linux-kernel - Re: [RFC 4/8] ext4: Add statx and other atomic write helper routines

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Message-Id: <87r0glp2j8.fsf@doe.com>
Date: Fri, 08 Mar 2024 13:40:19 +0530
From: Ritesh Harjani (IBM) <ritesh.list@...il.com>
To: John Garry <john.g.garry@...cle.com>, linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Cc: Ojaswin Mujoo <ojaswin@...ux.ibm.com>, Jan Kara <jack@...e.cz>, Theodore Ts'o <tytso@....edu>, Matthew Wilcox <willy@...radead.org>, "Darrick J . Wong" <djwong@...nel.org>, Luis Chamberlain <mcgrof@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC 4/8] ext4: Add statx and other atomic write helper routines

John Garry <john.g.garry@...cle.com> writes:

> On 02/03/2024 07:42, Ritesh Harjani (IBM) wrote:
>>   	}
>>   
>> +	if (request_mask & STATX_WRITE_ATOMIC) {
>> +		unsigned int fsawu_min = 0, fsawu_max = 0;
>> +
>> +		/*
>> +		 * Get fsawu_[min|max] value which we can advertise to userspace
>> +		 * in statx call, if we support atomic writes using
>> +		 * EXT4_MF_ATOMIC_WRITE_FSAWU.
>> +		 */
>> +		if (ext4_can_atomic_write_fsawu(inode->i_sb)) {
>
> To me, it does not make sense to fill this in unless 
> EXT4_INODE_ATOMIC_WRITE is also set for the inode.
>

I was thinking advertising filesystem atomic write unit on an inode
could still be advertized. But I don't have any strong objection either.
We can advertize this values only when the inode has the atomic write
attribute enabled. I think this makes more sense. 

Thanks
-ritesh

>> +			ext4_atomic_write_fsawu(inode->i_sb, &fsawu_min,
>> +						&fsawu_max);
>> +		}
>> +
>> +		generic_fill_statx_atomic_writes(stat, fsawu_min, fsawu_max);
>> +	}
>> +
>>   	flags = ei->i_flags & EXT4_FL_USER_VISIBLE;