/* * 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); /* * Set the sector range. * When this function is called, there must be no I/O in progress on the bufio * client. */ void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start); /* * 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 The data * pointer and dm_buffer pointer is no longer valid after this call.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); /* * Mark a part of the buffer dirty. * * The specified part of the buffer is scheduled to be written. dm-bufio may * write the specified part of the buffer or it may write a larger superset. */ void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, unsigned start, unsigned end); /* * 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