Excuse this reply to my own post, but more information:
I found that if I do a `/etc/init.d/autofs restart`, then with the order
of the lines in auto.master, my .junk directory is nowhere to be found.
I was only able to get it to work if I moved the "/- /etc/auto.data"
line _after_ the "/home" line in /etc/auto.master.  Why does the order
matter?  Should it?

> -----Original Message-----
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Stephen Biggs
> Sent: Wednesday, June 25, 2008 3:42 PM
> To: [email protected]
> Subject: [autofs] Direct mount newbie question
> 
> Automounter 5.0.3 unpatched, vanilla, 2.6.24 Linux kernel 
> also vanilla.
> 
> This is probably a really dumb question and the way I am 
> doing it is probably cause for some mirth, but if anybody 
> have a better way, I am all ears.
> 
> I have /home as an indirect mount point using a yp:auto.home key file.
> 
> I have an application that I have no control over nor ability 
> to change its behavior. It does many many searches for a file 
> that I will call .junk, starting at the cwd and going up the 
> tree until it either finds / or the file.  If the user is 
> anywhere under the /home directory, this search eventually 
> tries to open /home/.junk and fails, but not until it 
> triggers the automounter to try to mount a non-existent 
> directory named .junk.  Because of the many searches, it 
> seriously slows down execution due to the automounting storm 
> and consequent NFS dialogs over the network.
> 
> A solution would be to have a permanent empty /home/.junk 
> file present as a last resort fail point for an application 
> that searches for this file and causes an automount storm 
> since it  This seems to not be possible because /home is a 
> pseudo directory created by autofs as a place to hang mounts 
> off of (please correct me if this is an invalid assumption).
> 
> The best compromise I could think of was to have a 
> /home/.junk directory that is there the moment automounter 
> comes up and stays there, on all my systems. Then, the 
> application can try to open it but not trigger the 
> automounter, at least no more than once.
> 
> The best way I could see to do it was as such:
> 
> On the local auto.master, I added the line:
> /- /etc/auto.data
> 
> ...before the /home entry.  /etc/auto.data can be on the YP 
> repository some time in the future.
> 
> In /etc/auto.data, I have one line:
> /home/.junk -mode=555,fstype=tmpfs,ro :/.junk
> 
> This seems to work just fine, except for a couple of weirdnesses:
> 1. When I applied a -HUP to the automounter, it created a 
> ghosted directory with mode of 755 instead of 555. This may 
> be fixed by Ian's patches regarding "abuse" of ghosting.  
> But, upon first access, the directory (using ls -ld 
> /home/.junkdirectory) then has the correct mode.
> It looks like the local directory is remounted using the 
> -bind option and the proper mode.
> 
> 2. I think I saw the directory get expired and also all /- 
> entries in /var/log/messages.  Then, "ls 
> /home/.junkdirectory" came back with "ls:
> /home/.junkdirectory: No such file or directory".  If this is 
> true (that it will not be automounted again after 
> expiration), then this is not a good solution.  If so, I am 
> obviously misunderstanding direct mounts.
> This may have been because of my testing where I needed to 
> remove the entry for /- in /etc/auto.master and forgot to 
> send another HUP signal to the automounter when I put it back 
> in.  If this is true, then there should be no problem  Is it 
> possible that this can be expired off to the point of not 
> being able to be remounted?
> 
> In any event, can anyone suggest any better way to do what I 
> want to do?
> 
> TIA.
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