On Mon, Jul 06, 2015 at 05:42:17AM -0300, Christopher Pereira wrote: > On 06-07-2015 5:18, Niels de Vos wrote: > >On Mon, Jul 06, 2015 at 02:46:52AM -0300, J. Christopher Pereira Zimmermann wrote: > >>Hi Niels, > >> > >>Thanks for bouncing. > >> > >>I'm not sure if you are asking how to figure out the hole/data offsets from > >>the underlying fs at once, or about the ec communication. > >> > >>There is probably no standard way to query the allocation information with > >>the hole offsets at once from the fs, so lseeking from hole to hole would > >>be the only way. > >> > >>I quickly checked ext4's SEEK_HOLE implementation [1] and the holes seem to > >>be marked and sought on "ext4_map_blocks" [2]. > >>There seems to be no standard system call / data structure for getting all > >>the hole/data offsets at once. > >> > >>Is lseeking hole by hole ok? > >Thanks Christopher! > > > >Xavier also responded with details on how EC tracks holes. He is > >definitely one of the few that should know ;-) > > > >Only volumes with EC/stripe/sharding/bd xlators are not straight > >forward. For the less funky storage methods, lseek() can be used without > >difficulties. > > > >I did put a COPR together for Fedora 22 (x86_64) with a patched kernel > >and glusterfs packages. If you are eager to test, you can install these > >on a disposable environment. > > > > https://copr.fedoraproject.org/coprs/devos/glusterfs-SEEK_HOLE > > (NOT TESTED AT ALL! But it compiles...) > > > >Feedback welcome, but dont have too high expectations from those > >packages. > > Ok. I will give them a try and provide you feed back. > Is it possible to generate CentOS 7 builds? I've added them in the same COPR, building of the kernel will take a while though. You can check progress here: https://copr.fedoraproject.org/coprs/devos/glusterfs-SEEK_HOLE/monitor/ Niels
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