[PATCH] relay: migrate from relayfs to a generic relay API
Original patch from Paul Mundt, sysfs parts removed by me since they
were broken.
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/fs/Kconfig b/fs/Kconfig
index e9749b0..c8d0a20 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -859,18 +859,6 @@
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
diff --git a/fs/Makefile b/fs/Makefile
index 1db7113..080b386 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -91,7 +91,6 @@
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-$(CONFIG_XFS_FS) += xfs/
diff --git a/fs/relayfs/Makefile b/fs/relayfs/Makefile
deleted file mode 100644
index e76e182..0000000
--- a/fs/relayfs/Makefile
+++ /dev/null
@@ -1,4 +0,0 @@
-obj-$(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
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
deleted file mode 100644
index 3835230..0000000
--- a/fs/relayfs/inode.c
+++ /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
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/relay.h b/include/linux/relay.h
new file mode 100644
index 0000000..4bcc153
--- /dev/null
+++ b/include/linux/relay.h
@@ -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 */
+
diff --git a/init/Kconfig b/init/Kconfig
index 38416a1..1d19fd2 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -214,6 +214,17 @@
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
diff --git a/kernel/Makefile b/kernel/Makefile
index 4ae0fbd..aebd7a7 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -34,6 +34,7 @@
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
index 0000000..9358e8e
--- /dev/null
+++ b/kernel/relay.c
@@ -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);
