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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7f78e03513
Modify the request_module to prefix the file system type with "fs-" and add aliases to all of the filesystems that can be built as modules to match. A common practice is to build all of the kernel code and leave code that is not commonly needed as modules, with the result that many users are exposed to any bug anywhere in the kernel. Looking for filesystems with a fs- prefix limits the pool of possible modules that can be loaded by mount to just filesystems trivially making things safer with no real cost. Using aliases means user space can control the policy of which filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf with blacklist and alias directives. Allowing simple, safe, well understood work-arounds to known problematic software. This also addresses a rare but unfortunate problem where the filesystem name is not the same as it's module name and module auto-loading would not work. While writing this patch I saw a handful of such cases. The most significant being autofs that lives in the module autofs4. This is relevant to user namespaces because we can reach the request module in get_fs_type() without having any special permissions, and people get uncomfortable when a user specified string (in this case the filesystem type) goes all of the way to request_module. After having looked at this issue I don't think there is any particular reason to perform any filtering or permission checks beyond making it clear in the module request that we want a filesystem module. The common pattern in the kernel is to call request_module() without regards to the users permissions. In general all a filesystem module does once loaded is call register_filesystem() and go to sleep. Which means there is not much attack surface exposed by loading a filesytem module unless the filesystem is mounted. In a user namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT, which most filesystems do not set today. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Reported-by: Kees Cook <keescook@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
424 lines
8.9 KiB
C
424 lines
8.9 KiB
C
/*
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* Copyright (c) 2006, 2007 QLogic Corporation. All rights reserved.
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* Copyright (c) 2006 PathScale, Inc. All rights reserved.
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*
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* This software is available to you under a choice of one of two
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* licenses. You may choose to be licensed under the terms of the GNU
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* General Public License (GPL) Version 2, available from the file
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* COPYING in the main directory of this source tree, or the
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* OpenIB.org BSD license below:
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*
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* Redistribution and use in source and binary forms, with or
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* without modification, are permitted provided that the following
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* conditions are met:
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*
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* - Redistributions of source code must retain the above
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* copyright notice, this list of conditions and the following
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* disclaimer.
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*
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* - Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/namei.h>
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#include <linux/slab.h>
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#include "ipath_kernel.h"
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#define IPATHFS_MAGIC 0x726a77
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static struct super_block *ipath_super;
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static int ipathfs_mknod(struct inode *dir, struct dentry *dentry,
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umode_t mode, const struct file_operations *fops,
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void *data)
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{
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int error;
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struct inode *inode = new_inode(dir->i_sb);
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if (!inode) {
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error = -EPERM;
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goto bail;
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}
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inode->i_ino = get_next_ino();
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inode->i_mode = mode;
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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inode->i_private = data;
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if (S_ISDIR(mode)) {
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inode->i_op = &simple_dir_inode_operations;
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inc_nlink(inode);
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inc_nlink(dir);
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}
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inode->i_fop = fops;
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d_instantiate(dentry, inode);
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error = 0;
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bail:
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return error;
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}
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static int create_file(const char *name, umode_t mode,
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struct dentry *parent, struct dentry **dentry,
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const struct file_operations *fops, void *data)
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{
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int error;
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*dentry = NULL;
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mutex_lock(&parent->d_inode->i_mutex);
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*dentry = lookup_one_len(name, parent, strlen(name));
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if (!IS_ERR(*dentry))
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error = ipathfs_mknod(parent->d_inode, *dentry,
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mode, fops, data);
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else
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error = PTR_ERR(*dentry);
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mutex_unlock(&parent->d_inode->i_mutex);
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return error;
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}
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static ssize_t atomic_stats_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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return simple_read_from_buffer(buf, count, ppos, &ipath_stats,
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sizeof ipath_stats);
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}
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static const struct file_operations atomic_stats_ops = {
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.read = atomic_stats_read,
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.llseek = default_llseek,
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};
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static ssize_t atomic_counters_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct infinipath_counters counters;
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struct ipath_devdata *dd;
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dd = file_inode(file)->i_private;
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dd->ipath_f_read_counters(dd, &counters);
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return simple_read_from_buffer(buf, count, ppos, &counters,
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sizeof counters);
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}
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static const struct file_operations atomic_counters_ops = {
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.read = atomic_counters_read,
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.llseek = default_llseek,
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};
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static ssize_t flash_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct ipath_devdata *dd;
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ssize_t ret;
