diff options
| -rw-r--r-- | fs/Kconfig | 12 | ||||
| -rw-r--r-- | fs/Makefile | 1 | ||||
| -rw-r--r-- | fs/relayfs/Makefile | 4 | ||||
| -rw-r--r-- | fs/relayfs/buffers.c | 190 | ||||
| -rw-r--r-- | fs/relayfs/buffers.h | 12 | ||||
| -rw-r--r-- | fs/relayfs/inode.c | 581 | ||||
| -rw-r--r-- | fs/relayfs/relay.c | 482 | ||||
| -rw-r--r-- | fs/relayfs/relay.h | 8 | ||||
| -rw-r--r-- | include/linux/relay.h | 281 | ||||
| -rw-r--r-- | init/Kconfig | 11 | ||||
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/relay.c | 919 |
12 files changed, 1212 insertions, 1290 deletions
diff --git a/fs/Kconfig b/fs/Kconfig index e9749b0eecd8..c8d0a209120c 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -859,18 +859,6 @@ config RAMFS To compile this as a module, choose M here: the module will be called ramfs. -config RELAYFS_FS - tristate "Relayfs file system support" - ---help--- - Relayfs is a high-speed data relay filesystem designed to provide - an efficient mechanism for tools and facilities to relay large - amounts of data from kernel space to user space. - - To compile this code as a module, choose M here: the module will be - called relayfs. - - If unsure, say N. - config CONFIGFS_FS tristate "Userspace-driven configuration filesystem (EXPERIMENTAL)" depends on EXPERIMENTAL diff --git a/fs/Makefile b/fs/Makefile index 1db711319c80..080b3867be4d 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -91,7 +91,6 @@ obj-$(CONFIG_AUTOFS4_FS) += autofs4/ obj-$(CONFIG_ADFS_FS) += adfs/ obj-$(CONFIG_FUSE_FS) += fuse/ obj-$(CONFIG_UDF_FS) += udf/ -obj-$(CONFIG_RELAYFS_FS) += relayfs/ obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/ obj-$(CONFIG_JFS_FS) += jfs/ obj-$(CONFIG_XFS_FS) += xfs/ diff --git a/fs/relayfs/Makefile b/fs/relayfs/Makefile deleted file mode 100644 index e76e182cdb38..000000000000 --- a/fs/relayfs/Makefile +++ /dev/null @@ -1,4 +0,0 @@ -obj-$(CONFIG_RELAYFS_FS) += relayfs.o - -relayfs-y := relay.o inode.o buffers.o - diff --git a/fs/relayfs/buffers.c b/fs/relayfs/buffers.c deleted file mode 100644 index 10187812771e..000000000000 --- a/fs/relayfs/buffers.c +++ /dev/null @@ -1,190 +0,0 @@ -/* - * RelayFS buffer management code. - * - * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp - * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) - * - * This file is released under the GPL. - */ - -#include <linux/module.h> -#include <linux/vmalloc.h> -#include <linux/mm.h> -#include <linux/relayfs_fs.h> -#include "relay.h" -#include "buffers.h" - -/* - * close() vm_op implementation for relayfs file mapping. - */ -static void relay_file_mmap_close(struct vm_area_struct *vma) -{ - struct rchan_buf *buf = vma->vm_private_data; - buf->chan->cb->buf_unmapped(buf, vma->vm_file); -} - -/* - * nopage() vm_op implementation for relayfs file mapping. - */ -static struct page *relay_buf_nopage(struct vm_area_struct *vma, - unsigned long address, - int *type) -{ - struct page *page; - struct rchan_buf *buf = vma->vm_private_data; - unsigned long offset = address - vma->vm_start; - - if (address > vma->vm_end) - return NOPAGE_SIGBUS; /* Disallow mremap */ - if (!buf) - return NOPAGE_OOM; - - page = vmalloc_to_page(buf->start + offset); - if (!page) - return NOPAGE_OOM; - get_page(page); - - if (type) - *type = VM_FAULT_MINOR; - - return page; -} - -/* - * vm_ops for relay file mappings. - */ -static struct vm_operations_struct relay_file_mmap_ops = { - .nopage = relay_buf_nopage, - .close = relay_file_mmap_close, -}; - -/** - * relay_mmap_buf: - mmap channel buffer to process address space - * @buf: relay channel buffer - * @vma: vm_area_struct describing memory to be mapped - * - * Returns 0 if ok, negative on error - * - * Caller should already have grabbed mmap_sem. - */ -int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) -{ - unsigned long length = vma->vm_end - vma->vm_start; - struct file *filp = vma->vm_file; - - if (!buf) - return -EBADF; - - if (length != (unsigned long)buf->chan->alloc_size) - return -EINVAL; - - vma->vm_ops = &relay_file_mmap_ops; - vma->vm_private_data = buf; - buf->chan->cb->buf_mapped(buf, filp); - - return 0; -} - -/** - * relay_alloc_buf - allocate a channel buffer - * @buf: the buffer struct - * @size: total size of the buffer - * - * Returns a pointer to the resulting buffer, NULL if unsuccessful - */ -static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size) -{ - void *mem; - unsigned int i, j, n_pages; - - size = PAGE_ALIGN(size); - n_pages = size >> PAGE_SHIFT; - - buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL); - if (!buf->page_array) - return NULL; - - for (i = 0; i < n_pages; i++) { - buf->page_array[i] = alloc_page(GFP_KERNEL); - if (unlikely(!buf->page_array[i])) - goto depopulate; - } - mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); - if (!mem) - goto depopulate; - - memset(mem, 0, size); - buf->page_count = n_pages; - return mem; - -depopulate: - for (j = 0; j < i; j++) - __free_page(buf->page_array[j]); - kfree(buf->page_array); - return NULL; -} - -/** - * relay_create_buf - allocate and initialize a channel buffer - * @alloc_size: size of the buffer to allocate - * @n_subbufs: number of sub-buffers in the channel - * - * Returns channel buffer if successful, NULL otherwise - */ -struct rchan_buf *relay_create_buf(struct rchan *chan) -{ - struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL); - if (!buf) - return NULL; - - buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); - if (!buf->padding) - goto free_buf; - - buf->start = relay_alloc_buf(buf, chan->alloc_size); - if (!buf->start) - goto free_buf; - - buf->chan = chan; - kref_get(&buf->chan->kref); - return buf; - -free_buf: - kfree(buf->padding); - kfree(buf); - return NULL; -} - -/** - * relay_destroy_buf - destroy an rchan_buf struct and associated buffer - * @buf: the buffer struct - */ -void relay_destroy_buf(struct rchan_buf *buf) -{ - struct rchan *chan = buf->chan; - unsigned int i; - - if (likely(buf->start)) { - vunmap(buf->start); - for (i = 0; i < buf->page_count; i++) - __free_page(buf->page_array[i]); - kfree(buf->page_array); - } - kfree(buf->padding); - kfree(buf); - kref_put(&chan->kref, relay_destroy_channel); -} - -/** - * relay_remove_buf - remove a channel buffer - * - * Removes the file from the relayfs fileystem, which also frees the - * rchan_buf_struct and the channel buffer. Should only be called from - * kref_put(). - */ -void relay_remove_buf(struct kref *kref) -{ - struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); - buf->chan->cb->remove_buf_file(buf->dentry); - relay_destroy_buf(buf); -} diff --git a/fs/relayfs/buffers.h b/fs/relayfs/buffers.h deleted file mode 100644 index 37a12493f641..000000000000 --- a/fs/relayfs/buffers.h +++ /dev/null @@ -1,12 +0,0 @@ -#ifndef _BUFFERS_H -#define _BUFFERS_H - -/* This inspired by rtai/shmem */ -#define FIX_SIZE(x) (((x) - 1) & PAGE_MASK) + PAGE_SIZE - -extern int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma); -extern struct rchan_buf *relay_create_buf(struct rchan *chan); -extern void relay_destroy_buf(struct rchan_buf *buf); -extern void relay_remove_buf(struct kref *kref); - -#endif/* _BUFFERS_H */ diff --git a/fs/relayfs/inode.c b/fs/relayfs/inode.c deleted file mode 100644 index 383523011aad..000000000000 --- a/fs/relayfs/inode.c +++ /dev/null @@ -1,581 +0,0 @@ -/* - * VFS-related code for RelayFS, a high-speed data relay filesystem. - * - * Copyright (C) 2003-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp - * Copyright (C) 2003-2005 - Karim Yaghmour <karim@opersys.com> - * - * Based on ramfs, Copyright (C) 2002 - Linus Torvalds - * - * This file is released under the GPL. - */ - -#include <linux/module.h> -#include <linux/fs.h> -#include <linux/mount.h> -#include <linux/pagemap.h> -#include <linux/init.h> -#include <linux/string.h> -#include <linux/backing-dev.h> -#include <linux/namei.h> -#include <linux/poll.h> -#include <linux/relayfs_fs.h> -#include "relay.h" -#include "buffers.h" - -#define RELAYFS_MAGIC 0xF0B4A981 - -static struct vfsmount * relayfs_mount; -static int relayfs_mount_count; - -static struct backing_dev_info relayfs_backing_dev_info = { - .ra_pages = 0, /* No readahead */ - .