[PATCH] relay: migrate from relayfs to a generic relay API
Jens Axboe [Thu, 23 Mar 2006 18:56:55 +0000 (19:56 +0100)]
Original patch from Paul Mundt, sysfs parts removed by me since they
were broken.

Signed-off-by: Jens Axboe <axboe@suse.de>

12 files changed:
fs/Kconfig
fs/Makefile
fs/relayfs/Makefile [deleted file]
fs/relayfs/buffers.c [deleted file]
fs/relayfs/buffers.h [deleted file]
fs/relayfs/inode.c [deleted file]
fs/relayfs/relay.c [deleted file]
fs/relayfs/relay.h [deleted file]
include/linux/relay.h [new file with mode: 0644]
init/Kconfig
kernel/Makefile
kernel/relay.c [new file with mode: 0644]

index e9749b0..c8d0a20 100644 (file)
@@ -859,18 +859,6 @@ config RAMFS
          To compile this as a module, choose M here: the module will be called
          ramfs.
 
-config RELAYFS_FS
-       tristate "Relayfs file system support"
-       ---help---
-         Relayfs is a high-speed data relay filesystem designed to provide
-         an efficient mechanism for tools and facilities to relay large
-         amounts of data from kernel space to user space.
-
-         To compile this code as a module, choose M here: the module will be
-         called relayfs.
-
-         If unsure, say N.
-
 config CONFIGFS_FS
        tristate "Userspace-driven configuration filesystem (EXPERIMENTAL)"
        depends on EXPERIMENTAL
index 1db7113..080b386 100644 (file)
@@ -91,7 +91,6 @@ obj-$(CONFIG_AUTOFS4_FS)      += autofs4/
 obj-$(CONFIG_ADFS_FS)          += adfs/
 obj-$(CONFIG_FUSE_FS)          += fuse/
 obj-$(CONFIG_UDF_FS)           += udf/
-obj-$(CONFIG_RELAYFS_FS)       += relayfs/
 obj-$(CONFIG_SUN_OPENPROMFS)   += openpromfs/
 obj-$(CONFIG_JFS_FS)           += jfs/
 obj-$(CONFIG_XFS_FS)           += xfs/
diff --git a/fs/relayfs/Makefile b/fs/relayfs/Makefile
deleted file mode 100644 (file)
index e76e182..0000000
+++ /dev/null
@@ -1,4 +0,0 @@
-obj-$(CONFIG_RELAYFS_FS) += relayfs.o
-
-relayfs-y := relay.o inode.o buffers.o
-
diff --git a/fs/relayfs/buffers.c b/fs/relayfs/buffers.c
deleted file mode 100644 (file)
index 1018781..0000000
+++ /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 (file)
index 37a1249..0000000
+++ /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
deleted file mode 100644 (file)
index 3835230..0000000
+++ /dev/null
@@ -1,581 +0,0 @@
-/*
- * VFS-related code for RelayFS, a high-speed data relay filesystem.
- *
- * Copyright (C) 2003-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
- * Copyright (C) 2003-2005 - Karim Yaghmour <karim@opersys.com>
- *
- * Based on ramfs, Copyright (C) 2002 - Linus Torvalds
- *
- * This file is released under the GPL.
