On Wed, Nov 16, 2011 at 6:34 PM, Stefan Hajnoczi <stefa...@gmail.com> wrote: > 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 Why must we add one new option? I prefer to not adding new option, only enhance existing function of qemu-nbd -c 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 > >
-- Regards, Zhi Yong Wu
