On Fri, Oct 02, 2015 at 03:36:04PM +0100, Peter Maydell wrote: > On 29 September 2015 at 16:54, Richard W.M. Jones <rjo...@redhat.com> wrote: > > https://bugzilla.redhat.com/show_bug.cgi?id=1265196 > > > > The following command fails on an NFS mountpoint: > > > > $ qemu-img create -f qcow2 -o preallocation=falloc disk.img 262144 > > Formatting 'disk.img', fmt=qcow2 size=262144 encryption=off > > cluster_size=65536 preallocation='falloc' lazy_refcounts=off > > qemu-img: disk.img: Could not preallocate data for the new file: Bad file > > descriptor > > > > The reason turns out to be because NFS doesn't support the > > posix_fallocate call. glibc emulates it instead. However glibc's > > emulation involves using the pread(2) syscall. The pread syscall > > fails with EBADF if the file descriptor is opened without the read > > open-flag (ie. open (..., O_WRONLY)). > > > > I contacted glibc upstream about this, and their response is here: > > > > https://bugzilla.redhat.com/show_bug.cgi?id=1265196#c9 > > "You are not authorized to access bug #1265196." > > Any chance of a working URL if we're going to immortalize it > in QEMU's git log?
Sorry about that. I have now made the bug public -- there was absolutely no reason why it was private before. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org
