Merge branch 'debugfs_automount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull debugfs patches from Al Viro:
 "debugfs patches, mostly to make it possible for something like tracefs
  to be transparently automounted on given directory in debugfs.

  New primitive in there is debugfs_create_automount(name, parent, func,
  arg), which creates a directory and makes its ->d_automount() return
  func(arg).  Another missing primitive was debugfs_create_file_size() -
  open-coded in quite a few places.  Dave's patch adds it and converts
  the open-code instances to calling it"

* 'debugfs_automount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  debugfs: Provide a file creation function that also takes an initial size
  new primitive: debugfs_create_automount()
  debugfs: split end_creating() into success and failure cases
  debugfs: take mode-dependent parts of debugfs_get_inode() into callers
  fold debugfs_mknod() into callers
  fold debugfs_create() into caller
  fold debugfs_mkdir() into caller
  debugfs_mknod(): get rid useless arguments
  fold debugfs_link() into caller
  debugfs: kill __create_file()
  debugfs: split the beginning and the end of __create_file() off
  debugfs_{mkdir,create,link}(): get rid of redundant argument

1 files changed, 168 insertions, 123 deletions

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 05f2960ed7c3..45b18a5e225c 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -34,93 +34,16 @@ static struct vfsmount *debugfs_mount;
 static int debugfs_mount_count;
 static bool debugfs_registered;
 
-static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
-				       void *data, const struct file_operations *fops)
-
+static struct inode *debugfs_get_inode(struct super_block *sb)
 {
 	struct inode *inode = new_inode(sb);
-
 	if (inode) {
 		inode->i_ino = get_next_ino();
-		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_private = data;
-			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) */
-			inc_nlink(inode);
-			break;
-		}
 	}
 	return inode;
 }
 
-/* SMP-safe */
-static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
-			 umode_t 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, umode_t mode)
-{
-	int res;
-
-	mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
-	res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);
-	if (!res) {
-		inc_nlink(dir);
-		fsnotify_mkdir(dir, dentry);
-	}
-	return res;
-}
-
-static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
-			void *data)
-{
-	mode = (mode & S_IALLUGO) | S_IFLNK;
-	return debugfs_mknod(dir, dentry, mode, 0, data, NULL);
-}
-
-static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t 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);
@@ -252,6 +175,18 @@ static const struct super_operations debugfs_super_operations = {
 	.show_options	= debugfs_show_options,
 };
 
+static struct vfsmount *debugfs_automount(struct path *path)
+{
+	struct vfsmount *(*f)(void *);
+	f = (struct vfsmount *(*)(void *))path->dentry->d_fsdata;
+	return f(path->dentry->d_inode->i_private);
+}
+
+static const struct dentry_operations debugfs_dops = {
+	.d_delete = always_delete_dentry,
+	.d_automount = debugfs_automount,
+};
+
 static int debug_fill_super(struct super_block *sb, void *data, int silent)
 {
 	static struct tree_descr debug_files[] = {{""}};
@@ -276,6 +211,7 @@ static int debug_fill_super(struct super_block *sb, void *data, int silent)
 		goto fail;
 
 	sb->s_op = &debugfs_super_operations;
+	sb->s_d_op = &debugfs_dops;
 
 	debugfs_apply_options(sb);
 
@@ -302,11 +238,9 @@ static struct file_system_type debug_fs_type = {
 };
 MODULE_ALIAS_FS("debugfs");
 
-static struct dentry *__create_file(const char *name, umode_t mode,
-				    struct dentry *parent, void *data,
-				    const struct file_operations *fops)
+static struct dentry *start_creating(const char *name, struct dentry *parent)
 {
-	struct dentry *dentry = NULL;
+	struct dentry *dentry;
 	int error;
 
 	pr_debug("debugfs: creating file '%s'\n",name);
@@ -314,7 +248,7 @@ static struct dentry *__create_file(const char *name, umode_t mode,
 	error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
 			      &debugfs_mount_count);
 	if (error)
-		goto exit;
+		return ERR_PTR(error);
 
 	/* 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
@@ -326,31 +260,26 @@ static struct dentry *__create_file(const char *name, umode_t mode,
 