- */
-
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <linux/mount.h>
-#include <linux/pagemap.h>
-#include <linux/init.h>
-#include <linux/string.h>
-#include <linux/backing-dev.h>
-#include <linux/namei.h>
-#include <linux/poll.h>
-#include <linux/relayfs_fs.h>
-#include "relay.h"
-#include "buffers.h"
-
-#define RELAYFS_MAGIC                  0xF0B4A981
-
-static struct vfsmount *               relayfs_mount;
-static int                             relayfs_mount_count;
-
-static struct backing_dev_info         relayfs_backing_dev_info = {
-       .ra_pages       = 0,    /* No readahead */
-       .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
-};
-
-static struct inode *relayfs_get_inode(struct super_block *sb,
-                                      int mode,
-                                      struct file_operations *fops,
-                                      void *data)
-{
-       struct inode *inode;
-
-       inode = new_inode(sb);
-       if (!inode)
-               return NULL;
-
-       inode->i_mode = mode;
-       inode->i_uid = 0;
-       inode->i_gid = 0;
-       inode->i_blksize = PAGE_CACHE_SIZE;
-       inode->i_blocks = 0;
-       inode->i_mapping->backing_dev_info = &relayfs_backing_dev_info;
-       inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-       switch (mode & S_IFMT) {
-       case S_IFREG:
-               inode->i_fop = fops;
-               if (data)
-                       inode->u.generic_ip = data;
-               break;
-       case S_IFDIR:
-               inode->i_op = &simple_dir_inode_operations;
-               inode->i_fop = &simple_dir_operations;
-
-               /* directory inodes start off with i_nlink == 2 (for "." entry) */
-               inode->i_nlink++;
-               break;
-       default:
-               break;
-       }
-
-       return inode;
-}
-
-/**
- *     relayfs_create_entry - create a relayfs directory or file
- *     @name: the name of the file to create
- *     @parent: parent directory
- *     @mode: mode
- *     @fops: file operations to use for the file
- *     @data: user-associated data for this file
- *
- *     Returns the new dentry, NULL on failure
- *
- *     Creates a file or directory with the specifed permissions.
- */
-static struct dentry *relayfs_create_entry(const char *name,
-                                          struct dentry *parent,
-                                          int mode,
-                                          struct file_operations *fops,
-                                          void *data)
-{
-       struct dentry *d;
-       struct inode *inode;
-       int error = 0;
-
-       BUG_ON(!name || !(S_ISREG(mode) || S_ISDIR(mode)));
-
-       error = simple_pin_fs("relayfs", &relayfs_mount, &relayfs_mount_count);
-       if (error) {
-               printk(KERN_ERR "Couldn't mount relayfs: errcode %d\n", error);
-               return NULL;
-       }
-
-       if (!parent && relayfs_mount && relayfs_mount->mnt_sb)
-               parent = relayfs_mount->mnt_sb->s_root;
-
-       if (!parent) {
-               simple_release_fs(&relayfs_mount, &relayfs_mount_count);
-               return NULL;
-       }
-
-       parent = dget(parent);
-       mutex_lock(&parent->d_inode->i_mutex);
-       d = lookup_one_len(name, parent, strlen(name));
-       if (IS_ERR(d)) {
-               d = NULL;
-               goto release_mount;
-       }
-
-       if (d->d_inode) {
-               d = NULL;
-               goto release_mount;
-       }
-
-       inode = relayfs_get_inode(parent->d_inode->i_sb, mode, fops, data);
-       if (!inode) {
-               d = NULL;
-               goto release_mount;
-       }
-
-       d_instantiate(d, inode);
-       dget(d);        /* Extra count - pin the dentry in core */
-
-       if (S_ISDIR(mode))
-               parent->d_inode->i_nlink++;
-
-       goto exit;
-
-release_mount:
-       simple_release_fs(&relayfs_mount, &relayfs_mount_count);
-
-exit:
-       mutex_unlock(&parent->d_inode->i_mutex);
-       dput(parent);
-       return d;
-}
-
-/**
- *     relayfs_create_file - create a file in the relay filesystem
- *     @name: the name of the file to create
- *     @parent: parent directory
- *     @mode: mode, if not specied the default perms are used
- *     @fops: file operations to use for the file
- *     @data: user-associated data for this file
- *
- *     Returns file dentry if successful, NULL otherwise.
- *
- *     The file will be created user r on behalf of current user.
- */
-struct dentry *relayfs_create_file(const char *name,
-                                  struct dentry *parent,
-                                  int mode,
-                                  struct file_operations *fops,
-                                  void *data)
-{
-       BUG_ON(!fops);
-
-       if (!mode)
-               mode = S_IRUSR;
-       mode = (mode & S_IALLUGO) | S_IFREG;
-
-       return relayfs_create_entry(name, parent, mode, fops, data);
-}
-
-/**
- *     relayfs_create_dir - create a directory in the relay filesystem
- *     @name: the name of the directory to create
- *     @parent: parent directory, NULL if parent should be fs root
- *
- *     Returns directory dentry if successful, NULL otherwise.
