[PATCH 10/11] LTTng-core 0.5.108 : relayfs

[PATCH 10/11] LTTng-core 0.5.108 : relayfs

[Mathieu Desnoyers]

[-- Attachment #1: Type: text/plain, Size: 264 bytes --]

10 - Forward port of RelayFS 2.6.16 API, plus some enhancements.
patch-2.6.17-lttng-core-0.5.108-relayfs.diff

OpenPGP public key:              http://krystal.dyndns.org:8080/key/compudj.gpg
Key fingerprint:     8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68 

[-- Attachment #2: patch-2.6.17-lttng-core-0.5.108-relayfs.diff --]
[-- Type: text/plain, Size: 41660 bytes --]

--- a/Documentation/ioctl-number.txt
+++ b/Documentation/ioctl-number.txt
@@ -190,3 +190,6 @@ Code	Seq#	Include File		Comments
 					<mailto:aherrman@de.ibm.com>
 0xF3	00-3F	video/sisfb.h		sisfb (in development)
 					<mailto:thomas@winischhofer.net>
+0xF4	00-3F	linux/relayfs_fs.h RelayFS
+					<mailto:mathieu.desnoyers@polymtl.ca>
+
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -1,6 +1,7 @@
 /*
  * linux/include/linux/relay.h
  *
+ * Copyright (C) 2005, Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
  * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
  * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
  *
@@ -37,11 +38,13 @@ struct rchan_buf
 	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 */
+	atomic_t full;		/* buffer is in full state */
 	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 */
+	atomic_t open_count;			/* file open count */
 	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 */
@@ -60,11 +63,18 @@ struct rchan
 	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 */
+	int overwrite;			/* overwrite buffer when full? */
 	struct rchan_callbacks *cb;	/* client callbacks */
+	struct file_operations *fops; 	/* file operations */
+	void *client_data; 		/* client data associated with the
+					   client callbacks */
+	void (*free_client_data_cb)(void*); /* Callback function to free the
+					       client data */
 	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 */
+	struct module *client_module;	/* Client module */
 };
 
 /*
@@ -76,6 +86,7 @@ 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_idx: the previous sub-buffer's index
 	 * @prev_subbuf: the start of the previous sub-buffer
 	 * @prev_padding: unused space at the end of previous sub-buffer
 	 *
@@ -95,6 +106,18 @@ struct rchan_callbacks
 			     size_t prev_padding);
 
 	/*
+	 * deliver - deliver a guaranteed full sub-buffer to client
+	 * @buf: the channel buffer containing the sub-buffer
+	 * @subbuf_idx: the sub-buffer's index
+	 * @subbuf: the start of the new sub-buffer
+	 *
+	 * Only works if relay_commit is also used
+	 */
+	void (*deliver) (struct rchan_buf *buf,
+			 unsigned subbuf_idx,
+			 void *subbuf);
+
+	/*
 	 * buf_mapped - relay buffer mmap notification
 	 * @buf: the channel buffer
 	 * @filp: relay file pointer
@@ -113,6 +136,7 @@ struct rchan_callbacks
 	 */
         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
@@ -153,6 +177,31 @@ struct rchan_callbacks
 	 * The callback should return 0 if successful, negative if not.
 	 */
 	int (*remove_buf_file)(struct dentry *dentry);
+
+	/*
+	 * buf_full - relayfs buffer full notification
+	 * @buf: the channel channel buffer
+	 * @subbuf_idx: the current sub-buffer's index
+	 * @subbuf: the start of the current sub-buffer
+	 *
+	 * Called when a relayfs buffer becomes full
+	 */
+	void (*buf_full)(struct rchan_buf *buf,
+			unsigned subbuf_idx,
+			void *subbuf);
+
+	/*
+	 * buf_unfull - relayfs buffer unfull notification
+	 * @buf: the channel channel buffer
+	 * @subbuf_idx: the current sub-buffer's index
+	 * @subbuf: the start of the current sub-buffer
+	 *
+	 * Called when a relayfs buffer passes from full to not full
+	 */
+	void (*buf_unfull)(struct rchan_buf *buf,
+			unsigned subbuf_idx,
+			void *subbuf);
+
 };
 
