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ff9fb72bc0
When an error happens, debugfs should return an error pointer value, not NULL. This will prevent the totally theoretical error where a debugfs call fails due to lack of memory, returning NULL, and that dentry value is then passed to another debugfs call, which would end up succeeding, creating a file at the root of the debugfs tree, but would then be impossible to remove (because you can not remove the directory NULL). So, to make everyone happy, always return errors, this makes the users of debugfs much simpler (they do not have to ever check the return value), and everyone can rest easy. Reported-by: Gary R Hook <ghook@amd.com> Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reported-by: Masami Hiramatsu <mhiramat@kernel.org> Reported-by: Michal Hocko <mhocko@kernel.org> Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reported-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
866 lines
25 KiB
C
866 lines
25 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* inode.c - part of debugfs, a tiny little debug file system
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*
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* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
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* Copyright (C) 2004 IBM Inc.
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*
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* debugfs is for people to use instead of /proc or /sys.
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* See ./Documentation/core-api/kernel-api.rst for more details.
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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/kobject.h>
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#include <linux/namei.h>
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#include <linux/debugfs.h>
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#include <linux/fsnotify.h>
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#include <linux/string.h>
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#include <linux/seq_file.h>
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#include <linux/parser.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include "internal.h"
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#define DEBUGFS_DEFAULT_MODE 0700
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static struct vfsmount *debugfs_mount;
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static int debugfs_mount_count;
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static bool debugfs_registered;
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static struct inode *debugfs_get_inode(struct super_block *sb)
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{
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struct inode *inode = new_inode(sb);
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if (inode) {
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inode->i_ino = get_next_ino();
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inode->i_atime = inode->i_mtime =
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inode->i_ctime = current_time(inode);
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}
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return inode;
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}
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struct debugfs_mount_opts {
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kuid_t uid;
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kgid_t gid;
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umode_t mode;
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};
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enum {
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Opt_uid,
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Opt_gid,
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Opt_mode,
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Opt_err
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};
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static const match_table_t tokens = {
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{Opt_uid, "uid=%u"},
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{Opt_gid, "gid=%u"},
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{Opt_mode, "mode=%o"},
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{Opt_err, NULL}
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};
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struct debugfs_fs_info {
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struct debugfs_mount_opts mount_opts;
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};
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static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
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{
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substring_t args[MAX_OPT_ARGS];
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int option;
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int token;
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kuid_t uid;
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kgid_t gid;
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char *p;
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opts->mode = DEBUGFS_DEFAULT_MODE;
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while ((p = strsep(&data, ",")) != NULL) {
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if (!*p)
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continue;
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token = match_token(p, tokens, args);
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switch (token) {
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case Opt_uid:
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if (match_int(&args[0], &option))
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return -EINVAL;
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uid = make_kuid(current_user_ns(), option);
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if (!uid_valid(uid))
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return -EINVAL;
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opts->uid = uid;
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break;
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case Opt_gid:
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if (match_int(&args[0], &option))
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return -EINVAL;
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gid = make_kgid(current_user_ns(), option);
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if (!gid_valid(gid))
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return -EINVAL;
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opts->gid = gid;
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break;
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case Opt_mode:
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if (match_octal(&args[0], &option))
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return -EINVAL;
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opts->mode = option & S_IALLUGO;
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break;
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/*
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* We might like to report bad mount options here;
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* but traditionally debugfs has ignored all mount options
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*/
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}
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}
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return 0;
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}
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static int debugfs_apply_options(struct super_block *sb)
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{
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struct debugfs_fs_info *fsi = sb->s_fs_info;
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struct inode *inode = d_inode(sb->s_root);
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struct debugfs_mount_opts *opts = &fsi->mount_opts;
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inode->i_mode &= ~S_IALLUGO;
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inode->i_mode |= opts->mode;
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inode->i_uid = opts->uid;
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inode->i_gid = opts->gid;
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return 0;
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}
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static int debugfs_remount(struct super_block *sb, int *flags, char *data)
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{
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int err;
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struct debugfs_fs_info *fsi = sb->s_fs_info;
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sync_filesystem(sb);
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err = debugfs_parse_options(data, &fsi->mount_opts);
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if (err)
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goto fail;
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debugfs_apply_options(sb);
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fail:
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return err;
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}
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static int debugfs_show_options(struct seq_file *m, struct dentry *root)
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{
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struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
