diff options
Diffstat (limited to 'fs/debugfs/inode.c')
| -rw-r--r-- | fs/debugfs/inode.c | 328 |
1 files changed, 328 insertions, 0 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c new file mode 100644 index 000000000000..b529786699e7 --- /dev/null +++ b/fs/debugfs/inode.c @@ -0,0 +1,328 @@ +/* + * 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/config.h> +#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 = debugfs_get_inode(dir->i_sb, mode, dev); + int error = -EPERM; + + if (dentry->d_inode) + return -EEXIST; + + 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 struct dentry * get_dentry(struct dentry *parent, const char *name) +{ + struct qstr qstr; + + qstr.name = name; + qstr.len = strlen(name); + qstr.hash = full_name_hash(name,qstr.len); + return lookup_hash(&qstr,parent); +} + +static struct super_block *debug_get_sb(struct file_system_type *fs_type, + int flags, const char *dev_name, + void *data) +{ + return get_sb_single(fs_type, flags, data, debug_fill_super); +} + +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; + down(&parent->d_inode->i_sem); + *dentry = get_dentry (parent, 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); + up(&parent->d_inode->i_sem); + + 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, + struct file_operations *fops) +{ + struct dentry *dentry = NULL; + int error; + + pr_debug("debugfs: creating file '%s'\n",name); + + error = simple_pin_fs("debugfs", &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; + + down(&parent->d_inode->i_sem); + 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); + } + } + up(&parent->d_inode->i_sem); + 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"); + |