linux/fs/debugfs/inode.c

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/*
* file.c - part of debugfs, a tiny little debug file system
*
* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
* Copyright (C) 2004 IBM Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* debugfs is for people to use instead of /proc or /sys.
* See Documentation/DocBook/kernel-api for more details.
*
*/
/* uncomment to get debug messages from the debug filesystem, ah the irony. */
/* #define DEBUG */
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <linux/debugfs.h>
#include <linux/fsnotify.h>
#include <linux/string.h>
#include <linux/magic.h>
static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
static bool debugfs_registered;
static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev,
void *data, const struct file_operations *fops)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_mode = mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
switch (mode & S_IFMT) {
default:
init_special_inode(inode, mode, dev);
break;
case S_IFREG:
inode->i_fop = fops ? fops : &debugfs_file_operations;
inode->i_private = data;
break;
case S_IFLNK:
inode->i_op = &debugfs_link_operations;
inode->i_fop = fops;
inode->i_private = data;
break;
case S_IFDIR:
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = fops ? fops : &simple_dir_operations;
inode->i_private = data;
/* directory inodes start off with i_nlink == 2
* (for "." entry) */
inc_nlink(inode);
break;
}
}
return inode;
}
/* SMP-safe */
static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
int mode, dev_t dev, void *data,
const struct file_operations *fops)
{
struct inode *inode;
int error = -EPERM;
if (dentry->d_inode)
return -EEXIST;
inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
if (inode) {
d_instantiate(dentry, inode);
dget(dentry);
error = 0;
}
return error;
}
static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode,
void *data, const struct file_operations *fops)
{
int res;
mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
if (!res) {
inc_nlink(dir);
fsnotify_mkdir(dir, dentry);
}
return res;
}
static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode,
void *data, const struct file_operations *fops)
{
mode = (mode & S_IALLUGO) | S_IFLNK;
return debugfs_mknod(dir, dentry, mode, 0, data, fops);
}
static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode,
void *data, const struct file_operations *fops)
{
int res;
mode = (mode & S_IALLUGO) | S_IFREG;
res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
if (!res)
fsnotify_create(dir, dentry);
return res;
}
static inline int debugfs_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
}
static int debug_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr debug_files[] = {{""}};
return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
}
[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 09:02:57 +00:00
static int debug_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data, struct vfsmount *mnt)
{
[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 09:02:57 +00:00
return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
}
static struct file_system_type debug_fs_type = {
.owner = THIS_MODULE,
.name = "debugfs",
.get_sb = debug_get_sb,
.kill_sb = kill_litter_super,
};
static int debugfs_create_by_name(const char *name, mode_t mode,
struct dentry *parent,
struct dentry **dentry,
void *data,
const struct file_operations *fops)
{
int error = 0;
/* If the parent is not specified, we create it in the root.
* We need the root dentry to do this, which is in the super
* block. A pointer to that is in the struct vfsmount that we
* have around.
*/
if (!parent) {
if (debugfs_mount && debugfs_mount->mnt_sb) {
parent = debugfs_mount->mnt_sb->s_root;
}
}
if (!parent) {
pr_debug("debugfs: Ah! can not find a parent!\n");
return -EFAULT;
}
*dentry = NULL;
mutex_lock(&parent->d_inode->i_mutex);
*dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(*dentry)) {
switch (mode & S_IFMT) {
case S_IFDIR:
error = debugfs_mkdir(parent->d_inode, *dentry, mode,
data, fops);
break;
case S_IFLNK:
error = debugfs_link(parent->d_inode, *dentry, mode,
data, fops);
break;
default:
error = debugfs_create(parent->d_inode, *dentry, mode,
data, fops);
break;
}
dput(*dentry);
} else
error = PTR_ERR(*dentry);
mutex_unlock(&parent->d_inode->i_mutex);
return error;
}
/**
* debugfs_create_file - create a file in the debugfs filesystem
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this paramater is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @data: a pointer to something that the caller will want to get to later
* on. The inode.i_private pointer will point to this value on
* the open() call.
* @fops: a pointer to a struct file_operations that should be used for
* this file.
*
* This is the basic "create a file" function for debugfs. It allows for a
* wide range of flexibility in creating a file, or a directory (if you want
* to create a directory, the debugfs_create_dir() function is
* recommended to be used instead.)
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_create_file(const char *name, mode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
struct dentry *dentry = NULL;
int error;
pr_debug("debugfs: creating file '%s'\n",name);
error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
&debugfs_mount_count);
if (error)
goto exit;
error = debugfs_create_by_name(name, mode, parent, &dentry,
data, fops);
if (error) {
dentry = NULL;
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
goto exit;
}
exit:
return dentry;
}
EXPORT_SYMBOL_GPL(debugfs_create_file);
/**
* debugfs_create_dir - create a directory in the debugfs filesystem
* @name: a pointer to a string containing the name of the directory to
* create.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this paramater is NULL, then the
* directory will be created in the root of the debugfs filesystem.
