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    Subject[PATCH] relayfs: Convert to generic relay API.
    On Sun, Feb 19, 2006 at 11:27:48PM +0200, Paul Mundt wrote:
    > On Sun, Feb 19, 2006 at 04:21:22PM -0500, Dave Jones wrote:
    > > On Sun, Feb 19, 2006 at 11:07:33PM +0200, Paul Mundt wrote:
    > > > This is a small patch set for getting rid of relayfs, and moving the core of
    > > > its functionality to kernel/relay.c. The API is kept consistent for everything
    > > > but the relayfs-specific bits, meaning people will have to use other file
    > > > systems to implement relay channel buffers.
    > >
    > > What about the userspace visible API for things already using relayfs,
    > > like systemtap ? Whilst technically these patches may make sense,
    > > yanking the rug underneath applications as soon as they've started
    > > using it without warning or a migration period doesn't sound too good an idea.
    > >
    > Yes, that's why this is only done in the last two patches. The rest are
    > completely independent and don't interfere with the API (well, ok,
    > FIX_SIZE() needs to be dropped in fs/relayfs if it's fetching it from the
    > header, but that's it).
    >
    > > It's taken us *years* to try and get rid of devfs, why should relayfs
    > > get ripped out any quicker, when it has valid users?
    > >
    > I'm not advocating its removal, I'm more interested in using it from
    > sysfs and debugfs where it makes more sense. Splitting up CONFIG_RELAY
    > and CONFIG_RELAYFS_FS will allow for both, and it'll also be possible to
    > migrate the existing CONFIG_RELAYFS_FS code to use CONFIG_RELAY without
    > breaking the userspace APIs if we want to get rid of the duplication. The
    > only issue will be wrapping up the default callbacks, but that's a
    > trivial ifdef.

    And here's a patch doing that.. any other objections?

    This strips down relayfs to a minimum, removing everything already
    provided by CONFIG_RELAY. This leaves a userspace API compatible
    implementation on top of the new framework.

    Signed-off-by: Paul Mundt <lethal@linux-sh.org>

    ---

    fs/Kconfig | 1
    fs/relayfs/Makefile | 3
    fs/relayfs/buffers.c | 190 -----------------
    fs/relayfs/buffers.h | 12 -
    fs/relayfs/inode.c | 269 -------------------------
    fs/relayfs/relay.c | 482 --------------------------------------------
    fs/relayfs/relay.h | 8 -
    include/linux/relayfs_fs.h | 1
    kernel/relay.c | 9 +
    9 files changed, 12 insertions(+), 963 deletions(-)
    delete mode 100644 fs/relayfs/buffers.c
    delete mode 100644 fs/relayfs/buffers.h
    delete mode 100644 fs/relayfs/relay.c
    delete mode 100644 fs/relayfs/relay.h

    51d322e2944117ed6c01b79b73e18f15c2b8d09e
    diff --git a/fs/Kconfig b/fs/Kconfig
    index e9749b0..6245587 100644
    --- a/fs/Kconfig
    +++ b/fs/Kconfig
    @@ -861,6 +861,7 @@ config RAMFS

    config RELAYFS_FS
    tristate "Relayfs file system support"
    + select RELAY
    ---help---
    Relayfs is a high-speed data relay filesystem designed to provide
    an efficient mechanism for tools and facilities to relay large
    diff --git a/fs/relayfs/Makefile b/fs/relayfs/Makefile
    index e76e182..b45ffc0 100644
    --- a/fs/relayfs/Makefile
    +++ b/fs/relayfs/Makefile
    @@ -1,4 +1,3 @@
    obj-$(CONFIG_RELAYFS_FS) += relayfs.o

