I've been very busy trying to get Mirror Mounts out the door. Our last task was to fix a find bug:

[tdh@mrx ~]> sudo mount kanigix:/ /mnt
[tdh@mrx ~]> cd /mnt
[tdh@mrx /mnt]> cd zoo
[tdh@mrx zoo]> cd mms
[tdh@mrx mms]> ls -la
total 20
drwxr-xr-x   5 root     sys            5 Jul 19 21:41 .
drwxr-xr-x  11 root     sys           11 Oct  8 13:08 ..
drwxr-xr-x   5 root     sys            5 Jul 19 21:41 node1
drwxr-xr-x   5 root     sys            5 Jul 19 21:41 node2
drwxr-xr-x   5 root     sys            5 Jul 19 21:42 node3
[tdh@mrx mms]> df -F nfs -h
Filesystem             size   used  avail capacity  Mounted on
kanigix:/               20G   8.9G    11G    46%    /mnt
kanigix:/zoo           637G    42K   637G     1%    /mnt/zoo
kanigix:/zoo/mms       637G    31K   637G     1%    /mnt/zoo/mms

Now if we try to find, it should mount a subdirectory for us and traverse down it.

[tdh@mrx mms]> find .
.
./node3
find: cannot open .: Resource temporarily unavailable

It fails because of a security check to make sure the stat(2) information from before an opendir(2) matches a fstat(2) from after the opendir(2). The pre-stat gets the vnode which will be mounted on and the post-fstat gets the root of the new filesystem.

But now we can see that since the mount took place, that we pass the test which just failed.

[tdh@mrx mms]> df -F nfs -h
Filesystem             size   used  avail capacity  Mounted on
kanigix:/               20G   8.9G    11G    46%    /mnt
kanigix:/zoo           637G    42K   637G     1%    /mnt/zoo
kanigix:/zoo/mms       637G    31K   637G     1%    /mnt/zoo/mms
kanigix:/zoo/mms/node3
                       637G    31K   637G     1%    /mnt/zoo/mms/node3
[tdh@mrx mms]> find .
.
./node3
./node3/sub2
find: cannot open .: Resource temporarily unavailable
[tdh@mrx mms]> df -F nfs -h
Filesystem             size   used  avail capacity  Mounted on
kanigix:/               20G   8.9G    11G    46%    /mnt
kanigix:/zoo           637G    42K   637G     1%    /mnt/zoo
kanigix:/zoo/mms       637G    31K   637G     1%    /mnt/zoo/mms
kanigix:/zoo/mms/node3
                       637G    31K   637G     1%    /mnt/zoo/mms/node3
kanigix:/zoo/mms/node3/sub2
                       637G    31K   637G     1%    /mnt/zoo/mms/node3/sub2

But we puke on the next mirror mount.

The problem is actually deep down in nftw(2C) and you can look at the PSARC case at Add S_IFTRIGGER to st_mode [PSARC/2007/563 FastTrack timeout 10/04/2007]. This is pretty interesting reading. Most people told me that my proposal would generate considerable controversy.

The PSARC community decided that there was still a hole in the security check inside nftw(2C). While I can argue against this, it is pretty hard to rename/move an export on a live filesystem, in the end I decided that a counter-proposal made more sense that mine.

You've got to realize, I've been working on this project for the past 6 months. We were going to putback on Friday - time to turn over onto the pNFS project.

We decided as a group that the new proposal was the right thing to do for both the Mirror Mount project and Solaris (and indirectly OpenSolaris).