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, -}; - -static struct inode *relayfs_get_inode(struct super_block *sb, - int mode, - struct file_operations *fops, - void *data) -{ - struct inode *inode; - - inode = new_inode(sb); - if (!inode) - return NULL; - - inode->i_mode = mode; - inode->i_uid = 0; - inode->i_gid = 0; - inode->i_blksize = PAGE_CACHE_SIZE; - inode->i_blocks = 0; - inode->i_mapping->backing_dev_info = &relayfs_backing_dev_info; - inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; - switch (mode & S_IFMT) { - case S_IFREG: - inode->i_fop = fops; - if (data) - inode->u.generic_ip = data; - break; - case S_IFDIR: - inode->i_op = &simple_dir_inode_operations; - inode->i_fop = &simple_dir_operations; - - /* directory inodes start off with i_nlink == 2 (for "." entry) */ - inode->i_nlink++; - break; - default: - break; - } - - return inode; -} - -/** - * relayfs_create_entry - create a relayfs directory or file - * @name: the name of the file to create - * @parent: parent directory - * @mode: mode - * @fops: file operations to use for the file - * @data: user-associated data for this file - * - * Returns the new dentry, NULL on failure - * - * Creates a file or directory with the specifed permissions. - */ -static struct dentry *relayfs_create_entry(const char *name, - struct dentry *parent, - int mode, - struct file_operations *fops, - void *data) -{ - struct dentry *d; - struct inode *inode; - int error = 0; - - BUG_ON(!name || !(S_ISREG(mode) || S_ISDIR(mode))); - - error = simple_pin_fs("relayfs", &relayfs_mount, &relayfs_mount_count); - if (error) { - printk(KERN_ERR "Couldn't mount relayfs: errcode %d\n", error); - return NULL; - } - - if (!parent && relayfs_mount && relayfs_mount->mnt_sb) - parent = relayfs_mount->mnt_sb->s_root; - - if (!parent) { - simple_release_fs(&relayfs_mount, &relayfs_mount_count); - return NULL; - } - - parent = dget(parent); - mutex_lock(&parent->d_inode->i_mutex); - d = lookup_one_len(name, parent, strlen(name)); - if (IS_ERR(d)) { - d = NULL; - goto release_mount; - } - - if (d->d_inode) { - d = NULL; - goto release_mount; - } - - inode = relayfs_get_inode(parent->d_inode->i_sb, mode, fops, data); - if (!inode) { - d = NULL; - goto release_mount; - } - - d_instantiate(d, inode); - dget(d); /* Extra count - pin the dentry in core */ - - if (S_ISDIR(mode)) - parent->d_inode->i_nlink++; - - goto exit; - -release_mount: - simple_release_fs(&relayfs_mount, &relayfs_mount_count); - -exit: - mutex_unlock(&parent->d_inode->i_mutex); - dput(parent); - return d; -} - -/** - * relayfs_create_file - create a file in the relay filesystem - * @name: the name of the file to create - * @parent: parent directory - * @mode: mode, if not specied the default perms are used - * @fops: file operations to use for the file - * @data: user-associated data for this file - * - * Returns file dentry if successful, NULL otherwise. - * - * The file will be created user r on behalf of current user. - */ -struct dentry *relayfs_create_file(const char *name, - struct dentry *parent, - int mode, - struct file_operations *fops, - void *data) -{ - BUG_ON(!fops); - - if (!mode) - mode = S_IRUSR; - mode = (mode & S_IALLUGO) | S_IFREG; - - return relayfs_create_entry(name, parent, mode, fops, data); -} - -/** - * relayfs_create_dir - create a directory in the relay filesystem - * @name: the name of the directory to create - * @parent: parent directory, NULL if parent should be fs root - * - * Returns directory dentry if successful, NULL otherwise. - * - * The directory will be created world rwx on behalf of current user. - */ -struct dentry *relayfs_create_dir(const char *name, struct dentry *parent) -{ - int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; - return relayfs_create_entry(name, parent, mode, NULL, NULL); -} - -/** - * relayfs_remove - remove a file or directory in the relay filesystem - * @dentry: file or directory dentry - * - * Returns 0 if successful, negative otherwise. - */ -int relayfs_remove(struct dentry *dentry) -{ - struct dentry *parent; - int error = 0; - - if (!dentry) - return -EINVAL; - parent = dentry->d_parent; - if (!parent) - return -EINVAL; - - parent = dget(parent); - mutex_lock(&parent->d_inode->i_mutex); - if (dentry->d_inode) { - if (S_ISDIR(dentry->d_inode->i_mode)) - error = simple_rmdir(parent->d_inode, dentry); - else - error = simple_unlink(parent->d_inode, dentry); - if (!error) - d_delete(dentry); - } - if (!error) - dput(dentry); - mutex_unlock(&parent->d_inode->i_mutex); - dput(parent); - - if (!error) - simple_release_fs(&relayfs_mount, &relayfs_mount_count); - - return error; -} - -/** - * relayfs_remove_file - remove a file from relay filesystem - * @dentry: directory dentry - * - * Returns 0 if successful, negative otherwise. - */ -int relayfs_remove_file(struct dentry *dentry) -{ - return relayfs_remove(dentry); -} - -/** - * relayfs_remove_dir - remove a directory in the relay filesystem - * @dentry: directory dentry - * - * Returns 0 if successful, negative otherwise. - */ -int relayfs_remove_dir(struct dentry *dentry) -{ - return relayfs_remove(dentry); -} - -/** - * relay_file_open - open file op for relay files - * @inode: the inode - * @filp: the file - * - * Increments the channel buffer refcount. - */ -static int relay_file_open(struct inode *inode, struct file *filp) -{ - struct rchan_buf *buf = inode->u.generic_ip; - kref_get(&buf->kref); - filp->private_data = buf; - - return 0; -} - -/** - * relay_file_mmap - mmap file op for relay files - * @filp: the file - * @vma: the vma describing what to map - * - * Calls upon relay_mmap_buf to map the file into user space. - */ -static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) -{ - struct rchan_buf *buf = filp->private_data; - return relay_mmap_buf(buf, vma); -} - -/** - * relay_file_poll - poll file op for relay files - * @filp: the file - * @wait: poll table - * - * Poll implemention. - */ -static unsigned int relay_file_poll(struct file *filp, poll_table *wait) -{ - unsigned int mask = 0; - struct rchan_buf *buf = filp->private_data; - - if (buf->finalized) - return POLLERR; - - if (filp->f_mode & FMODE_READ) { - poll_wait(filp, &buf->read_wait, wait); - if (!relay_buf_empty(buf)) - mask |= POLLIN | POLLRDNORM; - } - - return mask; -} - -/** - * relay_file_release - release file op for relay files - * @inode: the inode - * @filp: the file - * - * Decrements the channel refcount, as the filesystem is - * no longer using it. - */ -static int relay_file_release(struct inode *inode, struct file *filp) -{ - struct rchan_buf *buf = filp->private_data; - kref_put(&buf->kref, relay_remove_buf); - - return 0; -} - -/** - * relay_file_read_consume - update the consumed count for the buffer - */ -static void relay_file_read_consume(struct rchan_buf *buf, - size_t read_pos, - size_t bytes_consumed) -{ - size_t subbuf_size = buf->chan->subbuf_size; - size_t n_subbufs = buf->chan->n_subbufs; - size_t read_subbuf; - - if (buf->bytes_consumed + bytes_consumed > subbuf_size) { - relay_subbufs_consumed(buf->chan, buf->cpu, 1); - buf->bytes_consumed = 0; - } - - buf->bytes_consumed += bytes_consumed; - read_subbuf = read_pos / buf->chan->subbuf_size; - if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { - if ((read_subbuf == buf->subbufs_produced % n_subbufs) && - (buf->offset == subbuf_size)) - return; - relay_subbufs_consumed(buf->chan, buf->cpu, 1); - buf->bytes_consumed = 0; - } -} - -/** - * relay_file_read_avail - boolean, are there unconsumed bytes available? - */ -static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) -{ - size_t bytes_produced, bytes_consumed, write_offset; - size_t subbuf_size = buf->chan->subbuf_size; - size_t n_subbufs = buf->chan->n_subbufs; - size_t produced = buf->subbufs_produced % n_subbufs; - size_t consumed = buf->subbufs_consumed % n_subbufs; - - write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; - - if (consumed > produced) { - if ((produced > n_subbufs) && - (produced + n_subbufs - consumed <= n_subbufs)) - produced += n_subbufs; - } else if (consumed == produced) { - if (buf->offset > subbuf_size) { - produced += n_subbufs; - if (buf->subbufs_produced == buf->subbufs_consumed) - consumed += n_subbufs; - } - } - - if (buf->offset > subbuf_size) - bytes_produced = (produced - 1) * subbuf_size + write_offset; - else - bytes_produced = produced * subbuf_size + write_offset; - bytes_consumed = consumed * subbuf_size + buf->bytes_consumed; - - if (bytes_produced == bytes_consumed) - return 0; - - relay_file_read_consume(buf, read_pos, 