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Message-ID: <180c98f5-faf9-4578-a069-3586c6b48252@oracle.com>
Date: Tue, 11 Jun 2024 08:29:56 +0100
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Subject: Re: [PATCH v3 14/21] iomap: Sub-extent zeroing
To: Long Li <leo.lilong@huawei.com>, david@fromorbit.com, djwong@kernel.org,
        hch@lst.de, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz,
        chandan.babu@oracle.com, willy@infradead.org
Cc: axboe@kernel.dk, martin.petersen@oracle.com, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com,
        ojaswin@linux.ibm.com, ritesh.list@gmail.com, mcgrof@kernel.org,
        p.raghav@samsung.com, linux-xfs@vger.kernel.org,
        catherine.hoang@oracle.com
References: <20240429174746.2132161-1-john.g.garry@oracle.com>
 <20240429174746.2132161-15-john.g.garry@oracle.com>
 <20240611031009.GA3408983@ceph-admin>
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From: John Garry <john.g.garry@oracle.com>
Organization: Oracle Corporation
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On 11/06/2024 04:10, Long Li wrote:
>>   	if (need_zeroout) {
>> -		/* zero out from the start of the block to the write offset */
>> -		pad = pos & (fs_block_size - 1);
>> +		/* zero out from the start of the region to the write offset */
>> +		pad = pos & (zeroing_size - 1);
>>   		if (pad)
>>   			iomap_dio_zero(iter, dio, pos - pad, pad);
>   
> Hi, John
> 
> I've been testing and using your atomic write patch series recently. I noticed
> that if zeroing_size is larger than a single page, the length passed to
> iomap_dio_zero() could also be larger than a page size. This seems incorrect
> because iomap_dio_zero() utilizes ZERO_PAGE(0), which is only a single page
> in size.

ok, thanks for the notice.

So 
https://lore.kernel.org/linux-xfs/20240607145902.1137853-1-kernel@pankajraghav.com/T/#m7ba4ed4f0f0f48be99042703c10b42b72c9fe37c 
is changing that same function increase the zero range past PAGE_SIZE. 
I'll just need to figure out how to make it support an arbitrary larger 
size.

Thanks,
John