 /*
@@ -163,7 +212,12 @@ struct rchan *relay_open(const char *bas
 			 struct dentry *parent,
 			 size_t subbuf_size,
 			 size_t n_subbufs,
-			 struct rchan_callbacks *cb);
+			 int overwrite,
+			 struct module *client_module,
+			 struct rchan_callbacks *cb,
+			 struct file_operations *fops,
+			 void *client_data,
+			 void (*free_client_data_cb)(void*));
 extern void relay_close(struct rchan *chan);
 extern void relay_flush(struct rchan *chan);
 extern void relay_subbufs_consumed(struct rchan *chan,
@@ -175,6 +229,17 @@ extern int relay_buf_full(struct rchan_b
 extern size_t relay_switch_subbuf(struct rchan_buf *buf,
 				  size_t length);
 
+extern struct dentry *relayfs_create_dir(const char *name,
+					 struct dentry *parent);
+extern int relayfs_remove_dir(struct dentry *dentry);
+extern struct dentry *relayfs_create_file(const char *name,
+					  struct dentry *parent,
+					  int mode,
+					  struct file_operations *fops,
+					  void *data);
+extern int relayfs_remove_file(struct dentry *dentry);
+
+
 /**
  *	relay_write - write data into the channel
  *	@chan: relay channel
@@ -251,6 +316,7 @@ static inline void *relay_reserve(struct
 		if (!length)
 			return NULL;
 	}
+
 	reserved = buf->data + buf->offset;
 	buf->offset += length;
 
