Pavel Emelyanov <xemul@xxxxxxxxxxxxx> writes: > On 08/20/2012 11:32 PM, J. Bruce Fields wrote: >> On Mon, Aug 20, 2012 at 11:06:06PM +0400, Cyrill Gorcunov wrote: >>> On Mon, Aug 20, 2012 at 02:32:25PM -0400, J. Bruce Fields wrote: >>>> On Mon, Aug 20, 2012 at 08:33:38PM +0400, Cyrill Gorcunov wrote: >>>>> On Mon, Aug 20, 2012 at 07:49:23PM +0530, Aneesh Kumar K.V wrote: >>>>>> Cyrill Gorcunov <gorcunov@xxxxxxxxxx> writes: >>>>>> >>>>>>> To provide fsnotify object inodes being watched without >>>>>>> binding to alphabetical path we need to encode them with >>>>>>> exportfs help. This patch adds a helper which operates >>>>>>> with plain inodes directly. >>>>>> >>>>>> doesn't name_to_handle_at() work for you ? It also allows to get a file >>>>>> handle using file descriptor. >>>>> >>>>> Hi, sorry for dealy. Well, the last idea is to get rid of this helper, >>>>> I've sent out an updated version where ino+dev is only printed. >>>> >>>> I don't understand how ino and dev are useful to you, though, if you're >>>> still hoping to be able to look up inodes using this information later >>>> on. >>> >>> Hi Bruce, I believe having ino+dev is better than nothing. Otherwise we >>> simply have no clue which targets are bound to inotify mark. Sometime >>> (!) we can try to generate fhandle in userspace from this ino+dev bundle >>> and then open the target file. >> >> That's insufficient to generate a filehandle in general. > > Yes, sure, but for live migration having inode and device is enough and that's why. > We can use two ways of having a filesystem on the target machine in the same > state (from paths points of view) as it was on destination one: > > 1. copy file tree in a rsync manner > 2. copy a virtual disk image file > > In the 1st case we can map inode number to path easily, since we iterate over a filesystem > anyway. I agree, that rsync is not perfect for migration but still. > > In the 2nd case we can generate filehandle out of an inode number only since we _do_ know > that inode will not get reused. If you are going to to use open_by_handle, then that handle is not sufficient right ? Or do you have open_by_inode ? as part of c/r ? > > > However, if you have some better ideas on what information about inode should be exported > to the userspace please share. > Why not use name_to_handle(fd,...) and open_by_handle(handle,..) ? >> (Also: there's the usual inode-number aliasing problem: the inode number >> could get reused by another file. Unless you know the file is being >> held open the whole time.) >> -aneesh -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
