* [RFC/PATCH 2/4] relayfs common, VFS, and klog code
@ 2003-12-01 20:55 Tom Zanussi
0 siblings, 0 replies; only message in thread
From: Tom Zanussi @ 2003-12-01 20:55 UTC (permalink / raw)
To: linux-kernel; +Cc: karim, bob
diff -urpN -X dontdiff linux-2.6.0-test11/fs/Kconfig linux-2.6.0-test11.cur/fs/Kconfig
--- linux-2.6.0-test11/fs/Kconfig Wed Nov 26 14:44:22 2003
+++ linux-2.6.0-test11.cur/fs/Kconfig Mon Dec 1 12:27:06 2003
@@ -893,6 +893,56 @@ config RAMFS
To compile this as a module, choose M here: the module will be called
ramfs.
+config RELAYFS_FS
+ tristate "Relayfs file system support"
+ ---help---
+ Relayfs is a high-speed data relay filesystem designed to provide
+ an efficient mechanism for tools and facilities to relay large
+ amounts of data from kernel space to user space. It's not useful
+ on its own, and should only be enabled if other facilities that
+ need it are enabled, such as for example klog or the Linux Trace
+ Toolkit.
+
+ See <file:Documentation/filesystems/relayfs.txt> for further
+ information.
+
+ This file system is also available as a module ( = code which can be
+ inserted in and removed from the running kernel whenever you want).
+ The module is called relayfs. If you want to compile it as a
+ module, say M here and read <file:Documentation/modules.txt>.
+
+ If unsure, say N.
+
+config KLOG_CHANNEL
+ bool "Enable klog debugging support"
+ depends on RELAYFS_FS
+ help
+ If you say Y to this, a relayfs channel named klog will be created
+ in the root of the relayfs file system. You can write to the klog
+ channel using klog() or klog_raw() from within the kernel or
+ kernel modules, and read from the klog channel by mounting relayfs
+ and using read(2) to read from it (or using cat). If you're not
+ sure, say N.
+
+config KLOG_CHANNEL_AUTOENABLE
+ bool "Enable klog logging on startup"
+ depends on KLOG_CHANNEL
+ default y
+ help
+ If you say Y to this, the klog channel will be automatically enabled
+ on startup. Otherwise, to turn klog logging on, you need use
+ sysctl (fs.relayfs.klog_enabled). This option is used in cases where
+ you don't actually want the channel to be written to until it's
+ enabled. If you're not sure, say Y.
+
+config KLOG_CHANNEL_SHIFT
+ depends on KLOG_CHANNEL
+ int "klog debugging channel size (14 => 16KB, 22 => 4MB)"
+ range 14 22
+ default 21
+ help
+ Select klog debugging channel size as a power of 2.
+
endmenu
menu "Miscellaneous filesystems"
@@ -1144,8 +1194,6 @@ config HPFS_FS
To compile this file system support as a module, choose M here: the
module will be called hpfs. If unsure, say N.
-
-
config QNX4FS_FS
tristate "QNX4 file system support (read only)"
help
@@ -1171,8 +1219,6 @@ config QNX4FS_RW
It's currently broken, so for now:
answer N.
-
-
config SYSV_FS
tristate "System V/Xenix/V7/Coherent file system support"
help
@@ -1208,8 +1254,6 @@ config SYSV_FS
sysv.
If you haven't heard about all of this before, it's safe to say N.
-
-
config UFS_FS
tristate "UFS file system support (read only)"
diff -urpN -X dontdiff linux-2.6.0-test11/fs/Makefile linux-2.6.0-test11.cur/fs/Makefile
--- linux-2.6.0-test11/fs/Makefile Wed Nov 26 14:44:23 2003
+++ linux-2.6.0-test11.cur/fs/Makefile Mon Dec 1 12:26:28 2003
@@ -51,6 +51,7 @@ obj-$(CONFIG_EXT2_FS) += ext2/
obj-$(CONFIG_CRAMFS) += cramfs/
obj-$(CONFIG_RAMFS) += ramfs/
obj-$(CONFIG_HUGETLBFS) += hugetlbfs/
+obj-$(CONFIG_RELAYFS_FS) += relayfs/
obj-$(CONFIG_CODA_FS) += coda/
obj-$(CONFIG_INTERMEZZO_FS) += intermezzo/
obj-$(CONFIG_MINIX_FS) += minix/
diff -urpN -X dontdiff linux-2.6.0-test11/fs/relayfs/Makefile linux-2.6.0-test11.cur/fs/relayfs/Makefile
--- linux-2.6.0-test11/fs/relayfs/Makefile Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test11.cur/fs/relayfs/Makefile Wed Nov 26 22:48:42 2003
@@ -0,0 +1,8 @@
+#
+# relayfs Makefile
+#
+
+obj-$(CONFIG_RELAYFS_FS) += relayfs.o
+
+relayfs-y := relay.o relay_lockless.o relay_locking.o inode.o resize.o
+relayfs-$(CONFIG_KLOG_CHANNEL) += klog.o
diff -urpN -X dontdiff linux-2.6.0-test11/fs/relayfs/inode.c linux-2.6.0-test11.cur/fs/relayfs/inode.c
--- linux-2.6.0-test11/fs/relayfs/inode.c Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test11.cur/fs/relayfs/inode.c Mon Dec 1 12:03:34 2003
@@ -0,0 +1,601 @@
+/*
+ * VFS-related code for RelayFS, a high-speed data relay filesystem.
+ *
+ * Copyright (C) 2003 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
+ * Copyright (C) 2003 - 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/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/namei.h>
+#include <linux/poll.h>
+#include <linux/klog.h>
+#include <asm/uaccess.h>
+#include <asm/relay.h>
+
+#define RELAYFS_MAGIC 0x26F82121
+
+static struct super_operations relayfs_ops;
+static struct address_space_operations relayfs_aops;
+static struct inode_operations relayfs_file_inode_operations;
+static struct file_operations relayfs_file_operations;
+static struct inode_operations relayfs_dir_inode_operations;
+
+static struct vfsmount * relayfs_mount;
+static int relayfs_mount_count;
+
+static struct backing_dev_info relayfs_backing_dev_info = {
+ .ra_pages = 0, /* No readahead */
+ .memory_backed = 1, /* Does not contribute to dirty memory */
+};
+
+static struct inode *
+relayfs_get_inode(struct super_block *sb, int mode, dev_t dev)
+{
+ struct inode * inode;
+
+ inode = new_inode(sb);
+
+ if (inode) {
+ inode->i_mode = mode;
+ inode->i_uid = current->fsuid;
+ inode->i_gid = current->fsgid;
+ inode->i_blksize = PAGE_CACHE_SIZE;
+ inode->i_blocks = 0;
+ inode->i_mapping->a_ops = &relayfs_aops;
+ 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) {
+ default:
+ init_special_inode(inode, mode, dev);
+ break;
+ case S_IFREG:
+ inode->i_op = &relayfs_file_inode_operations;
+ inode->i_fop = &relayfs_file_operations;
+ break;
+ case S_IFDIR:
+ inode->i_op = &relayfs_dir_inode_operations;
+ inode->i_fop = &simple_dir_operations;
+
+ /* directory inodes start off with i_nlink == 2 (for "." entry) */
+ inode->i_nlink++;
+ break;
+ case S_IFLNK:
+ inode->i_op = &page_symlink_inode_operations;
+ break;
+ }
+ }
+ return inode;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+/* SMP-safe */
+static int
+relayfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+{
+ struct inode * inode;
+ int error = -ENOSPC;
+
+ inode = relayfs_get_inode(dir->i_sb, mode, dev);
+
+ if (inode) {
+ d_instantiate(dentry, inode);
+ dget(dentry); /* Extra count - pin the dentry in core */
+ error = 0;
+ }
+ return error;
+}
+
+static int
+relayfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
+{
+ int retval;
+
+ retval = relayfs_mknod(dir, dentry, mode | S_IFDIR, 0);
+
+ if (!retval)
+ dir->i_nlink++;
+ return retval;
+}
+
+static int
+relayfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
+{
+ return relayfs_mknod(dir, dentry, mode | S_IFREG, 0);
+}
+
+static int
+relayfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
+{
+ struct inode *inode;
+ int error = -ENOSPC;
+
+ inode = relayfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
+
+ if (inode) {
+ int l = strlen(symname)+1;
+ error = page_symlink(inode, symname, l);
+ if (!error) {
+ d_instantiate(dentry, inode);
+ dget(dentry);
+ } else
+ iput(inode);
+ }
+ return error;
+}
+
+/**
+ * relayfs_create_entry - create a relayfs directory or file
+ * @name: the name of the file to create
+ * @parent: parent directory
+ * @dentry: result dentry
+ * @entry_type: type of file to create (S_IFREG, S_IFDIR)
+ * @mode: mode
+ * @data: data to associate with the file
+ *
+ * Creates a file or directory with the specifed permissions.
+ */
+static int
+relayfs_create_entry(const char * name, struct dentry * parent, struct dentry **dentry, int entry_type, int mode, void * data)
+{
+ struct qstr qname;
+ struct dentry * d;
+
+ int error = 0;
+
+ error = simple_pin_fs("relayfs", &relayfs_mount, &relayfs_mount_count);
+ if (error) {
+ printk(KERN_ERR "Couldn't mount relayfs: errcode %d\n", error);
+ return error;
+ }
+
+ qname.name = name;
+ qname.len = strlen(name);
+ qname.hash = full_name_hash(name, qname.len);
+
+ if (parent == NULL)
+ if (relayfs_mount && relayfs_mount->mnt_sb)
+ parent = relayfs_mount->mnt_sb->s_root;
+
+ if (parent == NULL) {
+ simple_release_fs(&relayfs_mount, &relayfs_mount_count);
+ return -EINVAL;
+ }
+
+ parent = dget(parent);
+ down(&parent->d_inode->i_sem);
+ d = lookup_hash(&qname, parent);
+ if (IS_ERR(d)) {
+ error = PTR_ERR(d);
+ goto release_mount;
+ }
+
+ if (d->d_inode) {
+ error = -EEXIST;
+ goto release_mount;
+ }
+
+ if (entry_type == S_IFREG)
+ error = relayfs_create(parent->d_inode, d, entry_type | mode, NULL);
+ else
+ error = relayfs_mkdir(parent->d_inode, d, entry_type | mode);
+ if (error)
+ goto release_mount;
+
+ if ((entry_type == S_IFREG) && data) {
+ d->d_inode->u.generic_ip = data;
+ goto exit; /* don't release mount for regular files */
+ }
+
+release_mount:
+ simple_release_fs(&relayfs_mount, &relayfs_mount_count);
+exit:
+ *dentry = d;
+ up(&parent->d_inode->i_sem);
+ dput(parent);
+
+ return error;
+}
+
+/**
+ * relayfs_create_file - create a file in the relay filesystem
+ * @name: the name of the file to create
+ * @parent: parent directory
+ * @dentry: result dentry
+ * @data: data to associate with the file
+ * @mode: mode, if not specied the default perms are used
+ *
+ * The file will be created user rw on behalf of current user.
