Re: [PATCH v2 00/16] block atomic writes

On Tue, Jan 09, 2024 at 09:55:24AM +0000, John Garry wrote:

So a user can issue:

quoted

xfs_io -c "atomic-writes 64K" mnt/file
xfs_io -c "atomic-writes" mnt/file

[65536] mnt/file

Let me try to decipher that:

 - the first call sets a 64k fsx_atomicwrites_size size
 - the secon call queries fsx_atomicwrites_size?

The user will still have to issue statx to get the actual atomic write 
limit for a file, as 'xfs_io -c "atomic-writes"' does not take into account 
any HW/linux block layer atomic write limits.

So will the set side never fail?

Is this the sort of userspace API which you would like to see?

What I had in mind (and that's doesn't mean it's right..) was that
the user just sets a binary flag, and the fs reports the best it
could.  But there might be reasons to do it differently.