On 07/11/16 17:34, J. Bruce Fields wrote: > On Sun, Nov 06, 2016 at 12:24:20PM +0000, Luis de Bethencourt wrote: >> On 05/11/16 22:03, NeilBrown wrote: >>> On Sat, Nov 05 2016, Luis de Bethencourt wrote: >>> >>>> Hi all, >>>> >>>> I recently played with adding the basics to make befs exportable via NFS [0]. >>>> >>>> I want to implement the get_parent member of the export_operations struct as >>>> well, but I can't seem to trigger this member being called. I have implemented >>>> a solution which I feel is wrong [1], but want to be able to test it before >>>> moving forward. >>>> >>>> When is this member triggered? Any advice? >>> >>> This is required when a filehandle for a directory arrives, but the >>> directory is not in the dcache. >>> NFSD needs to find dentries for the directory, the parent, the >>> grandparent etc all the way up to the root. >>> >>> The simplest way to trigger this is to mount the filesystem onto a >>> different machine, 'cd' into a fairly deep directory, then reboot the >>> server (or unexport, unmount, remount, re-export). >>> Now 'ls -l' on the client. That should trigger calls to ->get_parent. >>> >>> ->get_parent() is a log like performing a lookup of "..". >>> >>> NeilBrown >>> >> >> Nice! >> >> This makes a lot of sense. I just rebooted the server and saw the get_parent >> being called. Before I was mistakenly trying without a reboot, but thanks to your >> explanation now understand this better, the directory was still in the dcache and >> it was using this instead. > > I've also tested get_parent with "echo 2>/proc/sys/vm/drop_caches", > after first creating a 2000-deep subdirectory heirarchy (to stress > performance, and to make sure dcache had enough entries that drop_caches > would reliably drop what I wanted). And I used the filehandle syscalls > directly, to take nfsd out of the equation. See deep-fh-lookup in > git://linux-nfs.org/~bfields/fragments.git for my kludgey script. OK, > rebooting may be easier. > > --b. > Very interesting approach, stressing it. Will add it to my repertoire. Thanks, Luis -- 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
