linux-kernel - Re: [PATCH 6/6] fs: xfs: Set FMODE_CAN_ATOMIC_WRITE for FS_XFLAG

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Message-ID: <7e3b9556-f083-4c14-a48f-46242d1c744b@oracle.com>
Date: Mon, 5 Feb 2024 10:26:43 +0000
From: John Garry <john.g.garry@...cle.com>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: hch@....de, viro@...iv.linux.org.uk, brauner@...nel.org,
        dchinner@...hat.com, jack@...e.cz, chandan.babu@...cle.com,
        martin.petersen@...cle.com, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        tytso@....edu, jbongio@...gle.com, ojaswin@...ux.ibm.com
Subject: Re: [PATCH 6/6] fs: xfs: Set FMODE_CAN_ATOMIC_WRITE for
 FS_XFLAG_ATOMICWRITES set

On 02/02/2024 18:06, Darrick J. Wong wrote:
> On Wed, Jan 24, 2024 at 02:26:45PM +0000, John Garry wrote:
>> For when an inode is enabled for atomic writes, set FMODE_CAN_ATOMIC_WRITE
>> flag.
>>
>> Signed-off-by: John Garry <john.g.garry@...cle.com>
>> ---
>>   fs/xfs/xfs_file.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index e33e5e13b95f..1375d0089806 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -1232,6 +1232,8 @@ xfs_file_open(
>>   		return -EIO;
>>   	file->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC |
>>   			FMODE_DIO_PARALLEL_WRITE | FMODE_CAN_ODIRECT;
>> +	if (xfs_inode_atomicwrites(XFS_I(inode)))

Note to self: This should also check if O_DIRECT is set

> 
> Shouldn't we check that the device supports AWU at all before turning on
> the FMODE flag?

Can we easily get this sort of bdev info here?

Currently if we do try to issue an atomic write and AWU for the bdev is 
zero, then XFS iomap code will reject it.

Thanks,
John

> 
> --D
> 
>> +		file->f_mode |= FMODE_CAN_ATOMIC_WRITE;
>>   	return generic_file_open(inode, file);
>>   }
>>   
>> -- 
>> 2.31.1
>>
>>