Ian Kent wrote:
If wildcard map entries are not in autofs v3 then Jeremy implemented this in v4.
v3 has had wildcard map entries and substitutions for a very, very, very long time... it was a v2 feature, in fact.
And yes the host map is basically a program map and that's all. Worse, as pointed out in the paper it mounts everything under it. This is a source of stress for mount and umount. I have put in a fair bit of time on ugly hacks to work around this. This same problem is also evident in startup and shutdown for master maps with a good number of entries (~50 or more). A consequence of the current multiple daemon approach.
This is why one wants to implement a mount tree with "direct mount pads"; which also means keeping some state in the daemon.
For example, let's say one has a mount tree like:
/foo server1:/export/foo \ /foo/bar server1:/export/bar \ /bar server2:/export/bar
... then you actually have four diffenent filesystems involved: first, some kind of "scaffolding" (this can be part of the autofs filesystem itself or a ramfs) that hold the "foo" and "bar" directories, and then foo, foo/bar, and bar.
Consider the following implementation: when one encounters the above, the daemon stashes this away as an already-encountered map entry (in case the map entries change, we don't want to be inconsistent), creates a ramfs for the scaffolding, creates the "foo" and "bar" subdirectories and mount-traps "foo" and "bar". Then it releases userspace. When it encounters an access on "foo", it gets invoked again, looks it up in its "partial mounts" state, then mounts "foo" and mount-traps "foo/bar", then releases userspace.
In many ways this returns to the simplicity of the autofs v3 design where the atomicity constraints where guaranteed by the VFS itself, *as long as* mount traps can be atomically destroyed with umounting the underlying filesystem.
Great!
This is exactly what I found when looking into the situation. However, namespaces still break automounting unless you can rid yourself of the daemon. Move events into call_usermodehelper calls in current's namespace and maintain what little state you need as a set of tokens.
-- Mike Waychison Sun Microsystems, Inc. 1 (650) 352-5299 voice 1 (416) 202-8336 voice mailto: [EMAIL PROTECTED] http://www.sun.com
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