mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-21 11:44:01 +08:00
55b082e614
This patch modifies dm-snapshot so that it prefetches the buffers when loading the exceptions. The number of buffers read ahead is specified in the DM_PREFETCH_CHUNKS macro. The current value for DM_PREFETCH_CHUNKS (12) was found to provide the best performance on a single 15k SCSI spindle. In the future we may modify this default or make it configurable. Also, introduce the function dm_bufio_set_minimum_buffers to setup bufio's number of internal buffers before freeing happens. dm-bufio may hold more buffers if enough memory is available. There is no guarantee that the specified number of buffers will be available - if you need a guarantee, use the argument reserved_buffers for dm_bufio_client_create. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
133 lines
3.9 KiB
C
133 lines
3.9 KiB
C
/*
|
|
* Copyright (C) 2009-2011 Red Hat, Inc.
|
|
*
|
|
* Author: Mikulas Patocka <mpatocka@redhat.com>
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#ifndef DM_BUFIO_H
|
|
#define DM_BUFIO_H
|
|
|
|
#include <linux/blkdev.h>
|
|
#include <linux/types.h>
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
struct dm_bufio_client;
|
|
struct dm_buffer;
|
|
|
|
/*
|
|
* Create a buffered IO cache on a given device
|
|
*/
|
|
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 *));
|
|
|
|
/*
|
|
* Release a buffered IO cache.
|
|
*/
|
|
void dm_bufio_client_destroy(struct dm_bufio_client *c);
|
|
|
|
/*
|
|
* WARNING: to avoid deadlocks, these conditions are observed:
|
|
*
|
|
* - At most one thread can hold at most "reserved_buffers" simultaneously.
|
|
* - Each other threads can hold at most one buffer.
|
|
* - Threads which call only dm_bufio_get can hold unlimited number of
|
|
* buffers.
|
|
*/
|
|
|
|
/*
|
|
* Read a given block from disk. Returns pointer to data. Returns a
|
|
* pointer to dm_buffer that can be used to release the buffer or to make
|
|
* it dirty.
|
|
*/
|
|
void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
|
|
struct dm_buffer **bp);
|
|
|
|
/*
|
|
* Like dm_bufio_read, but return buffer from cache, don't read
|
|
* it. If the buffer is not in the cache, return NULL.
|
|
*/
|
|
void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
|
|
struct dm_buffer **bp);
|
|
|
|
/*
|
|
* Like dm_bufio_read, but don't read anything from the disk. It is
|
|
* expected that the caller initializes the buffer and marks it dirty.
|
|
*/
|
|
void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
|
|
struct dm_buffer **bp);
|
|
|
|
/*
|
|
* Prefetch the specified blocks to the cache.
|
|
* The function starts to read the blocks and returns without waiting for
|
|
* I/O to finish.
|
|
*/
|
|
void dm_bufio_prefetch(struct dm_bufio_client *c,
|
|
sector_t block, unsigned n_blocks);
|
|
|
|
/*
|
|
* Release a reference obtained with dm_bufio_{read,get,new}. The data
|
|
* pointer and dm_buffer pointer is no longer valid after this call.
|
|
*/
|
|
void dm_bufio_release(struct dm_buffer *b);
|
|
|
|
/*
|
|
* Mark a buffer dirty. It should be called after the buffer is modified.
|
|
*
|
|
* In case of memory pressure, the buffer may be written after
|
|
* dm_bufio_mark_buffer_dirty, but before dm_bufio_write_dirty_buffers. So
|
|
* dm_bufio_write_dirty_buffers guarantees that the buffer is on-disk but
|
|
* the actual writing may occur earlier.
|
|
*/
|
|
void dm_bufio_mark_buffer_dirty(struct dm_buffer *b);
|
|
|
|
/*
|
|
* Initiate writing of dirty buffers, without waiting for completion.
|
|
*/
|
|
void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c);
|
|
|
|
/*
|
|
* Write all dirty buffers. Guarantees that all dirty buffers created prior
|
|
* to this call are on disk when this call exits.
|
|
*/
|
|
int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c);
|
|
|
|
/*
|
|
* Send an empty write barrier to the device to flush hardware disk cache.
|
|
*/
|
|
int dm_bufio_issue_flush(struct dm_bufio_client *c);
|
|
|
|
/*
|
|
* Like dm_bufio_release but also move the buffer to the new
|
|
* block. dm_bufio_write_dirty_buffers is needed to commit the new block.
|
|
*/
|
|
void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/*
|
|
* Set the minimum number of buffers before cleanup happens.
|
|
*/
|
|
void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n);
|
|
|
|
unsigned dm_bufio_get_block_size(struct dm_bufio_client *c);
|
|
sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
|
|
sector_t dm_bufio_get_block_number(struct dm_buffer *b);
|
|
void *dm_bufio_get_block_data(struct dm_buffer *b);
|
|
void *dm_bufio_get_aux_data(struct dm_buffer *b);
|
|
struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b);
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
#endif
|