ubifs: Implement O_TMPFILE

This patchs adds O_TMPFILE support to UBIFS.
A temp file is a reference to an unlinked inode, a user
holding the reference can use it. As soon it is being closed
all data vanishes.

Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/dir.c

@@ -301,6 +301,76 @@ static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
  return err;
 }
 
+static int ubifs_tmpfile(struct inode *dir, struct dentry *dentry,
+ umode_t mode)
+{
+ struct inode *inode;
+ struct ubifs_info *c = dir->i_sb->s_fs_info;
+ struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1};
+ struct ubifs_budget_req ino_req = { .dirtied_ino = 1 };
+ struct ubifs_inode *ui, *dir_ui = ubifs_inode(dir);
+ int err, instantiated = 0;
+
+ /*
+ * Budget request settings: new dirty inode, new direntry,
+ * budget for dirtied inode will be released via writeback.
+ */
+
+ dbg_gen("dent '%pd', mode %#hx in dir ino %lu",
+ dentry, mode, dir->i_ino);
+
+ err = ubifs_budget_space(c, &req);
+ if (err)
+ return err;
+
+ err = ubifs_budget_space(c, &ino_req);
+ if (err) {
+ ubifs_release_budget(c, &req);
+ return err;
+ }
+
+ inode = ubifs_new_inode(c, dir, mode);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ goto out_budg;
+ }
+ ui = ubifs_inode(inode);
+
+ err = ubifs_init_security(dir, inode, &dentry->d_name);
+ if (err)
+ goto out_inode;
+
+ mutex_lock(&ui->ui_mutex);
+ insert_inode_hash(inode);
+ d_tmpfile(dentry, inode);
+ ubifs_assert(ui->dirty);
+ instantiated = 1;
+ mutex_unlock(&ui->ui_mutex);
+
+ mutex_lock(&dir_ui->ui_mutex);
+ err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 1, 0);
+ if (err)
+ goto out_cancel;
+ mutex_unlock(&dir_ui->ui_mutex);
+
+ ubifs_release_budget(c, &req);
+
+ return 0;
+
+out_cancel:
+ mutex_unlock(&dir_ui->ui_mutex);
+out_inode:
+ make_bad_inode(inode);
+ if (!instantiated)
+ iput(inode);
+out_budg:
+ ubifs_release_budget(c, &req);
+ if (!instantiated)
+ ubifs_release_budget(c, &ino_req);
+ ubifs_err(c, "cannot create temporary file, error %d", err);
+ return err;
+}
+
 /**
  * vfs_dent_type - get VFS directory entry type.
  * @type: UBIFS directory entry type
@@ -1189,6 +1259,7 @@ const struct inode_operations ubifs_dir_inode_operations = {
 #ifdef CONFIG_UBIFS_ATIME_SUPPORT
  .update_time = ubifs_update_time,
 #endif
+ .tmpfile = ubifs_tmpfile,
 };
 
 const struct file_operations ubifs_dir_operations = {