- *
- *     The directory will be created world rwx on behalf of current user.
- */
-struct dentry *relayfs_create_dir(const char *name, struct dentry *parent)
-{
-       int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
-       return relayfs_create_entry(name, parent, mode, NULL, NULL);
-}
-
-/**
- *     relayfs_remove - remove a file or directory in the relay filesystem
- *     @dentry: file or directory dentry
- *
- *     Returns 0 if successful, negative otherwise.
- */
-int relayfs_remove(struct dentry *dentry)
-{
-       struct dentry *parent;
-       int error = 0;
-
-       if (!dentry)
-               return -EINVAL;
-       parent = dentry->d_parent;
-       if (!parent)
-               return -EINVAL;
-
-       parent = dget(parent);
-       mutex_lock(&parent->d_inode->i_mutex);
-       if (dentry->d_inode) {
-               if (S_ISDIR(dentry->d_inode->i_mode))
-                       error = simple_rmdir(parent->d_inode, dentry);
-               else
-                       error = simple_unlink(parent->d_inode, dentry);
-               if (!error)
-                       d_delete(dentry);
-       }
-       if (!error)
-               dput(dentry);
-       mutex_unlock(&parent->d_inode->i_mutex);
-       dput(parent);
-
-       if (!error)
-               simple_release_fs(&relayfs_mount, &relayfs_mount_count);
-
-       return error;
-}
-
-/**
- *     relayfs_remove_file - remove a file from relay filesystem
- *     @dentry: directory dentry
- *
- *     Returns 0 if successful, negative otherwise.
- */
-int relayfs_remove_file(struct dentry *dentry)
-{
-       return relayfs_remove(dentry);
-}
-
-/**
- *     relayfs_remove_dir - remove a directory in the relay filesystem
- *     @dentry: directory dentry
- *
- *     Returns 0 if successful, negative otherwise.
- */
-int relayfs_remove_dir(struct dentry *dentry)
-{
-       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,
-};
-
-static int relayfs_fill_super(struct super_block * sb, void * data, int silent)
-{
-       struct inode *inode;
-       struct dentry *root;
-       int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
-
-       sb->s_blocksize = PAGE_CACHE_SIZE;
-       sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
-       sb->s_magic = RELAYFS_MAGIC;
-       sb->s_op = &relayfs_ops;
-       inode = relayfs_get_inode(sb, mode, NULL, NULL);
-
-       if (!inode)
-               return -ENOMEM;
-
-       root = d_alloc_root(inode);
-       if (!root) {
-               iput(inode);
-               return -ENOMEM;
-       }
-       sb->s_root = root;
-
-       return 0;
-}
-
-static struct super_block * relayfs_get_sb(struct file_system_type *fs_type,
-                                          int flags, const char *dev_name,
-                                          void *data)
-{
-       return get_sb_single(fs_type, flags, data, relayfs_fill_super);
-}
-
-static struct file_system_type relayfs_fs_type = {
-       .owner          = THIS_MODULE,
-       .name           = "relayfs",
-       .get_sb         = relayfs_get_sb,
-       .kill_sb        = kill_litter_super,
-};
-
-static int __init init_relayfs_fs(void)
-{
-       return register_filesystem(&relayfs_fs_type);
-}
-
-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);
-EXPORT_SYMBOL_GPL(relayfs_remove_file);
-
-MODULE_AUTHOR("Tom Zanussi <zanussi@us.ibm.com> and Karim Yaghmour <karim@opersys.com>");
-MODULE_DESCRIPTION("Relay Filesystem");
-MODULE_LICENSE("GPL");
-
diff --git a/fs/relayfs/relay.c b/fs/relayfs/relay.c
deleted file mode 100644 (file)
index abf3cea..0000000
+++ /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 (file)
index 0993d3e..0000000
+++ /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/relay.h b/include/linux/relay.h
new file mode 100644 (file)
index 0000000..4bcc153
--- /dev/null
@@ -0,0 +1,281 @@
+/*
+ * linux/include/linux/relay.h
+ *
+ * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
+ * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
+ *
+ * CONFIG_RELAY definitions and declarations
+ */
+
+#ifndef _LINUX_RELAY_H
+#define _LINUX_RELAY_H
+
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/list.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/kref.h>
+
+/* Needs a _much_ better name... */
+#define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE)
+
+/*
+ * Tracks changes to rchan/rchan_buf structs
+ */
+#define RELAYFS_CHANNEL_VERSION                6