    -relayfs-y := relay.o inode.o buffers.o
    -
    +relayfs-y := inode.o
    diff --git a/fs/relayfs/buffers.c b/fs/relayfs/buffers.c
    deleted file mode 100644
    index 1018781..0000000
    --- a/fs/relayfs/buffers.c
    +++ /dev/null
    @@ -1,190 +0,0 @@
    -/*
    - * RelayFS buffer management code.
    - *
    - * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
    - * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
    - *
    - * This file is released under the GPL.
    - */
    -
    -#include <linux/module.h>
    -#include <linux/vmalloc.h>
    -#include <linux/mm.h>
    -#include <linux/relayfs_fs.h>
    -#include "relay.h"
    -#include "buffers.h"
    -
    -/*
    - * close() vm_op implementation for relayfs file mapping.
    - */
    -static void relay_file_mmap_close(struct vm_area_struct *vma)
    -{
    - struct rchan_buf *buf = vma->vm_private_data;
    - buf->chan->cb->buf_unmapped(buf, vma->vm_file);
    -}
    -
    -/*
    - * nopage() vm_op implementation for relayfs file mapping.
    - */
    -static struct page *relay_buf_nopage(struct vm_area_struct *vma,
    - unsigned long address,
    - int *type)
    -{
    - struct page *page;
    - struct rchan_buf *buf = vma->vm_private_data;
    - unsigned long offset = address - vma->vm_start;
    -
    - if (address > vma->vm_end)
    - return NOPAGE_SIGBUS; /* Disallow mremap */
    - if (!buf)
    - return NOPAGE_OOM;
    -
    - page = vmalloc_to_page(buf->start + offset);
    - if (!page)
    - return NOPAGE_OOM;
    - get_page(page);
    -
    - if (type)
    - *type = VM_FAULT_MINOR;
    -
    - return page;
    -}
    -
    -/*
    - * vm_ops for relay file mappings.
    - */
    -static struct vm_operations_struct relay_file_mmap_ops = {
    - .nopage = relay_buf_nopage,
    - .close = relay_file_mmap_close,
    -};
    -
    -/**
    - * relay_mmap_buf: - mmap channel buffer to process address space
    - * @buf: relay channel buffer
    - * @vma: vm_area_struct describing memory to be mapped
    - *
    - * Returns 0 if ok, negative on error
    - *
    - * Caller should already have grabbed mmap_sem.
    - */
    -int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
    -{
    - unsigned long length = vma->vm_end - vma->vm_start;
    - struct file *filp = vma->vm_file;
    -
    - if (!buf)
    - return -EBADF;
    -
    - if (length != (unsigned long)buf->chan->alloc_size)
    - return -EINVAL;
    -
    - vma->vm_ops = &relay_file_mmap_ops;
    - vma->vm_private_data = buf;
    - buf->chan->cb->buf_mapped(buf, filp);
    -
    - return 0;
    -}
    -
    -/**
    - * relay_alloc_buf - allocate a channel buffer
    - * @buf: the buffer struct
    - * @size: total size of the buffer
    - *
    - * Returns a pointer to the resulting buffer, NULL if unsuccessful
    - */
    -static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size)
    -{
    - void *mem;
    - unsigned int i, j, n_pages;
    -
    - size = PAGE_ALIGN(size);
    - n_pages = size >> PAGE_SHIFT;
    -
    - buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
    - if (!buf->page_array)
    - return NULL;
    -
    - for (i = 0; i < n_pages; i++) {
    - buf->page_array[i] = alloc_page(GFP_KERNEL);
    - if (unlikely(!buf->page_array[i]))
    - goto depopulate;
    - }
    - mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
    - if (!mem)
    - goto depopulate;
    -
    - memset(mem, 0, size);
    - buf->page_count = n_pages;
    - return mem;
    -
    -depopulate:
    - for (j = 0; j < i; j++)
    - __free_page(buf->page_array[j]);
    - kfree(buf->page_array);
    - return NULL;
    -}
    -
    -/**
    - * relay_create_buf - allocate and initialize a channel buffer
    - * @alloc_size: size of the buffer to allocate
    - * @n_subbufs: number of sub-buffers in the channel
    - *
    - * Returns channel buffer if successful, NULL otherwise
    - */
    -struct rchan_buf *relay_create_buf(struct rchan *chan)
    -{
    - struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL);
    - if (!buf)
    - return NULL;
    -
    - buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
    - if (!buf->padding)
    - goto free_buf;
    -
    - buf->start = relay_alloc_buf(buf, chan->alloc_size);
    - if (!buf->start)
    - goto free_buf;
    -
    - buf->chan = chan;
    - kref_get(&buf->chan->kref);
    - return buf;
    -
    -free_buf:
    - kfree(buf->padding);
    - kfree(buf);
    - return NULL;
    -}
    -
    -/**
    - * relay_destroy_buf - destroy an rchan_buf struct and associated buffer
    - * @buf: the buffer struct
    - */
    -void relay_destroy_buf(struct rchan_buf *buf)
    -{
    - struct rchan *chan = buf->chan;
    - unsigned int i;
    -
    - if (likely(buf->start)) {
    - vunmap(buf->start);
    - for (i = 0; i < buf->page_count; i++)
    - __free_page(buf->page_array[i]);
    - kfree(buf->page_array);
    - }
    - kfree(buf->padding);
    - kfree(buf);
    - kref_put(&chan->kref, relay_destroy_channel);
    -}
    -
    -/**
    - * relay_remove_buf - remove a channel buffer
    - *
    - * Removes the file from the relayfs fileystem, which also frees the
    - * rchan_buf_struct and the channel buffer. Should only be called from
    - * kref_put().
    - */
    -void relay_remove_buf(struct kref *kref)
    -{
    - struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
    - buf->chan->cb->remove_buf_file(buf->dentry);
    - relay_destroy_buf(buf);
    -}
    diff --git a/fs/relayfs/buffers.h b/fs/relayfs/buffers.h
    deleted file mode 100644
    index 37a1249..0000000
    --- a/fs/relayfs/buffers.h
    +++ /dev/null
    @@ -1,12 +0,0 @@
    -#ifndef _BUFFERS_H
    -#define _BUFFERS_H
    -
    -/* This inspired by rtai/shmem */
    -#define FIX_SIZE(x) (((x) - 1) & PAGE_MASK) + PAGE_SIZE
    -
    -extern int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma);
    -extern struct rchan_buf *relay_create_buf(struct rchan *chan);
    -extern void relay_destroy_buf(struct rchan_buf *buf);
    -extern void relay_remove_buf(struct kref *kref);
    -
    -#endif/* _BUFFERS_H */
    diff --git a/fs/relayfs/inode.c b/fs/relayfs/inode.c
    index 3835230..6f58381 100644
    --- a/fs/relayfs/inode.c
    +++ b/fs/relayfs/inode.c
    @@ -19,8 +19,6 @@
    #include <linux/namei.h>
    #include <linux/poll.h>
    #include <linux/relayfs_fs.h>
    -#include "relay.h"
    -#include "buffers.h"

