linux-kernel - Re: [PATCH] nfs: don't update isize when NFS_INO_LAYOUTCOMMITTING in nfs_update

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Message-Id: <395EC1ED-E67E-4666-B170-5C5F00264496@primarydata.com>
Date:	Mon, 13 Jan 2014 11:28:22 -0500
From:	Trond Myklebust <trond.myklebust@...marydata.com>
To:	Myklebust Trond <trond.myklebust@...marydata.com>
Cc:	shaobingqing <shaobingqing@...tor.com.cn>,
	Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfs: don't update isize when NFS_INO_LAYOUTCOMMITTING in nfs_update_inode


On Jan 13, 2014, at 8:34, Trond Myklebust <trond.myklebust@...marydata.com> wrote:

> 
> On Jan 13, 2014, at 2:55, shaobingqing <shaobingqing@...tor.com.cn> wrote:
> 
>> When a file is in NFS_INO_LAYOUTCOMMITING status, its isize perhaps has not been 
>> transferred to the metadate server. So the isize getting from the metadata server
>> perhaps is out of date and cannot be used to update the isize of the client.
>> 
>> Signed-off-by: shaobingqing <shaobingqing@...tor.com.cn>
>> ---
>> fs/nfs/inode.c |    3 ++-
>> 1 files changed, 2 insertions(+), 1 deletions(-)
>> 
>> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
>> index ebeb94c..caf50a1 100644
>> --- a/fs/nfs/inode.c
>> +++ b/fs/nfs/inode.c
>> @@ -1402,7 +1402,8 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
>> 		if (new_isize != cur_isize) {
>> 			/* Do we perhaps have any outstanding writes, or has
>> 			 * the file grown beyond our last write? */
>> -			if ((nfsi->npages == 0 && !test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) ||
>> +			if ((nfsi->npages == 0 && !test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags) &&
>> +			     !test_bit(NFS_INO_LAYOUTCOMMITTING, &nfsi->flags)) ||
>> 			     new_isize > cur_isize) {
>> 				i_size_write(inode, new_isize);
>> 				invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
> 
> Ugh. Is there any reason why we can’t just keep NFS_INO_LAYOUTCOMMIT set until the layout commit operation is finished instead of multiplying the tests for it in generic NFS code paths such as nfs_update_inode?

Actually, no. The above is bogus, because LAYOUTCOMMIT doesn’t just affect the file size: it affects the NFSv4 change attribute, ctime and mtime values too.

I’ll draft a patch...

--
Trond Myklebust
Linux NFS client maintainer

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