0); - - return 1; -} - -/** - * relay_file_read_subbuf_avail - return bytes available in sub-buffer - */ -static size_t relay_file_read_subbuf_avail(size_t read_pos, - struct rchan_buf *buf) -{ - size_t padding, avail = 0; - size_t read_subbuf, read_offset, write_subbuf, write_offset; - size_t subbuf_size = buf->chan->subbuf_size; - - write_subbuf = (buf->data - buf->start) / subbuf_size; - write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; - read_subbuf = read_pos / subbuf_size; - read_offset = read_pos % subbuf_size; - padding = buf->padding[read_subbuf]; - - if (read_subbuf == write_subbuf) { - if (read_offset + padding < write_offset) - avail = write_offset - (read_offset + padding); - } else - avail = (subbuf_size - padding) - read_offset; - - return avail; -} - -/** - * relay_file_read_start_pos - find the first available byte to read - * - * If the read_pos is in the middle of padding, return the - * position of the first actually available byte, otherwise - * return the original value. - */ -static size_t relay_file_read_start_pos(size_t read_pos, - struct rchan_buf *buf) -{ - size_t read_subbuf, padding, padding_start, padding_end; - size_t subbuf_size = buf->chan->subbuf_size; - size_t n_subbufs = buf->chan->n_subbufs; - - read_subbuf = read_pos / subbuf_size; - padding = buf->padding[read_subbuf]; - padding_start = (read_subbuf + 1) * subbuf_size - padding; - padding_end = (read_subbuf + 1) * subbuf_size; - if (read_pos >= padding_start && read_pos < padding_end) { - read_subbuf = (read_subbuf + 1) % n_subbufs; - read_pos = read_subbuf * subbuf_size; - } - - return read_pos; -} - -/** - * relay_file_read_end_pos - return the new read position - */ -static size_t relay_file_read_end_pos(struct rchan_buf *buf, - size_t read_pos, - size_t count) -{ - size_t read_subbuf, padding, end_pos; - size_t subbuf_size = buf->chan->subbuf_size; - size_t n_subbufs = buf->chan->n_subbufs; - - read_subbuf = read_pos / subbuf_size; - padding = buf->padding[read_subbuf]; - if (read_pos % subbuf_size + count + padding == subbuf_size) - end_pos = (read_subbuf + 1) * subbuf_size; - else - end_pos = read_pos + count; - if (end_pos >= subbuf_size * n_subbufs) - end_pos = 0; - - return end_pos; -} - -/** - * relay_file_read - read file op for relay files - * @filp: the file - * @buffer: the userspace buffer - * @count: number of bytes to read - * @ppos: position to read from - * - * Reads count bytes or the number of bytes available in the - * current sub-buffer being read, whichever is smaller. - */ -static ssize_t relay_file_read(struct file *filp, - char __user *buffer, - size_t count, - loff_t *ppos) -{ - struct rchan_buf *buf = filp->private_data; - struct inode *inode = filp->f_dentry->d_inode; - size_t read_start, avail; - ssize_t ret = 0; - void *from; - - mutex_lock(&inode->i_mutex); - if(!relay_file_read_avail(buf, *ppos)) - goto out; - - read_start = relay_file_read_start_pos(*ppos, buf); - avail = relay_file_read_subbuf_avail(read_start, buf); - if (!avail) - goto out; - - from = buf->start + read_start; - ret = count = min(count, avail); - if (copy_to_user(buffer, from, count)) { - ret = -EFAULT; - goto out; - } - relay_file_read_consume(buf, read_start, count); - *ppos = relay_file_read_end_pos(buf, read_start, count); -out: - mutex_unlock(&inode->i_mutex); - return ret; -} - -struct file_operations relay_file_operations = { - .open = relay_file_open, - .poll = relay_file_poll, - .mmap = relay_file_mmap, - .read = relay_file_read, - .llseek = no_llseek, - .release = relay_file_release, -}; - -static struct super_operations relayfs_ops = { - .statfs = simple_statfs, - .drop_inode = generic_delete_inode, -}; - -static int relayfs_fill_super(struct super_block * sb, void * data, int silent) -{ - struct inode *inode; - struct dentry *root; - int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; - - sb->s_blocksize = PAGE_CACHE_SIZE; - sb->s_blocksize_bits = PAGE_CACHE_SHIFT; - sb->s_magic = RELAYFS_MAGIC; - sb->s_op = &relayfs_ops; - inode = relayfs_get_inode(sb, mode, NULL, NULL); - - if (!inode) - return -ENOMEM; - - root = d_alloc_root(inode); - if (!root) { - iput(inode); - return -ENOMEM; - } - sb->s_root = root; - - return 0; -} - -static struct super_block * relayfs_get_sb(struct file_system_type *fs_type, - int flags, const char *dev_name, - void *data) -{ - return get_sb_single(fs_type, flags, data, relayfs_fill_super); -} - -static struct file_system_type relayfs_fs_type = { - .owner = THIS_MODULE, - .name = "relayfs", - .get_sb = relayfs_get_sb, - .kill_sb = kill_litter_super, -}; - -static int __init init_relayfs_fs(void) -{ - return register_filesystem(&relayfs_fs_type); -} - -static void __exit exit_relayfs_fs(void) -{ - - - - - - unregister_filesystem(&relayfs_fs_type); -} - -module_init(init_relayfs_fs) -module_exit(exit_relayfs_fs) - -EXPORT_SYMBOL_GPL(relay_file_operations); -EXPORT_SYMBOL_GPL(relayfs_create_dir); -EXPORT_SYMBOL_GPL(relayfs_remove_dir); -EXPORT_SYMBOL_GPL(relayfs_create_file); -EXPORT_SYMBOL_GPL(relayfs_remove_file); - -MODULE_AUTHOR("Tom Zanussi <zanussi@us.ibm.com> and Karim Yaghmour <karim@opersys.com>"); -MODULE_DESCRIPTION("Relay Filesystem"); -MODULE_LICENSE("GPL"); - diff --git a/fs/relayfs/relay.c b/fs/relayfs/relay.c deleted file mode 100644 index abf3ceaace49..000000000000 --- a/fs/relayfs/relay.c +++ /dev/null @@ -1,482 +0,0 @@ -/* - * Public API and common code for RelayFS. - * - * See Documentation/filesystems/relayfs.txt for an overview of relayfs. - * - * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp - * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) - * - * This file is released under the GPL. - */ - -#include <linux/errno.h> -#include <linux/stddef.h> -#include <linux/slab.h> -#include <linux/module.h> -#include <linux/string.h> -#include <linux/relayfs_fs.h> -#include "relay.h" -#include "buffers.h" - -/** - * relay_buf_empty - boolean, is the channel buffer empty? - * @buf: channel buffer - * - * Returns 1 if the buffer is empty, 0 otherwise. - */ -int relay_buf_empty(struct rchan_buf *buf) -{ - return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; -} - -/** - * relay_buf_full - boolean, is the channel buffer full? - * @buf: channel buffer - * - * Returns 1 if the buffer is full, 0 otherwise. - */ -int relay_buf_full(struct rchan_buf *buf) -{ - size_t ready = buf->subbufs_produced - buf->subbufs_consumed; - return (ready >= buf->chan->n_subbufs) ? 1 : 0; -} - -/* - * High-level relayfs kernel API and associated functions. - */ - -/* - * rchan_callback implementations defining default channel behavior. Used - * in place of corresponding NULL values in client callback struct. - */ - -/* - * subbuf_start() default callback. Does nothing. - */ -static int subbuf_start_default_callback (struct rchan_buf *buf, - void *subbuf, - void *prev_subbuf, - size_t prev_padding) -{ - if (relay_buf_full(buf)) - return 0; - - return 1; -} - -/* - * buf_mapped() default callback. Does nothing. - */ -static void buf_mapped_default_callback(struct rchan_buf *buf, - struct file *filp) -{ -} - -/* - * buf_unmapped() default callback. Does nothing. - */ -static void buf_unmapped_default_callback(struct rchan_buf *buf, - struct file *filp) -{ -} - -/* - * create_buf_file_create() default callback. Creates file to represent buf. - */ -static struct dentry *create_buf_file_default_callback(const char *filename, - struct dentry *parent, - int mode, - struct rchan_buf *buf, - int *is_global) -{ - return relayfs_create_file(filename, parent, mode, - &relay_file_operations, buf); -} - -/* - * remove_buf_file() default callback. Removes file representing relay buffer. - */ -static int remove_buf_file_default_callback(struct dentry *dentry) -{ - return relayfs_remove(dentry); -} - -/* relay channel default callbacks */ -static struct rchan_callbacks default_channel_callbacks = { - .subbuf_start = subbuf_start_default_callback, - .buf_mapped = buf_mapped_default_callback, - .buf_unmapped = buf_unmapped_default_callback, - .create_buf_file = create_buf_file_default_callback, - .remove_buf_file = remove_buf_file_default_callback, -}; - -/** - * wakeup_readers - wake up readers waiting on a channel - * @private: the channel buffer - * - * This is the work function used to defer reader waking. The - * reason waking is deferred is that calling directly from write - * causes problems if