    #define RELAYFS_MAGIC 0xF0B4A981

    @@ -246,267 +244,6 @@ int relayfs_remove_dir(struct dentry *de
    return relayfs_remove(dentry);
    }

    -/**
    - * relay_file_open - open file op for relay files
    - * @inode: the inode
    - * @filp: the file
    - *
    - * Increments the channel buffer refcount.
    - */
    -static int relay_file_open(struct inode *inode, struct file *filp)
    -{
    - struct rchan_buf *buf = inode->u.generic_ip;
    - kref_get(&buf->kref);
    - filp->private_data = buf;
    -
    - return 0;
    -}
    -
    -/**
    - * relay_file_mmap - mmap file op for relay files
    - * @filp: the file
    - * @vma: the vma describing what to map
    - *
    - * Calls upon relay_mmap_buf to map the file into user space.
    - */
    -static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
    -{
    - struct rchan_buf *buf = filp->private_data;
    - return relay_mmap_buf(buf, vma);
    -}
    -
    -/**
    - * relay_file_poll - poll file op for relay files
    - * @filp: the file
    - * @wait: poll table
    - *
    - * Poll implemention.
    - */
    -static unsigned int relay_file_poll(struct file *filp, poll_table *wait)
    -{
    - unsigned int mask = 0;
    - struct rchan_buf *buf = filp->private_data;
    -
    - if (buf->finalized)
    - return POLLERR;
    -
    - if (filp->f_mode & FMODE_READ) {
    - poll_wait(filp, &buf->read_wait, wait);
    - if (!relay_buf_empty(buf))
    - mask |= POLLIN | POLLRDNORM;
    - }
    -
    - return mask;
    -}
    -
    -/**
    - * relay_file_release - release file op for relay files
    - * @inode: the inode
    - * @filp: the file
    - *
    - * Decrements the channel refcount, as the filesystem is
    - * no longer using it.
    - */
    -static int relay_file_release(struct inode *inode, struct file *filp)
    -{
    - struct rchan_buf *buf = filp->private_data;
    - kref_put(&buf->kref, relay_remove_buf);
    -
    - return 0;
    -}
    -
    -/**
    - * relay_file_read_consume - update the consumed count for the buffer
    - */
    -static void relay_file_read_consume(struct rchan_buf *buf,
    - size_t read_pos,
    - size_t bytes_consumed)
    -{
    - size_t subbuf_size = buf->chan->subbuf_size;
    - size_t n_subbufs = buf->chan->n_subbufs;
    - size_t read_subbuf;
    -
    - if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
    - relay_subbufs_consumed(buf->chan, buf->cpu, 1);
    - buf->bytes_consumed = 0;
    - }
    -
    - buf->bytes_consumed += bytes_consumed;
    - read_subbuf = read_pos / buf->chan->subbuf_size;
    - if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
    - if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
    - (buf->offset == subbuf_size))
    - return;
    - relay_subbufs_consumed(buf->chan, buf->cpu, 1);
    - buf->bytes_consumed = 0;
    - }
    -}
    -
    -/**
    - * relay_file_read_avail - boolean, are there unconsumed bytes available?
    - */
    -static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
    -{
    - size_t bytes_produced, bytes_consumed, write_offset;
    - size_t subbuf_size = buf->chan->subbuf_size;
    - size_t n_subbufs = buf->chan->n_subbufs;
    - size_t produced = buf->subbufs_produced % n_subbufs;
    - size_t consumed = buf->subbufs_consumed % n_subbufs;
    -
    - write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
    -
    - if (consumed > produced) {
    - if ((produced > n_subbufs) &&
    - (produced + n_subbufs - consumed <= n_subbufs))
    - produced += n_subbufs;
    - } else if (consumed == produced) {
    - if (buf->offset > subbuf_size) {
    - produced += n_subbufs;
    - if (buf->subbufs_produced == buf->subbufs_consumed)
    - consumed += n_subbufs;
    - }
    - }
    -
    - if (buf->offset > subbuf_size)
    - bytes_produced = (produced - 1) * subbuf_size + write_offset;
    - else
    - bytes_produced = produced * subbuf_size + write_offset;
    - bytes_consumed = consumed * subbuf_size + buf->bytes_consumed;
    -
    - if (bytes_produced == bytes_consumed)
    - return 0;
    -
    - relay_file_read_consume(buf, read_pos, 0);
    -
    - return 1;
    -}
    -
    -/**