+ */
+int
+relayfs_create_file(const char * name, struct dentry * parent, struct dentry **dentry, void * data, int mode)
+{
+ if (!mode)
+ mode = S_IRUSR | S_IWUSR;
+
+ return relayfs_create_entry(name, parent, dentry, S_IFREG,
+ mode, data);
+}
+
+/**
+ * relayfs_create_dir - create a directory in the relay filesystem
+ * @name: the name of the directory to create
+ * @parent: parent directory
+ * @dentry: result dentry
+ *
+ * The directory will be created world rwx on behalf of current user.
+ */
+int
+relayfs_create_dir(const char * name, struct dentry * parent, struct dentry **dentry)
+{
+ return relayfs_create_entry(name, parent, dentry, S_IFDIR,
+ S_IRWXU | S_IRUGO | S_IXUGO, NULL);
+}
+
+/**
+ * relayfs_remove_file - remove a file in the relay filesystem
+ * @dentry: file dentry
+ *
+ * Remove a file previously created by relayfs_create_file.
+ */
+int
+relayfs_remove_file(struct dentry *dentry)
+{
+ struct dentry *parent;
+ int is_reg;
+
+ parent = dentry->d_parent;
+ if (parent == NULL)
+ return -EINVAL;
+
+ is_reg = S_ISREG(dentry->d_inode->i_mode);
+
+ parent = dget(parent);
+ down(&parent->d_inode->i_sem);
+ if (dentry->d_inode) {
+ simple_unlink(parent->d_inode, dentry);
+ d_delete(dentry);
+ }
+ dput(dentry);
+ up(&parent->d_inode->i_sem);
+ dput(parent);
+
+ if(is_reg)
+ simple_release_fs(&relayfs_mount, &relayfs_mount_count);
+
+ return 0;
+}
+
+/**
+ * relayfs_open - open file op for relayfs files
+ * @inode: the inode
+ * @filp: the file
+ *
+ * Associates the channel with the file, and increments the
+ * channel refcount. Reads will be 'auto-consuming'.
+ */
+int
+relayfs_open(struct inode *inode, struct file *filp)
+{
+ struct rchan *rchan;
+ struct rchan_reader *reader;
+ int retval = 0;
+
+ if (inode->u.generic_ip) {
+ rchan = (struct rchan *)inode->u.generic_ip;
+ if (rchan == NULL)
+ return -EACCES;
+ reader = __add_rchan_reader(rchan, filp, 1, 0);
+ if (reader == NULL)
+ return -ENOMEM;
+ filp->private_data = reader;
+ retval = rchan->callbacks->fileop_notify(rchan->id, filp,
+ RELAY_FILE_OPEN);
+ if (retval == 0)
+ /* Inc relay channel refcount for file */
+ rchan_get(rchan->id);
+ else {
+ __remove_rchan_reader(reader);
+ retval = -EPERM;
+ }
+ }
+
+ return retval;
+}
+
+/**
+ * relayfs_mmap - mmap file op for relayfs files
+ * @filp: the file
+ * @vma: the vma describing what to map
+ *
+ * Calls upon relay_mmap_buffer to map the file into user space.
+ */
+int
+relayfs_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ struct rchan *rchan;
+
+ rchan = ((struct rchan_reader *)filp->private_data)->rchan;
+
+ return __relay_mmap_buffer(rchan, vma);
+}
+
+/**
+ * relayfs_file_read - read file op for relayfs files
+ * @filp: the file
+ * @buf: user buf to read into
+ * @count: bytes requested
+ * @offset: offset into file
+ *
+ * Reads count bytes from the channel, or as much as is available within
+ * the sub-buffer currently being read. Reads are 'auto-consuming'.
+ * See relay_read() for details.
+ *
+ * Returns bytes read on success, 0 or -EAGAIN if nothing available,
+ * negative otherwise.
+ */
+ssize_t
+relayfs_file_read(struct file *filp, char * buf, size_t count, loff_t *offset)
+{
+ size_t read_count;
+ struct rchan_reader *reader;
+ u32 dummy; /* all VFS readers are auto-consuming */
+
+ if (offset != &filp->f_pos) /* pread, seeking not supported */
+ return -ESPIPE;
+
+ if (count == 0)
+ return 0;
+
+ reader = (struct rchan_reader *)filp->private_data;
+ read_count = relay_read(reader, buf, count,
+ filp->f_flags & (O_NDELAY | O_NONBLOCK) ? 0 : 1, &dummy);
+
+ return read_count;
+}
+
+/**
+ * relayfs_file_write - write file op for relayfs files
+ * @filp: the file
+ * @buf: user buf to write from
+ * @count: bytes to write
+ * @offset: offset into file
+ *
+ * Reserves a slot in the relay buffer and writes count bytes
+ * into it. The current limit for a single write is 2 pages
+ * worth. The user_deliver() channel callback will be invoked on
+ *
+ * Returns bytes written on success, 0 or -EAGAIN if nothing available,
+ * negative otherwise.
+ */
+ssize_t
+relayfs_file_write(struct file *filp, const char *buf, size_t count, loff_t *offset)
+{
+ int write_count;
+ char * write_buf;
+ struct rchan *rchan;
+ int err = 0;
+ void *wrote_pos;
+ struct rchan_reader *reader;
+
+ reader = (struct rchan_reader *)filp->private_data;
+ if (reader == NULL)
+ return -EPERM;
+
+ rchan = reader->rchan;
+ if (rchan == NULL)
+ return -EPERM;
+
+ if (count == 0)
+ return 0;
+
+ /* Change this if need to write more than 2 pages at once */
+ if (count > 2 * PAGE_SIZE)
+ return -EINVAL;
+
+ write_buf = (char *)__get_free_pages(GFP_KERNEL, 1);
+ if (write_buf == NULL)
+ return -ENOMEM;
+
+ if (copy_from_user(write_buf, buf, count))
+ return -EFAULT;
+
+ if (filp->f_flags & (O_NDELAY | O_NONBLOCK)) {
+ write_count = relay_write(rchan->id, write_buf, count, -1, &wrote_pos);
+ if (write_count == 0)
+ return -EAGAIN;
+ } else {
+ err = wait_event_interruptible(rchan->write_wait,
+ (write_count = relay_write(rchan->id, write_buf, count, -1, &wrote_pos)));
+ if (err)
+ return err;
+ }
+
+ free_pages((unsigned long)write_buf, 1);
+
+ rchan->callbacks->user_deliver(rchan->id, wrote_pos, write_count);
+
+ return write_count;
+}
+
+/**
+ * relayfs_poll - poll file op for relayfs files
+ * @filp: the file
+ * @wait: poll table
+ *
+ * Poll implemention.
+ */
+static unsigned int
+relayfs_poll(struct file *filp, poll_table *wait)
+{
+ struct rchan_reader *reader;
+ unsigned int mask = 0;
+
+ reader = (struct rchan_reader *)filp->private_data;
+
+ if (reader->rchan->finalized)
+ return POLLERR;
+
+ if (filp->f_mode & FMODE_READ) {
+ poll_wait(filp, &reader->rchan->read_wait, wait);
+ if (!rchan_empty(reader))
+ mask |= POLLIN | POLLRDNORM;
+ }
+
+ if (filp->f_mode & FMODE_WRITE) {
+ poll_wait(filp, &reader->rchan->write_wait, wait);
+ if (!rchan_full(reader))
+ mask |= POLLOUT | POLLWRNORM;
+ }
+
+ return mask;
+}
+
+/**
+ * relayfs_release - release file op for relayfs files
+ * @inode: the inode
+ * @filp: the file
+ *
+ * Decrements the channel refcount, as the filesystem is
+ * no longer using it.
+ */
+int
+relayfs_release(struct inode *inode, struct file *filp)
+{
+ struct rchan_reader *reader;
+ struct rchan *rchan;
+
+ int err = 0;
+
+ reader = (struct rchan_reader *)filp->private_data;
+
+ if (reader == NULL || reader->rchan == NULL)
+ return -1;
+
+ rchan = reader->rchan;
+ rchan->callbacks->fileop_notify(reader->rchan->id, filp,
+ RELAY_FILE_CLOSE);
+
+ __remove_rchan_reader(reader);
+ /* The channel is no longer in use as far as this file is concerned */
+ rchan_put(rchan);
+
+ return err;
+}
+
+static struct address_space_operations relayfs_aops = {
+ .readpage = simple_readpage,
+ .prepare_write = simple_prepare_write,
+ .commit_write = simple_commit_write
+};
+
+static struct file_operations relayfs_file_operations = {
+ .open = relayfs_open,
+ .read = relayfs_file_read,
+ .write = relayfs_file_write,
+ .poll = relayfs_poll,
+ .mmap = relayfs_mmap,
+ .fsync = simple_sync_file,
+ .release = relayfs_release,
+};
+
+static struct inode_operations relayfs_file_inode_operations = {
+ .getattr = simple_getattr,
+};
+
+static struct inode_operations relayfs_dir_inode_operations = {
+ .create = relayfs_create,
+ .lookup = simple_lookup,
+ .link = simple_link,
+ .unlink = simple_unlink,
+ .symlink = relayfs_symlink,
+ .mkdir = relayfs_mkdir,
+ .rmdir = simple_rmdir,
+ .mknod = relayfs_mknod,
+ .rename = simple_rename,
+};
+
+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;
+
+ 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, S_IFDIR | 0755, 0);
+
+ 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)
+{
+ int err = register_filesystem(&relayfs_fs_type);
+#ifdef CONFIG_KLOG_CHANNEL
+ if (!err)
+ create_klog_channel();
+#endif
+ return err;
+}
+
+static void __exit
+exit_relayfs_fs(void)
+{
+#ifdef CONFIG_KLOG_CHANNEL
+ remove_klog_channel();
+#endif
+ unregister_filesystem(&relayfs_fs_type);
+}
+
+module_init(init_relayfs_fs)
+module_exit(exit_relayfs_fs)
+
+MODULE_AUTHOR("Tom Zanussi <zanussi@us.ibm.com> and Karim Yaghmour <karim@opersys.com>");
+MODULE_DESCRIPTION("Relay Filesystem");
+MODULE_LICENSE("GPL");
+
diff -urpN -X dontdiff linux-2.6.0-test11/fs/relayfs/klog.c linux-2.6.0-test11.cur/fs/relayfs/klog.c
--- linux-2.6.0-test11/fs/relayfs/klog.c Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test11.cur/fs/relayfs/klog.c Wed Nov 26 22:48:42 2003
@@ -0,0 +1,204 @@
+/*
+ * KLOG Generic Logging facility built upon the relayfs infrastructure
+ *
+ * Authors: Hubertus Franke (frankeh@us.ibm.com)
+ * Tom Zanussi (zanussi@us.ibm.com)
+ *
+ * Please direct all questions/comments to zanussi@us.ibm.com
+ *
+ * Copyright (C) 2003, IBM Corp
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/smp_lock.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/config.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+#include <linux/sysctl.h>
+#include <linux/relayfs_fs.h>
+#include <linux/klog.h>
+
+/* klog channel id */
+static int klog_channel = -1;
+
+/* maximum size of klog formatting buffer beyond which truncation will occur */
+#define KLOG_BUF_SIZE (512)
+/* per-cpu klog formatting buffer */
+static char buf[NR_CPUS][KLOG_BUF_SIZE];
+
+/*
+ * klog_enabled determines whether klog()/klog_raw() actually do write
+ * to the klog channel at any given time. If klog_enabled == 1 they do,
+ * otherwise they don't. Settable using sysctl fs.relayfs.klog_enabled.
