Re: [PATCH v7 5/8] xfs: Support FS_XFLAG_ATOMICWRITES

[Christoph Hellwig]

On Fri, Oct 04, 2024 at 02:07:05PM +0100, John Garry wrote:
> Sure, that is true (about being able to atomically write 1x FS block if the 
> bdev support it).
>
> But if we are going to add forcealign or similar later, then it would make 
> sense (to me) to have FS_XFLAG_ATOMICWRITES (and its other flags) from the 
> beginning. I mean, for example, if FS_XFLAG_FORCEALIGN were enabled and we 
> want atomic writes, setting FS_XFLAG_ATOMICWRITES would be rejected if AG 
> count is not aligned with extsize, or extsize is not a power-of-2, or 
> extsize exceeds bdev limits. So FS_XFLAG_ATOMICWRITES could have some value 
> there.
>
> As such, it makes sense to have a consistent user experience and require 
> FS_XFLAG_ATOMICWRITES from the beginning.

Well, even with forcealign we're not going to lose support for atomic
writes <= block size, are we?