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struct debugfs_mount_opts *opts = &fsi->mount_opts;
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if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
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seq_printf(m, ",uid=%u",
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from_kuid_munged(&init_user_ns, opts->uid));
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if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
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seq_printf(m, ",gid=%u",
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from_kgid_munged(&init_user_ns, opts->gid));
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if (opts->mode != DEBUGFS_DEFAULT_MODE)
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seq_printf(m, ",mode=%o", opts->mode);
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return 0;
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}
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static void debugfs_evict_inode(struct inode *inode)
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{
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truncate_inode_pages_final(&inode->i_data);
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clear_inode(inode);
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if (S_ISLNK(inode->i_mode))
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kfree(inode->i_link);
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}
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static const struct super_operations debugfs_super_operations = {
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.statfs = simple_statfs,
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.remount_fs = debugfs_remount,
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.show_options = debugfs_show_options,
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.evict_inode = debugfs_evict_inode,
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};
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static void debugfs_release_dentry(struct dentry *dentry)
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{
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void *fsd = dentry->d_fsdata;
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if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
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kfree(dentry->d_fsdata);
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}
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static struct vfsmount *debugfs_automount(struct path *path)
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{
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debugfs_automount_t f;
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f = (debugfs_automount_t)path->dentry->d_fsdata;
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return f(path->dentry, d_inode(path->dentry)->i_private);
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}
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static const struct dentry_operations debugfs_dops = {
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.d_delete = always_delete_dentry,
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.d_release = debugfs_release_dentry,
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.d_automount = debugfs_automount,
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};
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static int debug_fill_super(struct super_block *sb, void *data, int silent)
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{
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static const struct tree_descr debug_files[] = {{""}};
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struct debugfs_fs_info *fsi;
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int err;
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fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
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sb->s_fs_info = fsi;
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if (!fsi) {
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err = -ENOMEM;
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goto fail;
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}
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err = debugfs_parse_options(data, &fsi->mount_opts);
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if (err)
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goto fail;
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err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
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if (err)
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goto fail;
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sb->s_op = &debugfs_super_operations;
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sb->s_d_op = &debugfs_dops;
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debugfs_apply_options(sb);
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return 0;
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fail:
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kfree(fsi);
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sb->s_fs_info = NULL;
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return err;
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}
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static struct dentry *debug_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name,
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void *data)
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{
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return mount_single(fs_type, flags, data, debug_fill_super);
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}
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static struct file_system_type debug_fs_type = {
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.owner = THIS_MODULE,
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.name = "debugfs",
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.mount = debug_mount,
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.kill_sb = kill_litter_super,
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};
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MODULE_ALIAS_FS("debugfs");
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/**
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* debugfs_lookup() - look up an existing debugfs file
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* @name: a pointer to a string containing the name of the file to look up.
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* @parent: a pointer to the parent dentry of the file.
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*
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* This function will return a pointer to a dentry if it succeeds. If the file
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* doesn't exist or an error occurs, %ERR_PTR(-ERROR) will be returned. The
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* returned dentry must be passed to dput() when it is no longer needed.
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*
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* If debugfs is not enabled in the kernel, the value -%ENODEV will be
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* returned.
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*/
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struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
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{
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struct dentry *dentry;
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if (IS_ERR(parent))
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return parent;
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if (!parent)
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parent = debugfs_mount->mnt_root;
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dentry = lookup_one_len_unlocked(name, parent, strlen(name));
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if (IS_ERR(dentry))
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return dentry;
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if (!d_really_is_positive(dentry)) {
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dput(dentry);
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return ERR_PTR(-EINVAL);
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}
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return dentry;
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}
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EXPORT_SYMBOL_GPL(debugfs_lookup);
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static struct dentry *start_creating(const char *name, struct dentry *parent)
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{
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struct dentry *dentry;
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int error;
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pr_debug("debugfs: creating file '%s'\n",name);
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if (IS_ERR(parent))
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return parent;
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error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
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&debugfs_mount_count);
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if (error)
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return ERR_PTR(error);
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/* If the parent is not specified, we create it in the root.
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* We need the root dentry to do this, which is in the super
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* block. A pointer to that is in the struct vfsmount that we
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* have around.