you're writing from say the scheduler. - */ -static void wakeup_readers(void *private) -{ - struct rchan_buf *buf = private; - wake_up_interruptible(&buf->read_wait); -} - -/** - * __relay_reset - reset a channel buffer - * @buf: the channel buffer - * @init: 1 if this is a first-time initialization - * - * See relay_reset for description of effect. - */ -static inline void __relay_reset(struct rchan_buf *buf, unsigned int init) -{ - size_t i; - - if (init) { - init_waitqueue_head(&buf->read_wait); - kref_init(&buf->kref); - INIT_WORK(&buf->wake_readers, NULL, NULL); - } else { - cancel_delayed_work(&buf->wake_readers); - flush_scheduled_work(); - } - - buf->subbufs_produced = 0; - buf->subbufs_consumed = 0; - buf->bytes_consumed = 0; - buf->finalized = 0; - buf->data = buf->start; - buf->offset = 0; - - for (i = 0; i < buf->chan->n_subbufs; i++) - buf->padding[i] = 0; - - buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); -} - -/** - * relay_reset - reset the channel - * @chan: the channel - * - * This has the effect of erasing all data from all channel buffers - * and restarting the channel in its initial state. The buffers - * are not freed, so any mappings are still in effect. - * - * NOTE: Care should be taken that the channel isn't actually - * being used by anything when this call is made. - */ -void relay_reset(struct rchan *chan) -{ - unsigned int i; - struct rchan_buf *prev = NULL; - - if (!chan) - return; - - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i] || chan->buf[i] == prev) - break; - __relay_reset(chan->buf[i], 0); - prev = chan->buf[i]; - } -} - -/** - * relay_open_buf - create a new channel buffer in relayfs - * - * Internal - used by relay_open(). - */ -static struct rchan_buf *relay_open_buf(struct rchan *chan, - const char *filename, - struct dentry *parent, - int *is_global) -{ - struct rchan_buf *buf; - struct dentry *dentry; - - if (*is_global) - return chan->buf[0]; - - buf = relay_create_buf(chan); - if (!buf) - return NULL; - - /* Create file in fs */ - dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR, - buf, is_global); - if (!dentry) { - relay_destroy_buf(buf); - return NULL; - } - - buf->dentry = dentry; - __relay_reset(buf, 1); - - return buf; -} - -/** - * relay_close_buf - close a channel buffer - * @buf: channel buffer - * - * Marks the buffer finalized and restores the default callbacks. - * The channel buffer and channel buffer data structure are then freed - * automatically when the last reference is given up. - */ -static inline void relay_close_buf(struct rchan_buf *buf) -{ - buf->finalized = 1; - buf->chan->cb = &default_channel_callbacks; - cancel_delayed_work(&buf->wake_readers); - flush_scheduled_work(); - kref_put(&buf->kref, relay_remove_buf); -} - -static inline void setup_callbacks(struct rchan *chan, - struct rchan_callbacks *cb) -{ - if (!cb) { - chan->cb = &default_channel_callbacks; - return; - } - - if (!cb->subbuf_start) - cb->subbuf_start = subbuf_start_default_callback; - if (!cb->buf_mapped) - cb->buf_mapped = buf_mapped_default_callback; - if (!cb->buf_unmapped) - cb->buf_unmapped = buf_unmapped_default_callback; - if (!cb->create_buf_file) - cb->create_buf_file = create_buf_file_default_callback; - if (!cb->remove_buf_file) - cb->remove_buf_file = remove_buf_file_default_callback; - chan->cb = cb; -} - -/** - * relay_open - create a new relayfs channel - * @base_filename: base name of files to create - * @parent: dentry of parent directory, NULL for root directory - * @subbuf_size: size of sub-buffers - * @n_subbufs: number of sub-buffers - * @cb: client callback functions - * - * Returns channel pointer if successful, NULL otherwise. - * - * Creates a channel buffer for each cpu using the sizes and - * attributes specified. The created channel buffer files - * will be named base_filename0...base_filenameN-1. File - * permissions will be S_IRUSR. - */ -struct rchan *relay_open(const char *base_filename, - struct dentry *parent, - size_t subbuf_size, - size_t n_subbufs, - struct rchan_callbacks *cb) -{ - unsigned int i; - struct rchan *chan; - char *tmpname; - int is_global = 0; - - if (!base_filename) - return NULL; - - if (!(subbuf_size && n_subbufs)) - return NULL; - - chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL); - if (!chan) - return NULL; - - chan->version = RELAYFS_CHANNEL_VERSION; - chan->n_subbufs = n_subbufs; - chan->subbuf_size = subbuf_size; - chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); - setup_callbacks(chan, cb); - kref_init(&chan->kref); - - tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL); - if (!tmpname) - goto free_chan; - - for_each_online_cpu(i) { - sprintf(tmpname, "%s%d", base_filename, i); - chan->buf[i] = relay_open_buf(chan, tmpname, parent, - &is_global); - chan->buf[i]->cpu = i; - if (!chan->buf[i]) - goto free_bufs; - } - - kfree(tmpname); - return chan; - -free_bufs: - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i]) - break; - relay_close_buf(chan->buf[i]); - if (is_global) - break; - } - kfree(tmpname); - -free_chan: - kref_put(&chan->kref, relay_destroy_channel); - return NULL; -} - -/** - * relay_switch_subbuf - switch to a new sub-buffer - * @buf: channel buffer - * @length: size of current event - * - * Returns either the length passed in or 0 if full. - - * Performs sub-buffer-switch tasks such as invoking callbacks, - * updating padding counts, waking up readers, etc. - */ -size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) -{ - void *old, *new; - size_t old_subbuf, new_subbuf; - - if (unlikely(length > buf->chan->subbuf_size)) - goto toobig; - - if (buf->offset != buf->chan->subbuf_size + 1) { - buf->prev_padding = buf->chan->subbuf_size - buf->offset; - old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; - buf->padding[old_subbuf] = buf->prev_padding; - buf->subbufs_produced++; - if (waitqueue_active(&buf->read_wait)) { - PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf); - schedule_delayed_work(&buf->wake_readers, 1); - } - } - - old = buf->data; - new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; - new = buf->start + new_subbuf * buf->chan->subbuf_size; - buf->offset = 0; - if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { - buf->offset = buf->chan->subbuf_size + 1; - return 0; - } - buf->data = new; - buf->padding[new_subbuf] = 0; - - if (unlikely(length + buf->offset > buf->chan->subbuf_size)) - goto toobig; - - return length; - -toobig: - buf->chan->last_toobig = length; - return 0; -} - -/** - * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count - * @chan: the channel - * @cpu: the cpu associated with the channel buffer to update - * @subbufs_consumed: number of sub-buffers to add to current buf's count - * - * Adds to the channel buffer's consumed sub-buffer count. - * subbufs_consumed should be the number of sub-buffers newly consumed, - * not the total consumed. - * - * NOTE: kernel clients don't need to call this function if the channel - * mode is 'overwrite'. - */ -void relay_subbufs_consumed(struct rchan *chan, - unsigned int cpu, - size_t subbufs_consumed) -{ - struct rchan_buf *buf; - - if (!chan) - return; - - if (cpu >= NR_CPUS || !chan->buf[cpu]) - return; - - buf = chan->buf[cpu]; - buf->subbufs_consumed += subbufs_consumed; - if (buf->subbufs_consumed > buf->subbufs_produced) - buf->subbufs_consumed = buf->subbufs_produced; -} - -/** - * relay_destroy_channel - free the channel struct - * - * Should only be called from kref_put(). - */ -void relay_destroy_channel(struct kref *kref) -{ - struct rchan *chan = container_of(kref, struct rchan, kref); - kfree(chan); -} - -/** - * relay_close - close the channel - * @chan: the channel - * - * Closes all channel buffers and frees the channel. - */ -void relay_close(struct rchan *chan) -{ - unsigned int i; - struct rchan_buf *prev = NULL; - - if (!chan) - return; - - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i] || chan->buf[i] == prev) - break; - relay_close_buf(chan->buf[i]); - prev = chan->buf[i]; - } - - if (chan->last_toobig) - printk(KERN_WARNING "relayfs: one or more items not logged " - "[item size (%Zd) > sub-buffer size (%Zd)]\n", - chan->last_toobig, chan->subbuf_size); - - kref_put(&chan->kref, relay_destroy_channel); -} - -/** - * relay_flush - close the channel - * @chan: the channel - * - * Flushes all channel buffers i.e. forces buffer switch. - */ -void relay_flush(struct rchan *chan) -{ - unsigned int i; - struct rchan_buf *prev = NULL; - - if (!chan) - return; - - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i] || chan->buf[i] == prev) - break; - relay_switch_subbuf(chan->buf[i], 0); - prev = chan->buf[i]; - } -} - -EXPORT_SYMBOL_GPL(relay_open); -EXPORT_SYMBOL_GPL(relay_close); -EXPORT_SYMBOL_GPL(relay_flush); -EXPORT_SYMBOL_GPL(relay_reset); -EXPORT_SYMBOL_GPL(relay_subbufs_consumed); -EXPORT_SYMBOL_GPL(relay_switch_subbuf); -EXPORT_SYMBOL_GPL(relay_buf_full); diff --git a/fs/relayfs/relay.h b/fs/relayfs/relay.h deleted file mode 100644 index 0993d3e5753b..000000000000 --- a/fs/relayfs/relay.h +++ /dev/null @@ -1,8 +0,0 @@ -#ifndef _RELAY_H -#define _RELAY_H - -extern int relayfs_remove(struct dentry *dentry); -extern int relay_buf_empty(struct rchan_buf *buf); -extern void relay_destroy_channel(struct kref *kref); - -#endif /* _RELAY_H */ diff --git a/include/linux/relay.h b/include/linux/relay.h new file mode 100644 index 000000000000..4bcc1531d6a9 --- /dev/null +++ b/include/linux/relay.h @@ -0,0 +1,281 @@ +/* + * linux/include/linux/relay.h + * + * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp + * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com) + * + * CONFIG_RELAY definitions and declarations + */ + +#ifndef _LINUX_RELAY_H +#define _LINUX_RELAY_H + +#include <linux/config.h> +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/wait.h> +#include <linux/list.h> +#include <linux/fs.h> +#include <linux/poll.h> +#include <linux/kref.h> + +/* Needs a _much_ better name... */ +#define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE) + +/* + * Tracks changes to rchan/rchan_buf structs + */ +#define RELAYFS_CHANNEL_VERSION 6 + +/* + * Per-cpu relay channel buffer + */ +struct rchan_buf +{ + void *start; /* start of channel buffer */ + void *data; /* start of current sub-buffer */ + size_t offset; /* current offset into sub-buffer */ + size_t subbufs_produced; /* count of sub-buffers produced */ + size_t subbufs_consumed; /* count of sub-buffers consumed */ + struct rchan *chan; /* associated channel */ + wait_queue_head_t read_wait; /* reader wait queue */ + struct work_struct wake_readers; /* reader wake-up work struct */ + struct dentry *dentry; /* channel file dentry */ + struct kref kref; /* channel buffer refcount */ + struct page **page_array; /* array of current buffer pages */ + unsigned int page_count; /* number of current buffer pages */ + unsigned int finalized; /* buffer has been finalized */ + size_t *padding; /* padding counts per sub-buffer */ + size_t prev_padding; /* temporary variable */ + size_t bytes_consumed; /* bytes consumed in cur read subbuf */ + unsigned int cpu; /* this buf's cpu */ +} ____cacheline_aligned; + +/* + * Relay channel data structure + */ +struct rchan +{ + u32 version; /* the version of this struct */ + size_t subbuf_size; /* sub-buffer size */ + size_t n_subbufs; /* number of sub-buffers per buffer */ + size_t alloc_size; /* total buffer size allocated */ + struct rchan_callbacks *cb; /* client callbacks */ + struct kref kref; /* channel refcount */ + void *private_data; /* for user-defined data */ + size_t last_toobig; /* tried to log event > subbuf size */ + struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */ +}; + +/* + * Relay channel client callbacks + */ +struct rchan_callbacks +{ + /* + * subbuf_start - called on buffer-switch to a new sub-buffer + * @buf: the channel buffer containing the new sub-buffer + * @subbuf: the start of the new sub-buffer + * @prev_subbuf: the start of the previous sub-buffer + * @prev_padding: unused space at the end of previous sub-buffer + * + * The client should return 1 to continue logging, 0 to stop + * logging. + * + * NOTE: subbuf_start will also be invoked when the buffer is + * created, so that the first sub-buffer can be initialized + * if necessary. In this case, prev_subbuf will be NULL. + * + * NOTE: the client can reserve bytes at the beginning of the new + * sub-buffer by calling subbuf_start_reserve() in this callback. + */ + int (*subbuf_start) (struct rchan_buf *buf, + void *subbuf, + void *prev_subbuf, + size_t prev_padding); + + /* + * buf_mapped - relay buffer mmap notification + * @buf: the channel buffer + * @filp: relay file pointer + * + * Called when a relay file is successfully mmapped + */ + void (*buf_mapped)(struct rchan_buf *buf, + struct file *filp); + + /* + * buf_unmapped - relay buffer unmap notification + * @buf: the channel buffer + * @filp: relay file pointer + * + * Called when a relay file is successfully unmapped + */ + void (*buf_unmapped)(struct rchan_buf *buf, + struct file *filp); + /* + * create_buf_file - create file to represent a relay channel buffer + * @filename: the name of the file to create + * @parent: the parent of the file to create + * @mode: the mode of the file to create + * @buf: the channel buffer + * @is_global: outparam - set non-zero if the buffer should be global + * + * Called during relay_open(), once for each per-cpu buffer, + * to allow the client to create a file to be used to + * represent the corresponding channel buffer. If the file is + * created outside of relay, the parent must also exist in + * that filesystem. + * + * The callback should return the dentry of the file created + * to represent the relay buffer. + * + * Setting the is_global outparam to a non-zero value will + * cause relay_open() to create a single global buffer rather + * than the default set of per-cpu buffers. + * + * See Documentation/filesystems/relayfs.txt for more info. + */ + struct dentry *(*create_buf_file)(const char *filename, + struct dentry *parent, + int mode, + struct rchan_buf *buf, + int *is_global); + + /* + * remove_buf_file - remove file representing a relay channel buffer + * @dentry: the dentry of the file to remove + * + * Called during relay_close(), once for each per-cpu buffer, + * to allow the client to remove a file used to represent a + * channel buffer. + * + * The callback should return 0 if successful, negative if not. + */ + int (*remove_buf_file)(struct dentry *dentry); +}; + +/* + * CONFIG_RELAY kernel API, kernel/relay.c + */ + +struct rchan *relay_open(const char *base_filename, + struct dentry *parent, + size_t subbuf_size, + size_t n_subbufs, + struct rchan_callbacks *cb); +extern void relay_close(struct rchan *chan); +extern void relay_flush(struct rchan *chan); +extern void relay_subbufs_consumed(struct rchan *chan, + unsigned int cpu, + size_t consumed); +extern void relay_reset(struct rchan *chan); +extern int relay_buf_full(struct rchan_buf *buf); + +extern size_t relay_switch_subbuf(struct rchan_buf *buf, + size_t length); + +/** + * relay_write - write data into the channel + * @chan: relay channel + * @data: data to be written + * @length: number of bytes to write + * + * Writes data into the current cpu's channel buffer. + * + * Protects the buffer by disabling interrupts. Use this + * if you might be logging from interrupt context. Try + * __relay_write() if you know you won't be logging from + * interrupt context. + */ +static inline void relay_write(struct rchan *chan, + const void *data, + size_t length) +{ + unsigned long flags; + struct rchan_buf *buf; + + local_irq_save(flags); + buf = chan->buf[smp_processor_id()]; + if (unlikely(buf->offset + length > chan->subbuf_size)) + length = relay_switch_subbuf(buf, length); + memcpy(buf->data + buf->offset, data, length); + buf->offset += length; + local_irq_restore(flags); +} + +/** + * __relay_write - write data into the channel + * @chan: relay channel + * @data: data to be written + * @length: number of bytes to write + * + * Writes data into the current cpu's channel buffer. + * + * Protects the buffer by disabling preemption. Use + * relay_write() if you might be logging from interrupt + * context. + */ +static inline void __relay_write(struct rchan *chan, + const void *data, + size_t length) +{ + struct rchan_buf *buf; + + buf = chan->buf[get_cpu()]; + if (unlikely(buf->offset + length > buf->chan->subbuf_size)) + length = relay_switch_subbuf(buf, length); + memcpy(buf->data + buf->offset, data, length); + buf->offset += length; + put_cpu(); +} + +/** + * relay_reserve - reserve slot in channel buffer + * @chan: relay channel + * @length: number of bytes to reserve + * + * Returns pointer to reserved slot, NULL