2011/11/29 Stefan Hajnoczi <stefa...@gmail.com> > On Fri, Nov 25, 2011 at 10:19 AM, Chunyan Liu <cy...@suse.com> wrote: > > > > > > 2011/11/24 Stefan Hajnoczi <stefa...@gmail.com> > >> > >> On Thu, Nov 24, 2011 at 3:38 AM, Chunyan Liu <cy...@suse.com> wrote: > >> > > >> > > >> > 2011/11/23 Stefan Hajnoczi <stefa...@gmail.com> > >> >> > >> >> On Wed, Nov 23, 2011 at 10:14 AM, Chunyan Liu <cy...@suse.com> > wrote: > >> >> > V3: > >> >> > Remove file lock in main(). > >> >> > Try to find new free nbd device and connect to it if connecting to > >> >> > the > >> >> > first > >> >> > first found free nbd device failed. > >> >> > > >> >> > Signed-off-by: Chunyan Liu <cy...@suse.com> > >> >> > --- > >> >> > qemu-nbd.c | 80 > >> >> > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > >> >> > 1 files changed, 79 insertions(+), 1 deletions(-) > >> >> > >> >> I not seeing the part where you adjusted the ioctl order. > >> >> > >> >> The /proc/partitions scanning is unnecessary since we can just loop > >> >> over /dev/ndb%d and try to initialize. If a device is in use then > >> >> init will fail and we need to try the next one. If a device is free > >> >> we can continue with normal operation. I guess I'm saying that once > >> >> you fix the ioctl order then there's no need for another mechanism to > >> >> test whether or not a device is in use. > >> > > >> > The way of scanning /proc/partitions to find an unused nbd device > first > >> > can > >> > borrow the code for "qemu-nbd -c" to do the left things. . > >> > The way of loop over /dev/nbd%d and try to initialize, from the first > >> > thought, needs do all things in the loop, including handling -v, > >> > nbd_init, > >> > nbd_client, etc. That part of code is quite similar to "qemu-nbd -c". > I > >> > don't know if that is better? > >> > >> This might be a chance to refactor the code slightly, that would also > >> avoid you having to introduce a goto retry. > >> > > About detail implementation of the loop over /dev/nbd%d way, have done > some > > coding and testing. I'm afraid the reorganization work is not very > slight, > > not sure how do you think. > > First, through nbd_init() success or fail to check if the device is in > use, > > at least nbd_init() and operations before nbd_init() but device relative > > should be in the loop. Usually, there are two ways to be considered: > > 1. Try to divide current "qemu-nbd -c" processing code into two parts ( > > nbd_init() and before, and operations after nbd_init()), 1st part put > into > > the loop, 2nd part outside loop. This way is hard to achieve. nbd_init() > > should be in client thread, but the loop is outside that thread, it's not > > proper to drag out nbd_init() from client thread and put it into the > loop. > > 2. Put all "qemu-nbd -c" processing code (device relative) in the loop, > > directly check the "qemu-nbd -c /dev/nbd%d disk.img" result, if fail, try > > next nbd device. In this way, will adjust current code order and extract > > device related codes to a new function so that both "qemu-nbd -c" and > > "qemu-nbd -f" can use.(some initialization work and cleanup work to be > > cared) > > > > A draft is in attachment. qemu-nbd -f is working, since I'm not sure such > > change is acceptable or not, not extract code in the loop into a function > > yet. > > I think a common function makes sense. This may be nicest in two > patches, Patch 1 moves the code into a function, Patch 2 implements > -f/find. > > Just sent the patch sets according to above suggestion. Please review. 1/3-Update-ioctl-order-in-nbd_init-to-detect-EBUSY 2/3-Extract-code-to-nbd_setup-function-to-be-used-for-mamy-purposes 3/3-Add-f-option-to-qemu-nbd
Stefan > >