+ */
+#ifdef CONFIG_KLOG_CHANNEL_AUTOENABLE
+static int klog_enabled = 1;
+#else
+static int klog_enabled = 0;
+#endif
+
+/**
+ * klog - write a formatted string into the klog channel
+ * @fmt: format string
+ *
+ * Returns number of bytes written, negative number on failure.
+ */
+int klog(const char *fmt, ...)
+{
+ va_list args;
+ int len, err;
+ char *cbuf;
+ unsigned long flags;
+
+ if (!klog_enabled || klog_channel < 0)
+ return 0;
+
+ local_irq_save(flags);
+ cbuf = buf[smp_processor_id()];
+
+ va_start(args, fmt);
+ len = vsnprintf(cbuf, KLOG_BUF_SIZE, fmt, args);
+ va_end(args);
+
+ err = relay_write(klog_channel, cbuf, len, -1, NULL);
+ local_irq_restore(flags);
+
+ return err;
+}
+
+/**
+ * klog_raw - directly write into the klog channel
+ * @buf: buffer containing data to write
+ * @len: # bytes to write
+ *
+ * Returns number of bytes written, negative number on failure.
+ */
+int klog_raw(const char *buf,int len)
+{
+ int err = 0;
+
+ if (klog_enabled && klog_channel >= 0)
+ err = relay_write(klog_channel, buf, len, -1, NULL);
+
+ return err;
+}
+
+/**
+ * relayfs sysctl data
+ *
+ * Only sys/fs/relayfs/klog_enabled for now.
+ */
+#define CTL_ENABLE_KLOG 100
+#define CTL_RELAYFS 100
+
+static struct ctl_table_header *relayfs_ctl_table_header;
+
+static struct ctl_table relayfs_table[] =
+{
+ {
+ .ctl_name = CTL_ENABLE_KLOG,
+ .procname = "klog_enabled",
+ .data = &klog_enabled,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
+ 0
+ }
+};
+
+static struct ctl_table relayfs_dir_table[] =
+{
+ {
+ .ctl_name = CTL_RELAYFS,
+ .procname = "relayfs",
+ .data = NULL,
+ .maxlen = 0,
+ .mode = 0555,
+ .child = relayfs_table,
+ },
+ {
+ 0
+ }
+};
+
+static struct ctl_table relayfs_root_table[] =
+{
+ {
+ .ctl_name = CTL_FS,
+ .procname = "fs",
+ .data = NULL,
+ .maxlen = 0,
+ .mode = 0555,
+ .child = relayfs_dir_table,
+ },
+ {
+ 0
+ }
+};
+
+/**
+ * create_klog_channel - creates channel /mnt/relay/klog
+ *
+ * Returns channel id on success, negative otherwise.
+ */
+int
+create_klog_channel(void)
+{
+ u32 bufsize, nbufs;
+ u32 channel_flags;
+
+ channel_flags = RELAY_DELIVERY_PACKET | RELAY_USAGE_GLOBAL;
+ channel_flags |= RELAY_SCHEME_ANY | RELAY_TIMESTAMP_ANY;
+
+ bufsize = 1 << (CONFIG_KLOG_CHANNEL_SHIFT - 2);
+ nbufs = 4;
+
+ klog_channel = relay_open("klog",
+ bufsize,
+ nbufs,
+ channel_flags,
+ NULL,
+ 0,
+ 0,
+ 0,
+ 0,
+ 0,
+ 0);
+
+ if (klog_channel < 0)
+ printk("klog channel creation failed, errcode: %d\n", klog_channel);
+ else {
+ printk("klog channel created (%u bytes)\n", 1 << CONFIG_KLOG_CHANNEL_SHIFT);
+ relayfs_ctl_table_header = register_sysctl_table(relayfs_root_table, 1);
+ }
+
+ return klog_channel;
+}
+
+/**
+ * remove_klog_channel - destroys channel /mnt/relay/klog
+ *
+ * Returns 0, negative otherwise.
+ */
+int
+remove_klog_channel(void)
+{
+ if (relayfs_ctl_table_header)
+ unregister_sysctl_table(relayfs_ctl_table_header);
+
+ return relay_close(klog_channel);
+}
+
+EXPORT_SYMBOL(klog);
+EXPORT_SYMBOL(klog_raw);
+
diff -urpN -X dontdiff linux-2.6.0-test11/fs/relayfs/relay.c linux-2.6.0-test11.cur/fs/relayfs/relay.c
--- linux-2.6.0-test11/fs/relayfs/relay.c Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test11.cur/fs/relayfs/relay.c Mon Dec 1 10:11:42 2003
@@ -0,0 +1,1771 @@
+/*
+ * Public API and common code for RelayFS.
+ *
+ * Please see Documentation/filesystems/relayfs.txt for API description.
+ *
+ * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
+ * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/stddef.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/time.h>
+#include <linux/page-flags.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/delay.h>
+#include <linux/klog.h>
+
+#include <asm/io.h>
+#include <asm/current.h>
+#include <asm/uaccess.h>
+#include <asm/bitops.h>
+#include <asm/pgtable.h>
+#include <asm/relay.h>
+#include <asm/hardirq.h>
+
+#include "relay_lockless.h"
+#include "relay_locking.h"
+#include "resize.h"
+
+/* Relay channel table, indexed by channel id */
+static struct rchan * rchan_table[RELAY_MAX_CHANNELS];
+static rwlock_t rchan_table_lock = RW_LOCK_UNLOCKED;
+
+/* Relay operation structs, one per scheme */
+static struct relay_ops lockless_ops = {
+ .reserve = lockless_reserve,
+ .commit = lockless_commit,
+ .get_offset = lockless_get_offset,
+ .finalize = lockless_finalize,
+ .reset = lockless_reset,
+ .reset_index = lockless_reset_index
+};
+
+static struct relay_ops locking_ops = {
+ .reserve = locking_reserve,
+ .commit = locking_commit,
+ .get_offset = locking_get_offset,
+ .finalize = locking_finalize,
+ .reset = locking_reset,
+ .reset_index = locking_reset_index
+};
+
+/*
+ * Low-level relayfs kernel API. These functions should not normally be
+ * used by clients. See high-level kernel API below.
+ */
+
+/**
+ * rchan_get - get channel associated with id, incrementing refcount
+ * @rchan_id: the channel id
+ *
+ * Returns channel if successful, NULL otherwise.
+ */
+struct rchan *
+rchan_get(int rchan_id)
+{
+ struct rchan *rchan;
+
+ if ((rchan_id < 0) || (rchan_id >= RELAY_MAX_CHANNELS))
+ return NULL;
+
+ read_lock(&rchan_table_lock);
+ rchan = rchan_table[rchan_id];
+ if (rchan)
+ atomic_inc(&rchan->refcount);
+ read_unlock(&rchan_table_lock);
+
+ return rchan;
+}
+
+/**
+ * clear_readers - clear non-VFS readers
+ * @rchan: the channel
+ *
+ * Clear the channel pointers of all non-VFS readers open on the channel.
+ */
+static inline void
+clear_readers(struct rchan *rchan)
+{
+ struct list_head *p;
+ struct rchan_reader *reader;
+
+ read_lock(&rchan->open_readers_lock);
+ list_for_each(p, &rchan->open_readers) {
+ reader = list_entry(p, struct rchan_reader, list);
+ if (!reader->vfs_reader)
+ reader->rchan = NULL;
+ }
+ read_unlock(&rchan->open_readers_lock);
+}
+
+/**
+ * rchan_alloc_id - reserve a channel id and store associated channel
+ * @rchan: the channel
+ *
+ * Returns channel id if successful, -1 otherwise.
+ */
+static inline int
+rchan_alloc_id(struct rchan *rchan)
+{
+ int i;
+ int rchan_id = -1;
+
+ if (rchan == NULL)
+ return -1;
+
+ write_lock(&rchan_table_lock);
+ for (i = 0; i < RELAY_MAX_CHANNELS; i++) {
+ if (rchan_table[i] == NULL) {
+ rchan_table[i] = rchan;
+ rchan_id = rchan->id = i;
+ break;
+ }
+ }
+ if (rchan_id != -1)
+ atomic_inc(&rchan->refcount);
+ write_unlock(&rchan_table_lock);
+
+ return rchan_id;
+}
+
+/**
+ * rchan_free_id - revoke a channel id and remove associated channel
+ * @rchan_id: the channel id
+ */
+static inline void
+rchan_free_id(int rchan_id)
+{
+ struct rchan *rchan;
+
+ if ((rchan_id < 0) || (rchan_id >= RELAY_MAX_CHANNELS))
+ return;
+
+ write_lock(&rchan_table_lock);
+ rchan = rchan_table[rchan_id];
+ rchan_table[rchan_id] = NULL;
+ write_unlock(&rchan_table_lock);
+}
+
+/**
+ * relay_release - perform end-of-buffer processing for last buffer
+ * @rchan: the channel
+ *
+ * Returns 0 if successful, negative otherwise.
+ *
+ * Releases the channel buffer, destroys the channel, and removes the
+ * relay file from the relayfs filesystem. Should only be called from
+ * rchan_put(). If we're here, it means by definition refcount is 0.
