On Thu, 2008-08-14 at 15:01 -0700, Stephen Biggs wrote:
> After looking at the code for spawn_mounts in daemon/spawn.c, there are
> a couple of places that seem to bear more scrutiny.
>
> On or about line 329, an if block is started:
>
> if (!argv[argc]) {
> argv[argc + 1] = NULL;
> argv[argc] = argv[argc - 1];
> argv[argc - 1] = argv[argc - 2];
> argv[argc - 2] = arg_fake;
> }
>
> Note that "arg_fake" is only added to the argument string if the last
> argv pointer is null. But, the mount is retried anyway. I don't
> understand this check and don't understand if the "-f" is, in fact,
> passed to `mount` if the check fails.
>
> Also, the next if statement after the "while (retries--) {" block is
> checking for equality rather than using a bit test:
>
> if (ret == MTAB_NOTUPDATED) {
>
> This looks iffy to me.
>
> But, these are minor and may only be cosmetic.
>
> After looking at my logs more closely, it looks really strange. Is it
> possible that there is some sort of intra-thread locking issue within
> the automounter itself?
>
> ======== Look at this sequence (all names obfuscated):
>
> Aug 13 01:40:35 client-1 automount[30947]: handle_packet: type = 3
> Aug 13 01:40:35 client-1 automount[30947]:
> handle_packet_missing_indirect: token 2515187, name dir_to_automount,
> request pid 16344
> Aug 13 01:40:35 client-1 automount[30947]: attempting to mount entry
> /home/dir_to_automount
> Aug 13 01:40:35 client-1 automount[30947]: lookup_mount: lookup(yp):
> looking up dir_to_automount
> Aug 13 01:40:36 client-1 automount[30947]: lookup_mount: lookup(yp):
> dir_to_automount ->
> -rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> nfsserver:/vol/work/dir_to_automount
> Aug 13 01:40:36 client-1 automount[30947]: parse_mount: parse(sun):
> dequote("nfsserver:/vol/work/dir_to_automount") ->
> nfsserver:/vol/work/dir_to_automount
> Aug 13 01:40:36 client-1 automount[30947]: parse_mount: parse(sun): core
> of entry:
> options=rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp,
> loc=nfsserver:/vol/work/dir_to_automount
> Aug 13 01:40:36 client-1 automount[30947]: sun_mount: parse(sun):
> mounting root /home, mountpoint dir_to_automount, what
> nfsserver:/vol/work/dir_to_automount, fstype nfs, options
> rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> Aug 13 01:40:36 client-1 automount[30947]: mount_mount: mount(nfs):
> root=/home name=dir_to_automount
> what=nfsserver:/vol/work/dir_to_automount, fstype=nfs,
> options=rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> Aug 13 01:40:36 client-1 automount[30947]: mount_mount: mount(nfs): nfs
> options="rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp",
> nosymlink=0, ro=0
> Aug 13 01:40:36 client-1 automount[30947]: mount_mount: mount(nfs):
> calling mkdir_path /home/dir_to_automount
> Aug 13 01:40:36 client-1 automount[30947]: mount_mount: mount(nfs):
> calling mount -t nfs -s -o
> rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> nfsserver:/vol/work/dir_to_automount /home/dir_to_automount
>
> ======= so far, so good, the mount command is working. But, it takes up
> to 4 seconds to return, and before it does, the directory that hasn't
> been finished automounting already is getting expired, while it is in
> the middle of the automount sequence:
>
> Aug 13 01:40:40 client-1 automount[30947]: expire_proc_indirect: expire
> /home/dir_to_automount
> Aug 13 01:40:40 client-1 automount[30947]: 116 remaining in /home
>
> ======= only after that does the mount sequence finish, but I believe
> that this is where it is already messed up with the dir_to_automount
> directory already deleted in the automounter and the file system by the
> expire thread.