*
* This function creates a directory in debugfs with the given name.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
{
return debugfs_create_file(name,
S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
parent, NULL, NULL);
}
EXPORT_SYMBOL_GPL(debugfs_create_dir);
/**
* debugfs_create_symlink- create a symbolic link in the debugfs filesystem
* @name: a pointer to a string containing the name of the symbolic link to
* create.
* @parent: a pointer to the parent dentry for this symbolic link. This
* should be a directory dentry if set. If this paramater is NULL,
* then the symbolic link will be created in the root of the debugfs
* filesystem.
* @target: a pointer to a string containing the path to the target of the
* symbolic link.
*
* This function creates a symbolic link with the given name in debugfs that
* links to the given target path.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the symbolic
* link is to be removed (no automatic cleanup happens if your module is
* unloaded, you are responsible here.) If an error occurs, %NULL will be
* returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
const char *target)
{
struct dentry *result;
char *link;
link = kstrdup(target, GFP_KERNEL);
if (!link)
return NULL;
result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
NULL);
if (!result)
kfree(link);
return result;
}
EXPORT_SYMBOL_GPL(debugfs_create_symlink);
static void __debugfs_remove(struct dentry *dentry, struct dentry *parent)
{
int ret = 0;
if (debugfs_positive(dentry)) {
if (dentry->d_inode) {
dget(dentry);
switch (dentry->d_inode->i_mode & S_IFMT) {
case S_IFDIR:
ret = simple_rmdir(parent->d_inode, dentry);
break;
case S_IFLNK:
kfree(dentry->d_inode->i_private);
/* fall through */
default:
simple_unlink(parent->d_inode, dentry);
break;
}
if (!ret)
d_delete(dentry);
dput(dentry);
}
}
}
/**
* debugfs_remove - removes a file or directory from the debugfs filesystem
* @dentry: a pointer to a the dentry of the file or directory to be
* removed.
*
* This function removes a file or directory in debugfs that was previously
* created with a call to another debugfs function (like
* debugfs_create_file() or variants thereof.)
*
* This function is required to be called in order for the file to be
* removed, no automatic cleanup of files will happen when a module is
* removed, you are responsible here.
*/
void debugfs_remove(struct dentry *dentry)
{
struct dentry *parent;
if (!dentry)
return;
parent = dentry->d_parent;
if (!parent || !parent->d_inode)
return;
mutex_lock(&parent->d_inode->i_mutex);
__debugfs_remove(dentry, parent);
mutex_unlock(&parent->d_inode->i_mutex);
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
EXPORT_SYMBOL_GPL(debugfs_remove);
/**
* debugfs_remove_recursive - recursively removes a directory
* @dentry: a pointer to a the dentry of the directory to be removed.
*
* This function recursively removes a directory tree in debugfs that
* was previously created with a call to another debugfs function
* (like debugfs_create_file() or variants thereof.)
*
* This function is required to be called in order for the file to be
* removed, no automatic cleanup of files will happen when a module is
* removed, you are responsible here.
*/
void debugfs_remove_recursive(struct dentry *dentry)
{
struct dentry *child;
struct dentry *parent;
if (!dentry)
return;
parent = dentry->d_parent;
if (!parent || !parent->d_inode)
return;
parent = dentry;
mutex_lock(&parent->d_inode->i_mutex);
while (1) {
/*
* When all dentries under "parent" has been removed,
* walk up the tree until we reach our starting point.
*/
if (list_empty(&parent->d_subdirs)) {
mutex_unlock(&parent->d_inode->i_mutex);
if (parent == dentry)
break;
parent = parent->d_parent;
mutex_lock(&parent->d_inode->i_mutex);
}
child = list_entry(parent->d_subdirs.next, struct dentry,
d_u.d_child);
debugfs: dont stop on first failed recursive delete debugfs: dont stop on first failed recursive delete While running a while loop of removing a module that removes a debugfs directory with debugfs_remove_recursive, and at the same time doing a while loop of cat of a file in that directory, I would hit a point where somehow the cat of the file caused the remove to fail. The result is that other files did not get removed when the module was removed. I simple read of one of those file can oops the kernel because the operations to the file no longer exist (removed by module). The funny thing is that the file being cat'ed was removed. It was the siblings that were not. I see in the code to debugfs_remove_recursive there's a test that checks if the child fails to bail out of the loop to prevent an infinite loop. What this patch does is to still try any siblings in that directory. If all the siblings fail, or there are no more siblings, then we exit the loop. This fixes the above symptom, but... This is no full proof. It makes the debugfs_remove_recursive a bit more robust, but it does not explain why the one file failed. There may be some kind of delay deletion that makes the debugfs think it did not succeed. So this patch is more of a fix for the symptom but not the disease. This patch still makes the debugfs_remove_recursive more robust and until I can find out why the bug exists, this patch will keep the kernel from oopsing in most cases. Even after the cause is found I think this change can stand on its own and should be kept. [ Impact: prevent kernel oops on module unload and reading debugfs files ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-04-25 04:39:40 +00:00
next_sibling:
/*
* If "child" isn't empty, walk down the tree and
* remove all its descendants first.
