diff options
Diffstat (limited to 'include/linux/pipe_fs_i.h')
| -rw-r--r-- | include/linux/pipe_fs_i.h | 117 |
1 files changed, 81 insertions, 36 deletions
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index c8884f971228..8e4120285f72 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -9,13 +9,39 @@ #define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */ #define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */ +/** + * struct pipe_buffer - a linux kernel pipe buffer + * @page: the page containing the data for the pipe buffer + * @offset: offset of data inside the @page + * @len: length of data inside the @page + * @ops: operations associated with this buffer. See @pipe_buf_operations. + * @flags: pipe buffer flags. See above. + * @private: private data owned by the ops. + **/ struct pipe_buffer { struct page *page; unsigned int offset, len; const struct pipe_buf_operations *ops; unsigned int flags; + unsigned long private; }; +/** + * struct pipe_inode_info - a linux kernel pipe + * @wait: reader/writer wait point in case of empty/full pipe + * @nrbufs: the number of non-empty pipe buffers in this pipe + * @curbuf: the current pipe buffer entry + * @tmp_page: cached released page + * @readers: number of current readers of this pipe + * @writers: number of current writers of this pipe + * @waiting_writers: number of writers blocked waiting for room + * @r_counter: reader counter + * @w_counter: writer counter + * @fasync_readers: reader side fasync + * @fasync_writers: writer side fasync + * @inode: inode this pipe is attached to + * @bufs: the circular array of pipe buffers + **/ struct pipe_inode_info { wait_queue_head_t wait; unsigned int nrbufs, curbuf; @@ -34,22 +60,73 @@ struct pipe_inode_info { /* * Note on the nesting of these functions: * - * ->pin() + * ->confirm() * ->steal() * ... * ->map() * ... * ->unmap() * - * That is, ->map() must be called on a pinned buffer, same goes for ->steal(). + * That is, ->map() must be called on a confirmed buffer, + * same goes for ->steal(). See below for the meaning of each + * operation. Also see kerneldoc in fs/pipe.c for the pipe + * and generic variants of these hooks. */ struct pipe_buf_operations { + /* + * This is set to 1, if the generic pipe read/write may coalesce + * data into an existing buffer. If this is set to 0, a new pipe + * page segment is always used for new data. + */ int can_merge; + + /* + * ->map() returns a virtual address mapping of the pipe buffer. + * The last integer flag reflects whether this should be an atomic + * mapping or not. The atomic map is faster, however you can't take + * page faults before calling ->unmap() again. So if you need to eg + * access user data through copy_to/from_user(), then you must get + * a non-atomic map. ->map() uses the KM_USER0 atomic slot for + * atomic maps, so you can't map more than one pipe_buffer at once + * and you have to be careful if mapping another page as source + * or destination for a copy (IOW, it has to use something else + * than KM_USER0). + */ void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int); + + /* + * Undoes ->map(), finishes the virtual mapping of the pipe buffer. + */ void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *); - int (*pin)(struct pipe_inode_info *, struct pipe_buffer *); + + /* + * ->confirm() verifies that the data in the pipe buffer is there + * and that the contents are good. If the pages in the pipe belong + * to a file system, we may need to wait for IO completion in this + * hook. Returns 0 for good, or a negative error value in case of + * error. + */ + int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); + + /* + * When the contents of this pipe buffer has been completely + * consumed by a reader, ->release() is called. + */ void (*release)(struct pipe_inode_info *, struct pipe_buffer *); + + /* + * Attempt to take ownership of the pipe buffer and its contents. + * ->steal() returns 0 for success, in which case the contents + * of the pipe (the buf->page) is locked and now completely owned + * by the caller. The page may then be transferred to a different + * mapping, the most often used case is insertion into different + * file address space cache. + */ int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); + + /* + * Get a reference to the pipe buffer. + */ void (*get)(struct pipe_inode_info *, struct pipe_buffer *); }; @@ -68,39 +145,7 @@ void __free_pipe_info(struct pipe_inode_info *); void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int); void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *); void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); -int generic_pipe_buf_pin(struct pipe_inode_info *, struct pipe_buffer *); +int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); int generic_pipe_buf_steal(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. - */ -#define SPLICE_F_MOVE (0x01) /* move pages instead of copying */ -#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */ - /* we may still block on the fd we splice */ - /* from/to, of course */ -#define SPLICE_F_MORE (0x04) /* expect more data */ -#define SPLICE_F_GIFT (0x08) /* pages passed in are a gift */ - -/* - * Passed to the actors - */ -struct splice_desc { - unsigned int len, total_len; /* current and remaining length */ - unsigned int flags; /* splice flags */ - struct file *file; /* file to read/write */ - loff_t pos; /* file position */ -}; - -typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, - struct splice_desc *); - -extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *, - loff_t *, size_t, unsigned int, - splice_actor *); - -extern ssize_t __splice_from_pipe(struct pipe_inode_info *, struct file *, - loff_t *, size_t, unsigned int, - splice_actor *); - #endif |