--- /dev/null
+++ b/fs/relayfs/Makefile
@@ -0,0 +1,4 @@
+obj-$(CONFIG_RELAY)	 += relayfs.o
+
+relayfs-y := relay.o inode.o buffers.o
+
--- /dev/null
+++ b/fs/relayfs/inode.c
@@ -0,0 +1,591 @@
+/*
+ * 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/relay.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)
+{
+	if (!dentry)
+		return -EINVAL;
+
+	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;
+
+	if(!atomic_dec_and_test(&buf->open_count)) {
+		atomic_inc(&buf->open_count);
+		return -EACCES;
+	}
+	
+	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;
+
+	atomic_inc(&buf->open_count);
+	
+	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 = {
+	.owner = THIS_MODULE,
+	.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);
+}
+
+fs_initcall(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");
+
--- /dev/null
+++ b/fs/relayfs/relay.c
@@ -0,0 +1,560 @@
+/*
+ * 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/relay.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;
+}
+
+/*
+ * deliver() default callback.  Does nothing.
+ */
+static void deliver_default_callback (struct rchan_buf *buf,
+				      unsigned subbuf_idx,
+				      void *subbuf)
+{
+}
+
+/*
+ * 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, buf->chan->fops,
+				   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);
+}
+
+/*
+ * buf_full() default callback.  Does nothing.
+ */
+static void buf_full_default_callback(struct rchan_buf *buf,
+				      unsigned subbuf_idx,
+				      void *subbuf)
+{
+}
+
+/*
+ * buf_unfull() default callback.  Does nothing.
+ */
+static void buf_unfull_default_callback(struct rchan_buf *buf,
+				      unsigned subbuf_idx,
+				      void *subbuf)
+{
+}
+
+/* relay channel default callbacks */
+static struct rchan_callbacks default_channel_callbacks = {
+	.subbuf_start = subbuf_start_default_callback,
+	.deliver = deliver_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,
+	.buf_full = buf_full_default_callback,
+	.buf_unfull = buf_unfull_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);
+}
+
+/**
+ *	get_next_subbuf - return next sub-buffer within channel buffer
+ *	@buf: channel buffer
+ */
+static inline void *get_next_subbuf(struct rchan_buf *buf)
+{
+	void *next = buf->data + buf->chan->subbuf_size;
+	if (next >= buf->start + buf->chan->subbuf_size * buf->chan->n_subbufs)
+		next = buf->start;
+
+	return next;
+}
+
+/**
+ *	__relay_reset - reset a channel buffer
+ *	@buf: the channel buffer
+ *	@init: 1 if this is a first-time initialization
+ *	@subbufs_count number of subbuffers
+ *
+ *	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;
+	atomic_set(&buf->full, 0);
+	buf->finalized = 0;
+	buf->data = buf->start;
+	buf->offset = 0;
+	atomic_set(&buf->open_count, 1);
+
+	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
+ *
+ *	Returns 0 if successful, negative if not.
+ *
+ *	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->deliver)
+		cb->deliver = deliver_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;
+	if (!cb->buf_full)
+		cb->buf_full = buf_full_default_callback;
+	if (!cb->buf_unfull)
+		cb->buf_unfull = buf_unfull_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
+ *	@overwrite: overwrite buffer when full?
+ *	@cb: client callback functions
+ *	@fops: client file operations (override relayfs). NULL for default.
+ *	@client_data: client specific data
+ *	@free_client_data_cb: callback function to free the client data.
+ *
+ *	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.
+ *	relay_open increments the usage count of the client_module.
+ */
+struct rchan *relay_open(const char *base_filename,
+			 struct dentry *parent,
+			 size_t subbuf_size,
+			 size_t n_subbufs,
+			 int overwrite,
+			 struct module *client_module,
+			 struct rchan_callbacks *cb,
+			 struct file_operations *fops,
+			 void *client_data,
+			 void (*free_client_data_cb)(void*))
+{
+	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->overwrite = overwrite;
+	chan->n_subbufs = n_subbufs;
+	chan->subbuf_size = subbuf_size;
+	chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
+	chan->client_module = client_module;
+	//if(!try_module_get(client_module)) {
+	//	printk(KERN_ERR "RelayFS : cannot increment client module refcount\n");
+	//	return NULL;
+	//}
+	chan->client_data = client_data;
+	chan->free_client_data_cb = free_client_data_cb;
+	setup_callbacks(chan, cb);
+	if(fops) chan->fops = fops;
+	else chan->fops = &relay_file_operations;
+	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);
+	//module_put(chan->client_module);
+	if(chan->free_client_data_cb)
+		chan->free_client_data_cb(chan->client_data);
+	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);
--- /dev/null
+++ b/fs/relayfs/buffers.c
@@ -0,0 +1,190 @@
+/*
+ * 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/relay.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);
+}
--- /dev/null
+++ b/fs/relayfs/buffers.h
@@ -0,0 +1,9 @@
+#ifndef _BUFFERS_H
+#define _BUFFERS_H
+
+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 */
--- /dev/null
+++ b/fs/relayfs/relay.h
@@ -0,0 +1,12 @@
+#ifndef _RELAY_H
+#define _RELAY_H
+
+extern int relayfs_remove(struct dentry *dentry);
+extern int relay_buf_empty(struct rchan_buf *buf);
+extern int relay_buf_full(struct rchan_buf *buf);
+extern void relay_destroy_channel(struct kref *kref);
+extern void setup_fileops(struct rchan *chan,
+				   struct file_operations *fops,
+					 struct module *client_module);
+
+#endif /* _RELAY_H */
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -102,3 +102,4 @@ obj-$(CONFIG_HOSTFS)		+= hostfs/
 obj-$(CONFIG_HPPFS)		+= hppfs/
 obj-$(CONFIG_DEBUG_FS)		+= debugfs/
 obj-$(CONFIG_OCFS2_FS)		+= ocfs2/
+obj-$(CONFIG_RELAY)		+= relayfs/
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -330,7 +330,7 @@ static int blk_trace_setup(request_queue
 	if (!bt->dropped_file)
 		goto err;
 
-	bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks);
+	bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, 0, THIS_MODULE, &blk_relay_callbacks, NULL, NULL, NULL);
 	if (!bt->rchan)
 		goto err;
 	bt->rchan->private_data = bt;

Re: [PATCH 10/11] LTTng-core 0.5.108 : relayfs

[Jens Axboe]

On Wed, Sep 13 2006, Mathieu Desnoyers wrote:
> 10 - Forward port of RelayFS 2.6.16 API, plus some enhancements.
> patch-2.6.17-lttng-core-0.5.108-relayfs.diff

One big question - why?!