*/
if (!list_empty(&child->d_subdirs)) {
mutex_unlock(&parent->d_inode->i_mutex);
parent = child;
mutex_lock(&parent->d_inode->i_mutex);
continue;
}
__debugfs_remove(child, parent);
if (parent->d_subdirs.next == &child->d_u.d_child) {
debugfs: dont stop on first failed recursive delete debugfs: dont stop on first failed recursive delete While running a while loop of removing a module that removes a debugfs directory with debugfs_remove_recursive, and at the same time doing a while loop of cat of a file in that directory, I would hit a point where somehow the cat of the file caused the remove to fail. The result is that other files did not get removed when the module was removed. I simple read of one of those file can oops the kernel because the operations to the file no longer exist (removed by module). The funny thing is that the file being cat'ed was removed. It was the siblings that were not. I see in the code to debugfs_remove_recursive there's a test that checks if the child fails to bail out of the loop to prevent an infinite loop. What this patch does is to still try any siblings in that directory. If all the siblings fail, or there are no more siblings, then we exit the loop. This fixes the above symptom, but... This is no full proof. It makes the debugfs_remove_recursive a bit more robust, but it does not explain why the one file failed. There may be some kind of delay deletion that makes the debugfs think it did not succeed. So this patch is more of a fix for the symptom but not the disease. This patch still makes the debugfs_remove_recursive more robust and until I can find out why the bug exists, this patch will keep the kernel from oopsing in most cases. Even after the cause is found I think this change can stand on its own and should be kept. [ Impact: prevent kernel oops on module unload and reading debugfs files ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-04-25 04:39:40 +00:00
/*
* Try the next sibling.
*/
if (child->d_u.d_child.next != &parent->d_subdirs) {
child = list_entry(child->d_u.d_child.next,
struct dentry,
d_u.d_child);
goto next_sibling;
}
/*
* Avoid infinite loop if we fail to remove
* one dentry.
*/
mutex_unlock(&parent->d_inode->i_mutex);
break;
}
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
parent = dentry->d_parent;
mutex_lock(&parent->d_inode->i_mutex);
__debugfs_remove(dentry, parent);
mutex_unlock(&parent->d_inode->i_mutex);
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
/**
* debugfs_rename - rename a file/directory in the debugfs filesystem
* @old_dir: a pointer to the parent dentry for the renamed object. This
* should be a directory dentry.
* @old_dentry: dentry of an object to be renamed.
* @new_dir: a pointer to the parent dentry where the object should be
* moved. This should be a directory dentry.
* @new_name: a pointer to a string containing the target name.
*
* This function renames a file/directory in debugfs. The target must not
* exist for rename to succeed.
*
* This function will return a pointer to old_dentry (which is updated to
* reflect renaming) if it succeeds. If an error occurs, %NULL will be
* returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
struct dentry *new_dir, const char *new_name)
{
int error;
struct dentry *dentry = NULL, *trap;
const char *old_name;
trap = lock_rename(new_dir, old_dir);
/* Source or destination directories don't exist? */
if (!old_dir->d_inode || !new_dir->d_inode)
goto exit;
/* Source does not exist, cyclic rename, or mountpoint? */
if (!old_dentry->d_inode || old_dentry == trap ||
d_mountpoint(old_dentry))
goto exit;
dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
/* Lookup failed, cyclic rename or target exists? */
if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
goto exit;
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
dentry);
if (error) {
fsnotify_oldname_free(old_name);
goto exit;
}
d_move(old_dentry, dentry);
fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
old_dentry->d_name.name, S_ISDIR(old_dentry->d_inode->i_mode),
NULL, old_dentry);
fsnotify_oldname_free(old_name);
unlock_rename(new_dir, old_dir);
dput(dentry);
return old_dentry;
exit:
if (dentry && !IS_ERR(dentry))
dput(dentry);
unlock_rename(new_dir, old_dir);
return NULL;
}
EXPORT_SYMBOL_GPL(debugfs_rename);
/**
* debugfs_initialized - Tells whether debugfs has been registered
*/
bool debugfs_initialized(void)
{
return debugfs_registered;
}
EXPORT_SYMBOL_GPL(debugfs_initialized);
static struct kobject *debug_kobj;
static int __init debugfs_init(void)
{
int retval;
debug_kobj = kobject_create_and_add("debug", kernel_kobj);
if (!debug_kobj)
return -EINVAL;
retval = register_filesystem(&debug_fs_type);
if (retval)
kobject_put(debug_kobj);
else
debugfs_registered = true;
return retval;
}
static void __exit debugfs_exit(void)
{
debugfs_registered = false;
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
unregister_filesystem(&debug_fs_type);
kobject_put(debug_kobj);
}
core_initcall(debugfs_init);
module_exit(debugfs_exit);
MODULE_LICENSE("GPL");