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loff_t pos;
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char *tmp;
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pos = *ppos;
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if ( pos < 0) {
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ret = -EINVAL;
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goto bail;
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}
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if (pos >= sizeof(struct ipath_flash)) {
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ret = 0;
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goto bail;
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}
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if (count > sizeof(struct ipath_flash) - pos)
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count = sizeof(struct ipath_flash) - pos;
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tmp = kmalloc(count, GFP_KERNEL);
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if (!tmp) {
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ret = -ENOMEM;
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goto bail;
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}
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dd = file_inode(file)->i_private;
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if (ipath_eeprom_read(dd, pos, tmp, count)) {
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ipath_dev_err(dd, "failed to read from flash\n");
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ret = -ENXIO;
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goto bail_tmp;
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}
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if (copy_to_user(buf, tmp, count)) {
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ret = -EFAULT;
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goto bail_tmp;
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}
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*ppos = pos + count;
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ret = count;
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bail_tmp:
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kfree(tmp);
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bail:
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return ret;
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}
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static ssize_t flash_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct ipath_devdata *dd;
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ssize_t ret;
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loff_t pos;
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char *tmp;
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pos = *ppos;
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if (pos != 0) {
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ret = -EINVAL;
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goto bail;
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}
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if (count != sizeof(struct ipath_flash)) {
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ret = -EINVAL;
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goto bail;
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}
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tmp = kmalloc(count, GFP_KERNEL);
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if (!tmp) {
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ret = -ENOMEM;
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goto bail;
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}
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if (copy_from_user(tmp, buf, count)) {
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ret = -EFAULT;
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goto bail_tmp;
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}
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dd = file_inode(file)->i_private;
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if (ipath_eeprom_write(dd, pos, tmp, count)) {
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ret = -ENXIO;
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ipath_dev_err(dd, "failed to write to flash\n");
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goto bail_tmp;
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}
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*ppos = pos + count;
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ret = count;
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bail_tmp:
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kfree(tmp);
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bail:
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return ret;
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}
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static const struct file_operations flash_ops = {
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.read = flash_read,
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.write = flash_write,
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.llseek = default_llseek,
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};
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static int create_device_files(struct super_block *sb,
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struct ipath_devdata *dd)
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{
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struct dentry *dir, *tmp;
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char unit[10];
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int ret;
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snprintf(unit, sizeof unit, "%02d", dd->ipath_unit);
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ret = create_file(unit, S_IFDIR|S_IRUGO|S_IXUGO, sb->s_root, &dir,
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&simple_dir_operations, dd);
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if (ret) {
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printk(KERN_ERR "create_file(%s) failed: %d\n", unit, ret);
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goto bail;
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}
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ret = create_file("atomic_counters", S_IFREG|S_IRUGO, dir, &tmp,
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&atomic_counters_ops, dd);
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if (ret) {
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printk(KERN_ERR "create_file(%s/atomic_counters) "
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"failed: %d\n", unit, ret);
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goto bail;
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}
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ret = create_file("flash", S_IFREG|S_IWUSR|S_IRUGO, dir, &tmp,
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&flash_ops, dd);
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if (ret) {
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printk(KERN_ERR "create_file(%s/flash) "
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"failed: %d\n", unit, ret);
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goto bail;
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}
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bail:
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return ret;
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}
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static int remove_file(struct dentry *parent, char *name)
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{
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struct dentry *tmp;
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int ret;
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tmp = lookup_one_len(name, parent, strlen(name));
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if (IS_ERR(tmp)) {
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ret = PTR_ERR(tmp);
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goto bail;
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}
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spin_lock(&tmp->d_lock);
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if (!(d_unhashed(tmp) && tmp->d_inode)) {
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dget_dlock(tmp);
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__d_drop(tmp);
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spin_unlock(&tmp->d_lock);
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simple_unlink(parent->d_inode, tmp);
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} else
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spin_unlock(&tmp->d_lock);
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ret = 0;
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bail:
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/*
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* We don't expect clients to care about the return value, but
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* it's there if they need it.
