struct pipe_inode_info — a linux kernel pipe
struct pipe_inode_info {
wait_queue_head_t wait;
unsigned int nrbufs;
unsigned int curbuf;
struct page * tmp_page;
unsigned int readers;
unsigned int writers;
unsigned int waiting_writers;
unsigned int r_counter;
unsigned int w_counter;
struct fasync_struct * fasync_readers;
struct fasync_struct * fasync_writers;
struct inode * inode;
struct pipe_buffer bufs[PIPE_BUFFERS];
}; reader/writer wait point in case of empty/full pipe
the number of non-empty pipe buffers in this pipe
the current pipe buffer entry
cached released page
number of current readers of this pipe
number of current writers of this pipe
number of writers blocked waiting for room
reader counter
writer counter
reader side fasync
writer side fasync
inode this pipe is attached to
the circular array of pipe buffers