On 26.09.2014 01:14, Tony Breeds wrote:
try_fiemap() uses FIEMAP_FLAG_SYNC which has a significant performance
impact.
Prefer seek_hole() over fiemap() to avoid this impact where possible.
seek_hole is more widely used and, arguably, has potential to be
optimised in the kernel.
Reported-By: Michael Steffens <michael_steff...@posteo.de>
Signed-off-by: Tony Breeds <t...@bakeyournoodle.com>
Cc: Kevin Wolf <kw...@redhat.com>
Cc: Markus Armbruster <arm...@redhat.com>
Cc: Stefan Hajnoczi <stefa...@redhat.com>
Cc: Max Reitz <mre...@redhat.com>
Cc: Pádraig Brady <pbr...@redhat.com>
Cc: Eric Blake <ebl...@redhat.com>
---
Changes since v1:
- split in to 2 patches
- tried to make the commit messages better
I used this order in at least one of the non-final versions of 4f11aa8a,
so I'm fine with it. The reason it got rejected was (as far as I
remember) that the FIEMAP ioctl() returns ENOTSUP if not supported,
whereas lseek() with SEEK_HOLE/SEEK_DATA returns some failsafe value,
probably reporting no holes at all. By reversing the order of
try_fiemap() and try_seek_hole(), try_fiemap() therefore may very well
become dead code. I don't object, however.
Reviewed-by: Max Reitz <mre...@redhat.com>
