From f84d751994441292593523c7069ed147176f6cab Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 1 May 2006 19:59:03 +0200 Subject: [PATCH] pipe: introduce ->pin() buffer operation The ->map() function is really expensive on highmem machines right now, since it has to use the slower kmap() instead of kmap_atomic(). Splice rarely needs to access the virtual address of a page, so it's a waste of time doing it. Introduce ->pin() to take over the responsibility of making sure the page data is valid. ->map() is then reduced to just kmap(). That way we can also share a most of the pipe buffer ops between pipe.c and splice.c Signed-off-by: Jens Axboe --- include/linux/pipe_fs_i.h | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'include/linux/pipe_fs_i.h') diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index 3130977fc6a..b8aae1fc518 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -14,10 +14,23 @@ struct pipe_buffer { unsigned int flags; }; +/* + * Note on the nesting of these functions: + * + * ->pin() + * ->steal() + * ... + * ->map() + * ... + * ->unmap() + * + * That is, ->map() must be called on a pinned buffer, same goes for ->steal(). + */ struct pipe_buf_operations { int can_merge; - void * (*map)(struct file *, struct pipe_inode_info *, struct pipe_buffer *); + void * (*map)(struct pipe_inode_info *, struct pipe_buffer *); void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *); + int (*pin)(struct pipe_inode_info *, struct pipe_buffer *); void (*release)(struct pipe_inode_info *, struct pipe_buffer *); int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); void (*get)(struct pipe_inode_info *, struct pipe_buffer *); @@ -50,6 +63,12 @@ struct pipe_inode_info * alloc_pipe_info(struct inode * inode); void free_pipe_info(struct inode * inode); void __free_pipe_info(struct pipe_inode_info *); +/* Generic pipe buffer ops functions */ +void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *); +void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *); +void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); +int generic_pipe_buf_pin(struct pipe_inode_info *, struct pipe_buffer *); + /* * splice is tied to pipes as a transport (at least for now), so we'll just * add the splice flags here. -- cgit v1.2.3