On Wed, Nov 16, 2011 at 6:57 AM, Chunyan Liu <cy...@suse.com> wrote: > Currently qemu-nbd does not support finding free nbd device for users like > "losetup -f" and issuing "qemu-nbd -c /dev/nbdX disk.img" won't report error > message when /dev/nbd is already in use. It makes things a little confusing. > This patch adds "-f" option to qemu-nbd to support finding a free nbd device > for users. Please review and share your comments. Thanks. > > Signed-off-by: Chunyan Liu <cy...@suse.com> > --- > qemu-nbd.c | 65 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 files changed, 64 insertions(+), 1 deletions(-)
This patch finds a free device but does not immediately attach to it and use it. Interfaces like this are prone to race conditions, I think it would make more sense to combine the -f option with running the actual NBD server. I suggest: qemu-nbd -f disk.img That way it is safe to execute multiple qemu-nbd -f at the same time without race conditions. Plus it probably makes the user's life easier than having to say qemu-nbd -c $(qemu-nbd -f) disk.img. Stefan