+ */
+static int
+relay_release(struct rchan *rchan)
+{
+ if (rchan == NULL)
+ return -EBADF;
+
+ if (rchan->buf != NULL)
+ free_rchan_buf(rchan->buf, rchan->buf_page_array, rchan->buf_page_count);
+
+ rchan_free_id(rchan->id);
+ relayfs_remove_file(rchan->dentry);
+ kfree(rchan);
+
+ return 0;
+}
+
+/**
+ * rchan_get - decrement channel refcount, releasing it if 0
+ * @rchan: the channel
+ *
+ * If the refcount reaches 0, the channel will be destroyed.
+ */
+void
+rchan_put(struct rchan *rchan)
+{
+ if (atomic_dec_and_test(&rchan->refcount))
+ relay_release(rchan);
+}
+
+/**
+ * relay_reserve - reserve a slot in the channel buffer
+ * @rchan: the channel
+ * @len: the length of the slot to reserve
+ * @td: the time delta between buffer start and current write, or TSC
+ * @err: receives the result flags
+ * @interrupting: 1 if interrupting previous, used only in locking scheme
+ *
+ * Returns pointer to the beginning of the reserved slot, NULL if error.
+ *
+ * The errcode value contains the result flags and is an ORed combination
+ * of the following:
+ *
+ * RELAY_BUFFER_SWITCH_NONE - no buffer switch occurred
+ * RELAY_EVENT_DISCARD_NONE - event should not be discarded
+ * RELAY_BUFFER_SWITCH - buffer switch occurred
+ * RELAY_EVENT_DISCARD - event should be discarded (all buffers are full)
+ * RELAY_EVENT_TOO_LONG - event won't fit into even an empty buffer
+ *
+ * buffer_start and buffer_end callbacks are triggered at this point
+ * if applicable.
+ */
+char *
+relay_reserve(struct rchan *rchan,
+ u32 len,
+ struct timeval *ts,
+ u32 *td,
+ int *err,
+ int *interrupting)
+{
+ if (rchan == NULL)
+ return NULL;
+
+ *interrupting = 0;
+
+ return rchan->relay_ops->reserve(rchan, len, ts, td, err, interrupting);
+}
+
+
+/**
+ * wakeup_readers - wake up VFS readers waiting on a channel
+ * @private: the channel
+ *
+ * This is the work function used to defer reader waking. The
+ * reason waking is deferred is that calling directly from commit
+ * causes problems if you're writing from say the scheduler.
+ */
+static void
+wakeup_readers(void *private)
+{
+ struct rchan *rchan = (struct rchan *)private;
+
+ wake_up_interruptible(&rchan->read_wait);
+}
+
+
+/**
+ * relay_commit - commit a reserved slot in the buffer
+ * @rchan: the channel
+ * @from: commit the length starting here
+ * @len: length committed
+ * @interrupting: 1 if interrupting previous, used only in locking scheme
+ *
+ * After the write into the reserved buffer has been complted, this
+ * function must be called in order for the relay to determine whether
+ * buffers are complete and to wake up VFS readers.
+ *
+ * delivery callback is triggered at this point if applicable.
+ */
+void
+relay_commit(struct rchan *rchan,
+ char *from,
+ u32 len,
+ int reserve_code,
+ int interrupting)
+{
+ int deliver;
+
+ if (rchan == NULL)
+ return;
+
+ deliver = packet_delivery(rchan) ||
+ (reserve_code & RELAY_BUFFER_SWITCH);
+
+ rchan->relay_ops->commit(rchan, from, len, deliver, interrupting);
+
+ /* The params are always the same, so no worry about re-queuing */
+ if (deliver && waitqueue_active(&rchan->read_wait)) {
+ PREPARE_WORK(&rchan->wake_readers, wakeup_readers, rchan);
+ schedule_delayed_work(&rchan->wake_readers, 1);
+ }
+}
+
+/**
+ * relay_get_offset - get current and max channel buffer offsets
+ * @rchan: the channel
+ * @max_offset: maximum channel offset
+ *
+ * Returns the current and maximum channel buffer offsets.
+ */
+u32
+relay_get_offset(struct rchan *rchan, u32 *max_offset)
+{
+ return rchan->relay_ops->get_offset(rchan, max_offset);
+}
+
+/**
+ * reset_index - try once to reset the current channel index
+ * @rchan: the channel
+ * @old_index: the index read before reset
+ *
+ * Attempts to reset the channel index to 0. It tries once, and
+ * if it fails, returns negative, 0 otherwise.
+ */
+int
+reset_index(struct rchan *rchan, u32 old_index)
+{
+ return rchan->relay_ops->reset_index(rchan, old_index);
+}
+
+/*
+ * close() vm_op implementation for relayfs file mapping.
+ */
+static void
+relay_file_mmap_close(struct vm_area_struct *vma)
+{
+ struct file *filp = vma->vm_file;
+ struct rchan_reader *reader;
+ struct rchan *rchan;
+
+ reader = (struct rchan_reader *)filp->private_data;
+ rchan = reader->rchan;
+
+ atomic_dec(&rchan->mapped);
+
+ rchan->callbacks->fileop_notify(reader->rchan->id, filp,
+ RELAY_FILE_UNMAP);
+}
+
+/*
+ * vm_ops for relay file mappings.
+ */
+static struct vm_operations_struct relay_file_mmap_ops = {
+ .close = relay_file_mmap_close
+};
+
+/* \begin{Code inspired from BTTV driver} */
+static inline unsigned long
+kvirt_to_pa(unsigned long adr)
+{
+ unsigned long kva, ret;
+
+ kva = (unsigned long) page_address(vmalloc_to_page((void *) adr));
+ kva |= adr & (PAGE_SIZE - 1);
+ ret = __pa(kva);
+ return ret;
+}
+
+static int
+relay_mmap_region(struct vm_area_struct *vma,
+ const char *adr,
+ const char *start_pos,
+ unsigned long size)
+{
+ unsigned long start = (unsigned long) adr;
+ unsigned long page, pos;
+
+ pos = (unsigned long) start_pos;
+
+ while (size > 0) {
+ page = kvirt_to_pa(pos);
+ if (remap_page_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
+ return -EAGAIN;
+ start += PAGE_SIZE;
+ pos += PAGE_SIZE;
+ size -= PAGE_SIZE;
+ }
+
+ return 0;
+}
+/* \end{Code inspired from BTTV driver} */
+
+/**
+ * relay_mmap_buffer: - mmap buffer to process address space
+ * @rchan_id: relay channel id
+ * @vma: vm_area_struct describing memory to be mapped
+ *
+ * Returns:
+ * 0 if ok
+ * -EAGAIN, when remap failed
+ * -EINVAL, invalid requested length
+ *
+ * Caller should already have grabbed mmap_sem.
+ */
+int
+__relay_mmap_buffer(struct rchan *rchan,
+ struct vm_area_struct *vma)
+{
+ int err = 0;
+ unsigned long length = vma->vm_end - vma->vm_start;
+ struct file *filp = vma->vm_file;
+
+ if (rchan == NULL) {
+ err = -EBADF;
+ goto exit;
+ }
+
+ if (length != (unsigned long)rchan->alloc_size) {
+ err = -EINVAL;
+ goto exit;
+ }
+
+ err = relay_mmap_region(vma,
+ (char *)vma->vm_start,
+ rchan->buf,
+ rchan->alloc_size);
+
+ if (err == 0) {
+ vma->vm_ops = &relay_file_mmap_ops;
+ err = rchan->callbacks->fileop_notify(rchan->id, filp,
+ RELAY_FILE_MAP);
+ if (err == 0)
+ atomic_inc(&rchan->mapped);
+ }
+exit:
+ return err;
+}
+
+/*
+ * High-level relayfs kernel API. See Documentation/filesystems/relafys.txt.
+ */
+
+/*
+ * rchan_callback implementations defining default channel behavior. Used
+ * in place of corresponding NULL values in client callback struct.
+ */
+
+/*
+ * buffer_end() default callback. Does nothing.
+ */
+static int
+buffer_end_default_callback(int rchan_id,
+ char *current_write_pos,
+ char *end_of_buffer,
+ struct timeval end_time,
+ u32 end_tsc,
+ int using_tsc)
+{
+ return 0;
+}
+
+/*
+ * buffer_start() default callback. Does nothing.
+ */
+static int
+buffer_start_default_callback(int rchan_id,
+ char *current_write_pos,
+ u32 buffer_id,
+ struct timeval start_time,
+ u32 start_tsc,
+ int using_tsc)
+{
+ return 0;
+}
+
+/*
+ * deliver() default callback. Does nothing.
+ */
+static void
+deliver_default_callback(int rchan_id, char *from, u32 len)
+{
+}
+
+/*
+ * user_deliver() default callback. Does nothing.
+ */
+static void
+user_deliver_default_callback(int rchan_id, char *from, u32 len)
+{
+}
+
+/*
+ * needs_resize() default callback. Does nothing.
+ */
+static void
+needs_resize_default_callback(int rchan_id,
+ int resize_type,
+ u32 suggested_buf_size,
+ u32 suggested_n_bufs)
+{
+}
+
+/*
+ * fileop_notify() default callback. Does nothing.
+ */
+static int
+fileop_notify_default_callback(int rchan_id,
+ struct file *filp,
+ enum relay_fileop fileop)
+{
+ return 0;
+}
+
+/* relay channel default callbacks */
+static struct rchan_callbacks default_channel_callbacks = {
+ .buffer_start = buffer_start_default_callback,
+ .buffer_end = buffer_end_default_callback,
+ .deliver = deliver_default_callback,
+ .user_deliver = user_deliver_default_callback,
+ .needs_resize = needs_resize_default_callback,
+ .fileop_notify = fileop_notify_default_callback,
+};
+
+/**
+ * check_attribute_flags - check sanity of channel attributes
+ * @flags: channel attributes
+ * @resizeable: 1 if true
+ *
+ * Returns 0 if successful, negative otherwise.