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*/
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return ret;
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}
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static int remove_device_files(struct super_block *sb,
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struct ipath_devdata *dd)
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{
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struct dentry *dir, *root;
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char unit[10];
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int ret;
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root = dget(sb->s_root);
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mutex_lock(&root->d_inode->i_mutex);
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snprintf(unit, sizeof unit, "%02d", dd->ipath_unit);
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dir = lookup_one_len(unit, root, strlen(unit));
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if (IS_ERR(dir)) {
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ret = PTR_ERR(dir);
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printk(KERN_ERR "Lookup of %s failed\n", unit);
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goto bail;
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}
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remove_file(dir, "flash");
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remove_file(dir, "atomic_counters");
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d_delete(dir);
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ret = simple_rmdir(root->d_inode, dir);
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bail:
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mutex_unlock(&root->d_inode->i_mutex);
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dput(root);
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return ret;
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}
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static int ipathfs_fill_super(struct super_block *sb, void *data,
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int silent)
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{
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struct ipath_devdata *dd, *tmp;
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unsigned long flags;
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int ret;
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static struct tree_descr files[] = {
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[2] = {"atomic_stats", &atomic_stats_ops, S_IRUGO},
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{""},
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};
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ret = simple_fill_super(sb, IPATHFS_MAGIC, files);
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if (ret) {
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printk(KERN_ERR "simple_fill_super failed: %d\n", ret);
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goto bail;
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}
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spin_lock_irqsave(&ipath_devs_lock, flags);
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list_for_each_entry_safe(dd, tmp, &ipath_dev_list, ipath_list) {
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spin_unlock_irqrestore(&ipath_devs_lock, flags);
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ret = create_device_files(sb, dd);
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if (ret)
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goto bail;
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spin_lock_irqsave(&ipath_devs_lock, flags);
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}
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spin_unlock_irqrestore(&ipath_devs_lock, flags);
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bail:
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return ret;
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}
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static struct dentry *ipathfs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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struct dentry *ret;
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ret = mount_single(fs_type, flags, data, ipathfs_fill_super);
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if (!IS_ERR(ret))
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ipath_super = ret->d_sb;
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return ret;
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}
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static void ipathfs_kill_super(struct super_block *s)
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{
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kill_litter_super(s);
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ipath_super = NULL;
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}
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int ipathfs_add_device(struct ipath_devdata *dd)
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{
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int ret;
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if (ipath_super == NULL) {
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ret = 0;
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goto bail;
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}
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ret = create_device_files(ipath_super, dd);
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bail:
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return ret;
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}
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int ipathfs_remove_device(struct ipath_devdata *dd)
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{
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int ret;
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if (ipath_super == NULL) {
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ret = 0;
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goto bail;
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}
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ret = remove_device_files(ipath_super, dd);
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bail:
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return ret;
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}
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static struct file_system_type ipathfs_fs_type = {
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.owner = THIS_MODULE,
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.name = "ipathfs",
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.mount = ipathfs_mount,
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.kill_sb = ipathfs_kill_super,
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};
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MODULE_ALIAS_FS("ipathfs");
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int __init ipath_init_ipathfs(void)
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{
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return register_filesystem(&ipathfs_fs_type);
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}
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void __exit ipath_exit_ipathfs(void)
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{
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unregister_filesystem(&ipathfs_fs_type);
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}
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