+
+/*
+ * Per-cpu relay channel buffer
+ */
+struct rchan_buf
+{
+       void *start;                    /* start of channel buffer */
+       void *data;                     /* start of current sub-buffer */
+       size_t offset;                  /* current offset into sub-buffer */
+       size_t subbufs_produced;        /* count of sub-buffers produced */
+       size_t subbufs_consumed;        /* count of sub-buffers consumed */
+       struct rchan *chan;             /* associated channel */
+       wait_queue_head_t read_wait;    /* reader wait queue */
+       struct work_struct wake_readers; /* reader wake-up work struct */
+       struct dentry *dentry;          /* channel file dentry */
+       struct kref kref;               /* channel buffer refcount */
+       struct page **page_array;       /* array of current buffer pages */
+       unsigned int page_count;        /* number of current buffer pages */
+       unsigned int finalized;         /* buffer has been finalized */
+       size_t *padding;                /* padding counts per sub-buffer */
+       size_t prev_padding;            /* temporary variable */
+       size_t bytes_consumed;          /* bytes consumed in cur read subbuf */
+       unsigned int cpu;               /* this buf's cpu */
+} ____cacheline_aligned;
+
+/*
+ * Relay channel data structure
+ */
+struct rchan
+{
+       u32 version;                    /* the version of this struct */
+       size_t subbuf_size;             /* sub-buffer size */
+       size_t n_subbufs;               /* number of sub-buffers per buffer */
+       size_t alloc_size;              /* total buffer size allocated */
+       struct rchan_callbacks *cb;     /* client callbacks */
+       struct kref kref;               /* channel refcount */
+       void *private_data;             /* for user-defined data */
+       size_t last_toobig;             /* tried to log event > subbuf size */
+       struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */
+};
+
+/*
+ * Relay channel client callbacks
+ */
+struct rchan_callbacks
+{
+       /*
+        * subbuf_start - called on buffer-switch to a new sub-buffer
+        * @buf: the channel buffer containing the new sub-buffer
+        * @subbuf: the start of the new sub-buffer
+        * @prev_subbuf: the start of the previous sub-buffer
+        * @prev_padding: unused space at the end of previous sub-buffer
+        *
+        * The client should return 1 to continue logging, 0 to stop
+        * logging.
+        *
+        * NOTE: subbuf_start will also be invoked when the buffer is
+        *       created, so that the first sub-buffer can be initialized
+        *       if necessary.  In this case, prev_subbuf will be NULL.
+        *
+        * NOTE: the client can reserve bytes at the beginning of the new
+        *       sub-buffer by calling subbuf_start_reserve() in this callback.
+        */
+       int (*subbuf_start) (struct rchan_buf *buf,
+                            void *subbuf,
+                            void *prev_subbuf,
+                            size_t prev_padding);
+
+       /*
+        * buf_mapped - relay buffer mmap notification
+        * @buf: the channel buffer
+        * @filp: relay file pointer
+        *
+        * Called when a relay file is successfully mmapped
+        */
+        void (*buf_mapped)(struct rchan_buf *buf,
+                          struct file *filp);
+
+       /*
+        * buf_unmapped - relay buffer unmap notification
+        * @buf: the channel buffer
+        * @filp: relay file pointer
+        *
+        * Called when a relay file is successfully unmapped
+        */
+        void (*buf_unmapped)(struct rchan_buf *buf,
+                            struct file *filp);
+       /*
+        * create_buf_file - create file to represent a relay channel buffer
+        * @filename: the name of the file to create
+        * @parent: the parent of the file to create
+        * @mode: the mode of the file to create
+        * @buf: the channel buffer
+        * @is_global: outparam - set non-zero if the buffer should be global
+        *
+        * Called during relay_open(), once for each per-cpu buffer,
+        * to allow the client to create a file to be used to
+        * represent the corresponding channel buffer.  If the file is
+        * created outside of relay, the parent must also exist in
+        * that filesystem.
