From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B67E8847C; Mon, 1 Jul 2024 02:26:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719800793; cv=none; b=ToGHeKOpoqt2rBbejRAHNsb+31IYnkXz6GD0u00OBSOL0GTPQS5xL8XKiG3jHST8Sn3RAV8ARnWjnskgRqeb9bPKZehSvLaHUA+gg2dPUVRTZtLVrY6G/sGB0qkWKIibV2k4mQ3lVYHNjUETLHgRrIX8lcWvyWSisgyWpalMjog= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719800793; c=relaxed/simple; bh=sSXuzX+WtTkW5UROQw7ByVRKZjhDpJk2+IFTmWsInT0=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=fPjzfRKrH1omWY8rq75UC6NCUt6jMbD5fsIvTcQilo11VVaKgAwxkQ5JYiubR5LrnOjlzUwme5LH/x0RYc8hV/eRPecAjbyCWLYD7gvhinTWVri+CPzfkAzwfwG6PWjK4Gra6OpUKzt2AY0VcG39yFkRv0VfrFuZJbq5tqWrjnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4WC8zh10Yqz4f3jHw; Mon, 1 Jul 2024 10:26:08 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.75]) by mail.maildlp.com (Postfix) with ESMTP id 814ED1A016E; Mon, 1 Jul 2024 10:26:20 +0800 (CST) Received: from [10.174.179.80] (unknown [10.174.179.80]) by APP2 (Coremail) with SMTP id Syh0CgAnkYbKE4JmQUVRAw--.39659S3; Mon, 01 Jul 2024 10:26:20 +0800 (CST) Subject: Re: [PATCH -next v6 1/2] xfs: reserve blocks for truncating large realtime inode To: Dave Chinner Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, djwong@kernel.org, hch@infradead.org, brauner@kernel.org, chandanbabu@kernel.org, John Garry , jack@suse.cz, yi.zhang@huawei.com, chengzhihao1@huawei.com, yukuai3@huawei.com References: <20240618142112.1315279-1-yi.zhang@huaweicloud.com> <20240618142112.1315279-2-yi.zhang@huaweicloud.com> From: Zhang Yi Message-ID: Date: Mon, 1 Jul 2024 10:26:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CM-TRANSID:Syh0CgAnkYbKE4JmQUVRAw--.39659S3 X-Coremail-Antispam: 1UD129KBjvJXoWxuryDZr13tr1Dury8ArWrZrb_yoW5ury3pF Z7Ca1UKFZ8Xry0kaySyF1ay3Wjkw1rKr42kryYgr1Iv34DXr1ftrn7tr4UKF1UJr4kWa1j gr15A3y3Zw15ZFJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvIb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7Mxk0xIA0c2IE e2xFo4CEbIxvr21l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxV Aqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q 6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6x kF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE 14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf 9x07UWE__UUUUU= X-CM-SenderInfo: d1lo6xhdqjqx5xdzvxpfor3voofrz/ On 2024/7/1 9:16, Dave Chinner wrote: > On Tue, Jun 18, 2024 at 10:21:11PM +0800, Zhang Yi wrote: >> From: Zhang Yi >> >> When unaligned truncate down a big realtime file, xfs_truncate_page() >> only zeros out the tail EOF block, __xfs_bunmapi() should split the tail >> written extent and convert the later one that beyond EOF block to >> unwritten, but it couldn't work as expected now since the reserved block >> is zero in xfs_setattr_size(), this could expose stale data just after >> commit '943bc0882ceb ("iomap: don't increase i_size if it's not a write >> operation")'. >> >> If we truncate file that contains a large enough written extent: >> >> |< rxext >|< rtext >| >> ...WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW >> ^ (new EOF) ^ old EOF >> >> Since we only zeros out the tail of the EOF block, and >> xfs_itruncate_extents()->..->__xfs_bunmapi() unmap the whole ailgned >> extents, it becomes this state: >> >> |< rxext >| >> ...WWWzWWWWWWWWWWWWW >> ^ new EOF >> >> Then if we do an extending write like this, the blocks in the previous >> tail extent becomes stale: >> >> |< rxext >| >> ...WWWzSSSSSSSSSSSSS..........WWWWWWWWWWWWWWWWW >> ^ old EOF ^ append start ^ new EOF >> >> Fix this by reserving XFS_DIOSTRAT_SPACE_RES blocks for big realtime >> inode. > > This same problem is going to happen with force aligned allocations, > right? i.e. it is a result of having a allocation block size larger > than one filesystem block? > Yeah, right. +cc John > If so, then.... > >> Signed-off-by: Zhang Yi >> Reviewed-by: Christoph Hellwig >> --- >> fs/xfs/xfs_iops.c | 15 ++++++++++++++- >> 1 file changed, 14 insertions(+), 1 deletion(-) >> >> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c >> index ff222827e550..a00dcbc77e12 100644 >> --- a/fs/xfs/xfs_iops.c >> +++ b/fs/xfs/xfs_iops.c >> @@ -17,6 +17,8 @@ >> #include "xfs_da_btree.h" >> #include "xfs_attr.h" >> #include "xfs_trans.h" >> +#include "xfs_trans_space.h" >> +#include "xfs_bmap_btree.h" >> #include "xfs_trace.h" >> #include "xfs_icache.h" >> #include "xfs_symlink.h" >> @@ -811,6 +813,7 @@ xfs_setattr_size( >> struct xfs_trans *tp; >> int error; >> uint lock_flags = 0; >> + uint resblks = 0; >> bool did_zeroing = false; >> >> xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL); >> @@ -917,7 +920,17 @@ xfs_setattr_size( >> return error; >> } >> >> - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp); >> + /* >> + * For realtime inode with more than one block rtextsize, we need the >> + * block reservation for bmap btree block allocations/splits that can >> + * happen since it could split the tail written extent and convert the >> + * right beyond EOF one to unwritten. >> + */ >> + if (xfs_inode_has_bigrtalloc(ip)) >> + resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0); > > .... should this be doing this generic check instead: > > if (xfs_inode_alloc_unitsize(ip) > 1) if (xfs_inode_alloc_unitsize(ip) > i_blocksize(inode)) ? > resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0); > Yeah, it makes sense to me, but Christoph suggested to think about force aligned allocations later, so I only dealt with the big RT inode case here. I can revise it if John and Christoph don't object. Thanks, Yi.