-- 
Jens Axboe

Re: [PATCH 10/11] LTTng-core 0.5.108 : relayfs

[Paul Mundt]

On Wed, Sep 13, 2006 at 11:49:40PM -0400, Mathieu Desnoyers wrote:
> --- a/Documentation/ioctl-number.txt
> +++ b/Documentation/ioctl-number.txt
> @@ -190,3 +190,6 @@ Code	Seq#	Include File		Comments
>  					<mailto:aherrman@de.ibm.com>
>  0xF3	00-3F	video/sisfb.h		sisfb (in development)
>  					<mailto:thomas@winischhofer.net>
> +0xF4	00-3F	linux/relayfs_fs.h RelayFS
> +					<mailto:mathieu.desnoyers@polymtl.ca>
> +
Even if you were to add the file system back in for some nonsensical
reason, the header is still wrong.

> --- a/include/linux/relay.h
> +++ b/include/linux/relay.h
> @@ -1,6 +1,7 @@
>  /*
>   * linux/include/linux/relay.h
>   *
> + * Copyright (C) 2005, Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
>   * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
>   * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
>   *
> @@ -37,11 +38,13 @@ struct rchan_buf
>  	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 */
> +	atomic_t full;		/* buffer is in full state */
>  	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 */
> +	atomic_t open_count;			/* file open count */
>  	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 */
> @@ -60,11 +63,18 @@ struct rchan
>  	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 */
> +	int overwrite;			/* overwrite buffer when full? */
>  	struct rchan_callbacks *cb;	/* client callbacks */
> +	struct file_operations *fops; 	/* file operations */
> +	void *client_data; 		/* client data associated with the
> +					   client callbacks */
> +	void (*free_client_data_cb)(void*); /* Callback function to free the
> +					       client data */
>  	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 */
> +	struct module *client_module;	/* Client module */
>  };
>  
>  /*
> @@ -76,6 +86,7 @@ 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_idx: the previous sub-buffer's index
>  	 * @prev_subbuf: the start of the previous sub-buffer
>  	 * @prev_padding: unused space at the end of previous sub-buffer
>  	 *
> @@ -95,6 +106,18 @@ struct rchan_callbacks
>  			     size_t prev_padding);
>  
>  	/*
> +	 * deliver - deliver a guaranteed full sub-buffer to client
> +	 * @buf: the channel buffer containing the sub-buffer
> +	 * @subbuf_idx: the sub-buffer's index
> +	 * @subbuf: the start of the new sub-buffer
> +	 *
> +	 * Only works if relay_commit is also used
> +	 */
> +	void (*deliver) (struct rchan_buf *buf,
> +			 unsigned subbuf_idx,
> +			 void *subbuf);
> +
> +	/*
>  	 * buf_mapped - relay buffer mmap notification
>  	 * @buf: the channel buffer
>  	 * @filp: relay file pointer
> @@ -113,6 +136,7 @@ struct rchan_callbacks
>  	 */
>          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
> @@ -153,6 +177,31 @@ struct rchan_callbacks
>  	 * The callback should return 0 if successful, negative if not.
>  	 */
>  	int (*remove_buf_file)(struct dentry *dentry);
> +
> +	/*
> +	 * buf_full - relayfs buffer full notification
> +	 * @buf: the channel channel buffer
> +	 * @subbuf_idx: the current sub-buffer's index
> +	 * @subbuf: the start of the current sub-buffer
> +	 *
> +	 * Called when a relayfs buffer becomes full
> +	 */
> +	void (*buf_full)(struct rchan_buf *buf,
> +			unsigned subbuf_idx,
> +			void *subbuf);
> +
> +	/*
> +	 * buf_unfull - relayfs buffer unfull notification
> +	 * @buf: the channel channel buffer
> +	 * @subbuf_idx: the current sub-buffer's index
> +	 * @subbuf: the start of the current sub-buffer
> +	 *
> +	 * Called when a relayfs buffer passes from full to not full
> +	 */
> +	void (*buf_unfull)(struct rchan_buf *buf,
> +			unsigned subbuf_idx,
> +			void *subbuf);
> +
>  };
>  
>  /*
> @@ -163,7 +212,12 @@ struct rchan *relay_open(const char *bas
>  			 struct dentry *parent,
>  			 size_t subbuf_size,
>  			 size_t n_subbufs,
> -			 struct rchan_callbacks *cb);
> +			 int overwrite,
> +			 struct module *client_module,
> +			 struct rchan_callbacks *cb,
> +			 struct file_operations *fops,
> +			 void *client_data,
> +			 void (*free_client_data_cb)(void*));
>  extern void relay_close(struct rchan *chan);
>  extern void relay_flush(struct rchan *chan);
>  extern void relay_subbufs_consumed(struct rchan *chan,

