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.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org