    - * relay_file_read_subbuf_avail - return bytes available in sub-buffer
    - */
    -static size_t relay_file_read_subbuf_avail(size_t read_pos,
    - struct rchan_buf *buf)
    -{
    - size_t padding, avail = 0;
    - size_t read_subbuf, read_offset, write_subbuf, write_offset;
    - size_t subbuf_size = buf->chan->subbuf_size;
    -
    - write_subbuf = (buf->data - buf->start) / subbuf_size;
    - write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
    - read_subbuf = read_pos / subbuf_size;
    - read_offset = read_pos % subbuf_size;
    - padding = buf->padding[read_subbuf];
    -
    - if (read_subbuf == write_subbuf) {
    - if (read_offset + padding < write_offset)
    - avail = write_offset - (read_offset + padding);
    - } else
    - avail = (subbuf_size - padding) - read_offset;
    -
    - return avail;
    -}
    -
    -/**
    - * relay_file_read_start_pos - find the first available byte to read
    - *
    - * If the read_pos is in the middle of padding, return the
    - * position of the first actually available byte, otherwise
    - * return the original value.
    - */
    -static size_t relay_file_read_start_pos(size_t read_pos,
    - struct rchan_buf *buf)
    -{
    - size_t read_subbuf, padding, padding_start, padding_end;
    - size_t subbuf_size = buf->chan->subbuf_size;
    - size_t n_subbufs = buf->chan->n_subbufs;
    -
    - read_subbuf = read_pos / subbuf_size;
    - padding = buf->padding[read_subbuf];
    - padding_start = (read_subbuf + 1) * subbuf_size - padding;
    - padding_end = (read_subbuf + 1) * subbuf_size;
    - if (read_pos >= padding_start && read_pos < padding_end) {
    - read_subbuf = (read_subbuf + 1) % n_subbufs;
    - read_pos = read_subbuf * subbuf_size;
    - }
    -
    - return read_pos;
    -}
    -
    -/**
    - * relay_file_read_end_pos - return the new read position
    - */
    -static size_t relay_file_read_end_pos(struct rchan_buf *buf,
    - size_t read_pos,
    - size_t count)
    -{
    - size_t read_subbuf, padding, end_pos;
    - size_t subbuf_size = buf->chan->subbuf_size;
    - size_t n_subbufs = buf->chan->n_subbufs;
    -
    - read_subbuf = read_pos / subbuf_size;
    - padding = buf->padding[read_subbuf];
    - if (read_pos % subbuf_size + count + padding == subbuf_size)
    - end_pos = (read_subbuf + 1) * subbuf_size;
    - else
    - end_pos = read_pos + count;
    - if (end_pos >= subbuf_size * n_subbufs)
    - end_pos = 0;
    -
    - return end_pos;
    -}
    -
    -/**
    - * relay_file_read - read file op for relay files
    - * @filp: the file
    - * @buffer: the userspace buffer
    - * @count: number of bytes to read
    - * @ppos: position to read from
    - *
    - * Reads count bytes or the number of bytes available in the
    - * current sub-buffer being read, whichever is smaller.
    - */
    -static ssize_t relay_file_read(struct file *filp,
    - char __user *buffer,
    - size_t count,
    - loff_t *ppos)
    -{
    - struct rchan_buf *buf = filp->private_data;
    - struct inode *inode = filp->f_dentry->d_inode;
    - size_t read_start, avail;
    - ssize_t ret = 0;
    - void *from;
    -
    - mutex_lock(&inode->i_mutex);
    - if(!relay_file_read_avail(buf, *ppos))
    - goto out;
    -
    - read_start = relay_file_read_start_pos(*ppos, buf);
    - avail = relay_file_read_subbuf_avail(read_start, buf);
    - if (!avail)
    - goto out;
    -
    - from = buf->start + read_start;
    - ret = count = min(count, avail);
    - if (copy_to_user(buffer, from, count)) {
    - ret = -EFAULT;
    - goto out;
    - }
    - relay_file_read_consume(buf, read_start, count);
    - *ppos = relay_file_read_end_pos(buf, read_start, count);
    -out:
    - mutex_unlock(&inode->i_mutex);
    - return ret;
    -}
    -
    -struct file_operations relay_file_operations = {
    - .open = relay_file_open,
    - .poll = relay_file_poll,
    - .mmap = relay_file_mmap,
    - .read = relay_file_read,
    - .llseek = no_llseek,
    - .release = relay_file_release,
    -};
    -
    static struct super_operations relayfs_ops = {
    .statfs = simple_statfs,
    .drop_inode = generic_delete_inode,
    @@ -558,18 +295,12 @@ static int __init init_relayfs_fs(void)

