/* * 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/namei.h> #include <linux/debugfs.h> #define DEBUGFS_MAGIC 0x64626720 /* declared over in file.c */ extern struct file_operations debugfs_file_operations; static struct vfsmount *debugfs_mount; static int debugfs_mount_count; static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev) { struct inode *inode = new_inode(sb); if (inode) { inode->i_mode = mode; inode->i_uid = 0; inode->i_gid = 0; inode->i_blksize = PAGE_CACHE_SIZE; inode->i_blocks = 0; 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 = &debugfs_file_operations; break; case S_IFDIR: inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ inode->i_nlink++; break; } } return inode; } /* SMP-safe */ static int debugfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) { struct inode *inode; int error = -EPERM; if (dentry->d_inode) return -EEXIST; inode = debugfs_get_inode(dir->i_sb, mode, dev); if (inode) { d_instantiate(dentry, inode); dget(dentry); error = 0; } return error; } static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) { int res; mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; res = debugfs_mknod(dir, dentry, mode, 0); if (!res) dir->i_nlink++; return res; } static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode) { mode = (mode & S_IALLUGO) | S_IFREG; return debugfs_mknod(dir, dentry, mode, 0); } 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); } static int debug_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { 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) { 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)) { if ((mode & S_IFMT) == S_IFDIR) error = debugfs_mkdir(parent->d_inode, *dentry, mode); else error = debugfs_create(parent->d_inode, *dentry, mode); } 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.u.generic_ip 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 createing 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. It is not wise to check for this value, but rather, check for * NULL or !NULL instead as to eliminate the need for #ifdef in the calling * code. */ 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); if (error) { dentry = NULL; goto exit; } if (dentry->d_inode) { if (data) dentry->d_inode->u.generic_ip = data; if (fops) dentry->d_inode->i_fop = fops; } 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. It is not wise to check for this value, but rather, check for * NULL or !NULL instead as to eliminate the need for #ifdef in the calling * code. */ 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_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 * debufs_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); if (debugfs_positive(dentry)) { if (dentry->d_inode) { if (S_ISDIR(dentry->d_inode->i_mode)) simple_rmdir(parent->d_inode, dentry); else simple_unlink(parent->d_inode, dentry); dput(dentry); } } mutex_unlock(&parent->d_inode->i_mutex); simple_release_fs(&debugfs_mount, &debugfs_mount_count); } EXPORT_SYMBOL_GPL(debugfs_remove); static decl_subsys(debug, NULL, NULL); static int __init debugfs_init(void) { int retval; kset_set_kset_s(&debug_subsys, kernel_subsys); retval = subsystem_register(&debug_subsys); if (retval) return retval; retval = register_filesystem(&debug_fs_type); if (retval) subsystem_unregister(&debug_subsys); return retval; } static void __exit debugfs_exit(void) { simple_release_fs(&debugfs_mount, &debugfs_mount_count); unregister_filesystem(&debug_fs_type); subsystem_unregister(&debug_subsys); } core_initcall(debugfs_init); module_exit(debugfs_exit); MODULE_LICENSE("GPL");