From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:58483 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751971Ab2LEKxs (ORCPT ); Wed, 5 Dec 2012 05:53:48 -0500 Received: from fnstmail02.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id qB5ArqnQ019325 for ; Wed, 5 Dec 2012 18:53:52 +0800 Message-ID: <50BF27D4.3000504@cn.fujitsu.com> Date: Wed, 05 Dec 2012 18:54:12 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com MIME-Version: 1.0 To: Linux Btrfs Subject: [PATCH 4/6] Btrfs: fix the page that is beyond EOF Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Steps to reproduce: # mkfs.btrfs # mount # dd if=/dev/zero of=/ bs=512 seek=5 count=8 # fallocate -p -o 2048 -l 16384 / # dd if=/dev/zero of=/ bs=4096 seek=3 count=8 conv=notrunc,nocreat # umount # dmesg WARNING: at fs/btrfs/inode.c:7140 btrfs_destroy_inode+0x2eb/0x330 The reason is that we inputed a range which is beyond the end of the file. And because the end of this range was not page-aligned, we had to truncate the last page in this range, this operation is similar to a buffered file write. In other words, we reserved enough space and clear the data which was in the hole range on that page. But when we expanded that test file, write the data into the same page, we forgot that we have reserved enough space for the buffered write of that page because in most cases there is no page that is beyond the end of the file. As a result, we reserved the space twice. In fact, we needn't truncate the page if it is beyond the end of the file, just release the allocated space in that range. Fix the above problem by this way. Signed-off-by: Miao Xie --- fs/btrfs/file.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index b477da2..e91c99b 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1872,9 +1872,9 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len) struct btrfs_path *path; struct btrfs_block_rsv *rsv; struct btrfs_trans_handle *trans; - u64 mask = BTRFS_I(inode)->root->sectorsize - 1; - u64 lockstart = (offset + mask) & ~mask; - u64 lockend = ((offset + len) & ~mask) - 1; + u64 lockstart = round_up(offset, BTRFS_I(inode)->root->sectorsize); + u64 lockend = round_down(offset + len, + BTRFS_I(inode)->root->sectorsize) - 1; u64 cur_offset = lockstart; u64 min_size = btrfs_calc_trunc_metadata_size(root, 1); u64 drop_end; @@ -1910,10 +1910,12 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len) } /* zero the front end of the last page */ - ret = btrfs_truncate_page(inode, offset + len, 0, 1); - if (ret) { - mutex_unlock(&inode->i_mutex); - return ret; + if (offset + len < round_up(inode->i_size, PAGE_CACHE_SIZE)) { + ret = btrfs_truncate_page(inode, offset + len, 0, 1); + if (ret) { + mutex_unlock(&inode->i_mutex); + return ret; + } } if (lockend < lockstart) { -- 1.7.11.7