The name 'pin' was badly chosen, it doesn't pin a pipe buffer in the most commonly used sense in the kernel. So change the name to 'confirm', after debating this issue with Hugh Dickins a bit. A good return from ->confirm() means that the buffer is really there, and that the contents are good. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
77 lines
2.3 KiB
C
77 lines
2.3 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 /* page is on the LRU */
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#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */
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#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */
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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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const struct pipe_buf_operations *ops;
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unsigned int flags;
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unsigned long private;
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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 page *tmp_page;
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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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struct pipe_buffer bufs[PIPE_BUFFERS];
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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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* ->confirm()
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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 confirmed buffer,
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* 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 *, int);
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void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
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int (*confirm)(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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/* 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 *, int);
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void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
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void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
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int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
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int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
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#endif
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