+        *
+        * The callback should return the dentry of the file created
+        * to represent the relay buffer.
+        *
+        * Setting the is_global outparam to a non-zero value will
+        * cause relay_open() to create a single global buffer rather
+        * than the default set of per-cpu buffers.
+        *
+        * See Documentation/filesystems/relayfs.txt for more info.
+        */
+       struct dentry *(*create_buf_file)(const char *filename,
+                                         struct dentry *parent,
+                                         int mode,
+                                         struct rchan_buf *buf,
+                                         int *is_global);
+
+       /*
+        * remove_buf_file - remove file representing a relay channel buffer
+        * @dentry: the dentry of the file to remove
+        *
+        * Called during relay_close(), once for each per-cpu buffer,
+        * to allow the client to remove a file used to represent a
+        * channel buffer.
+        *
+        * The callback should return 0 if successful, negative if not.
+        */
+       int (*remove_buf_file)(struct dentry *dentry);
+};
+
+/*
+ * CONFIG_RELAY kernel API, kernel/relay.c
+ */
+
+struct rchan *relay_open(const char *base_filename,
+                        struct dentry *parent,
+                        size_t subbuf_size,
+                        size_t n_subbufs,
+                        struct rchan_callbacks *cb);
+extern void relay_close(struct rchan *chan);
+extern void relay_flush(struct rchan *chan);
+extern void relay_subbufs_consumed(struct rchan *chan,
+                                  unsigned int cpu,
+                                  size_t consumed);
+extern void relay_reset(struct rchan *chan);
+extern int relay_buf_full(struct rchan_buf *buf);
+
+extern size_t relay_switch_subbuf(struct rchan_buf *buf,
+                                 size_t length);
+
+/**
+ *     relay_write - write data into the channel
+ *     @chan: relay channel
+ *     @data: data to be written
+ *     @length: number of bytes to write
+ *
+ *     Writes data into the current cpu's channel buffer.
+ *
+ *     Protects the buffer by disabling interrupts.  Use this
+ *     if you might be logging from interrupt context.  Try
+ *     __relay_write() if you know you won't be logging from
+ *     interrupt context.
+ */
+static inline void relay_write(struct rchan *chan,
+                              const void *data,
+                              size_t length)
+{
+       unsigned long flags;
+       struct rchan_buf *buf;
+
+       local_irq_save(flags);
+       buf = chan->buf[smp_processor_id()];
+       if (unlikely(buf->offset + length > chan->subbuf_size))
+               length = relay_switch_subbuf(buf, length);
+       memcpy(buf->data + buf->offset, data, length);
+       buf->offset += length;
+       local_irq_restore(flags);
+}
+
+/**
+ *     __relay_write - write data into the channel
+ *     @chan: relay channel
+ *     @data: data to be written
+ *     @length: number of bytes to write
+ *
+ *     Writes data into the current cpu's channel buffer.
+ *
+ *     Protects the buffer by disabling preemption.  Use
+ *     relay_write() if you might be logging from interrupt
+ *     context.
+ */
+static inline void __relay_write(struct rchan *chan,
+                                const void *data,
+                                size_t length)
+{
+       struct rchan_buf *buf;
+
+       buf = chan->buf[get_cpu()];
+       if (unlikely(buf->offset + length > buf->chan->subbuf_size))
+               length = relay_switch_subbuf(buf, length);
+       memcpy(buf->data + buf->offset, data, length);
+       buf->offset += length;
+       put_cpu();
+}
+
+/**
+ *     relay_reserve - reserve slot in channel buffer
+ *     @chan: relay channel
+ *     @length: number of bytes to reserve
+ *
+ *     Returns pointer to reserved slot, NULL if full.
+ *
+ *     Reserves a slot in the current cpu's channel buffer.
