2005-12-15 23:29:43 +01:00
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/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* mount.c - operations for initializing and mounting configfs.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*
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* Based on sysfs:
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* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
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*
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* configfs Copyright (C) 2005 Oracle. All rights reserved.
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*/
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#include <linux/fs.h>
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#include <linux/module.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/configfs.h>
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#include "configfs_internal.h"
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/* Random magic number */
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#define CONFIGFS_MAGIC 0x62656570
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struct vfsmount * configfs_mount = NULL;
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struct super_block * configfs_sb = NULL;
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2006-12-07 05:33:20 +01:00
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struct kmem_cache *configfs_dir_cachep;
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2005-12-15 23:29:43 +01:00
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static int configfs_mnt_count = 0;
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2007-02-12 09:55:41 +01:00
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static const struct super_operations configfs_ops = {
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2005-12-15 23:29:43 +01:00
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.statfs = simple_statfs,
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.drop_inode = generic_delete_inode,
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};
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static struct config_group configfs_root_group = {
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.cg_item = {
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.ci_namebuf = "root",
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.ci_name = configfs_root_group.cg_item.ci_namebuf,
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},
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};
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int configfs_is_root(struct config_item *item)
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{
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return item == &configfs_root_group.cg_item;
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}
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static struct configfs_dirent configfs_root = {
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.s_sibling = LIST_HEAD_INIT(configfs_root.s_sibling),
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.s_children = LIST_HEAD_INIT(configfs_root.s_children),
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.s_element = &configfs_root_group.cg_item,
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.s_type = CONFIGFS_ROOT,
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2006-01-25 22:31:07 +01:00
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.s_iattr = NULL,
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2005-12-15 23:29:43 +01:00
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};
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static int configfs_fill_super(struct super_block *sb, void *data, int silent)
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{
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struct inode *inode;
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struct dentry *root;
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sb->s_blocksize = PAGE_CACHE_SIZE;
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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sb->s_magic = CONFIGFS_MAGIC;
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sb->s_op = &configfs_ops;
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2006-01-25 22:31:07 +01:00
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sb->s_time_gran = 1;
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2005-12-15 23:29:43 +01:00
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configfs_sb = sb;
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2006-01-25 22:31:07 +01:00
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inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
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&configfs_root);
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2005-12-15 23:29:43 +01:00
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if (inode) {
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inode->i_op = &configfs_dir_inode_operations;
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inode->i_fop = &configfs_dir_operations;
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/* directory inodes start off with i_nlink == 2 (for "." entry) */
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2006-10-01 08:29:04 +02:00
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inc_nlink(inode);
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2005-12-15 23:29:43 +01:00
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} else {
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pr_debug("configfs: could not get root inode\n");
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return -ENOMEM;
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}
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root = d_alloc_root(inode);
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if (!root) {
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pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
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iput(inode);
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return -ENOMEM;
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}
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config_group_init(&configfs_root_group);
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configfs_root_group.cg_item.ci_dentry = root;
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root->d_fsdata = &configfs_root;
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sb->s_root = root;
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return 0;
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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 11:02:57 +02:00
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static int configfs_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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2005-12-15 23:29:43 +01:00
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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 11:02:57 +02:00
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return get_sb_single(fs_type, flags, data, configfs_fill_super, mnt);
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2005-12-15 23:29:43 +01:00
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}
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static struct file_system_type configfs_fs_type = {
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.owner = THIS_MODULE,
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.name = "configfs",
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.get_sb = configfs_get_sb,
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.kill_sb = kill_litter_super,
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};
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int configfs_pin_fs(void)
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{
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2006-06-09 15:34:16 +02:00
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return simple_pin_fs(&configfs_fs_type, &configfs_mount,
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2005-12-15 23:29:43 +01:00
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&configfs_mnt_count);
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}
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void configfs_release_fs(void)
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{
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simple_release_fs(&configfs_mount, &configfs_mnt_count);
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}
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static decl_subsys(config, NULL, NULL);
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static int __init configfs_init(void)
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{
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2006-01-25 22:31:07 +01:00
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int err = -ENOMEM;
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configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
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sizeof(struct configfs_dirent),
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0, 0, NULL, NULL);
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if (!configfs_dir_cachep)
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goto out;
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2005-12-15 23:29:43 +01:00
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kset_set_kset_s(&config_subsys, kernel_subsys);
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err = subsystem_register(&config_subsys);
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2006-01-25 22:31:07 +01:00
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if (err) {
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kmem_cache_destroy(configfs_dir_cachep);
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configfs_dir_cachep = NULL;
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goto out;
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}
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2005-12-15 23:29:43 +01:00
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err = register_filesystem(&configfs_fs_type);
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if (err) {
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printk(KERN_ERR "configfs: Unable to register filesystem!\n");
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subsystem_unregister(&config_subsys);
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2006-01-25 22:31:07 +01:00
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kmem_cache_destroy(configfs_dir_cachep);
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configfs_dir_cachep = NULL;
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2005-12-15 23:29:43 +01:00
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}
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2006-01-25 22:31:07 +01:00
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out:
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2005-12-15 23:29:43 +01:00
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return err;
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}
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static void __exit configfs_exit(void)
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{
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unregister_filesystem(&configfs_fs_type);
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subsystem_unregister(&config_subsys);
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2006-01-25 22:31:07 +01:00
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kmem_cache_destroy(configfs_dir_cachep);
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configfs_dir_cachep = NULL;
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2005-12-15 23:29:43 +01:00
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}
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MODULE_AUTHOR("Oracle");
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MODULE_LICENSE("GPL");
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2006-01-25 22:31:07 +01:00
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MODULE_VERSION("0.0.2");
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2005-12-15 23:29:43 +01:00
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MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
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module_init(configfs_init);
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module_exit(configfs_exit);
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