Re: [Qemu-devel] [PATCH] block/io.c: fix for the allocation failure

[Denis V. Lunev]

On 8/17/19 5:56 PM, Eric Blake wrote:
> On 8/17/19 9:49 AM, Eric Blake wrote:
>
>>> This change is a regression of sorts.  Now, you are unconditionally
>>> attempting the fallback for ALL failures (such as EIO) and for all
>>> drivers, even when that was not previously attempted and increases the
>>> traffic.  I think we should revert this patch and instead fix the
>>> fallocate() path to convert whatever ACTUAL errno you got from unaligned
>>> fallocate failure into ENOTSUP (that is, just the file-posix.c location
>>> that failed), while leaving all other errors as immediately fatal.
> Or even better, fix the call site of fallocate() to skip attempting an
> unaligned fallocate(), and just directly return ENOTSUP, rather than
> trying to diagnose EINVAL after the fact.
>
No way. Single ENOTSUP will turn off fallocate() support on caller side
while
aligned (99.99% of calls) works normally.

Den