    static void __exit exit_relayfs_fs(void)
    {
    -
    -
    -
    -
    -
    unregister_filesystem(&relayfs_fs_type);
    }

    module_init(init_relayfs_fs)
    module_exit(exit_relayfs_fs)

    -EXPORT_SYMBOL_GPL(relay_file_operations);
    EXPORT_SYMBOL_GPL(relayfs_create_dir);
    EXPORT_SYMBOL_GPL(relayfs_remove_dir);
    EXPORT_SYMBOL_GPL(relayfs_create_file);
    diff --git a/fs/relayfs/relay.c b/fs/relayfs/relay.c
    deleted file mode 100644
    index abf3cea..0000000
    --- a/fs/relayfs/relay.c
    +++ /dev/null
    @@ -1,482 +0,0 @@
    -/*
    - * Public API and common code for RelayFS.
    - *
    - * See Documentation/filesystems/relayfs.txt for an overview of relayfs.
    - *
    - * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
    - * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
    - *
    - * This file is released under the GPL.
    - */
    -
    -#include <linux/errno.h>
    -#include <linux/stddef.h>
    -#include <linux/slab.h>
    -#include <linux/module.h>
    -#include <linux/string.h>
    -#include <linux/relayfs_fs.h>
    -#include "relay.h"
    -#include "buffers.h"
    -
    -/**
    - * relay_buf_empty - boolean, is the channel buffer empty?
    - * @buf: channel buffer
    - *
    - * Returns 1 if the buffer is empty, 0 otherwise.
    - */
    -int relay_buf_empty(struct rchan_buf *buf)
    -{
    - return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
    -}
    -
    -/**
    - * relay_buf_full - boolean, is the channel buffer full?
    - * @buf: channel buffer
    - *
    - * Returns 1 if the buffer is full, 0 otherwise.
    - */
    -int relay_buf_full(struct rchan_buf *buf)
    -{
    - size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
    - return (ready >= buf->chan->n_subbufs) ? 1 : 0;
    -}
    -
    -/*
    - * High-level relayfs kernel API and associated functions.
    - */
    -
    -/*
    - * rchan_callback implementations defining default channel behavior. Used
    - * in place of corresponding NULL values in client callback struct.
    - */
    -
    -/*
    - * subbuf_start() default callback. Does nothing.
    - */
    -static int subbuf_start_default_callback (struct rchan_buf *buf,
    - void *subbuf,
    - void *prev_subbuf,
    - size_t prev_padding)
    -{
    - if (relay_buf_full(buf))
    - return 0;
    -
    - return 1;
    -}
    -
    -/*
    - * buf_mapped() default callback. Does nothing.
    - */
    -static void buf_mapped_default_callback(struct rchan_buf *buf,
    - struct file *filp)
    -{
    -}
    -
    -/*
    - * buf_unmapped() default callback. Does nothing.
    - */
    -static void buf_unmapped_default_callback(struct rchan_buf *buf,
    - struct file *filp)
    -{
    -}
    -
    -/*
    - * create_buf_file_create() default callback. Creates file to represent buf.
    - */
    -static struct dentry *create_buf_file_default_callback(const char *filename,
    - struct dentry *parent,
    - int mode,
    - struct rchan_buf *buf,
    - int *is_global)
    -{
    - return relayfs_create_file(filename, parent, mode,
    - &relay_file_operations, buf);
    -}
    -
    -/*
    - * remove_buf_file() default callback. Removes file representing relay buffer.
    - */
    -static int remove_buf_file_default_callback(struct dentry *dentry)
    -{
    - return relayfs_remove(dentry);
    -}
    -
    -/* relay channel default callbacks */
    -static struct rchan_callbacks default_channel_callbacks = {
    - .subbuf_start = subbuf_start_default_callback,
    - .buf_mapped = buf_mapped_default_callback,
    - .buf_unmapped = buf_unmapped_default_callback,
    - .create_buf_file = create_buf_file_default_callback,
    - .remove_buf_file = remove_buf_file_default_callback,
    -};
    -
    -/**
    - * wakeup_readers - wake up readers waiting on a channel
    - * @private: the channel buffer
    - *
    - * This is the work function used to defer reader waking. The
    - * reason waking is deferred is that calling directly from write
    - * causes problems if you're writing from say the scheduler.
