f2fs: release inmemory pages when the file was closed

If file is closed, let's drop inmemory pages.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -901,6 +901,14 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
 	return f2fs_convert_inline_inode(inode);
 }
 
+static int f2fs_release_file(struct inode *inode, struct file *filp)
+{
+	/* some remained atomic pages should discarded */
+	if (f2fs_is_atomic_file(inode) || f2fs_is_volatile_file(inode))
+		commit_inmem_pages(inode, true);
+	return 0;
+}
+
 static int f2fs_ioc_commit_atomic_write(struct file *filp)
 {
 	struct inode *inode = file_inode(filp);
@@ -1010,6 +1018,7 @@ const struct file_operations f2fs_file_operations = {
 	.read_iter	= generic_file_read_iter,
 	.write_iter	= generic_file_write_iter,
 	.open		= generic_file_open,
+	.release	= f2fs_release_file,
 	.mmap		= f2fs_file_mmap,
 	.fsync		= f2fs_sync_file,
 	.fallocate	= f2fs_fallocate,