2005-04-17 06:20:36 +08:00
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/*
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* linux/fs/proc/root.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* proc root directory handling functions
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*/
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#include <asm/uaccess.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/proc_fs.h>
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#include <linux/stat.h>
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#include <linux/init.h>
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2006-10-19 01:55:46 +08:00
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#include <linux/sched.h>
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2005-04-17 06:20:36 +08:00
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/smp_lock.h>
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2006-10-02 17:17:07 +08:00
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#include <linux/mount.h>
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2005-04-17 06:20:36 +08:00
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2006-01-08 17:04:16 +08:00
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#include "internal.h"
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2007-09-12 18:01:34 +08:00
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struct proc_dir_entry *proc_bus, *proc_root_fs, *proc_root_driver;
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2005-04-17 06:20:36 +08:00
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[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 17:02:57 +08:00
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static int proc_get_sb(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data, struct vfsmount *mnt)
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2005-04-17 06:20:36 +08:00
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{
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2006-10-02 17:17:07 +08:00
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if (proc_mnt) {
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/* Seed the root directory with a pid so it doesn't need
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* to be special in base.c. I would do this earlier but
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* the only task alive when /proc is mounted the first time
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* is the init_task and it doesn't have any pids.
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*/
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struct proc_inode *ei;
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ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
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if (!ei->pid)
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ei->pid = find_get_pid(1);
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}
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[PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.
The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).
The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.
This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.
The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.
(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().
(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().
This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.
However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.
[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.
[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 17:02:57 +08:00
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return get_sb_single(fs_type, flags, data, proc_fill_super, mnt);
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2005-04-17 06:20:36 +08:00
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}
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static struct file_system_type proc_fs_type = {
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.name = "proc",
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.get_sb = proc_get_sb,
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.kill_sb = kill_anon_super,
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};
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void __init proc_root_init(void)
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{
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int err = proc_init_inodecache();
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if (err)
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return;
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err = register_filesystem(&proc_fs_type);
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if (err)
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return;
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proc_mnt = kern_mount(&proc_fs_type);
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err = PTR_ERR(proc_mnt);
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if (IS_ERR(proc_mnt)) {
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unregister_filesystem(&proc_fs_type);
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return;
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}
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proc_misc_init();
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2007-09-12 18:01:34 +08:00
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proc_net_init();
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2005-04-17 06:20:36 +08:00
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#ifdef CONFIG_SYSVIPC
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proc_mkdir("sysvipc", NULL);
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#endif
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proc_root_fs = proc_mkdir("fs", NULL);
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proc_root_driver = proc_mkdir("driver", NULL);
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proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
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#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
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/* just give it a mountpoint */
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proc_mkdir("openprom", NULL);
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#endif
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proc_tty_init();
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#ifdef CONFIG_PROC_DEVICETREE
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proc_device_tree_init();
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#endif
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proc_bus = proc_mkdir("bus", NULL);
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2007-02-14 16:34:12 +08:00
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proc_sys_init();
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2005-04-17 06:20:36 +08:00
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}
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2006-02-09 03:37:40 +08:00
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static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
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)
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2005-04-17 06:20:36 +08:00
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{
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2006-02-09 03:37:40 +08:00
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generic_fillattr(dentry->d_inode, stat);
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stat->nlink = proc_root.nlink + nr_processes();
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return 0;
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}
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2005-04-17 06:20:36 +08:00
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2006-02-09 03:37:40 +08:00
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static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
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{
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2005-04-17 06:20:36 +08:00
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if (!proc_lookup(dir, dentry, nd)) {
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return NULL;
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}
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return proc_pid_lookup(dir, dentry, nd);
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}
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static int proc_root_readdir(struct file * filp,
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void * dirent, filldir_t filldir)
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{
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unsigned int nr = filp->f_pos;
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int ret;
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lock_kernel();
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if (nr < FIRST_PROCESS_ENTRY) {
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int error = proc_readdir(filp, dirent, filldir);
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if (error <= 0) {
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unlock_kernel();
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return error;
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}
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filp->f_pos = FIRST_PROCESS_ENTRY;
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}
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unlock_kernel();
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ret = proc_pid_readdir(filp, dirent, filldir);
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return ret;
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}
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/*
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* The root /proc directory is special, as it has the
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* <pid> directories. Thus we don't use the generic
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* directory handling functions for that..
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*/
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2007-02-12 16:55:34 +08:00
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static const struct file_operations proc_root_operations = {
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2005-04-17 06:20:36 +08:00
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.read = generic_read_dir,
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.readdir = proc_root_readdir,
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};
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/*
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* proc root can do almost nothing..
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*/
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2007-02-12 16:55:40 +08:00
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static const struct inode_operations proc_root_inode_operations = {
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2005-04-17 06:20:36 +08:00
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.lookup = proc_root_lookup,
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2006-02-09 03:37:40 +08:00
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.getattr = proc_root_getattr,
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2005-04-17 06:20:36 +08:00
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};
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/*
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* This is the root "inode" in the /proc tree..
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*/
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struct proc_dir_entry proc_root = {
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.low_ino = PROC_ROOT_INO,
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.namelen = 5,
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.name = "/proc",
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.mode = S_IFDIR | S_IRUGO | S_IXUGO,
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.nlink = 2,
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.proc_iops = &proc_root_inode_operations,
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.proc_fops = &proc_root_operations,
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.parent = &proc_root,
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};
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EXPORT_SYMBOL(proc_symlink);
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EXPORT_SYMBOL(proc_mkdir);
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EXPORT_SYMBOL(create_proc_entry);
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EXPORT_SYMBOL(remove_proc_entry);
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EXPORT_SYMBOL(proc_root);
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EXPORT_SYMBOL(proc_root_fs);
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EXPORT_SYMBOL(proc_bus);
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EXPORT_SYMBOL(proc_root_driver);
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