    - */
    -static void wakeup_readers(void *private)
    -{
    - struct rchan_buf *buf = private;
    - wake_up_interruptible(&buf->read_wait);
    -}
    -
    -/**
    - * __relay_reset - reset a channel buffer
    - * @buf: the channel buffer
    - * @init: 1 if this is a first-time initialization
    - *
    - * See relay_reset for description of effect.
    - */
    -static inline void __relay_reset(struct rchan_buf *buf, unsigned int init)
    -{
    - size_t i;
    -
    - if (init) {
    - init_waitqueue_head(&buf->read_wait);
    - kref_init(&buf->kref);
    - INIT_WORK(&buf->wake_readers, NULL, NULL);
    - } else {
    - cancel_delayed_work(&buf->wake_readers);
    - flush_scheduled_work();
    - }
    -
    - buf->subbufs_produced = 0;
    - buf->subbufs_consumed = 0;
    - buf->bytes_consumed = 0;
    - buf->finalized = 0;
    - buf->data = buf->start;
    - buf->offset = 0;
    -
    - for (i = 0; i < buf->chan->n_subbufs; i++)
    - buf->padding[i] = 0;
    -
    - buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
    -}
    -
    -/**
    - * relay_reset - reset the channel
    - * @chan: the channel
    - *
    - * This has the effect of erasing all data from all channel buffers
    - * and restarting the channel in its initial state. The buffers
    - * are not freed, so any mappings are still in effect.
    - *
    - * NOTE: Care should be taken that the channel isn't actually
    - * being used by anything when this call is made.
    - */
    -void relay_reset(struct rchan *chan)
    -{
    - unsigned int i;
    - struct rchan_buf *prev = NULL;
    -
    - if (!chan)
    - return;
    -
    - for (i = 0; i < NR_CPUS; i++) {
    - if (!chan->buf[i] || chan->buf[i] == prev)
    - break;
    - __relay_reset(chan->buf[i], 0);
    - prev = chan->buf[i];
    - }
    -}
    -
    -/**
    - * relay_open_buf - create a new channel buffer in relayfs
    - *
    - * Internal - used by relay_open().
    - */
    -static struct rchan_buf *relay_open_buf(struct rchan *chan,
    - const char *filename,
    - struct dentry *parent,
    - int *is_global)
    -{
    - struct rchan_buf *buf;
    - struct dentry *dentry;
    -
    - if (*is_global)
    - return chan->buf[0];
    -
    - buf = relay_create_buf(chan);
    - if (!buf)
    - return NULL;
    -
    - /* Create file in fs */
    - dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR,
    - buf, is_global);
    - if (!dentry) {
    - relay_destroy_buf(buf);
    - return NULL;
    - }
    -
    - buf->dentry = dentry;
    - __relay_reset(buf, 1);
    -
    - return buf;
    -}
    -
    -/**
    - * relay_close_buf - close a channel buffer
    - * @buf: channel buffer
    - *
    - * Marks the buffer finalized and restores the default callbacks.
    - * The channel buffer and channel buffer data structure are then freed
    - * automatically when the last reference is given up.
    - */
    -static inline void relay_close_buf(struct rchan_buf *buf)
    -{
    - buf->finalized = 1;
    - buf->chan->cb = &default_channel_callbacks;
    - cancel_delayed_work(&buf->wake_readers);
    - flush_scheduled_work();
    - kref_put(&buf->kref, relay_remove_buf);
    -}
    -
    -static inline void setup_callbacks(struct rchan *chan,
    - struct rchan_callbacks *cb)
    -{
    - if (!cb) {
    - chan->cb = &default_channel_callbacks;
    - return;
    - }
    -
    - if (!cb->subbuf_start)
    - cb->subbuf_start = subbuf_start_default_callback;
    - if (!cb->buf_mapped)
    - cb->buf_mapped = buf_mapped_default_callback;
    - if (!cb->buf_unmapped)
    - cb->buf_unmapped = buf_unmapped_default_callback;
    - if (!cb->create_buf_file)
    - cb->create_buf_file = create_buf_file_default_callback;
    - if (!cb->remove_buf_file)
    - cb->remove_buf_file = remove_buf_file_default_callback;
    - chan->cb = cb;
    -}
    -
    -/**
    - * relay_open - create a new relayfs channel
    - * @base_filename: base name of files to create
    - * @parent: dentry of parent directory, NULL for root directory
