Re: [Qemu-devel] [PATCH v2] block/raw-posix: Try both FIEMAP and SEEK_HOLE

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 05/06/2014 03:18 PM, Eric Blake wrote:
>
>> ...if you are on a file system where SEEK_HOLE triggers the kernel
>> fallback of "entire file is allocated", but where FIEMAP is wired up for
>> that file system, would it make sense to have try_seek_hole return -1 in
>> situations where lseek(s->fd, 0, SEEK_HOLE) returns the end of the file?
>>  Even more, should skip_seek_hole be a tri-state?
>
> On the other hand, such systems are getting vanishingly rare as people
> upgrade to newer kernels.  Do we care about catering to them, or is it
> fair game to just tell people to upgrade if they want performance?

My tolerance for code complications to speed up things under old kernels
isn't zero, but close.  Leave these games to downstreams sporting such
kernels.