From afa53df869121fd4f6f1265cbe794d64387890ae Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Thu, 15 Mar 2018 16:02:31 -0400 Subject: dm bufio: move dm-bufio.h to include/linux/ Move dm-bufio.h to include/linux/ so that external GPL'd DM target modules can use it. It is better to allow the use of dm-bufio than force external modules to implement the equivalent buffered IO mechanism in some new way. The hope is this will encourage the use of dm-bufio; which will then make it easier for a GPL'd external DM target module to be included upstream. A couple dm-bufio EXPORT_SYMBOL exports have also been updated to use EXPORT_SYMBOL_GPL. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- include/linux/dm-bufio.h | 148 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 include/linux/dm-bufio.h (limited to 'include/linux/dm-bufio.h') diff --git a/include/linux/dm-bufio.h b/include/linux/dm-bufio.h new file mode 100644 index 000000000000..3c8b7d274bd9 --- /dev/null +++ b/include/linux/dm-bufio.h @@ -0,0 +1,148 @@ +/* + * Copyright (C) 2009-2011 Red Hat, Inc. + * + * Author: Mikulas Patocka + * + * This file is released under the GPL. + */ + +#ifndef _LINUX_DM_BUFIO_H +#define _LINUX_DM_BUFIO_H + +#include +#include + +/*----------------------------------------------------------------*/ + +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 -- cgit