 	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);
-
-			break;
-		case S_IFLNK:
-			error = debugfs_link(parent->d_inode, dentry, mode,
-					     data);
-			break;
-		default:
-			error = debugfs_create(parent->d_inode, dentry, mode,
-					       data, fops);
-			break;
-		}
+	if (!IS_ERR(dentry) && dentry->d_inode) {
 		dput(dentry);
-	} else
-		error = PTR_ERR(dentry);
-	mutex_unlock(&parent->d_inode->i_mutex);
-
-	if (error) {
-		dentry = NULL;
-		simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+		dentry = ERR_PTR(-EEXIST);
 	}
-exit:
+	if (IS_ERR(dentry))
+		mutex_unlock(&parent->d_inode->i_mutex);
+	return dentry;
+}
+
+static struct dentry *failed_creating(struct dentry *dentry)
+{
+	mutex_unlock(&dentry->d_parent->d_inode->i_mutex);
+	dput(dentry);
+	simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+	return NULL;
+}
+
+static struct dentry *end_creating(struct dentry *dentry)
+{
+	mutex_unlock(&dentry->d_parent->d_inode->i_mutex);
 	return dentry;
 }
 
@@ -384,19 +313,71 @@ struct dentry *debugfs_create_file(const char *name, umode_t mode,
 				   struct dentry *parent, void *data,
 				   const struct file_operations *fops)
 {
-	switch (mode & S_IFMT) {
-	case S_IFREG:
-	case 0:
-		break;
-	default:
-		BUG();
-	}
+	struct dentry *dentry;
+	struct inode *inode;
+
+	if (!(mode & S_IFMT))
+		mode |= S_IFREG;
+	BUG_ON(!S_ISREG(mode));
+	dentry = start_creating(name, parent);
+
+	if (IS_ERR(dentry))
+		return NULL;
 
-	return __create_file(name, mode, parent, data, fops);
+	inode = debugfs_get_inode(dentry->d_sb);
+	if (unlikely(!inode))
+		return failed_creating(dentry);
+
+	inode->i_mode = mode;
+	inode->i_fop = fops ? fops : &debugfs_file_operations;
+	inode->i_private = data;
+	d_instantiate(dentry, inode);
+	fsnotify_create(dentry->d_parent->d_inode, dentry);
+	return end_creating(dentry);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_file);
 
 /**
+ * debugfs_create_file_size - 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 parameter 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.
+ * @file_size: initial file size
+ *
+ * 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_size(const char *name, umode_t mode,
+					struct dentry *parent, void *data,
+					const struct file_operations *fops,
+					loff_t file_size)
+{
+	struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
+
+	if (de)
+		de->d_inode->i_size = file_size;
+	return de;
+}
+EXPORT_SYMBOL_GPL(debugfs_create_file_size);
+
+/**
  * debugfs_create_dir - create a directory in the debugfs filesystem
  * @name: a pointer to a string containing the name of the directory to
  *        create.
@@ -416,12 +397,65 @@ EXPORT_SYMBOL_GPL(debugfs_create_file);
  */
 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
 {
-	return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
-				   parent, NULL, NULL);
+	struct dentry *dentry = start_creating(name, parent);
+	struct inode *inode;
+
+	if (IS_ERR(dentry))
+		return NULL;
+
+	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(dentry->d_parent->d_inode);
+	fsnotify_mkdir(dentry->d_parent->d_inode, 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,
+					struct vfsmount *(*f)(void *),
+					void *data)
+{
+	struct dentry *dentry = start_creating(name, parent);
+	struct inode *inode;
+
+	if (IS_ERR(dentry))
+		return NULL;
+
+	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_flags |= S_AUTOMOUNT;
+	inode->i_private = data;
+	dentry->d_fsdata = (void *)f;
+	d_instantiate(dentry, inode);
+	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.
@@ -447,17 +481,28 @@ EXPORT_SYMBOL_GPL(debugfs_create_dir);
 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
 				      const char *target)
 {
-	struct dentry *result;
-	char *link;
-
-	link = kstrdup(target, GFP_KERNEL);
+	struct dentry *dentry;
+	struct inode *inode;
+	char *link = kstrdup(target, GFP_KERNEL);
 	if (!link)
 		return NULL;
 
-	result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);
-	if (!result)
+	dentry = start_creating(name, parent);
+	if (IS_ERR(dentry)) {
 		kfree(link);
-	return result;
+		return NULL;
+	}
+
+	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 = &debugfs_link_operations;
+	inode->i_private = link;
+	d_instantiate(dentry, inode);
+	return end_creating(dentry);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_symlink);