if full. + * + * Reserves a slot in the current cpu's channel buffer. + * Does not protect the buffer at all - caller must provide + * appropriate synchronization. + */ +static inline void *relay_reserve(struct rchan *chan, size_t length) +{ + void *reserved; + struct rchan_buf *buf = chan->buf[smp_processor_id()]; + + if (unlikely(buf->offset + length > buf->chan->subbuf_size)) { + length = relay_switch_subbuf(buf, length); + if (!length) + return NULL; + } + reserved = buf->data + buf->offset; + buf->offset += length; + + return reserved; +} + +/** + * subbuf_start_reserve - reserve bytes at the start of a sub-buffer + * @buf: relay channel buffer + * @length: number of bytes to reserve + * + * Helper function used to reserve bytes at the beginning of + * a sub-buffer in the subbuf_start() callback. + */ +static inline void subbuf_start_reserve(struct rchan_buf *buf, + size_t length) +{ + BUG_ON(length >= buf->chan->subbuf_size - 1); + buf->offset = length; +} + +/* + * exported relay file operations, kernel/relay.c + */ +extern struct file_operations relay_file_operations; + +#endif /* _LINUX_RELAY_H */ + diff --git a/init/Kconfig b/init/Kconfig index 38416a199def..1d19fd25204b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -214,6 +214,17 @@ config CPUSETS Say N if unsure. +config RELAY + bool "Kernel->user space relay support (formerly relayfs)" + help + This option enables support for relay interface support in + certain file systems (such as debugfs). + It is designed to provide an efficient mechanism for tools and + facilities to relay large amounts of data from kernel space to + user space. + + If unsure, say N. + source "usr/Kconfig" config UID16 diff --git a/kernel/Makefile b/kernel/Makefile index 4ae0fbde815d..aebd7a78984e 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -34,6 +34,7 @@ obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o +obj-$(CONFIG_RELAY) += relay.o ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y) # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is diff --git a/kernel/relay.c b/kernel/relay.c new file mode 100644 index 000000000000..9358e8eb8476 --- /dev/null +++ b/kernel/relay.c @@ -0,0 +1,919 @@ +/* + * Public API and common code for kernel->userspace relay file support. + * + * See Documentation/filesystems/relayfs.txt for an overview of relayfs. + * + * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp + * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) + * + * Moved to kernel/relay.c by Paul Mundt, 2006. + * + * This file is released under the GPL. + */ +#include <linux/errno.h> +#include <linux/stddef.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/string.h> +#include <linux/relay.h> +#include <linux/vmalloc.h> +#include <linux/mm.h> + +/* + * close() vm_op implementation for relay file mapping. + */ +static void relay_file_mmap_close(struct vm_area_struct *vma) +{ + struct rchan_buf *buf = vma->vm_private_data; + buf->chan->cb->buf_unmapped(buf, vma->vm_file); +} + +/* + * nopage() vm_op implementation for relay file mapping. + */ +static struct page *relay_buf_nopage(struct vm_area_struct *vma, + unsigned long address, + int *type) +{ + struct page *page; + struct rchan_buf *buf = vma->vm_private_data; + unsigned long offset = address - vma->vm_start; + + if (address > vma->vm_end) + return NOPAGE_SIGBUS; /* Disallow mremap */ + if (!buf) + return NOPAGE_OOM; + + page = vmalloc_to_page(buf->start + offset); + if (!page) + return NOPAGE_OOM; + get_page(page); + + if (type) + *type = VM_FAULT_MINOR; + + return page; +} + +/* + * vm_ops for relay file mappings. + */ +static struct vm_operations_struct relay_file_mmap_ops = { + .nopage = relay_buf_nopage, + .close = relay_file_mmap_close, +}; + +/** + * relay_mmap_buf: - mmap channel buffer to process address space + * @buf: relay channel buffer + * @vma: vm_area_struct describing memory to be mapped + * + * Returns 0 if ok, negative on error + * + * Caller should already have grabbed mmap_sem. + */ +int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) +{ + unsigned long length = vma->vm_end - vma->vm_start; + struct file *filp = vma->vm_file; + + if (!buf) + return -EBADF; + + if (length != (unsigned long)buf->chan->alloc_size) + return -EINVAL; + + vma->vm_ops = &relay_file_mmap_ops; + vma->vm_private_data = buf; + buf->chan->cb->buf_mapped(buf, filp); + + return 0; +} + +/** + * relay_alloc_buf - allocate a channel buffer + * @buf: the buffer struct + * @size: total size of the buffer + * + * Returns a pointer to the resulting buffer, NULL if unsuccessful + */ +static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size) +{ + void *mem; + unsigned int i, j, n_pages; + + size = PAGE_ALIGN(size); + n_pages = size >> PAGE_SHIFT; + + buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL); + if (!buf->page_array) + return NULL; + + for (i = 0; i < n_pages; i++) { + buf->page_array[i] = alloc_page(GFP_KERNEL); + if (unlikely(!buf->page_array[i])) + goto depopulate; + } + mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); + if (!mem) + goto depopulate; + + memset(mem, 0, size); + buf->page_count = n_pages; + return mem; + +depopulate: + for (j = 0; j < i; j++) + __free_page(buf->page_array[j]); + kfree(buf->page_array); + return NULL; +} + +/** + * relay_create_buf - allocate and initialize a channel buffer + * @alloc_size: size of the buffer to allocate + * @n_subbufs: number of sub-buffers in the channel + * + * Returns channel buffer if successful, NULL otherwise + */ +struct rchan_buf *relay_create_buf(struct rchan *chan) +{ + struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL); + if (!buf) + return NULL; + + buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); + if (!buf->padding) + goto free_buf; + + buf->start = relay_alloc_buf(buf, chan->alloc_size); + if (!buf->start) + goto free_buf; + + buf->chan = chan; + kref_get(&buf->chan->kref); + return buf; + +free_buf: + kfree(buf->padding); + kfree(buf); + return NULL; +} + +/** + * relay_destroy_channel - free the channel struct + * + * Should only be called from kref_put(). + */ +void relay_destroy_channel(struct kref *kref) +{ + struct rchan *chan = container_of(kref, struct rchan, kref); + kfree(chan); +} + +/** + * relay_destroy_buf - destroy an rchan_buf struct and associated buffer + * @buf: the buffer struct + */ +void relay_destroy_buf(struct rchan_buf *buf) +{ + struct rchan *chan = buf->chan; + unsigned int i; + + if (likely(buf->start)) { + vunmap(buf->start); + for (i = 0; i < buf->page_count; i++) + __free_page(buf->page_array[i]); + kfree(buf->page_array); + } + kfree(buf->padding); + kfree(buf); + kref_put(&chan->kref, relay_destroy_channel); +} + +/** + * relay_remove_buf - remove a channel buffer + * + * Removes the file from the fileystem, which also frees the + * rchan_buf_struct and the channel buffer. Should only be called from + * kref_put(). + */ +void relay_remove_buf(struct kref *kref) +{ + struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); + buf->chan->cb->remove_buf_file(buf->dentry); + relay_destroy_buf(buf); +} + +/** + * relay_buf_empty - boolean, is the channel buffer empty? + * @buf: channel buffer + * + * Returns 1 if the buffer is empty, 0 otherwise. + */ +int relay_buf_empty(struct rchan_buf *buf) +{ + return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; +} +EXPORT_SYMBOL_GPL(relay_buf_empty); + +/** + * relay_buf_full - boolean, is the channel buffer full? + * @buf: channel buffer + * + * Returns 1 if the buffer is full, 0 otherwise. + */ +int relay_buf_full(struct rchan_buf *buf) +{ + size_t ready = buf->subbufs_produced - buf->subbufs_consumed; + return (ready >= buf->chan->n_subbufs) ? 