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);