end_io(&b->bio, error ? -EIO : 0);
|
|
}
|
|
|
|
static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
|
|
bio_end_io_t *end_io)
|
|
{
|
|
int r;
|
|
struct dm_io_request io_req = {
|
|
.bi_rw = rw,
|
|
.notify.fn = dmio_complete,
|
|
.notify.context = b,
|
|
.client = b->c->dm_io,
|
|
};
|
|
struct dm_io_region region = {
|
|
.bdev = b->c->bdev,
|
|
.sector = block << b->c->sectors_per_block_bits,
|
|
.count = b->c->block_size >> SECTOR_SHIFT,
|
|
};
|
|
|
|
if (b->data_mode != DATA_MODE_VMALLOC) {
|
|
io_req.mem.type = DM_IO_KMEM;
|
|
io_req.mem.ptr.addr = b->data;
|
|
} else {
|
|
io_req.mem.type = DM_IO_VMA;
|
|
io_req.mem.ptr.vma = b->data;
|
|
}
|
|
|
|
b->bio.bi_end_io = end_io;
|
|
|
|
r = dm_io(&io_req, 1, ®ion, NULL);
|
|
if (r)
|
|
end_io(&b->bio, r);
|
|
}
|
|
|
|
static void inline_endio(struct bio *bio, int error)
|
|
{
|
|
bio_end_io_t *end_fn = bio->bi_private;
|
|
|
|
/*
|
|
* Reset the bio to free any attached resources
|
|
* (e.g. bio integrity profiles).
|
|
*/
|
|
bio_reset(bio);
|
|
|
|
end_fn(bio, error);
|
|
}
|
|
|
|
static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
|
|
bio_end_io_t *end_io)
|
|
{
|
|
char *ptr;
|
|
int len;
|
|
|
|
bio_init(&b->bio);
|
|
b->bio.bi_io_vec = b->bio_vec;
|
|
b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
|
|
b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
|
|
b->bio.bi_bdev = 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;
|
|
|
|
/*
|
|
* We assume that if len >= PAGE_SIZE ptr is page-aligned.
|
|
* If len < PAGE_SIZE the buffer doesn't cross page boundary.
|
|
*/
|
|
ptr = b->data;
|
|
len = b->c->block_size;
|
|
|
|
if (len >= PAGE_SIZE)
|
|
BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1));
|
|
else
|
|
BUG_ON((unsigned long)ptr & (len - 1));
|
|
|
|
do {
|
|
if (!bio_add_page(&b->bio, virt_to_page(ptr),
|
|
len < PAGE_SIZE ? len : PAGE_SIZE,
|
|
virt_to_phys(ptr) & (PAGE_SIZE - 1))) {
|
|
BUG_ON(b->c->block_size <= PAGE_SIZE);
|
|
use_dmio(b, rw, block, end_io);
|
|
return;
|
|
}
|
|
|
|
len -= PAGE_SIZE;
|
|
ptr += PAGE_SIZE;
|
|
} while (len > 0);
|
|
|
|
submit_bio(rw, &b->bio);
|
|
}
|
|
|
|
static void submit_io(struct dm_buffer *b, int rw, sector_t block,
|
|
bio_end_io_t *end_io)
|
|
{
|
|
if (rw == WRITE && b->c->write_callback)
|
|
b->c->write_callback(b);
|
|
|
|
if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
|
|
b->data_mode != DATA_MODE_VMALLOC)
|
|
use_inline_bio(b, rw, block, end_io);
|
|
else
|
|
use_dmio(b, rw, block, 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, int error)
|
|
{
|
|
struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
|
|
|
|
b->write_error = error;
|
|
if (unlikely(error)) {
|
|
struct dm_bufio_client *c = b->c;
|
|
(void)cmpxchg(&c->async_write_error, 0, error);
|
|
}
|
|
|
|
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);
|
|
|
|
if (!write_list)
|
|
submit_io(b, WRITE, b->block, 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, WRITE, b->block, write_endio);
|
|
dm_bufio_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;
|
|
}
|
|
dm_bufio_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;
|
|
}
|
|
dm_bufio_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_task_state(current, 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;
|
|
|
|
/*
|
|
* 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_NOIO: don't recurse into the I/O layer
|
|
* __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_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
|
|
if (b)
|
|
return b;
|
|
}
|
|
|
|
if (nf == NF_PREFETCH)
|
|
return NULL;
|
|
|
|
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);
|
|
dm_bufio_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 (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
|
|
mutex_lock(&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 = 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);
|
|
dm_bufio_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, int error)
|
|
{
|
|
struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
|
|
|
|
b->read_error = error;
|
|
|
|
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);
|
|
dm_bufio_unlock(c);
|
|
|
|
__flush_write_list(&write_list);
|
