Am 29.09.2015 um 17:54 hat Richard W.M. Jones geschrieben: > 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 > > There are two possible fixes: Use Linux fallocate directly, or (this > fix) work around the problem in qemu by opening the file with O_RDWR > instead of O_WRONLY. > > Signed-off-by: Richard W.M. Jones <[email protected]> > BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1265196
Thanks, applied to the block branch. Kevin