    - * @subbuf_size: size of sub-buffers
    - * @n_subbufs: number of sub-buffers
    - * @cb: client callback functions
    - *
    - * Returns channel pointer if successful, NULL otherwise.
    - *
    - * Creates a channel buffer for each cpu using the sizes and
    - * attributes specified. The created channel buffer files
    - * will be named base_filename0...base_filenameN-1. File
    - * permissions will be S_IRUSR.
    - */
    -struct rchan *relay_open(const char *base_filename,
    - struct dentry *parent,
    - size_t subbuf_size,
    - size_t n_subbufs,
    - struct rchan_callbacks *cb)
    -{
    - unsigned int i;
    - struct rchan *chan;
    - char *tmpname;
    - int is_global = 0;
    -
    - if (!base_filename)
    - return NULL;
    -
    - if (!(subbuf_size && n_subbufs))
    - return NULL;
    -
    - chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL);
    - if (!chan)
    - return NULL;
    -
    - chan->version = RELAYFS_CHANNEL_VERSION;
    - chan->n_subbufs = n_subbufs;
    - chan->subbuf_size = subbuf_size;
    - chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
    - setup_callbacks(chan, cb);
    - kref_init(&chan->kref);
    -
    - tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL);
    - if (!tmpname)
    - goto free_chan;
    -
    - for_each_online_cpu(i) {
    - sprintf(tmpname, "%s%d", base_filename, i);
    - chan->buf[i] = relay_open_buf(chan, tmpname, parent,
    - &is_global);
    - chan->buf[i]->cpu = i;
    - if (!chan->buf[i])
    - goto free_bufs;
    - }
    -
    - kfree(tmpname);
    - return chan;
    -
    -free_bufs:
    - for (i = 0; i < NR_CPUS; i++) {
    - if (!chan->buf[i])
    - break;
    - relay_close_buf(chan->buf[i]);
    - if (is_global)
    - break;
    - }
    - kfree(tmpname);
    -
    -free_chan:
    - kref_put(&chan->kref, relay_destroy_channel);
    - return NULL;
    -}
    -
    -/**
    - * relay_switch_subbuf - switch to a new sub-buffer
    - * @buf: channel buffer
    - * @length: size of current event
    - *
    - * Returns either the length passed in or 0 if full.
    -
    - * Performs sub-buffer-switch tasks such as invoking callbacks,
    - * updating padding counts, waking up readers, etc.
    - */
    -size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
    -{
    - void *old, *new;
    - size_t old_subbuf, new_subbuf;
    -
    - if (unlikely(length > buf->chan->subbuf_size))
    - goto toobig;
    -
    - if (buf->offset != buf->chan->subbuf_size + 1) {
    - buf->prev_padding = buf->chan->subbuf_size - buf->offset;
    - old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
    - buf->padding[old_subbuf] = buf->prev_padding;
    - buf->subbufs_produced++;
    - if (waitqueue_active(&buf->read_wait)) {
    - PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf);
    - schedule_delayed_work(&buf->wake_readers, 1);
    - }
    - }
    -
    - old = buf->data;
    - new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
    - new = buf->start + new_subbuf * buf->chan->subbuf_size;
    - buf->offset = 0;
    - if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
    - buf->offset = buf->chan->subbuf_size + 1;
    - return 0;
    - }
    - buf->data = new;
    - buf->padding[new_subbuf] = 0;
    -
    - if (unlikely(length + buf->offset > buf->chan->subbuf_size))
    - goto toobig;
    -
    - return length;
    -
    -toobig:
    - buf->chan->last_toobig = length;
    - return 0;
    -}
    -
    -/**
    - * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
    - * @chan: the channel
    - * @cpu: the cpu associated with the channel buffer to update
    - * @subbufs_consumed: number of sub-buffers to add to current buf's count
    - *
    - * Adds to the channel buffer's consumed sub-buffer count.
    - * subbufs_consumed should be the number of sub-buffers newly consumed,
    - * not the total consumed.
    - *
    - * NOTE: kernel clients don't need to call this function if the channel
    - * mode is 'overwrite'.
    - */
    -void relay_subbufs_consumed(struct rchan *chan,
