ext4: fix punch hole for inline_data file systems

If a program attempts to punch a hole on an inline data file, we need
to convert it to a normal file first.

This was detected using ext4/032 using the adv configuration.  Simple
reproducer:

mke2fs -Fq -t ext4 -O inline_data /dev/vdc
mount /vdc
echo "" > /vdc/testfile
xfs_io -c 'truncate 33554432' /vdc/testfile
xfs_io -c 'fpunch 0 1048576' /vdc/testfile
umount /vdc
e2fsck -fy /dev/vdc

Cc: stable@vger.kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/inode.c

@@ -4236,6 +4236,15 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
 
 	trace_ext4_punch_hole(inode, offset, length, 0);
 
+	ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
+	if (ext4_has_inline_data(inode)) {
+		down_write(&EXT4_I(inode)->i_mmap_sem);
+		ret = ext4_convert_inline_data(inode);
+		up_write(&EXT4_I(inode)->i_mmap_sem);
+		if (ret)
+			return ret;
+	}
+
 	/*
 	 * Write out all dirty pages to avoid race conditions
 	 * Then release them.