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*/
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if (!parent)
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parent = debugfs_mount->mnt_root;
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inode_lock(d_inode(parent));
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dentry = lookup_one_len(name, parent, strlen(name));
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if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
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dput(dentry);
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dentry = ERR_PTR(-EEXIST);
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}
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if (IS_ERR(dentry)) {
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inode_unlock(d_inode(parent));
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simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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}
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return dentry;
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}
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static struct dentry *failed_creating(struct dentry *dentry)
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{
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inode_unlock(d_inode(dentry->d_parent));
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dput(dentry);
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simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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return ERR_PTR(-ENOMEM);
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}
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static struct dentry *end_creating(struct dentry *dentry)
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{
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inode_unlock(d_inode(dentry->d_parent));
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return dentry;
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}
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static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *proxy_fops,
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const struct file_operations *real_fops)
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{
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struct dentry *dentry;
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struct inode *inode;
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if (!(mode & S_IFMT))
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mode |= S_IFREG;
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BUG_ON(!S_ISREG(mode));
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dentry = start_creating(name, parent);
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if (IS_ERR(dentry))
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return dentry;
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inode = debugfs_get_inode(dentry->d_sb);
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if (unlikely(!inode))
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return failed_creating(dentry);
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inode->i_mode = mode;
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inode->i_private = data;
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inode->i_fop = proxy_fops;
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dentry->d_fsdata = (void *)((unsigned long)real_fops |
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DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
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d_instantiate(dentry, inode);
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fsnotify_create(d_inode(dentry->d_parent), dentry);
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return end_creating(dentry);
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}
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/**
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* debugfs_create_file - create a file in the debugfs filesystem
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* @name: a pointer to a string containing the name of the file to create.
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* @mode: the permission that the file should have.
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this parameter is NULL, then the
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* file will be created in the root of the debugfs filesystem.
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* @data: a pointer to something that the caller will want to get to later
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* on. The inode.i_private pointer will point to this value on
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* the open() call.
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* @fops: a pointer to a struct file_operations that should be used for
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* this file.
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*
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* This is the basic "create a file" function for debugfs. It allows for a
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* wide range of flexibility in creating a file, or a directory (if you want
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* to create a directory, the debugfs_create_dir() function is
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* recommended to be used instead.)
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*
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* This function will return a pointer to a dentry if it succeeds. This
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* pointer must be passed to the debugfs_remove() function when the file is
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* to be removed (no automatic cleanup happens if your module is unloaded,
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* you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
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* returned.
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*
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* If debugfs is not enabled in the kernel, the value -%ENODEV will be
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* returned.
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*/
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struct dentry *debugfs_create_file(const char *name, umode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *fops)
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{
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return __debugfs_create_file(name, mode, parent, data,
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fops ? &debugfs_full_proxy_file_operations :
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&debugfs_noop_file_operations,
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fops);
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}
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EXPORT_SYMBOL_GPL(debugfs_create_file);
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/**
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* debugfs_create_file_unsafe - create a file in the debugfs filesystem
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* @name: a pointer to a string containing the name of the file to create.
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* @mode: the permission that the file should have.
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this parameter is NULL, then the
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* file will be created in the root of the debugfs filesystem.
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* @data: a pointer to something that the caller will want to get to later
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* on. The inode.i_private pointer will point to this value on
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* the open() call.
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* @fops: a pointer to a struct file_operations that should be used for
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* this file.
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*
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* debugfs_create_file_unsafe() is completely analogous to
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* debugfs_create_file(), the only difference being that the fops
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* handed it will not get protected against file removals by the
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* debugfs core.
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*
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* It is your responsibility to protect your struct file_operation
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* methods against file removals by means of debugfs_use_file_start()
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* and debugfs_use_file_finish(). ->open() is still protected by
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* debugfs though.
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*
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* Any struct file_operations defined by means of
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* DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
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* thus, may be used here.
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*/
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struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *fops)
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{
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return __debugfs_create_file(name, mode, parent, data,
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fops ? &debugfs_open_proxy_file_operations :
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&debugfs_noop_file_operations,
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fops);
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}
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EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
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/**
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* debugfs_create_file_size - create a file in the debugfs filesystem
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* @name: a pointer to a string containing the name of the file to create.
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* @mode: the permission that the file should have.
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this parameter is NULL, then the
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* file will be created in the root of the debugfs filesystem.
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* @data: a pointer to something that the caller will want to get to later
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* on. The inode.i_private pointer will point to this value on
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* the open() call.
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* @fops: a pointer to a struct file_operations that should be used for
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* this file.
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* @file_size: initial file size
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*
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* This is the basic "create a file" function for debugfs. It allows for a
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* wide range of flexibility in creating a file, or a directory (if you want
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* to create a directory, the debugfs_create_dir() function is
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* recommended to be used instead.)
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*
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* This function will return a pointer to a dentry if it succeeds. This
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* pointer must be passed to the debugfs_remove() function when the file is
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* to be removed (no automatic cleanup happens if your module is unloaded,
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* you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
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* returned.
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*
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* If debugfs is not enabled in the kernel, the value -%ENODEV will be
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* returned.