+ */
+static int
+check_attribute_flags(u32 *attribute_flags, int resizeable)
+{
+ u32 flags = *attribute_flags;
+
+ if (!(flags & RELAY_DELIVERY_BULK) && !(flags & RELAY_DELIVERY_PACKET))
+ return -EINVAL; /* Delivery mode must be specified */
+
+ if (!(flags & RELAY_USAGE_SMP) && !(flags & RELAY_USAGE_GLOBAL))
+ return -EINVAL; /* Usage must be specified */
+
+ if (resizeable) { /* Resizeable can never be continuous */
+ *attribute_flags &= ~RELAY_MODE_CONTINUOUS;
+ *attribute_flags |= RELAY_MODE_NO_OVERWRITE;
+ }
+
+ if ((flags & RELAY_MODE_CONTINUOUS) &&
+ (flags & RELAY_MODE_NO_OVERWRITE))
+ return -EINVAL; /* Can't have it both ways */
+
+ if (!(flags & RELAY_MODE_CONTINUOUS) &&
+ !(flags & RELAY_MODE_NO_OVERWRITE))
+ *attribute_flags |= RELAY_MODE_CONTINUOUS; /* Default to continuous */
+
+ if (!(flags & RELAY_SCHEME_ANY))
+ return -EINVAL; /* One or both must be specified */
+ else if (flags & RELAY_SCHEME_LOCKLESS) {
+ if (have_cmpxchg())
+ *attribute_flags &= ~RELAY_SCHEME_LOCKING;
+ else if (flags & RELAY_SCHEME_LOCKING)
+ *attribute_flags &= ~RELAY_SCHEME_LOCKLESS;
+ else
+ return -EINVAL; /* Locking scheme not an alternative */
+ }
+
+ if (!(flags & RELAY_TIMESTAMP_ANY))
+ return -EINVAL; /* One or both must be specified */
+ else if (flags & RELAY_TIMESTAMP_TSC) {
+ if (have_tsc())
+ *attribute_flags &= ~RELAY_TIMESTAMP_GETTIMEOFDAY;
+ else if (flags & RELAY_TIMESTAMP_GETTIMEOFDAY)
+ *attribute_flags &= ~RELAY_TIMESTAMP_TSC;
+ else
+ return -EINVAL; /* gettimeofday not an alternative */
+ }
+
+ return 0;
+}
+
+/*
+ * High-level API functions.
+ */
+
+/**
+ * __relay_reset - internal reset function
+ * @rchan: the channel
+ * @init: 1 if this is a first-time channel initialization
+ *
+ * See relay_reset for description of effect.
+ */
+void
+__relay_reset(struct rchan *rchan, int init)
+{
+ int i;
+
+ if (init) {
+ rchan->version = RELAYFS_CHANNEL_VERSION;
+ init_MUTEX(&rchan->resize_sem);
+ init_waitqueue_head(&rchan->read_wait);
+ init_waitqueue_head(&rchan->write_wait);
+ atomic_set(&rchan->refcount, 0);
+ INIT_LIST_HEAD(&rchan->open_readers);
+ rchan->open_readers_lock = RW_LOCK_UNLOCKED;
+ }
+
+ rchan->buf_id = rchan->buf_idx = 0;
+ atomic_set(&rchan->suspended, 0);
+ atomic_set(&rchan->mapped, 0);
+ rchan->half_switch = 0;
+ rchan->bufs_produced = 0;
+ rchan->bufs_consumed = 0;
+ rchan->bytes_consumed = 0;
+ rchan->initialized = 0;
+ rchan->finalized = 0;
+ rchan->resize_min = rchan->resize_max = 0;
+ rchan->resizing = 0;
+ rchan->replace_buffer = 0;
+ rchan->resize_buf = NULL;
+ rchan->resize_buf_size = 0;
+ rchan->resize_alloc_size = 0;
+ rchan->resize_n_bufs = 0;
+ rchan->resize_err = 0;
+ rchan->resize_failures = 0;
+ rchan->resize_order = 0;
+
+ rchan->expand_page_array = NULL;
+ rchan->expand_page_count = 0;
+ rchan->shrink_page_array = NULL;
+ rchan->shrink_page_count = 0;
+ rchan->resize_page_array = NULL;
+ rchan->resize_page_count = 0;
+ rchan->old_buf_page_array = NULL;
+
+ INIT_WORK(&rchan->wake_readers, NULL, NULL);
+ INIT_WORK(&rchan->wake_writers, NULL, NULL);
+
+ for (i = 0; i < RELAY_MAX_BUFS; i++)
+ rchan->unused_bytes[i] = 0;
+
+ rchan->relay_ops->reset(rchan, init);
+}
+
+/**
+ * relay_reset - reset the channel
+ * @rchan: the channel
+ *
+ * Returns 0 if successful, negative if not.
+ *
+ * This has the effect of erasing all data from the buffer and
+ * restarting the channel in its initial state. The buffer itself
+ * is not freed, so any mappings are still in effect.
+ *
+ * NOTE: Care should be taken that the channnel isn't actually
+ * being used by anything when this call is made.
+ */
+int
+relay_reset(int rchan_id)
+{
+ struct rchan *rchan;
+
+ rchan = rchan_get(rchan_id);
+ if (rchan == NULL)
+ return -EBADF;
+
+ __relay_reset(rchan, 0);
+
+ rchan_put(rchan);
+
+ return 0;
+}
+
+/**
+ * rchan_create - allocate and initialize a channel, including buffer
+ * @chanpath: path specifying the relayfs channel file to create
+ * @bufsize: the size of the sub-buffers within the channel buffer
+ * @nbufs: the number of sub-buffers within the channel buffer
+ * @rchan_flags: flags specifying buffer attributes
+ * @err: err code
+ *
+ * Returns channel if successful, NULL otherwise, err receives errcode.
+ *
+ * Allocates a struct rchan representing a relay channel, according
+ * to the attributes passed in via rchan_flags. Does some basic sanity
+ * checking but doesn't try to do anything smart. In particular, the
+ * number of buffers must be a power of 2, and if the lockless scheme
+ * is being used, the sub-buffer size must also be a power of 2. The
+ * locking scheme can use buffers of any size.
+ */
+static struct rchan *
+rchan_create(const char *chanpath,
+ int bufsize,
+ int nbufs,
+ u32 rchan_flags,
+ int *err)
+{
+ int size_alloc;
+ struct rchan *rchan = NULL;
+ struct page **page_array;
+ int page_count;
+
+ *err = 0;
+
+ rchan = (struct rchan *)kmalloc(sizeof(struct rchan), GFP_KERNEL);
+ if (rchan == NULL) {
+ *err = -ENOMEM;
+ return NULL;
+ }
+
+ if (nbufs == 1 && bufsize) {
+ rchan->n_bufs = nbufs;
+ rchan->buf_size = bufsize;
+ size_alloc = bufsize;
+ goto alloc;
+ }
+
+ if (bufsize <= 0 ||
+ (rchan_flags & RELAY_SCHEME_LOCKLESS && hweight32(bufsize) != 1) ||
+ hweight32(nbufs) != 1 ||
+ nbufs < RELAY_MIN_BUFS ||
+ nbufs > RELAY_MAX_BUFS) {
+ *err = -EINVAL;
+ goto exit;
+ }
+
+ size_alloc = FIX_SIZE(bufsize * nbufs);
+ if (size_alloc > RELAY_MAX_BUF_SIZE) {
+ *err = -EINVAL;
+ goto exit;
+ }
+ rchan->n_bufs = nbufs;
+ rchan->buf_size = bufsize;
+
+ if (rchan_flags & RELAY_SCHEME_LOCKLESS) {
+ offset_bits(rchan) = ffs(bufsize) - 1;
+ offset_mask(rchan) = RELAY_BUF_OFFSET_MASK(offset_bits(rchan));
+ bufno_bits(rchan) = ffs(nbufs) - 1;
+ }
+alloc:
+ if ((rchan->buf = (char *)alloc_rchan_buf(size_alloc, &page_array, &page_count)) == NULL) {
+ rchan->buf_page_array = NULL;
+ rchan->buf_page_count = 0;
+
+ *err = -ENOMEM;
+ goto exit;
+ }
+
+ rchan->buf_page_array = page_array;
+ rchan->buf_page_count = page_count;
+
+ if (rchan_alloc_id(rchan) == -1) {
+ *err = -ENOMEM;
+ goto exit;
+ }
+
+ rchan->alloc_size = size_alloc;
+
+ if (rchan_flags & RELAY_SCHEME_LOCKLESS)
+ rchan->relay_ops = &lockless_ops;
+ else
+ rchan->relay_ops = &locking_ops;
+
+exit:
+ if (*err) {
+ kfree(rchan);
+ rchan = NULL;
+ }
+
+ return rchan;
+}
+
+
+static char tmpname[NAME_MAX];
+
+/**
+ * rchan_create_dir - create directory for file
+ * @chanpath: path to file, including filename
+ * @residual: filename remaining after parse
+ * @topdir: the directory filename should be created in
+ *
+ * Returns 0 if successful, negative otherwise.
+ *
+ * Inspired by xlate_proc_name() in procfs. Given a file path which
+ * includes the filename, creates any and all directories necessary
+ * to create the file.
+ */
+static int
+rchan_create_dir(const char * chanpath,
+ const char **residual,
+ struct dentry **topdir)
+{
+ const char *cp = chanpath, *next;
+ struct dentry *parent = NULL;
+ int len, err = 0;
+
+ while (1) {
+ next = strchr(cp, '/');
+ if (!next)
+ break;
+
+ len = next - cp;
+
+ strncpy(tmpname, cp, len);
+ tmpname[len] = '\0';
+ err = relayfs_create_dir(tmpname, parent, &parent);
+ if (err && (err != -EEXIST))
+ return err;
+ cp += len + 1;
+ }
+
+ *residual = cp;
+ *topdir = parent;
+
+ return err;
+}
+
+/**
+ * rchan_create_file - create file, including parent directories
+ * @chanpath: path to file, including filename
+ * @dentry: result dentry
+ * @data: data to associate with the file
+ *
+ * Returns 0 if successful, negative otherwise.
+ */
+static int
+rchan_create_file(const char * chanpath,
+ struct dentry **dentry,
+ struct rchan * data,
+ int mode)
+{
+ int err;
+ const char * fname;
+ struct dentry *topdir;
+
+ err = rchan_create_dir(chanpath, &fname, &topdir);
+ if (err && (err != -EEXIST))
+ return err;
+
+ err = relayfs_create_file(fname, topdir, dentry, (void *)data, mode);
+
+ return err;
+}
+
+/**
+ * relay_open - create a new file/channel buffer in relayfs
+ * @chanpath: name of file to create, including path
+ * @bufsize: size of sub-buffers
+ * @nbufs: number of sub-buffers
+ * @flags: channel attributes
+ * @callbacks: client callback functions
+ * @start_reserve: number of bytes to reserve at start of each sub-buffer
+ * @end_reserve: number of bytes to reserve at end of each sub-buffer
+ * @rchan_start_reserve: additional reserve at start of first sub-buffer
+ * @resize_min: minimum total buffer size, if set
+ * @resize_max: maximum total buffer size, if set
+ * @mode: the perms to be given to the relayfs file, 0 to accept defaults
+ *
+ * Returns channel id if successful, negative otherwise.
