debugfs: implement symbolic links (66f54963) · Commits · e / devices / android_kernel_xiaomi_markw

fs/debugfs/file.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@
		#include <linux/module.h>
		#include <linux/fs.h>
		#include <linux/pagemap.h>
		#include <linux/namei.h>
		#include <linux/debugfs.h>

		static ssize_t default_read_file(struct file file, char __user buf,
		@@ -44,6 +45,17 @@ const struct file_operations debugfs_file_operations = {
		.open = default_open,
		};

		static void debugfs_follow_link(struct dentry dentry, struct nameidata *nd)
		{
		nd_set_link(nd, dentry->d_inode->i_private);
		return NULL;
		}

		const struct inode_operations debugfs_link_operations = {
		.readlink = generic_readlink,
		.follow_link = debugfs_follow_link,
		};

		static void debugfs_u8_set(void *data, u64 val)
		{
		(u8 )data = val;

fs/debugfs/inode.c

+72 −4

Original line number	Diff line number	Diff line
		@@ -25,11 +25,13 @@
		#include <linux/namei.h>
		#include <linux/debugfs.h>
		#include <linux/fsnotify.h>
		#include <linux/string.h>

		#define DEBUGFS_MAGIC 0x64626720

		/* declared over in file.c */
		extern struct file_operations debugfs_file_operations;
		extern struct inode_operations debugfs_link_operations;

		static struct vfsmount *debugfs_mount;
		static int debugfs_mount_count;
		@@ -51,6 +53,9 @@ static struct inode debugfs_get_inode(struct super_block sb, int mode, dev_t d
		case S_IFREG:
		inode->i_fop = &debugfs_file_operations;
		break;
		case S_IFLNK:
		inode->i_op = &debugfs_link_operations;
		break;
		case S_IFDIR:
		inode->i_op = &simple_dir_inode_operations;
		inode->i_fop = &simple_dir_operations;
		@@ -96,6 +101,12 @@ static int debugfs_mkdir(struct inode dir, struct dentry dentry, int mode)
		return res;
		}

		static int debugfs_link(struct inode dir, struct dentry dentry, int mode)
		{
		mode = (mode & S_IALLUGO) \| S_IFLNK;
		return debugfs_mknod(dir, dentry, mode, 0);
		}

		static int debugfs_create(struct inode dir, struct dentry dentry, int mode)
		{
		int res;
		@@ -158,10 +169,17 @@ static int debugfs_create_by_name(const char *name, mode_t mode,
		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)
		switch (mode & S_IFMT) {
		case S_IFDIR:
		error = debugfs_mkdir(parent->d_inode, *dentry, mode);
		else
		break;
		case S_IFLNK:
		error = debugfs_link(parent->d_inode, *dentry, mode);
		break;
		default:
		error = debugfs_create(parent->d_inode, *dentry, mode);
		break;
		}
		dput(*dentry);
		} else
		error = PTR_ERR(*dentry);
		@@ -258,6 +276,49 @@ struct dentry debugfs_create_dir(const char name, struct dentry *parent)
		}
		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. 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_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);

		/**
		* 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
		@@ -287,15 +348,22 @@ void debugfs_remove(struct dentry *dentry)
		if (debugfs_positive(dentry)) {
		if (dentry->d_inode) {
		dget(dentry);
		if (S_ISDIR(dentry->d_inode->i_mode)) {
		switch (dentry->d_inode->i_mode & S_IFMT) {
		case S_IFDIR:
		ret = simple_rmdir(parent->d_inode, dentry);
		if (ret)
		printk(KERN_ERR
		"DebugFS rmdir on %s failed : "
		"directory not empty.\n",
		dentry->d_name.name);
		} else
		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);

include/linux/debugfs.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,9 @@ struct dentry debugfs_create_file(const char name, mode_t mode,

		struct dentry debugfs_create_dir(const char name, struct dentry *parent);

		struct dentry debugfs_create_symlink(const char name, struct dentry *parent,
		const char *dest);

		void debugfs_remove(struct dentry *dentry);

		struct dentry debugfs_create_u8(const char name, mode_t mode,
		@@ -70,6 +73,13 @@ static inline struct dentry debugfs_create_dir(const char name,
		return ERR_PTR(-ENODEV);
		}

		static inline struct dentry debugfs_create_symlink(const char name,
		struct dentry *parent,
		const char *dest)
		{
		return ERR_PTR(-ENODEV);
		}

		static inline void debugfs_remove(struct dentry *dentry)
		{ }