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*/
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struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *fops,
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loff_t file_size)
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{
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struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
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if (de)
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d_inode(de)->i_size = file_size;
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return de;
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}
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EXPORT_SYMBOL_GPL(debugfs_create_file_size);
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/**
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* debugfs_create_dir - create a directory in the debugfs filesystem
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* @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 parameter 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, %ERR_PTR(-ERROR) 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)
|
|
{
|
|
struct dentry *dentry = start_creating(name, parent);
|
|
struct inode *inode;
|
|
|
|
if (IS_ERR(dentry))
|
|
return dentry;
|
|
|
|
inode = debugfs_get_inode(dentry->d_sb);
|
|
if (unlikely(!inode))
|
|
return failed_creating(dentry);
|
|
|
|
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
|
|
inode->i_op = &simple_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
|
|
/* directory inodes start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
d_instantiate(dentry, inode);
|
|
inc_nlink(d_inode(dentry->d_parent));
|
|
fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
|
|
return end_creating(dentry);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_create_dir);
|
|
|
|
/**
|
|
* debugfs_create_automount - create automount point in the debugfs filesystem
|
|
* @name: a pointer to a string containing the name of the file to create.
|
|
* @parent: a pointer to the parent dentry for this file. This should be a
|
|
* directory dentry if set. If this parameter is NULL, then the
|
|
* file will be created in the root of the debugfs filesystem.
|
|
* @f: function to be called when pathname resolution steps on that one.
|
|
* @data: opaque argument to pass to f().
|
|
*
|
|
* @f should return what ->d_automount() would.
|
|
*/
|
|
struct dentry *debugfs_create_automount(const char *name,
|
|
struct dentry *parent,
|
|
debugfs_automount_t f,
|
|
void *data)
|
|
{
|
|
struct dentry *dentry = start_creating(name, parent);
|
|
struct inode *inode;
|
|
|
|
if (IS_ERR(dentry))
|
|
return dentry;
|
|
|
|
inode = debugfs_get_inode(dentry->d_sb);
|
|
if (unlikely(!inode))
|
|
return failed_creating(dentry);
|
|
|
|
make_empty_dir_inode(inode);
|
|
inode->i_flags |= S_AUTOMOUNT;
|
|
inode->i_private = data;
|
|
dentry->d_fsdata = (void *)f;
|
|
/* directory inodes start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
d_instantiate(dentry, inode);
|
|
inc_nlink(d_inode(dentry->d_parent));
|
|
fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
|
|
return end_creating(dentry);
|
|
}
|
|
EXPORT_SYMBOL(debugfs_create_automount);
|
|
|
|
/**
|
|
* 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 parameter 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, %ERR_PTR(-ERROR)
|
|
* 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 *dentry;
|
|
struct inode *inode;
|
|
char *link = kstrdup(target, GFP_KERNEL);
|
|
if (!link)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
dentry = start_creating(name, parent);
|
|
if (IS_ERR(dentry)) {
|
|
kfree(link);
|
|
return dentry;
|
|
}
|
|
|
|
inode = debugfs_get_inode(dentry->d_sb);
|
|
if (unlikely(!inode)) {
|
|
kfree(link);
|
|
return failed_creating(dentry);
|
|
}
|
|
inode->i_mode = S_IFLNK | S_IRWXUGO;
|
|
inode->i_op = &simple_symlink_inode_operations;
|
|
inode->i_link = link;
|
|
d_instantiate(dentry, inode);
|
|
return end_creating(dentry);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_create_symlink);
|
|
|
|
static void __debugfs_remove_file(struct dentry *dentry, struct dentry *parent)
|
|
{
|
|
struct debugfs_fsdata *fsd;
|
|
|
|
simple_unlink(d_inode(parent), dentry);
|
|
d_delete(dentry);
|
|
|
|
/*
|
|
* Paired with the closing smp_mb() implied by a successful
|
|
* cmpxchg() in debugfs_file_get(): either
|
|
* debugfs_file_get() must see a dead dentry or we must see a
|
|
* debugfs_fsdata instance at ->d_fsdata here (or both).
|
|
*/
|
|
smp_mb();
|
|
fsd = READ_ONCE(dentry->d_fsdata);
|
|
if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
|
|
return;
|
|
if (!refcount_dec_and_test(&fsd->active_users))
|
|
wait_for_completion(&fsd->active_users_drained);
|
|
}
|
|
|
|
static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (simple_positive(dentry)) {
|
|
dget(dentry);
|
|
if (!d_is_reg(dentry)) {
|
|
if (d_is_dir(dentry))
|
|
ret = simple_rmdir(d_inode(parent), dentry);
|
|
else
|
|
simple_unlink(d_inode(parent), dentry);
|
|
if (!ret)
|
|
d_delete(dentry);
|
|
} else {
|
|
__debugfs_remove_file(dentry, parent);
|
|
}
|
|
dput(dentry);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* 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. If this parameter is NULL or an error value, nothing
|
|
* will be done.
