Re: [PATCH v3 00/15] block atomic writes

[John Garry]

On 29/01/2024 06:18, Christoph Hellwig wrote:
> Do you have a git tree with all patches somewhere?

Hi Christoph,

Please let me know if you had a chance to look at this series or what 
your plans are.

BTW, about testing, it would be good to know your thoughts on power-fail 
testing.

I have done much testing for ensuring that writes are properly issued to 
HW with no undesired splitting/merging, etc for normal operation. I have 
also tested crashing the kernel only to see if atomic writes get 
corrupted. This all looks ok.

About PF testing, I have an NVMe M.2 drive, but it supports just 4K 
nawupf. In addition, unfortunately the port on my machine does not allow 
me to power it off, so I need to plug out the power cable to test PF :(

We do also support atomic writes on our SCSI storage servers, but it is 
not practically possible to PF them.

For actual PF testing, I have been using fio in crc64 verify mode with a 
couple of tweaks to support atomic writes.

What I find from limited testing for XFS and bdev atomic writes on that 
NVMe card is that indeed 4K writes are PF-safe, but 16K (this is an 
arbitrary large block size which I chose) is not. But I think all cards 
will be 4K PF safe, even if not declared.

Thanks,
John