On Wed, 2008-06-25 at 16:52 -0700, Stephen Biggs wrote:
> 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?

The order matters because the autofs file system mounted on /home over
mounts the file system path /home/.junk at /home making it invisible.
You would get further problems with mount and expire, in this case, with
unusual symptoms.

> 
> > -----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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