114 lines
4.0 KiB
Plaintext
114 lines
4.0 KiB
Plaintext
# -*- text -*-
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# This file is README.autofs
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# am-utils-6.0
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# Erez Zadok <ezk@cs.columbia.edu>
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#
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** General notes about the autofs support in am-utils
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The autofs code in am-utils is VERY much pre-alpha quality!
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* Caveats:
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- amd acts as *both* /usr/lib/autofs/automountd and /usr/sbin/automount.
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There's no way to distinguish the two. When amd starts, it first registers
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itself as an autofs server (automountd), then parses its maps, and decides
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on which autofs type mounts to make (automount does that). After the autofs
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mounts are made, amd listens for RPCs from the kernel-based autofs, and acts
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upon them.
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- I only tested it under Solaris 2.5.1 (sparc). Don't expect irix/linux
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autofs support any time soon. Also, the autofs API in Solaris 2.6 is very
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different from 2.5.1; for now, am-utils does not even compile in the autofs
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code in Solaris 2.6.
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- I did not test mixed autofs and normal amd mount points in the same
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amd.conf file, but it should work.
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- I tested it as a separate amd process, which registered under an alternate
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RPC number (300020). (The multiple amd-support available in a9 really saved
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the day.)
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- I did not test amd running autofs mounts while Sun's automounter is
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running. I don't expect the interaction between the two to be good for your
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health.
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* amd.conf requirements:
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To tell amd to use an autofs-style mount point and mounts for a map, turn on
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mount_type = autofs
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in the map sections you wish.
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* Map changes:
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I used this sample map for testing autofs:
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# /home map
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ezk -rhost:=shekel;opts:=rw,intr,bg,overlay;fs:=${path} \
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host!=shekel;type:=nfs;rfs:=/n/shekel/u/zing/${key} \
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host==shekel;type:=lofs;rfs:=/n/shekel/u/zing/${key}
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Note that this implementation of autofs is still infant. Several important
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changes must be made to your maps to support autofs:
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(1) you must supply the 'overlay' option to opts. Read the autofs paper to
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see why that is crucial, else you will hang amd!
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(2) the 'fs' variable in the maps must point to the actual mount point
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inside the autofs/amd mount point, not to where the autodir was. That is
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because in-place mounts are done.
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For example, in the past, /home/ezk would be a symlink to /n/shekel/u/zing,
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which is where shekel:/n/shekel/u/zing was mounted on. But now /home/ezk is
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a directory on which shekel:/n/shekel/u/zing is directly mounted upon.
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(Yes, this means that finally $PWD is the same as `/bin/pwd`.)
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* Todo:
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I'm looking for volunteers to improve the autofs code!
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(1) These fixes are needed to avoid having to change amd maps:
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- the overlay option should be turned on for autofs mounts automatically,
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without having to require it in the maps.
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- the 'fs' variable should be ignored in the maps of type autofs. Rather,
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it should always be set to "/${path}".
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- when the mount type is 'link', transparently translate it into a loopback
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file system mount (lofs), that would mount in place, rather than supply a
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symlink instead.
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- if amd is killed or dies, the autofs mounts will remain intact as required
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(your system is _not_ hung, yay!) However, if you restart amd, it will not
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correctly 'restart' the autofs mounts as the Sun automounter does. Rather,
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it will cause another mount to happen, which leaves your /etc/mnttab
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cluttered with older mounts entries which cannot be unmounted.
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(2) Code expansion:
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- (amd/ops_autofs.c) autofs_unmount_1_svc() is not implemented at all.
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- autofs has many types of mount types which are not supported. Right now
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amd will assume a 'direct' mount. Types which are not supported are
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'indirect', 'offset', and 'multiple' or 'hierarchical'.
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- implement the sockets version of amu_get_autofs_address() and
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create_autofs_service(), in conf/transp/transp_sockets.c.
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(3) Testing and porting to other systems:
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- nothing has been tested on irix, which reportedly has a similar
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functioning autofs to Solaris'.
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- no testing or even preliminary research was done to find out how to
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support linux autofs.
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- did not test the new and improved autofs in Solaris 2.6 either.
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- did not test Solaris 2.5.1 on x86, or earlier versions of Solaris on
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either Sparc or x86.
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