+ *
+ * Creates a relay channel using the sizes and attributes specified.
+ * The default permissions, used if mode == 0 are S_IRUSR | S_IWUSR. See
+ * Documentation/filesystems/relayfs.txt for details.
+ */
+int
+relay_open(const char *chanpath,
+ int bufsize,
+ int nbufs,
+ u32 flags,
+ struct rchan_callbacks *channel_callbacks,
+ u32 start_reserve,
+ u32 end_reserve,
+ u32 rchan_start_reserve,
+ u32 resize_min,
+ u32 resize_max,
+ int mode)
+{
+ int err;
+ struct rchan *rchan;
+ struct dentry *dentry;
+ struct rchan_callbacks *callbacks = NULL;
+
+ if (chanpath == NULL)
+ return -EINVAL;
+
+ if (nbufs != 1) {
+ err = check_attribute_flags(&flags, resize_min ? 1 : 0);
+ if (err)
+ return err;
+ }
+
+ rchan = rchan_create(chanpath, bufsize, nbufs, flags, &err);
+
+ if (err < 0)
+ return err;
+
+ /* Create file in fs */
+ if ((err = rchan_create_file(chanpath, &dentry, rchan, mode)) < 0) {
+ rchan_free_id(rchan->id);
+ kfree(rchan);
+ return err;
+ }
+
+ rchan->dentry = dentry;
+
+ if (channel_callbacks == NULL)
+ callbacks = &default_channel_callbacks;
+ else
+ callbacks = channel_callbacks;
+
+ if (callbacks->buffer_end == NULL)
+ callbacks->buffer_end = buffer_end_default_callback;
+ if (callbacks->buffer_start == NULL)
+ callbacks->buffer_start = buffer_start_default_callback;
+ if (callbacks->deliver == NULL)
+ callbacks->deliver = deliver_default_callback;
+ if (callbacks->user_deliver == NULL)
+ callbacks->user_deliver = user_deliver_default_callback;
+ if (callbacks->needs_resize == NULL)
+ callbacks->needs_resize = needs_resize_default_callback;
+ if (callbacks->fileop_notify == NULL)
+ callbacks->fileop_notify = fileop_notify_default_callback;
+ rchan->callbacks = callbacks;
+
+ /* Just to let the client know the sizes used */
+ rchan->callbacks->needs_resize(rchan->id,
+ RELAY_RESIZE_REPLACED,
+ rchan->buf_size,
+ rchan->n_bufs);
+
+ rchan->flags = flags;
+ rchan->start_reserve = start_reserve;
+ rchan->end_reserve = end_reserve;
+ rchan->rchan_start_reserve = rchan_start_reserve;
+
+ __relay_reset(rchan, 1);
+
+ if (resize_min > 0 && resize_max > 0 &&
+ resize_max < RELAY_MAX_TOTAL_BUF_SIZE) {
+ rchan->resize_min = resize_min;
+ rchan->resize_max = resize_max;
+ init_shrink_timer(rchan);
+ }
+
+ rchan_get(rchan->id);
+
+ return rchan->id;
+}
+
+/**
+ * relay_finalize - perform end-of-buffer processing for last buffer
+ * @rchan_id: the channel id
+ * @releasing: true if called when releasing file
+ *
+ * Returns 0 if successful, negative otherwise.
+ */
+static int
+relay_finalize(int rchan_id)
+{
+ struct rchan *rchan = rchan_get(rchan_id);
+ if (rchan == NULL)
+ return -EBADF;
+
+ if (rchan->finalized == 0) {
+ rchan->relay_ops->finalize(rchan);
+ rchan->finalized = 1;
+ }
+
+ if (waitqueue_active(&rchan->read_wait)) {
+ PREPARE_WORK(&rchan->wake_readers, wakeup_readers, rchan);
+ schedule_delayed_work(&rchan->wake_readers, 1);
+ }
+
+ rchan_put(rchan);
+
+ return 0;
+}
+
+/**
+ * relay_close - close the channel
+ * @rchan_id: relay channel id
+ *
+ * Finalizes the last sub-buffer and marks the channel as finalized.
+ * The channel buffer and channel data structure are then freed
+ * automatically when the last reference to the channel is given up.
+ */
+int
+relay_close(int rchan_id)
+{
+ int err;
+ struct rchan *rchan;
+
+ if ((rchan_id < 0) || (rchan_id >= RELAY_MAX_CHANNELS))
+ return -EBADF;
+
+ err = relay_finalize(rchan_id);
+
+ if (!err) {
+ read_lock(&rchan_table_lock);
+ rchan = rchan_table[rchan_id];
+ read_unlock(&rchan_table_lock);
+
+ if (rchan) {
+ rchan->callbacks = &default_channel_callbacks;
+ clear_readers(rchan);
+ if (rchan->resize_min)
+ del_timer(&rchan->shrink_timer);
+ rchan_put(rchan);
+ }
+ }
+
+ return err;
+}
+
+/**
+ * relay_write - reserve a slot in the channel and write data into it
+ * @rchan_id: relay channel id
+ * @data_ptr: data to be written into reserved slot
+ * @count: number of bytes to write
+ * @td_offset: optional offset where time delta should be written
+ * @wrote_pos: optional ptr returning buf pos written to, ignored if NULL
+ *
+ * Returns the number of bytes written, 0 or negative on failure.
+ *
+ * Reserves space in the channel and writes count bytes of data_ptr
+ * to it. Automatically performs any necessary locking, depending
+ * on the scheme and SMP usage in effect (no locking is done for the
+ * lockless scheme regardless of usage).
+ *
+ * If td_offset is >= 0, the internal time delta calculated when
+ * slot was reserved will be written at that offset.
+ *
+ * If wrote_pos is non-NULL, it will receive the location the data
+ * was written to, which may be needed for some applications but is not
+ * normally interesting.
+ */
+int
+relay_write(int rchan_id,
+ const void *data_ptr,
+ size_t count,
+ int td_offset,
+ void **wrote_pos)
+{
+ unsigned long flags;
+ char *reserved, *write_pos;
+ int bytes_written = 0;
+ int reserve_code, interrupting;
+ struct timeval ts;
+ u32 td;
+ struct rchan *rchan;
+
+ rchan = rchan_get(rchan_id);
+ if (rchan == NULL)
+ return -EBADF;
+
+ relay_lock_channel(rchan, flags); /* nop for lockless */
+
+ write_pos = reserved = relay_reserve(rchan, count, &ts, &td,
+ &reserve_code, &interrupting);
+
+ if (reserved != NULL) {
+ relay_write_direct(write_pos, data_ptr, count);
+ if ((td_offset >= 0) && (td_offset < count - sizeof(td)))
+ *((u32 *)(reserved + td_offset)) = td;
+ bytes_written = count;
+ } else if (reserve_code == RELAY_WRITE_TOO_LONG)
+ bytes_written = -EINVAL;
+
+ if (bytes_written > 0)
+ relay_commit(rchan, reserved, bytes_written, reserve_code, interrupting);
+
+ relay_unlock_channel(rchan, flags); /* nop for lockless */
+
+ rchan_put(rchan);
+
+ if (wrote_pos)
+ *wrote_pos = reserved;
+
+ return bytes_written;
+}
+
+/**
+ * wakeup_writers - wake up VFS writers waiting on a channel
+ * @private: the channel
+ *
+ * This is the work function used to defer writer waking. The
+ * reason waking is deferred is that calling directly from
+ * buffers_consumed causes problems if you're writing from say
+ * the scheduler.
+ */
+static void
+wakeup_writers(void *private)
+{
+ struct rchan *rchan = (struct rchan *)private;
+
+ wake_up_interruptible(&rchan->write_wait);
+}
+
+
+/**
+ * __relay_buffers_consumed - internal version of relay_buffers_consumed
+ * @rchan: the relay channel
+ * @bufs_consumed: number of buffers to add to current count for channel
+ *
+ * Internal - updates the channel's consumed buffer count.
+ */
+static void
+__relay_buffers_consumed(struct rchan *rchan, u32 bufs_consumed)
+{
+ rchan->bufs_consumed += bufs_consumed;
+
+ if (rchan->bufs_consumed > rchan->bufs_produced)
+ rchan->bufs_consumed = rchan->bufs_produced;
+
+ atomic_set(&rchan->suspended, 0);
+
+ PREPARE_WORK(&rchan->wake_writers, wakeup_writers, rchan);
+ schedule_delayed_work(&rchan->wake_writers, 1);
+}
+
+/**
+ * __reader_buffers_consumed - update reader/channel consumed buffer count
+ * @reader: channel reader
+ * @bufs_consumed: number of buffers to add to current count for channel
+ *
+ * Internal - updates the reader's consumed buffer count. If the reader's
+ * resulting total is greater than the channel's, update the channel's.
+*/
+static void
+__reader_buffers_consumed(struct rchan_reader *reader, u32 bufs_consumed)
+{
+ reader->bufs_consumed += bufs_consumed;
+
+ if (reader->bufs_consumed > reader->rchan->bufs_consumed)
+ __relay_buffers_consumed(reader->rchan, bufs_consumed);
+}
+
+/**
+ * relay_buffers_consumed - add to the # buffers consumed for the channel
+ * @reader: channel reader
+ * @bufs_consumed: number of buffers to add to current count for channel
+ *
+ * Adds to the channel's consumed buffer count. buffers_consumed should
+ * be the number of buffers newly consumed, not the total number consumed.
+ *
+ * NOTE: kernel clients don't need to call this function if the reader
+ * is auto-consuming or the channel is MODE_CONTINUOUS.
+ */
+void
+relay_buffers_consumed(struct rchan_reader *reader, u32 bufs_consumed)
+{
+ if (reader && reader->rchan)
+ __reader_buffers_consumed(reader, bufs_consumed);
+}
+
+/**
+ * __relay_bytes_consumed - internal version of relay_bytes_consumed
+ * @rchan: the relay channel
+ * @bytes_consumed: number of bytes to add to current count for channel
+ * @read_offset: where the bytes were consumed from
+ *
+ * Internal - updates the channel's consumed count.