1 : 0; +} +EXPORT_SYMBOL_GPL(relay_buf_full); + +/* + * High-level relay kernel API and associated functions. + */ + +/* + * rchan_callback implementations defining default channel behavior. Used + * in place of corresponding NULL values in client callback struct. + */ + +/* + * subbuf_start() default callback. Does nothing. + */ +static int subbuf_start_default_callback (struct rchan_buf *buf, + void *subbuf, + void *prev_subbuf, + size_t prev_padding) +{ + if (relay_buf_full(buf)) + return 0; + + return 1; +} + +/* + * buf_mapped() default callback. Does nothing. + */ +static void buf_mapped_default_callback(struct rchan_buf *buf, + struct file *filp) +{ +} + +/* + * buf_unmapped() default callback. Does nothing. + */ +static void buf_unmapped_default_callback(struct rchan_buf *buf, + struct file *filp) +{ +} + +/* + * create_buf_file_create() default callback. Does nothing. + */ +static struct dentry *create_buf_file_default_callback(const char *filename, + struct dentry *parent, + int mode, + struct rchan_buf *buf, + int *is_global) +{ + return NULL; +} + +/* + * remove_buf_file() default callback. Does nothing. + */ +static int remove_buf_file_default_callback(struct dentry *dentry) +{ + return -EINVAL; +} + +/* relay channel default callbacks */ +static struct rchan_callbacks default_channel_callbacks = { + .subbuf_start = subbuf_start_default_callback, + .buf_mapped = buf_mapped_default_callback, + .buf_unmapped = buf_unmapped_default_callback, + .create_buf_file = create_buf_file_default_callback, + .remove_buf_file = remove_buf_file_default_callback, +}; + +/** + * wakeup_readers - wake up readers waiting on a channel + * @private: the channel buffer + * + * This is the work function used to defer reader waking. The + * reason waking is deferred is that calling directly from write + * causes problems if you're writing from say the scheduler. + */ +static void wakeup_readers(void *private) +{ + struct rchan_buf *buf = private; + wake_up_interruptible(&buf->read_wait); +} + +/** + * __relay_reset - reset a channel buffer + * @buf: the channel buffer + * @init: 1 if this is a first-time initialization + * + * See relay_reset for description of effect. + */ +static inline void __relay_reset(struct rchan_buf *buf, unsigned int init) +{ + size_t i; + + if (init) { + init_waitqueue_head(&buf->read_wait); + kref_init(&buf->kref); + INIT_WORK(&buf->wake_readers, NULL, NULL); + } else { + cancel_delayed_work(&buf->wake_readers); + flush_scheduled_work(); + } + + buf->subbufs_produced = 0; + buf->subbufs_consumed = 0; + buf->bytes_consumed = 0; + buf->finalized = 0; + buf->data = buf->start; + buf->offset = 0; + + for (i = 0; i < buf->chan->n_subbufs; i++) + buf->padding[i] = 0; + + buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); +} + +/** + * relay_reset - reset the channel + * @chan: the channel + * + * This has the effect of erasing all data from all channel buffers + * and restarting the channel in its initial state. The buffers + * are not freed, so any mappings are still in effect. + * + * NOTE: Care should be taken that the channel isn't actually + * being used by anything when this call is made. + */ +void relay_reset(struct rchan *chan) +{ + unsigned int i; + struct rchan_buf *prev = NULL; + + if (!chan) + return; + + for (i = 0; i < NR_CPUS; i++) { + if (!chan->buf[i] || chan->buf[i] == prev) + break; + __relay_reset(chan->buf[i], 0); + prev = chan->buf[i]; + } +} +EXPORT_SYMBOL_GPL(relay_reset); + +/** + * relay_open_buf - create a new relay channel buffer + * + * Internal - used by relay_open(). + */ +static struct rchan_buf *relay_open_buf(struct rchan *chan, + const char *filename, + struct dentry *parent, + int *is_global) +{ + struct rchan_buf *buf; + struct dentry *dentry; + + if (*is_global) + return chan->buf[0]; + + buf = relay_create_buf(chan); + if (!buf) + return NULL; + + /* Create file in fs */ + dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR, + buf, is_global); + if (!dentry) { + relay_destroy_buf(buf); + return NULL; + } + + buf->dentry = dentry; + __relay_reset(buf, 1); + + return buf; +} + +/** + * relay_close_buf - close a channel buffer + * @buf: channel buffer + * + * Marks the buffer finalized and restores the default callbacks. + * The channel buffer and channel buffer data structure are then freed + * automatically when the last reference is given up. + */ +static inline void relay_close_buf(struct rchan_buf *buf) +{ + buf->finalized = 1; + cancel_delayed_work(&buf->wake_readers); + flush_scheduled_work(); + kref_put(&buf->kref, relay_remove_buf); +} + +static inline void setup_callbacks(struct rchan *chan, + struct rchan_callbacks *cb) +{ + if (!cb) { + chan->cb = &default_channel_callbacks; + return; + } + + if (!cb->subbuf_start) + cb->subbuf_start = subbuf_start_default_callback; + if (!cb->buf_mapped) + cb->buf_mapped = buf_mapped_default_callback; + if (!cb->buf_unmapped) + cb->buf_unmapped = buf_unmapped_default_callback; + if (!cb->create_buf_file) + cb->create_buf_file = create_buf_file_default_callback; + if (!cb->remove_buf_file) + cb->remove_buf_file = remove_buf_file_default_callback; + chan->cb = cb; +} + +/** + * relay_open - create a new relay channel + * @base_filename: base name of files to create + * @parent: dentry of parent directory, NULL for root directory + * @subbuf_size: size of sub-buffers + * @n_subbufs: number of sub-buffers + * @cb: client callback functions + * + * Returns channel pointer if successful, NULL otherwise. + * + * Creates a channel buffer for each cpu using the sizes and + * attributes specified. The created channel buffer files + * will be named base_filename0...base_filenameN-1. File + * permissions will be S_IRUSR. + */ +struct rchan *relay_open(const char *base_filename, + struct dentry *parent, + size_t subbuf_size, + size_t n_subbufs, + struct rchan_callbacks *cb) +{ + unsigned int i; + struct rchan *chan; + char *tmpname; + int is_global = 0; + + if (!base_filename) + return NULL; + + if (!(subbuf_size && n_subbufs)) + return NULL; + + chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL); + if (!chan) + return NULL; + + chan->version = RELAYFS_CHANNEL_VERSION; + chan->n_subbufs = n_subbufs; + chan->subbuf_size = subbuf_size; + chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); + setup_callbacks(chan, cb); + kref_init(&chan->kref); + + tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL); + if (!tmpname) + goto free_chan; + + for_each_online_cpu(i) { + sprintf(tmpname, "%s%d", base_filename, i); + chan->buf[i] = relay_open_buf(chan, tmpname, parent, + &is_global); + if (!chan->buf[i]) + goto free_bufs; + + chan->buf[i]->cpu = i; + } + + kfree(tmpname); + return chan; + +free_bufs: + for (i = 0; i < NR_CPUS; i++) { + if (!chan->buf[i]) + break; + relay_close_buf(chan->buf[i]); + if (is_global) + break; + } + kfree(tmpname); + +free_chan: + kref_put(&chan->kref, relay_destroy_channel); + return NULL; +} +EXPORT_SYMBOL_GPL(relay_open); + +/** + * relay_switch_subbuf - switch to a new sub-buffer + * @buf: channel buffer + * @length: size of current event + * + * Returns either the length passed in or 0 if full. + * + * Performs sub-buffer-switch tasks such as invoking callbacks, + * updating padding counts, waking up readers, etc. + */ +size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) +{ + void *old, *new; + size_t old_subbuf, new_subbuf; + + if (unlikely(length > buf->chan->subbuf_size)) + goto toobig; + + if (buf->offset != buf->chan->subbuf_size + 1) { + buf->prev_padding = buf->chan->subbuf_size - buf->offset; + old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; + buf->padding[old_subbuf] = buf->prev_padding; + buf->subbufs_produced++; + if (waitqueue_active(&buf->read_wait)) { + PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf); + schedule_delayed_work(&buf->wake_readers, 1); + } + } + + old = buf->data; + new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; + new = buf->start + new_subbuf * buf->chan->subbuf_size; + buf->offset = 0; + if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { + buf->offset = buf->chan->subbuf_size + 1; + return 0; + } + buf->data = new; + buf->padding[new_subbuf] = 0; + + if (unlikely(length + buf->offset > buf->chan->subbuf_size)) + goto toobig; + + return length; + +toobig: + buf->chan->last_toobig = length; + return 0; +} +EXPORT_SYMBOL_GPL(relay_switch_subbuf); + +/** + * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count + * @chan: the channel + * @cpu: the cpu associated with the channel buffer to update + * @subbufs_consumed: number of sub-buffers to add to current buf's count + * + * Adds to the channel buffer's consumed sub-buffer count. + * subbufs_consumed should be the number of sub-buffers newly consumed, + * not the total consumed. + * + * NOTE: kernel clients don't need to call this function if the channel + * mode is 'overwrite'. + */ +void relay_subbufs_consumed(struct rchan *chan, + unsigned int cpu, + size_t subbufs_consumed) +{ + struct rchan_buf *buf; + + if (!chan) + return; + + if (cpu >= NR_CPUS || !chan->buf[cpu]) + return; + + buf = chan->buf[cpu]; + buf->subbufs_consumed += subbufs_consumed; + if (buf->subbufs_consumed > buf->subbufs_produced) + buf->subbufs_consumed = buf->subbufs_produced; +} +EXPORT_SYMBOL_GPL(relay_subbufs_consumed); + +/** + * relay_close - close the channel + * @chan: the channel + * + * Closes all channel buffers and frees the channel. + */ +void relay_close(struct rchan *chan) +{ + unsigned int i; + struct rchan_buf *prev = NULL; + + if (!chan) + return; + + for (i = 0; i < NR_CPUS; i++) { + if (!chan->buf[i] || chan->buf[i] == prev) + break; + relay_close_buf(chan->buf[i]); + prev = chan->buf[i]; + } + + if (chan->last_toobig) + printk(KERN_WARNING "relay: one or more items not logged " + "[item size (%Zd) > sub-buffer size (%Zd)]\n", + chan->last_toobig, chan->subbuf_size); + + kref_put(&chan->kref, relay_destroy_channel); +} +EXPORT_SYMBOL_GPL(relay_close); + +/** + * relay_flush - close the channel + * @chan: the channel + * + * Flushes all channel buffers i.e. forces buffer switch. + */ +void relay_flush(struct rchan *chan) +{ + unsigned int i; + struct rchan_buf *prev = NULL; + + if (!chan) + return; + + for (i = 0; i < NR_CPUS; i++) { + if (!chan->buf[i] || chan->buf[i] == prev) + break; + relay_switch_subbuf(chan->buf[i], 0); + prev = chan->buf[i]; + } +} +EXPORT_SYMBOL_GPL(relay_flush); + +/** + * relay_file_open - open file op for relay files + * @inode: the inode + * @filp: the file + * + * Increments the channel buffer refcount. + */ +static int relay_file_open(struct inode *inode, struct file *filp) +{ + struct rchan_buf *buf = inode->u.generic_ip; + kref_get(&buf->kref); + filp->private_data = buf; + + return 0; +} + +/** + * relay_file_mmap - mmap file op for relay files + * @filp: the file + * @vma: the vma describing what to map + * + * Calls upon relay_mmap_buf to map the file into user space. + */ +static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) +{ + struct rchan_buf *buf = filp->private_data; + return relay_mmap_buf(buf, vma); +} + +/** + * relay_file_poll - poll file op for relay files + * @filp: the file + * @wait: poll table + * + * Poll implemention. + */ +static unsigned int relay_file_poll(struct file *filp, poll_table *wait) +{ + unsigned int mask = 0; + struct rchan_buf *buf = filp->private_data; + + if (buf->finalized) + return POLLERR; + + if (filp->f_mode & FMODE_READ) { + poll_wait(filp, &buf->read_wait, wait); + if (!relay_buf_empty(buf)) + mask |= POLLIN | POLLRDNORM; + } + + return mask; +} + +/** + * relay_file_release - release file op for relay files + * @inode: the inode + * @filp: the file + * + * Decrements the channel refcount, as the filesystem is + * no longer using it. + */ +static int relay_file_release(struct inode *inode, struct file *filp) +{ + struct rchan_buf *buf = filp->private_data; + kref_put(&buf->kref, relay_remove_buf); + + return 0; +} + +/** + * relay_file_read_consume - update the consumed count for the buffer + */ +static void relay_file_read_consume(struct rchan_buf *buf, + size_t read_pos, + size_t bytes_consumed) +{ + size_t subbuf_size = buf->chan->subbuf_size; + size_t n_subbufs = buf->chan->n_subbufs; + size_t read_subbuf; + + if (buf->bytes_consumed + bytes_consumed > subbuf_size) { + relay_subbufs_consumed(buf->chan, buf->cpu, 1); + buf->bytes_consumed = 0; + } + + buf->bytes_consumed += bytes_consumed; + read_subbuf = read_pos / buf->chan->subbuf_size; + if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { + if ((read_subbuf == buf->subbufs_produced % n_subbufs) && + (buf->offset == subbuf_size)) + return; + relay_subbufs_consumed(buf->chan, buf->cpu, 1); + buf->bytes_consumed = 0; + } +} + +/** + * relay_file_read_avail - boolean, are there unconsumed bytes available? + */ +static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) +{ + size_t bytes_produced, bytes_consumed, write_offset; + size_t subbuf_size = buf->chan->subbuf_size; + size_t n_subbufs = buf->chan->n_subbufs; + size_t produced = buf->subbufs_produced % n_subbufs; + size_t consumed = buf->subbufs_consumed % n_subbufs; + + write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; + + if (consumed > produced) { + if ((produced > n_subbufs) && + (produced + n_subbufs - consumed <= n_subbufs)) + produced += n_subbufs; + } else if (consumed == produced) { + if (buf->offset > subbuf_size) { + produced += n_subbufs; + if (buf->subbufs_produced == buf->subbufs_consumed) + consumed += n_subbufs; + } + } + + if (buf->offset > subbuf_size) + bytes_produced = (produced - 1) * subbuf_size + write_offset; + else + bytes_produced = produced * subbuf_size + write_offset; + bytes_consumed = consumed * subbuf_size + buf->bytes_consumed; + + if (bytes_produced == bytes_consumed) + return 0; + + relay_file_read_consume(buf, read_pos, 0); + + return 1; +} + +/** + * relay_file_read_subbuf_avail - return bytes available in sub-buffer + */ +static size_t relay_file_read_subbuf_avail(size_t read_pos, + struct rchan_buf *buf) +{ + size_t padding, avail = 0; + size_t read_subbuf, read_offset, write_subbuf, write_offset; + size_t subbuf_size = buf->chan->subbuf_size; + + write_subbuf = (buf->data - buf->start) / subbuf_size; + write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; + read_subbuf = read_pos / subbuf_size; + read_offset = read_pos % subbuf_size; + padding = buf->padding[read_subbuf]; + + if (read_subbuf == write_subbuf) { + if (read_offset + padding < write_offset) + avail = write_offset - (read_offset + padding); + } else + avail = (subbuf_size - padding) - read_offset; + + return avail; +} + +/** + * relay_file_read_start_pos - find the first available byte to read + * + * If the read_pos is in the middle of padding, return the + * position of the first actually available byte, otherwise + * return the original value. + */ +static size_t relay_file_read_start_pos(size_t read_pos, + struct rchan_buf *buf) +{ + size_t read_subbuf, padding, padding_start, padding_end; + size_t subbuf_size = buf->chan->subbuf_size; + size_t n_subbufs = buf->chan->n_subbufs; + + read_subbuf = read_pos / subbuf_size; + padding = buf->padding[read_subbuf]; + padding_start = (read_subbuf + 1) * subbuf_size - padding; + padding_end = (read_subbuf + 1) * subbuf_size; + if (read_pos >= padding_start && read_pos < padding_end) { + read_subbuf = (read_subbuf + 1) % n_subbufs; + read_pos = read_subbuf * subbuf_size; + } + + return read_pos; +} + +/** + * relay_file_read_end_pos - return the new read position + */ +static size_t relay_file_read_end_pos(struct rchan_buf *buf, + size_t read_pos, + size_t count) +{ + size_t read_subbuf, padding, end_pos; + size_t subbuf_size = buf->chan->subbuf_size; + size_t n_subbufs = buf->chan->n_subbufs; + + read_subbuf = read_pos / subbuf_size; + padding = buf->padding[read_subbuf]; + if (read_pos % subbuf_size + count + padding == subbuf_size) + end_pos = (read_subbuf + 1) * subbuf_size; + else + end_pos = read_pos + count; + if (end_pos >= subbuf_size * n_subbufs) + end_pos = 0; + + return end_pos; +} + +/** + * relay_file_read - read file op for relay files + * @filp: the file + * @buffer: the userspace buffer + * @count: number of bytes to read + * @ppos: position to read from + * + * Reads count bytes or the number of bytes available in the + * current sub-buffer being read, whichever is smaller. + */ +static ssize_t relay_file_read(struct file *filp, + char __user *buffer, + size_t count, + loff_t *ppos) +{ + struct rchan_buf *buf = filp->private_data; + struct inode *inode = filp->f_dentry->d_inode; + size_t read_start, avail; + ssize_t ret = 0; + void *from; + + mutex_lock(&inode->i_mutex); + if(!relay_file_read_avail(buf, *ppos)) + goto out; + + read_start = relay_file_read_start_pos(*ppos, buf); + avail = relay_file_read_subbuf_avail(read_start, buf); + if (!avail) + goto out; + + from = buf->start + read_start; + ret = count = min(count, avail); + if (copy_to_user(buffer, from, count)) { + ret = -EFAULT; + goto out; + } + relay_file_read_consume(buf, read_start, count); + *ppos = relay_file_read_end_pos(buf, read_start, count); +out: + mutex_unlock(&inode->i_mutex); + return ret; +} + +struct file_operations relay_file_operations = { + .open = relay_file_open, + .poll = relay_file_poll, + .mmap = relay_file_mmap, + .read = relay_file_read, + .llseek = no_llseek, + .release = relay_file_release, +}; +EXPORT_SYMBOL_GPL(relay_file_operations); |