These should be split out with the corresponding kernel/relay.c updates
and posted separately. fops as an argument looks very suspect.

> @@ -175,6 +229,17 @@ extern int relay_buf_full(struct rchan_b
>  extern size_t relay_switch_subbuf(struct rchan_buf *buf,
>  				  size_t length);
>  
> +extern struct dentry *relayfs_create_dir(const char *name,
> +					 struct dentry *parent);
> +extern int relayfs_remove_dir(struct dentry *dentry);
> +extern struct dentry *relayfs_create_file(const char *name,
> +					  struct dentry *parent,
> +					  int mode,
> +					  struct file_operations *fops,
> +					  void *data);
> +extern int relayfs_remove_file(struct dentry *dentry);
> +
> +
>  /**
>   *	relay_write - write data into the channel
>   *	@chan: relay channel
> @@ -251,6 +316,7 @@ static inline void *relay_reserve(struct
>  		if (!length)
>  			return NULL;
>  	}
> +
>  	reserved = buf->data + buf->offset;
>  	buf->offset += length;
>  
None of this matters, use debugfs, it already does it for you.

Re: [PATCH 10/11] LTTng-core 0.5.108 : relayfs

[Mathieu Desnoyers]

* Jens Axboe (axboe@kernel.dk) wrote:
> On Wed, Sep 13 2006, Mathieu Desnoyers wrote:
> > 10 - Forward port of RelayFS 2.6.16 API, plus some enhancements.
> > patch-2.6.17-lttng-core-0.5.108-relayfs.diff
> 
> One big question - why?!
> 
(repeated)
It's a temporary solution only used because relayfs has been such
a moving target lately that I decided to wait for things to settle down before
switching. I plan to switch to the new relay.o and use DebugFS for filesystem.
I just haven't done the change yet.

Mathieu


> -- 
> Jens Axboe
> 
OpenPGP public key:              http://krystal.dyndns.org:8080/key/compudj.gpg
Key fingerprint:     8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68 

Re: [PATCH 10/11] LTTng-core 0.5.108 : relayfs

[Mathieu Desnoyers]

* Paul Mundt (lethal@linux-sh.org) wrote:
> None of this matters, use debugfs, it already does it for you.

Yes, this is what I plan to do. :)

OpenPGP public key:              http://krystal.dyndns.org:8080/key/compudj.gpg
Key fingerprint:     8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68 

Re: [PATCH 10/11] LTTng-core 0.5.108 : relayfs

[Jens Axboe]

On Thu, Sep 14 2006, Mathieu Desnoyers wrote:
> * Jens Axboe (axboe@kernel.dk) wrote:
> > On Wed, Sep 13 2006, Mathieu Desnoyers wrote:
> > > 10 - Forward port of RelayFS 2.6.16 API, plus some enhancements.
> > > patch-2.6.17-lttng-core-0.5.108-relayfs.diff
> > 
> > One big question - why?!
> > 
> (repeated)
> It's a temporary solution only used because relayfs has been such a
> moving target lately that I decided to wait for things to settle down
> before switching. I plan to switch to the new relay.o and use DebugFS
> for filesystem.  I just haven't done the change yet.

Since going into the kernel, it's only changed once and that was 6
(something like that) months ago. So I'd say that your statement there
is hugely exaggerated. Just get it fixed up, if you are serious in any
way with posting your patches.

-- 
Jens Axboe