+*/
+static void
+__relay_bytes_consumed(struct rchan *rchan, u32 bytes_consumed, u32 read_offset)
+{
+ u32 consuming_idx;
+ u32 unused;
+
+ consuming_idx = read_offset / rchan->buf_size;
+
+ if (consuming_idx >= rchan->n_bufs)
+ consuming_idx = rchan->n_bufs - 1;
+ rchan->bytes_consumed += bytes_consumed;
+
+ unused = rchan->unused_bytes[consuming_idx];
+
+ if (rchan->bytes_consumed + unused >= rchan->buf_size) {
+ __relay_buffers_consumed(rchan, 1);
+ rchan->bytes_consumed = 0;
+ }
+}
+
+/**
+ * __reader_bytes_consumed - update reader/channel consumed count
+ * @reader: channel reader
+ * @bytes_consumed: number of bytes to add to current count for channel
+ * @read_offset: where the bytes were consumed from
+ *
+ * Internal - updates the reader's consumed count. If the reader's
+ * resulting total is greater than the channel's, update the channel's.
+*/
+static void
+__reader_bytes_consumed(struct rchan_reader *reader, u32 bytes_consumed, u32 read_offset)
+{
+ u32 consuming_idx;
+ u32 unused;
+
+ consuming_idx = read_offset / reader->rchan->buf_size;
+
+ if (consuming_idx >= reader->rchan->n_bufs)
+ consuming_idx = reader->rchan->n_bufs - 1;
+
+ reader->bytes_consumed += bytes_consumed;
+
+ unused = reader->rchan->unused_bytes[consuming_idx];
+
+ if (reader->bytes_consumed + unused >= reader->rchan->buf_size) {
+ reader->bufs_consumed++;
+ reader->bytes_consumed = 0;
+ }
+
+ if ((reader->bufs_consumed > reader->rchan->bufs_consumed) ||
+ ((reader->bufs_consumed == reader->rchan->bufs_consumed) &&
+ (reader->bytes_consumed > reader->rchan->bytes_consumed)))
+ __relay_bytes_consumed(reader->rchan, bytes_consumed, read_offset);
+}
+
+/**
+ * relay_bytes_consumed - add to the # bytes consumed for the channel
+ * @reader: channel reader
+ * @bytes_consumed: number of bytes to add to current count for channel
+ * @read_offset: where the bytes were consumed from
+ *
+ * Adds to the channel's consumed count. bytes_consumed should be the
+ * number of bytes actually read e.g. return value of relay_read() and
+ * the read_offset should be the actual offset the bytes were read from
+ * e.g. the actual_read_offset set by relay_read(). See
+ * Documentation/filesystems/relayfs.txt for more details.
+ *
+ * NOTE: kernel clients don't need to call this function if the reader
+ * is auto-consuming or the channel is MODE_CONTINUOUS.
+ */
+void
+relay_bytes_consumed(struct rchan_reader *reader, u32 bytes_consumed, u32 read_offset)
+{
+ if (reader && reader->rchan)
+ __reader_bytes_consumed(reader, bytes_consumed, read_offset);
+}
+
+/**
+ * update_readers_consumed - apply offset change to reader
+ * @rchan: the channel
+ *
+ * Apply the consumed counts to all readers open on the channel.
+ */
+void
+update_readers_consumed(struct rchan *rchan, u32 bufs_consumed, u32 bytes_consumed)
+{
+ struct list_head *p;
+ struct rchan_reader *reader;
+
+ read_lock(&rchan->open_readers_lock);
+ list_for_each(p, &rchan->open_readers) {
+ reader = list_entry(p, struct rchan_reader, list);
+ reader->bufs_consumed = bufs_consumed;
+ reader->bytes_consumed = bytes_consumed;
+ if (reader->vfs_reader)
+ reader->pos.file->f_pos = 0;
+ else
+ reader->pos.f_pos = 0;
+ reader->offset_changed = 1;
+ }
+ read_unlock(&rchan->open_readers_lock);
+}
+
+/**
+ * do_read - utility function to do the actual read to user
+ * @rchan: the channel
+ * @buf: user buf to read into, NULL if just getting info
+ * @count: bytes requested
+ * @read_offset: offset into channel
+ * @new_offset: new offset into channel after read
+ * @actual_read_offset: read offset actually used
+ *
+ * Returns the number of bytes read, 0 if none.
+ */
+static ssize_t
+do_read(struct rchan *rchan, char *buf, size_t count, u32 read_offset, u32 *new_offset, u32 *actual_read_offset)
+{
+ u32 read_bufno, cur_bufno;
+ u32 avail_offset, cur_idx, max_offset, buf_end_offset;
+ u32 avail_count, buf_size;
+ int unused_bytes = 0;
+ size_t read_count = 0;
+ u32 last_buf_byte_offset;
+
+ *actual_read_offset = read_offset;
+
+ buf_size = rchan->buf_size;
+ if (unlikely(!buf_size)) BUG();
+
+ read_bufno = read_offset / buf_size;
+ if (unlikely(read_bufno >= RELAY_MAX_BUFS)) BUG();
+ unused_bytes = rchan->unused_bytes[read_bufno];
+
+ avail_offset = cur_idx = relay_get_offset(rchan, &max_offset);
+
+ if (cur_idx == read_offset) {
+ if (atomic_read(&rchan->suspended) == 1) {
+ read_offset += 1;
+ if (read_offset >= max_offset)
+ read_offset = 0;
+ *actual_read_offset = read_offset;
+ } else {
+ *new_offset = read_offset;
+ return 0;
+ }
+ } else {
+ last_buf_byte_offset = (read_bufno + 1) * buf_size - 1;
+ if (read_offset == last_buf_byte_offset) {
+ if (unused_bytes != 1) {
+ read_offset += 1;
+ if (read_offset >= max_offset)
+ read_offset = 0;
+ *actual_read_offset = read_offset;
+ }
+ }
+ }
+
+ read_bufno = read_offset / buf_size;
+ if (unlikely(read_bufno >= RELAY_MAX_BUFS)) BUG();
+ unused_bytes = rchan->unused_bytes[read_bufno];
+
+ cur_bufno = cur_idx / buf_size;
+
+ buf_end_offset = (read_bufno + 1) * buf_size - unused_bytes;
+ if (avail_offset > buf_end_offset)
+ avail_offset = buf_end_offset;
+ else if (avail_offset < read_offset)
+ avail_offset = buf_end_offset;
+ avail_count = avail_offset - read_offset;
+ read_count = avail_count >= count ? count : avail_count;
+
+ if (read_count && buf != NULL)
+ if (copy_to_user(buf, rchan->buf + read_offset, read_count))
+ return -EFAULT;
+
+ if (read_bufno == cur_bufno)
+ if (read_count && (read_offset + read_count >= buf_end_offset) && (read_offset + read_count <= cur_idx)) {
+ *new_offset = cur_idx;
+ return read_count;
+ }
+
+ if (read_offset + read_count + unused_bytes > max_offset)
+ *new_offset = 0;
+ else if (read_offset + read_count >= buf_end_offset)
+ *new_offset = read_offset + read_count + unused_bytes;
+ else
+ *new_offset = read_offset + read_count;
+
+ return read_count;
+}
+
+/**
+ * __relay_read - read bytes from channel, relative to current reader pos
+ * @reader: channel reader
+ * @buf: user buf to read into, NULL if just getting info
+ * @count: bytes requested
+ * @read_offset: offset into channel
+ * @new_offset: new offset into channel after read
+ * @actual_read_offset: read offset actually used
+ * @wait: if non-zero, wait for something to read
+ *
+ * Internal - see relay_read() for details.
+ *
+ * Returns the number of bytes read, 0 if none, negative on failure.
+ */
+static ssize_t
+__relay_read(struct rchan_reader *reader, char *buf, size_t count, u32 read_offset, u32 *new_offset, u32 *actual_read_offset, int wait)
+{
+ int err = 0;
+ size_t read_count = 0;
+ struct rchan *rchan = reader->rchan;
+
+ if (!wait && !rchan->initialized)
+ return -EINTR;
+
+ if (using_lockless(rchan))
+ read_offset &= idx_mask(rchan);
+
+ if (read_offset >= rchan->n_bufs * rchan->buf_size) {
+ *new_offset = 0;
+ return -EINTR;
+ }
+
+ if (buf != NULL && wait) {
+ err = wait_event_interruptible(rchan->read_wait,
+ ((rchan->finalized == 1) ||
+ (atomic_read(&rchan->suspended) == 1) ||
+ (relay_get_offset(rchan, NULL) != read_offset)));
+
+ if (rchan->finalized)
+ return 0;
+
+ if (reader->offset_changed) {
+ reader->offset_changed = 0;
+ return -EINTR;
+ }
+
+ if (err)
+ return err;
+ }
+
+ read_count = do_read(rchan, buf, count, read_offset, new_offset, actual_read_offset);
+
+ if (read_count < 0)
+ err = read_count;
+
+ if (err)
+ return err;
+ else
+ return read_count;
+}
+
+/**
+ * relay_read - read bytes from channel, relative to current reader pos
+ * @reader: channel reader
+ * @buf: user buf to read into, NULL if just getting info
+ * @count: bytes requested
+ * @wait: if non-zero, wait for something to read
+ * @actual_read_offset: set read offset actually used, must not be NULL
+ *
+ * Reads count bytes from the channel, or as much as is available within
+ * the sub-buffer currently being read. The read offset that will be
+ * read from is the position contained within the reader object. If the
+ * wait flag is set, buf is non-NULL, and there is nothing available,
+ * it will wait until there is. If the wait flag is 0 and there is
+ * nothing available, -EAGAIN is returned. If buf is NULL, the value
+ * returned is the number of bytes that would have been read.
+ * actual_read_offset is the value that should be passed as the read
+ * offset to relay_bytes_consumed, needed only if the reader is not
+ * auto-consuming and the channel is MODE_NO_OVERWRITE, but in any case,
+ * it must not be NULL. See Documentation/filesystems/relayfs.txt for
+ * more details.
+ */
+ssize_t
+relay_read(struct rchan_reader *reader, char *buf, size_t count, int wait, u32 *actual_read_offset)
+{
+ u32 new_offset;
+ u32 read_offset;
+ ssize_t read_count;
+
+ if (reader == NULL || reader->rchan == NULL)
+ return -EBADF;
+
+ if (actual_read_offset == NULL)
+ return -EINVAL;
+
+ if (reader->vfs_reader)
+ read_offset = (u32)(reader->pos.file->f_pos);
+ else
+ read_offset = reader->pos.f_pos;
+ *actual_read_offset = read_offset;
+
+ read_count = __relay_read(reader, buf, count, read_offset,
+ &new_offset, actual_read_offset, wait);
+
+ if (read_count < 0)
+ return read_count;
+
+ if (reader->vfs_reader)
+ reader->pos.file->f_pos = new_offset;
+ else
+ reader->pos.f_pos = new_offset;
+
+ if (reader->auto_consume && ((read_count) || (new_offset != read_offset)))
+ __reader_bytes_consumed(reader, read_count, *actual_read_offset);
+
+ if (read_count == 0 && !wait)
+ return -EAGAIN;
+
+ return read_count;
+}
+
+/**
+ * relay_bytes_avail - number of bytes available in current sub-buffer
+ * @reader: channel reader
+ *
+ * Returns the number of bytes available relative to the reader's
+ * current read position within the corresponding sub-buffer, 0 if
+ * there is nothing available. See Documentation/filesystems/relayfs.txt
+ * for more details.
