linux-kernel - Re: [PATCH v10 7/8] xfs: Validate atomic writes

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Message-ID: <c4edb568-6fac-4c30-9ca3-12fbefc761e2@oracle.com>
Date: Sun, 20 Oct 2024 12:09:31 +0100
From: John Garry <john.g.garry@...cle.com>
To: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>, axboe@...nel.dk,
        brauner@...nel.org, djwong@...nel.org, viro@...iv.linux.org.uk,
        jack@...e.cz, dchinner@...hat.com, hch@....de, cem@...nel.org
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org, hare@...e.de,
        martin.petersen@...cle.com, catherine.hoang@...cle.com,
        mcgrof@...nel.org, ojaswin@...ux.ibm.com
Subject: Re: [PATCH v10 7/8] xfs: Validate atomic writes

On 20/10/2024 10:44, Ritesh Harjani (IBM) wrote:
>> +	if (iocb->ki_flags & IOCB_ATOMIC) {
>> +		/*
>> +		 * Currently only atomic writing of a single FS block is
>> +		 * supported. It would be possible to atomic write smaller than
>> +		 * a FS block, but there is no requirement to support this.
>> +		 * Note that iomap also does not support this yet.
>> +		 */
>> +		if (ocount != ip->i_mount->m_sb.sb_blocksize)
>> +			return -EINVAL;
> Shouldn't we "return -ENOTSUPP" ?
> Given we are later going to add support for ocount > sb_blocksize.

So far we have been reporting -EINVAL for an invalid atomic write size 
(according to atomic write unit min and max reported for that inode).

-ENOTSUPP is used for times when we just don't support atomic writes, 
like non-DIO.

Thanks,
John