On Thu, Sep 03, 2026 at 01:04:49AM -0700, Paul Eggert wrote:
> On 2026-09-02 15:00, Pádraig Brady wrote:
> > On 02/09/2026 20:47, Paul Eggert wrote:
> > Don't we need to be careful with some errors as per
> > https://github.com/coreutils/coreutils/commit/f6c93f334
> > https://bugs.gnu.org/60489 ?
> 
> Thanks for bringing that up; I'd forgotten that. Unfortunately, though, 
> bug#60489 seems to have given us some incorrect advice. In it, Noah Misch 
> wrote "One could argue that ENOSPC also warrants termination, since no 
> fallback reduces space usage." - but in this thread people are saying that 
> the fallback read+write can work even when ioctl+FICLONE fails with ENOSPC.

That is good to know.

> Also, Noah's bug#60489 comments about EIO suggest that when EIO occurs, the 
> entire file or maybe even the entire file system (not just this open file 
> descriptor) is at risk of being inconsistent, which is a kernel bug that we 
> can't reasonably expect cp to work around.
> 
> All that being said, it does seem prudent to go back to having cp give up on 
> the file entirely (not just revert to read+write) if FICLONE fails with EIO. 
> I did that by installing the attached.

I agree with this outcome.



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