|
|
*
|
|
* 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;
|
|
int ret;
|
|
|
|
if (IS_ERR_OR_NULL(dentry))
|
|
return;
|
|
|
|
parent = dentry->d_parent;
|
|
inode_lock(d_inode(parent));
|
|
ret = __debugfs_remove(dentry, parent);
|
|
inode_unlock(d_inode(parent));
|
|
if (!ret)
|
|
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. If this
|
|
* parameter is NULL or an error value, nothing will be done.
|
|
*
|
|
* 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, *parent;
|
|
|
|
if (IS_ERR_OR_NULL(dentry))
|
|
return;
|
|
|
|
parent = dentry;
|
|
down:
|
|
inode_lock(d_inode(parent));
|
|
loop:
|
|
/*
|
|
* The parent->d_subdirs is protected by the d_lock. Outside that
|
|
* lock, the child can be unlinked and set to be freed which can
|
|
* use the d_u.d_child as the rcu head and corrupt this list.
|
|
*/
|
|
spin_lock(&parent->d_lock);
|
|
list_for_each_entry(child, &parent->d_subdirs, d_child) {
|
|
if (!simple_positive(child))
|
|
continue;
|
|
|
|
/* perhaps simple_empty(child) makes more sense */
|
|
if (!list_empty(&child->d_subdirs)) {
|
|
spin_unlock(&parent->d_lock);
|
|
inode_unlock(d_inode(parent));
|
|
parent = child;
|
|
goto down;
|
|
}
|
|
|
|
spin_unlock(&parent->d_lock);
|
|
|
|
if (!__debugfs_remove(child, parent))
|
|
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
|
|
|
|
/*
|
|
* The parent->d_lock protects agaist child from unlinking
|
|
* from d_subdirs. When releasing the parent->d_lock we can
|
|
* no longer trust that the next pointer is valid.
|
|
* Restart the loop. We'll skip this one with the
|
|
* simple_positive() check.
|
|
*/
|
|
goto loop;
|
|
}
|
|
spin_unlock(&parent->d_lock);
|
|
|
|
inode_unlock(d_inode(parent));
|
|
child = parent;
|
|
parent = parent->d_parent;
|
|
inode_lock(d_inode(parent));
|
|
|
|
if (child != dentry)
|
|
/* go up */
|
|
goto loop;
|
|
|
|
if (!__debugfs_remove(child, parent))
|
|
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
|
|
inode_unlock(d_inode(parent));
|
|
}
|
|
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;
|
|
struct name_snapshot old_name;
|
|
|
|
if (IS_ERR(old_dir))
|
|
return old_dir;
|
|
if (IS_ERR(new_dir))
|
|
return new_dir;
|
|
if (IS_ERR_OR_NULL(old_dentry))
|
|
return old_dentry;
|
|
|
|
trap = lock_rename(new_dir, old_dir);
|
|
/* Source or destination directories don't exist? */
|
|
if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
|
|
goto exit;
|
|
/* Source does not exist, cyclic rename, or mountpoint? */
|
|
if (d_really_is_negative(old_dentry) || 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 || d_really_is_positive(dentry))
|
|
goto exit;
|
|
|
|
take_dentry_name_snapshot(&old_name, old_dentry);
|
|
|
|
error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
|
|
dentry, 0);
|
|
if (error) {
|
|
release_dentry_name_snapshot(&old_name);
|
|
goto exit;
|
|
}
|
|
d_move(old_dentry, dentry);
|
|
fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name,
|
|
d_is_dir(old_dentry),
|
|
NULL, old_dentry);
|
|
release_dentry_name_snapshot(&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);
|
|
if (IS_ERR(dentry))
|
|
return dentry;
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
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 int __init debugfs_init(void)
|
|
{
|
|
int retval;
|
|
|
|
retval = sysfs_create_mount_point(kernel_kobj, "debug");
|
|
if (retval)
|
|
return retval;
|
|
|
|
retval = register_filesystem(&debug_fs_type);
|
|
if (retval)
|
|
sysfs_remove_mount_point(kernel_kobj, "debug");
|
|
else
|
|
debugfs_registered = true;
|
|
|
|
return retval;
|
|
}
|
|
core_initcall(debugfs_init);
|
|
|