    - unsigned int cpu,
    - size_t subbufs_consumed)
    -{
    - struct rchan_buf *buf;
    -
    - if (!chan)
    - return;
    -
    - if (cpu >= NR_CPUS || !chan->buf[cpu])
    - return;
    -
    - buf = chan->buf[cpu];
    - buf->subbufs_consumed += subbufs_consumed;
    - if (buf->subbufs_consumed > buf->subbufs_produced)
    - buf->subbufs_consumed = buf->subbufs_produced;
    -}
    -
    -/**
    - * relay_destroy_channel - free the channel struct
    - *
    - * Should only be called from kref_put().
    - */
    -void relay_destroy_channel(struct kref *kref)
    -{
    - struct rchan *chan = container_of(kref, struct rchan, kref);
    - kfree(chan);
    -}
    -
    -/**
    - * relay_close - close the channel
    - * @chan: the channel
    - *
    - * Closes all channel buffers and frees the channel.
    - */
    -void relay_close(struct rchan *chan)
    -{
    - unsigned int i;
    - struct rchan_buf *prev = NULL;
    -
    - if (!chan)
    - return;
    -
    - for (i = 0; i < NR_CPUS; i++) {
    - if (!chan->buf[i] || chan->buf[i] == prev)
    - break;
    - relay_close_buf(chan->buf[i]);
    - prev = chan->buf[i];
    - }
    -
    - if (chan->last_toobig)
    - printk(KERN_WARNING "relayfs: one or more items not logged "
    - "[item size (%Zd) > sub-buffer size (%Zd)]\n",
    - chan->last_toobig, chan->subbuf_size);
    -
    - kref_put(&chan->kref, relay_destroy_channel);
    -}
    -
    -/**
    - * relay_flush - close the channel
    - * @chan: the channel
    - *
    - * Flushes all channel buffers i.e. forces buffer switch.
    - */
    -void relay_flush(struct rchan *chan)
    -{
    - unsigned int i;
    - struct rchan_buf *prev = NULL;
    -
    - if (!chan)
    - return;
    -
    - for (i = 0; i < NR_CPUS; i++) {
    - if (!chan->buf[i] || chan->buf[i] == prev)
    - break;
    - relay_switch_subbuf(chan->buf[i], 0);
    - prev = chan->buf[i];
    - }
    -}
    -
    -EXPORT_SYMBOL_GPL(relay_open);
    -EXPORT_SYMBOL_GPL(relay_close);
    -EXPORT_SYMBOL_GPL(relay_flush);
    -EXPORT_SYMBOL_GPL(relay_reset);
    -EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
    -EXPORT_SYMBOL_GPL(relay_switch_subbuf);
    -EXPORT_SYMBOL_GPL(relay_buf_full);
    diff --git a/fs/relayfs/relay.h b/fs/relayfs/relay.h
    deleted file mode 100644
    index 0993d3e..0000000
    --- a/fs/relayfs/relay.h
    +++ /dev/null
    @@ -1,8 +0,0 @@
    -#ifndef _RELAY_H
    -#define _RELAY_H
    -
    -extern int relayfs_remove(struct dentry *dentry);
    -extern int relay_buf_empty(struct rchan_buf *buf);
    -extern void relay_destroy_channel(struct kref *kref);
    -
    -#endif /* _RELAY_H */
    diff --git a/include/linux/relayfs_fs.h b/include/linux/relayfs_fs.h
    index 435ebb1..1ef4108 100644
    --- a/include/linux/relayfs_fs.h
    +++ b/include/linux/relayfs_fs.h
    @@ -183,6 +183,7 @@ extern struct dentry *relayfs_create_fil
    struct file_operations *fops,
    void *data);
    extern int relayfs_remove_file(struct dentry *dentry);
    +extern int relayfs_remove(struct dentry *dentry);

    /**
    * relay_write - write data into the channel
    diff --git a/kernel/relay.c b/kernel/relay.c
    index 7dd674b..9cff3b3 100644
    --- a/kernel/relay.c
    +++ b/kernel/relay.c
    @@ -278,7 +278,12 @@ static struct dentry *create_buf_file_de
    struct rchan_buf *buf,
    int *is_global)
    {
    +#ifdef CONFIG_RELAYFS_FS
    + return relayfs_create_file(filename, parent, mode,
    + &relay_file_operations, buf);
    +#else
    return NULL;
    +#endif
    }

    /*
    @@ -286,7 +291,11 @@ static struct dentry *create_buf_file_de
    */
    static int remove_buf_file_default_callback(struct dentry *dentry)
    {
    +#ifdef CONFIG_RELAYFS_FS
    + return relayfs_remove(dentry);
    +#else
    return -EINVAL;
    +#endif
    }

    /* relay channel default callbacks */
    --
    1.0.GIT
    -
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      Last update: 2006-02-19 22:57    [W:0.081 / U:1.060 seconds]
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