From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:33320 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935190AbcKDTND (ORCPT ); Fri, 4 Nov 2016 15:13:03 -0400 From: Liu Bo To: linux-btrfs@vger.kernel.org Cc: David Sterba Subject: [PATCH] Btrfs: adjust len of writes if following a preallocated extent Date: Fri, 4 Nov 2016 12:20:54 -0700 Message-Id: <1478287254-5458-1-git-send-email-bo.li.liu@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: If we have |0--hole--4095||4096--preallocate--12287| instead of using preallocated space, a 8K direct write will just create a new 8K extent and it'll end up with |0--new extent--8191||8192--preallocate--12287| It's because we find a hole em and then go to create a new 8K extent directly without adjusting @len. Signed-off-by: Liu Bo --- fs/btrfs/inode.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 2b790bd..48e9356 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7783,10 +7783,12 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, } /* - * this will cow the extent, reset the len in case we changed - * it above + * this will cow the extent, if em is within [start, len], then + * probably we've found a preallocated/existing extent, let's + * give it a chance to use preallocated space. */ - len = bh_result->b_size; + len = min_t(u64, bh_result->b_size, em->len - (start - em->start)); + len = ALIGN(len, root->sectorsize); free_extent_map(em); em = btrfs_new_extent_direct(inode, start, len); if (IS_ERR(em)) { -- 2.5.5