X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=include%2Flinux%2Fpipe_fs_i.h;h=8e4120285f72ef3379be0de768880b67453437c9;hb=856f6fd119411d5701d5db96e1aae1dd69923887;hp=ec384958d509690090aa1936b4624cb3da05b2d8;hpb=3e7ee3e7b36fa4e2d88d8fb0a2577be95fc4636d;p=safe%2Fjmp%2Flinux-2.6 diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index ec38495..8e41202 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -5,30 +5,47 @@ #define PIPE_BUFFERS (16) -#define PIPE_BUF_FLAG_STOLEN 0x01 -#define PIPE_BUF_FLAG_LRU 0x02 +#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */ +#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; - struct pipe_buf_operations *ops; + const struct pipe_buf_operations *ops; unsigned int flags; + unsigned long private; }; -struct pipe_buf_operations { - int can_merge; - void * (*map)(struct file *, struct pipe_inode_info *, struct pipe_buffer *); - void (*unmap)(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 *); -}; - +/** + * 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; - struct pipe_buffer bufs[PIPE_BUFFERS]; struct page *tmp_page; - unsigned int start; unsigned int readers; unsigned int writers; unsigned int waiting_writers; @@ -36,36 +53,99 @@ struct pipe_inode_info { unsigned int w_counter; struct fasync_struct *fasync_readers; struct fasync_struct *fasync_writers; + struct inode *inode; + struct pipe_buffer bufs[PIPE_BUFFERS]; +}; + +/* + * Note on the nesting of these functions: + * + * ->confirm() + * ->steal() + * ... + * ->map() + * ... + * ->unmap() + * + * 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 *); + + /* + * ->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 *); }; /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ #define PIPE_SIZE PAGE_SIZE -#define PIPE_MUTEX(inode) (&(inode).i_mutex) -#define PIPE_WAIT(inode) (&(inode).i_pipe->wait) -#define PIPE_READERS(inode) ((inode).i_pipe->readers) -#define PIPE_WRITERS(inode) ((inode).i_pipe->writers) -#define PIPE_WAITING_WRITERS(inode) ((inode).i_pipe->waiting_writers) -#define PIPE_RCOUNTER(inode) ((inode).i_pipe->r_counter) -#define PIPE_WCOUNTER(inode) ((inode).i_pipe->w_counter) -#define PIPE_FASYNC_READERS(inode) (&((inode).i_pipe->fasync_readers)) -#define PIPE_FASYNC_WRITERS(inode) (&((inode).i_pipe->fasync_writers)) - /* Drop the inode semaphore and wait for a pipe event, atomically */ -void pipe_wait(struct inode * inode); +void pipe_wait(struct pipe_inode_info *pipe); -struct inode* pipe_new(struct inode* inode); -void free_pipe_info(struct inode* inode); +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 *); -/* - * 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 */ +/* Generic pipe buffer ops functions */ +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_confirm(struct pipe_inode_info *, struct pipe_buffer *); +int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); #endif