+ */
+ssize_t
+relay_bytes_avail(struct rchan_reader *reader)
+{
+ u32 f_pos;
+ u32 new_offset;
+ u32 actual_read_offset;
+ ssize_t bytes_read;
+
+ if (reader == NULL || reader->rchan == NULL)
+ return -EBADF;
+
+ if (reader->vfs_reader)
+ f_pos = (u32)reader->pos.file->f_pos;
+ else
+ f_pos = reader->pos.f_pos;
+ new_offset = f_pos;
+
+ bytes_read = __relay_read(reader, NULL, reader->rchan->buf_size,
+ f_pos, &new_offset, &actual_read_offset, 0);
+
+ if ((new_offset != f_pos) &&
+ ((bytes_read == -EINTR) || (bytes_read == 0)))
+ bytes_read = -EAGAIN;
+ else if ((bytes_read < 0) && (bytes_read != -EAGAIN))
+ bytes_read = 0;
+
+ return bytes_read;
+}
+
+/**
+ * rchan_empty - boolean, is the channel empty wrt reader?
+ * @reader: channel reader
+ *
+ * Returns 1 if the channel is empty, 0 otherwise.
+ */
+int
+rchan_empty(struct rchan_reader *reader)
+{
+ ssize_t avail_count;
+ u32 buffers_ready;
+ struct rchan *rchan = reader->rchan;
+ u32 cur_idx, curbuf_bytes;
+ int mapped;
+
+ if (atomic_read(&rchan->suspended) == 1)
+ return 0;
+
+ mapped = atomic_read(&rchan->mapped);
+
+ if (mapped && bulk_delivery(rchan)) {
+ buffers_ready = rchan->bufs_produced - rchan->bufs_consumed;
+ return buffers_ready ? 0 : 1;
+ }
+
+ if (mapped && packet_delivery(rchan)) {
+ buffers_ready = rchan->bufs_produced - rchan->bufs_consumed;
+ if (buffers_ready)
+ return 0;
+ else {
+ cur_idx = relay_get_offset(rchan, NULL);
+ curbuf_bytes = cur_idx % rchan->buf_size;
+ return curbuf_bytes == rchan->bytes_consumed ? 1 : 0;
+ }
+ }
+
+ avail_count = relay_bytes_avail(reader);
+
+ return avail_count ? 0 : 1;
+}
+
+/**
+ * rchan_full - boolean, is the channel full wrt consuming reader?
+ * @reader: channel reader
+ *
+ * Returns 1 if the channel is full, 0 otherwise.
+ */
+int
+rchan_full(struct rchan_reader *reader)
+{
+ u32 buffers_ready;
+ struct rchan *rchan = reader->rchan;
+
+ if (mode_continuous(rchan))
+ return 0;
+
+ buffers_ready = rchan->bufs_produced - rchan->bufs_consumed;
+
+ return buffers_ready > reader->rchan->n_bufs - 1 ? 1 : 0;
+}
+
+/**
+ * relay_info - get status and other information about a relay channel
+ * @rchan_id: relay channel id
+ * @rchan_info: pointer to the rchan_info struct to be filled in
+ *
+ * Fills in an rchan_info struct with channel status and attribute
+ * information. See Documentation/filesystems/relayfs.txt for details.
+ *
+ * Returns 0 if successful, negative otherwise.
+ */
+int
+relay_info(int rchan_id, struct rchan_info *rchan_info)
+{
+ int i;
+ struct rchan *rchan;
+
+ rchan = rchan_get(rchan_id);
+ if (rchan == NULL)
+ return -EBADF;
+
+ rchan_info->flags = rchan->flags;
+ rchan_info->buf_size = rchan->buf_size;
+ rchan_info->buf_addr = rchan->buf;
+ rchan_info->alloc_size = rchan->alloc_size;
+ rchan_info->n_bufs = rchan->n_bufs;
+ rchan_info->bufs_produced = rchan->bufs_produced;
+ rchan_info->bufs_consumed = rchan->bufs_consumed;
+ rchan_info->buf_id = rchan->buf_id;
+
+ for (i = 0; i < rchan->n_bufs; i++) {
+ rchan_info->unused_bytes[i] = rchan->unused_bytes[i];
+ if (using_lockless(rchan))
+ rchan_info->buffer_complete[i] = (atomic_read(&fill_count(rchan, i)) == rchan->buf_size);
+ else
+ rchan_info->buffer_complete[i] = 0;
+ }
+
+ rchan_put(rchan);
+
+ return 0;
+}
+
+/**
+ * __add_rchan_reader - creates and adds a reader to a channel
+ * @rchan: relay channel
+ * @filp: the file associated with rchan, if applicable
+ * @auto_consume: boolean, whether reader's reads automatically consume
+ * @map_reader: boolean, whether reader's reading via a channel mapping
+ *
+ * Returns a pointer to the reader object create, NULL if unsuccessful
+ *
+ * Creates and initializes an rchan_reader object for reading the channel.
+ * If filp is non-NULL, the reader is a VFS reader, otherwise not.
+ *
+ * If the reader is a map reader, it isn't considered a VFS reader for
+ * our purposes. Also, map_readers can't be auto-consuming.
+ */
+struct rchan_reader *
+__add_rchan_reader(struct rchan *rchan, struct file *filp, int auto_consume, int map_reader)
+{
+ struct rchan_reader *reader;
+ u32 will_read;
+
+ reader = kmalloc(sizeof(struct rchan_reader), GFP_KERNEL);
+
+ if (reader) {
+ write_lock(&rchan->open_readers_lock);
+ reader->rchan = rchan;
+ if (filp) {
+ reader->vfs_reader = 1;
+ reader->pos.file = filp;
+ } else {
+ reader->vfs_reader = 0;
+ reader->pos.f_pos = 0;
+ }
+ reader->map_reader = map_reader;
+ reader->auto_consume = auto_consume;
+
+ if (!map_reader) {
+ will_read = rchan->bufs_produced % rchan->n_bufs;
+ if (!will_read && atomic_read(&rchan->suspended))
+ will_read = rchan->n_bufs;
+ reader->bufs_consumed = rchan->bufs_produced - will_read;
+ rchan->bufs_consumed = reader->bufs_consumed;
+ rchan->bytes_consumed = reader->bytes_consumed = 0;
+ reader->offset_changed = 0;
+ }
+
+ list_add(&reader->list, &rchan->open_readers);
+ write_unlock(&rchan->open_readers_lock);
+ }
+
+ return reader;
+}
+
+/**
+ * add_rchan_reader - create a reader for a channel
+ * @rchan_id: relay channel handle
+ * @auto_consume: boolean, whether reader's reads automatically consume
+ *
+ * Returns a pointer to the reader object created, NULL if unsuccessful
+ *
+ * Creates and initializes an rchan_reader object for reading the channel.
+ * This function is useful only for non-VFS readers.
+ */
+struct rchan_reader *
+add_rchan_reader(int rchan_id, int auto_consume)
+{
+ struct rchan *rchan = rchan_get(rchan_id);
+ if (rchan == NULL)
+ return NULL;
+
+ return __add_rchan_reader(rchan, NULL, auto_consume, 0);
+}
+
+/**
+ * add_map_reader - create a map reader for a channel
+ * @rchan_id: relay channel handle
+ *
+ * Returns a pointer to the reader object created, NULL if unsuccessful
+ *
+ * Creates and initializes an rchan_reader object for reading the channel.
+ * This function is useful only for map readers.
+ */
+struct rchan_reader *
+add_map_reader(int rchan_id)
+{
+ struct rchan *rchan = rchan_get(rchan_id);
+ if (rchan == NULL)
+ return NULL;
+
+ return __add_rchan_reader(rchan, NULL, 0, 1);
+}
+
+/**
+ * __remove_rchan_reader - destroy a channel reader
+ * @reader: channel reader
+ *
+ * Internal - removes reader from the open readers list, and frees it.
+ */
+void
+__remove_rchan_reader(struct rchan_reader *reader)
+{
+ struct list_head *p;
+ struct rchan_reader *found_reader = NULL;
+
+ write_lock(&reader->rchan->open_readers_lock);
+ list_for_each(p, &reader->rchan->open_readers) {
+ found_reader = list_entry(p, struct rchan_reader, list);
+ if (found_reader == reader) {
+ list_del(&found_reader->list);
+ break;
+ }
+ }
+ write_unlock(&reader->rchan->open_readers_lock);
+
+ if (found_reader)
+ kfree(found_reader);
+}
+
+/**
+ * remove_rchan_reader - destroy a channel reader
+ * @reader: channel reader
+ *
+ * Finds and removes the given reader from the channel. This function
+ * is useful only for non-VFS readers.
+ *
+ * Returns 0 if successful, negative otherwise.
+ */
+int
+remove_rchan_reader(struct rchan_reader *reader)
+{
+ int err = 0;
+
+ if (reader) {
+ rchan_put(reader->rchan);
+ __remove_rchan_reader(reader);
+ } else
+ err = -EINVAL;
+
+ return err;
+}
+
+/**
+ * remove_map_reader - destroy a map reader
+ * @reader: channel reader
+ *
+ * Finds and removes the given map reader from the channel. This function
+ * is useful only for map readers.
+ *
+ * Returns 0 if successful, negative otherwise.
+ */
+int
+remove_map_reader(struct rchan_reader *reader)
+{
+ return remove_rchan_reader(reader);
+}
+
+EXPORT_SYMBOL(relay_open);
+EXPORT_SYMBOL(relay_close);
+EXPORT_SYMBOL(relay_reset);
+EXPORT_SYMBOL(relay_reserve);
+EXPORT_SYMBOL(relay_commit);
+EXPORT_SYMBOL(relay_read);
+EXPORT_SYMBOL(relay_write);
+EXPORT_SYMBOL(relay_bytes_avail);
+EXPORT_SYMBOL(relay_buffers_consumed);
+EXPORT_SYMBOL(relay_bytes_consumed);
+EXPORT_SYMBOL(relay_info);
+
+
+
--
Regards,
Tom Zanussi <zanussi@us.ibm.com>
IBM Linux Technology Center/RAS
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