+ *     Does not protect the buffer at all - caller must provide
+ *     appropriate synchronization.
+ */
+static inline void *relay_reserve(struct rchan *chan, size_t length)
+{
+       void *reserved;
+       struct rchan_buf *buf = chan->buf[smp_processor_id()];
+
+       if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
+               length = relay_switch_subbuf(buf, length);
+               if (!length)
+                       return NULL;
+       }
+       reserved = buf->data + buf->offset;
+       buf->offset += length;
+
+       return reserved;
+}
+
+/**
+ *     subbuf_start_reserve - reserve bytes at the start of a sub-buffer
+ *     @buf: relay channel buffer
+ *     @length: number of bytes to reserve
+ *
+ *     Helper function used to reserve bytes at the beginning of
+ *     a sub-buffer in the subbuf_start() callback.
+ */
+static inline void subbuf_start_reserve(struct rchan_buf *buf,
+                                       size_t length)
+{
+       BUG_ON(length >= buf->chan->subbuf_size - 1);
+       buf->offset = length;
+}
+
+/*
+ * exported relay file operations, kernel/relay.c
+ */
+extern struct file_operations relay_file_operations;
+
+#endif /* _LINUX_RELAY_H */
+
index 38416a1..1d19fd2 100644 (file)
@@ -214,6 +214,17 @@ config CPUSETS
 
          Say N if unsure.
 
+config RELAY
+       bool "Kernel->user space relay support (formerly relayfs)"
+       help
+         This option enables support for relay interface support in
+         certain file systems (such as debugfs).
+         It is designed to provide an efficient mechanism for tools and
+         facilities to relay large amounts of data from kernel space to
+         user space.
+
+         If unsure, say N.
+
 source "usr/Kconfig"
 
 config UID16
index 4ae0fbd..aebd7a7 100644 (file)
@@ -34,6 +34,7 @@ obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o
 obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
 obj-$(CONFIG_SECCOMP) += seccomp.o
 obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
+obj-$(CONFIG_RELAY) += relay.o
 
 ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff --git a/kernel/relay.c b/kernel/relay.c
new file mode 100644 (file)
index 0000000..9358e8e
--- /dev/null
@@ -0,0 +1,919 @@
+/*
+ * Public API and common code for kernel->userspace relay file support.
+ *
+ * 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)
+ *
+ * Moved to kernel/relay.c by Paul Mundt, 2006.
+ *
+ * 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/relay.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+
+/*
+ * close() vm_op implementation for relay 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 relay 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_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_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 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);
+}
+
+/**
+ *     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;
+}
+EXPORT_SYMBOL_GPL(relay_buf_empty);
+
+/**
+ *     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;
+}
+EXPORT_SYMBOL_GPL(relay_buf_full);
+
+/*
+ * High-level relay 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.  Does nothing.
+ */
+static struct dentry *create_buf_file_default_callback(const char *filename,
+                                                      struct dentry *parent,
+                                                      int mode,
+                                                      struct rchan_buf *buf,
+                                                      int *is_global)
+{
+       return NULL;
+}
+
+/*
+ * remove_buf_file() default callback.  Does nothing.
+ */
+static int remove_buf_file_default_callback(struct dentry *dentry)
+{
+       return -EINVAL;
+}
+
+/* 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];
+       }
+}
+EXPORT_SYMBOL_GPL(relay_reset);
+
+/**
+ *     relay_open_buf - create a new relay channel buffer
+ *
+ *     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;
+       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 relay 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);
+               if (!chan->buf[i])
+                       goto free_bufs;
+
+               chan->buf[i]->cpu = i;
+       }
+
+       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;
+}
+EXPORT_SYMBOL_GPL(relay_open);
+
+/**
+ *     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;
+}
+EXPORT_SYMBOL_GPL(relay_switch_subbuf);
+
+/**
+ *     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;
+}
+EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
+
+/**
+ *     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 "relay: 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);
+}
+EXPORT_SYMBOL_GPL(relay_close);
+
+/**
+ *     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_flush);
+
+/**
+ *     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,
+};
+EXPORT_SYMBOL_GPL(relay_file_operations);