f84d751994
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 <axboe@suse.de>
99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
#ifndef _LINUX_PIPE_FS_I_H
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#define _LINUX_PIPE_FS_I_H
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#define PIPEFS_MAGIC 0x50495045
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#define PIPE_BUFFERS (16)
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#define PIPE_BUF_FLAG_LRU 0x01
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struct pipe_buffer {
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struct page *page;
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unsigned int offset, len;
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struct pipe_buf_operations *ops;
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unsigned int flags;
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};
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/*
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* Note on the nesting of these functions:
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*
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* ->pin()
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* ->steal()
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* ...
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* ->map()
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* ...
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* ->unmap()
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*
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* That is, ->map() must be called on a pinned buffer, same goes for ->steal().
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*/
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struct pipe_buf_operations {
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int can_merge;
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void * (*map)(struct pipe_inode_info *, struct pipe_buffer *);
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void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *);
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int (*pin)(struct pipe_inode_info *, struct pipe_buffer *);
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void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
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int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
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void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
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};
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struct pipe_inode_info {
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wait_queue_head_t wait;
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unsigned int nrbufs, curbuf;
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struct pipe_buffer bufs[PIPE_BUFFERS];
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struct page *tmp_page;
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unsigned int start;
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unsigned int readers;
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unsigned int writers;
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unsigned int waiting_writers;
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unsigned int r_counter;
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unsigned int w_counter;
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struct fasync_struct *fasync_readers;
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struct fasync_struct *fasync_writers;
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struct inode *inode;
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};
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/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
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memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
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#define PIPE_SIZE PAGE_SIZE
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/* Drop the inode semaphore and wait for a pipe event, atomically */
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void pipe_wait(struct pipe_inode_info *pipe);
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struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
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void free_pipe_info(struct inode * inode);
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void __free_pipe_info(struct pipe_inode_info *);
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/* Generic pipe buffer ops functions */
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void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *);
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void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *);
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void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
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int generic_pipe_buf_pin(struct pipe_inode_info *, struct pipe_buffer *);
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/*
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* splice is tied to pipes as a transport (at least for now), so we'll just
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* add the splice flags here.
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*/
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#define SPLICE_F_MOVE (0x01) /* move pages instead of copying */
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#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
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/* we may still block on the fd we splice */
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/* from/to, of course */
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#define SPLICE_F_MORE (0x04) /* expect more data */
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/*
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* Passed to the actors
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*/
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struct splice_desc {
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unsigned int len, total_len; /* current and remaining length */
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unsigned int flags; /* splice flags */
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struct file *file; /* file to read/write */
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loff_t pos; /* file position */
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};
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typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
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struct splice_desc *);
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extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
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loff_t *, size_t, unsigned int,
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splice_actor *);
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#endif
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