Date: Sat, 10 Feb 2018 12:47:48 -0700 From: Ian Lepore <ian@freebsd.org> To: Alan Somers <asomers@freebsd.org> Cc: Willem Jan Withagen <wjw@digiware.nl>, freebsd current <freebsd-current@freebsd.org> Subject: Re: posix_fallocate on ZFS Message-ID: <1518292068.32585.230.camel@freebsd.org> In-Reply-To: <CAOtMX2jeEHowvTCmBe5=kdArtw9okCd42JmaQnZteidJray_jA@mail.gmail.com> References: <1e2f43fd-85da-6629-62d1-6e96790278e5@digiware.nl> <CAOtMX2jZr_kvJgOZWeiB-AZ3-7-uUu%2BUQ3P0nKhGZ0eNRzwMOQ@mail.gmail.com> <1518291799.32585.228.camel@freebsd.org> <CAOtMX2jeEHowvTCmBe5=kdArtw9okCd42JmaQnZteidJray_jA@mail.gmail.com>
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On Sat, 2018-02-10 at 12:45 -0700, Alan Somers wrote: > On Sat, Feb 10, 2018 at 12:43 PM, Ian Lepore <ian@freebsd.org> wrote: > > > > > On Sat, 2018-02-10 at 11:24 -0700, Alan Somers wrote: > > > > > > On Sat, Feb 10, 2018 at 10:28 AM, Willem Jan Withagen > > > wrote: > > > > > > > > > > > > > > > Hi, > > > > > > > > This has been disabled on ZFS since last November. > > > > And I do understand the rationale on this. > > > > > > > > BUT > > > > > > > > I've now upgraded some of my HEAD Ceph test systems and they now fail, > > > > since Ceph uses posix_fallocate() to allocate space for the > > > > FileStore-journal. > > > > > > > > Is there any expectation that this is going to fixed in any near > > future? > > > > > > > > > > > > > > > --WjW > > > > > > > No. It's fundamentally impossible to support posix_fallocate on a COW > > > filesystem like ZFS. Ceph should be taught to ignore an EINVAL result, > > > since the system call is merely advisory. > > > > > > -Alan > > Unfortunately, posix documents that the function returns EINVAL only > > due to bad input parameters, so ignoring that seems like a bad idea. > > > > Wouldn't it be better if we returned EOPNOTSUP if that's the actual > > situation? That could be safely ignored. > > > I'm afraid you are mistaken. Posix _should've_ required EOPNOTSUP in this, > but it actually requires EINVAL. > > http://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_fallocate.html Oops, I apparently was looking at the prior version of the spec. Nevermind. :) -- Ian
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