|
|
|
if (!b)
|
|
return b;
|
|
|
|
if (need_submit)
|
|
submit_io(b, READ, b->block, read_endio);
|
|
|
|
wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
|
|
|
|
if (b->read_error) {
|
|
int error = 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, READ, b->block, read_endio);
|
|
dm_bufio_release(b);
|
|
|
|
dm_bufio_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_buffer_dirty(struct dm_buffer *b)
|
|
{
|
|
struct dm_bufio_client *c = b->c;
|
|
|
|
dm_bufio_lock(c);
|
|
|
|
BUG_ON(test_bit(B_READING, &b->state));
|
|
|
|
if (!test_and_set_bit(B_DIRTY, &b->state))
|
|
__relink_lru(b, LIST_DIRTY);
|
|
|
|
dm_bufio_unlock(c);
|
|
}
|
|
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);
|
|
|
|
dm_bufio_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_rw = WRITE_FLUSH,
|
|
.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);
|
|
__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, WRITE, new_block, 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;
|
|
|
|
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)
|
|
DMERR("leaked buffer %llx, hold count %u, list %d",
|
|
(unsigned long long)b->block, b->hold_count, i);
|
|
|
|
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 get_retain_buffers(struct dm_bufio_client *c)
|
|
{
|
|
unsigned retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes);
|
|
return retain_bytes / c->block_size;
|
|
}
|
|
|
|
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 = nr_to_scan;
|
|
unsigned 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;
|
|
dm_bufio_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;
|
|
unsigned long count;
|
|
|
|
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 0;
|
|
|
|
count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
|
|
dm_bufio_unlock(c);
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* 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) - 1 - SECTOR_SHIFT;
|
|
c->pages_per_block_bits = (ffs(block_size) - 1 >= PAGE_SHIFT) ?
|
|
ffs(block_size) - 1 - PAGE_SHIFT : 0;
|
|
c->blocks_per_page_bits = (ffs(block_size) - 1 < PAGE_SHIFT ?
|
|
PAGE_SHIFT - (ffs(block_size) - 1) : 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_cache;
|
|
}
|
|
}
|
|
|
|
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_cache;
|
|
}
|
|
}
|
|
}
|
|
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_buffer;
|
|
}
|
|
__free_buffer_wake(b);
|
|
}
|
|
|
|
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);
|
|
|
|
c->shrinker.count_objects = dm_bufio_shrink_count;
|
|
c->shrinker.scan_objects = dm_bufio_shrink_scan;
|
|
c->shrinker.seeks = 1;
|
|
c->shrinker.batch = 0;
|
|
register_shrinker(&c->shrinker);
|
|
|
|
return c;
|
|
|
|
bad_buffer:
|
|
bad_cache:
|
|
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:
|
|
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);
|
|
kfree(c);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
|
|
|
|
static unsigned get_max_age_hz(void)
|
|
{
|
|
unsigned max_age = ACCESS_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 (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 retain_target = get_retain_buffers(c);
|
|
unsigned count;
|
|
|
|
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--;
|
|
|
|
dm_bufio_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);
|
|
|
|
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)((totalram_pages - totalhigh_pages) *
|
|
DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT;
|
|
|
|
if (mem > ULONG_MAX)
|
|
mem = ULONG_MAX;
|
|
|
|
#ifdef CONFIG_MMU
|
|
/*
|
|
* Get the size of vmalloc space the same way as VMALLOC_TOTAL
|
|
* in fs/proc/internal.h
|
|
*/
|
|
if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100)
|
|
mem = (VMALLOC_END - VMALLOC_START) * 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 = create_singlethread_workqueue("dm_bufio_cache");
|
|
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++) {
|
|
struct kmem_cache *kc = dm_bufio_caches[i];
|
|
|
|
if (kc)
|
|
kmem_cache_destroy(kc);
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
if (bug)
|
|
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, uint, 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");
|