From patchwork Thu Apr 6 16:07:56 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 9667783 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 44981601EB for ; Thu, 6 Apr 2017 16:08:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98B7F28535 for ; Thu, 6 Apr 2017 16:08:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8CD4E2858C; Thu, 6 Apr 2017 16:08:06 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E00E028535 for ; Thu, 6 Apr 2017 16:08:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933614AbdDFQID (ORCPT ); Thu, 6 Apr 2017 12:08:03 -0400 Received: from mail.kernel.org ([198.145.29.136]:59074 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932595AbdDFQIC (ORCPT ); Thu, 6 Apr 2017 12:08:02 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7C5112022D for ; Thu, 6 Apr 2017 16:08:00 +0000 (UTC) Received: from debian3.lan (bl12-226-64.dsl.telepac.pt [85.245.226.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 157E2201EF for ; Thu, 6 Apr 2017 16:07:58 +0000 (UTC) From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH] Btrfs: send, fix file hole not being preserved due to inline extent Date: Thu, 6 Apr 2017 17:07:56 +0100 Message-Id: <1491494876-14433-1-git-send-email-fdmanana@kernel.org> X-Mailer: git-send-email 2.7.0.rc3 X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Filipe Manana Normally we don't have inline extents followed by regular extents, but there's currently at least one harmless case where this happens. For example, when the page size is 4Kb and compression is enabled: $ mkfs.btrfs -f /dev/sdb $ mount -o compress /dev/sdb /mnt $ xfs_io -f -c "pwrite -S 0xaa 0 4K" -c "fsync" /mnt/foobar $ xfs_io -c "pwrite -S 0xbb 8K 4K" -c "fsync" /mnt/foobar In this case we get a compressed inline extent, representing 4Kb of data, followed by a hole extent and then a regular data extent. The inline extent was not expanded/converted to a regular extent exactly because it represents 4Kb of data. This does not cause any apparent problem (such as the issue solved by commit e1699d2d7bf6 ("btrfs: add missing memset while reading compressed inline extents")) except trigger an unexpected case in the incremental send code path that makes us issue an operation to write a hole when it's not needed, resulting in more writes at the receiver and wasting space at the receiver. So teach the incremental send code to deal with this particular case. The issue can be currently triggered by running fstests btrfs/137 with compression enabled (MOUNT_OPTIONS="-o compress" ./check btrfs/137). Signed-off-by: Filipe Manana Reviewed-by: Liu Bo --- fs/btrfs/send.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 456c890..f66095a 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -5184,13 +5184,19 @@ static int is_extent_unchanged(struct send_ctx *sctx, while (key.offset < ekey->offset + left_len) { ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); right_type = btrfs_file_extent_type(eb, ei); - if (right_type != BTRFS_FILE_EXTENT_REG) { + if (right_type != BTRFS_FILE_EXTENT_REG && + right_type != BTRFS_FILE_EXTENT_INLINE) { ret = 0; goto out; } right_disknr = btrfs_file_extent_disk_bytenr(eb, ei); - right_len = btrfs_file_extent_num_bytes(eb, ei); + if (right_type == BTRFS_FILE_EXTENT_INLINE) { + right_len = btrfs_file_extent_inline_len(eb, slot, ei); + right_len = PAGE_ALIGN(right_len); + } else { + right_len = btrfs_file_extent_num_bytes(eb, ei); + } right_offset = btrfs_file_extent_offset(eb, ei); right_gen = btrfs_file_extent_generation(eb, ei); @@ -5204,6 +5210,19 @@ static int is_extent_unchanged(struct send_ctx *sctx, goto out; } + /* + * We just wanted to see if when we have an inline extent, what + * follows it is a regular extent (wanted to check the above + * condition for inline extents too). This should normally not + * happen but it's possible for example when we have an inline + * compressed extent representing data with a size matching + * the page size (currently the same as sector size). + */ + if (right_type == BTRFS_FILE_EXTENT_INLINE) { + ret = 0; + goto out; + } + left_offset_fixed = left_offset; if (key.offset < ekey->offset) { /* Fix the right offset for 2a and 7. */