On Thu, Apr 26, 2012 at 02:45:54PM +0100, David Howells wrote: > Steve French <smfrench@xxxxxxxxx> wrote: > > > I also would prefer that we simply treat the time granularity as part > > of the superblock (mounted volume) ie returned on fstat rather than on > > every stat of the filesystem. For cifs mounts we could conceivably > > have different time granularity (1 or 2 second) on mounts to old > > servers rather than 100 nanoseconds. > > The question is whether you want to have to do a statfs in addition to a stat? > I suppose you can potentially cache the statfs based on device number. > > That said, there are cases where caching filesystem-level info based on i_dev > doesn't work. OpenAFS springs to mind as that only has one superblock and > thus one set of device numbers, but keeps all the inodes for all the different > volumes it may have mounted there. > > I don't know whether this would be a problem for CIFS too - say on a windows > server you fabricate P:, for example, by joining together several filesystems > (with junctions?). How does this appear on a Linux client when it steps from > one filesystem to another within a mounted share? In the NFS case we do try to preserve filesystem boundaries as well as we can--the protocol has an fsid field and the client creates a new mount each time it sees it change. And the protocol defines time_delta as a per-filesystem attribute (though, somewhat hilariously, there's also a per-filesystem "homogeneous" attribute that a server can clear to indicate the per-filesystem attributes might actually vary within the filesystem.) --b. -- 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