>
> Aug 13 01:40:40 client-1 automount[30947]: mount(nfs): mounted
> nfsserver:/vol/work/dir_to_automount on /home/dir_to_automount
> Aug 13 01:40:40 client-1 automount[30947]: expire_cleanup: got thid
> 3073362864 path /home stat 119
> Aug 13 01:40:40 client-1 automount[30947]: expire_cleanup: sigchld: exp
> 3073362864 finished, switching from 2 to 1
> Aug 13 01:40:40 client-1 automount[30947]: send_ready: token = 2515187
> Aug 13 01:40:40 client-1 automount[30947]: mounted
> /home/dir_to_automount
>
> ====== We then immediately get another request to automount and the
> automounter never heard of it before, even though it is now really
> mounted:
> Aug 13 01:40:40 client-1 automount[30947]: handle_packet: type = 3
> Aug 13 01:40:41 client-1 automount[30947]:
> handle_packet_missing_indirect: token 2515193, name dir_to_automount,
> request pid 16376
> Aug 13 01:40:41 client-1 automount[30947]: attempting to mount entry
> /home/dir_to_automount
> Aug 13 01:40:41 client-1 automount[30947]: lookup_mount: lookup(yp):
> looking up dir_to_automount
> Aug 13 01:40:41 client-1 automount[30947]: lookup_mount: lookup(yp):
> dir_to_automount ->
> -rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> nfsserver:/vol/work/dir_to_automount
> Aug 13 01:40:41 client-1 automount[30947]: parse_mount: parse(sun):
> expanded entry:
> -rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> nfsserver:/vol/work/dir_to_automount
> Aug 13 01:40:41 client-1 automount[30947]: parse_mount: parse(sun):
> gathered options:
> rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> Aug 13 01:40:41 client-1 automount[30947]: parse_mount: parse(sun):
> dequote("nfsserver:/vol/work/dir_to_automount") ->
> nfsserver:/vol/work/dir_to_automount
> Aug 13 01:40:41 client-1 automount[30947]: parse_mount: parse(sun): core
> of entry:
> options=rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp,
> loc=nfsserver:/vol/work/dir_to_automount
> Aug 13 01:40:41 client-1 automount[30947]: sun_mount: parse(sun):
> mounting root /home, mountpoint dir_to_automount, what
> nfsserver:/vol/work/dir_to_automount, fstype nfs, options
> rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> Aug 13 01:40:41 client-1 automount[30947]: mount_mount: mount(nfs):
> root=/home name=dir_to_automount
> what=nfsserver:/vol/work/dir_to_automount, fstype=nfs,
> options=rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp
> Aug 13 01:40:41 client-1 automount[30947]: mount_mount: mount(nfs): nfs
> options="rw,intr,retrans=10,timeo=600,hard,rsize=32768,wsize=32768,tcp",
> nosymlink=0, ro=0
> Aug 13 01:40:41 client-1 automount[30947]: mount_mount: mount(nfs):
> calling mkdir_path /home/dir_to_automount
>
> ======= We're already dead in the water here:
>
> Aug 13 01:40:41 client-1 automount[30947]: mount_mount: mount(nfs):
> warning: /home/dir_to_automount is already mounted
> Aug 13 01:40:41 client-1 automount[30947]: mount(nfs): nfs: mount
> failure nfsserver:/vol/work/dir_to_automount on /home/dir_to_automount
> Aug 13 01:40:42 client-1 automount[30947]: failed to mount
> /home/dir_to_automount
>
> ========
>
>
> There are a few more attempts to automount 'dir_to_automount' at the
> same time that the expire thread is trying to expire it.
>
> Also, after that expire attempt in the middle of the automount sequence,
> about 5 more automounted directories started acting the same way, that
> is, mounted via NFS but automounter didn't know about them... No other
> expiry in the middle of the automount sequence as far as I can see.
>
> 'umount -a' may work, but it will also kill any local mounts.
>
> 'umount -a -t nfs' may be better, but anybody is mounting an NFS
> resource that is not automounted, this will also mess things up.
You've convinced me.
I think your seeing the kernel issue I spoke about.
Ian
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