Messages in this thread | | | From | Jeff Moyer <> | Date | Thu, 22 Sep 2005 17:09:11 -0400 | Subject | Re: autofs4 looks up wrong path element when ghosting is enabled |
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==> Regarding Re: autofs4 looks up wrong path element when ghosting is enabled; Ian Kent <raven@themaw.net> adds:
raven> On Tue, 20 Sep 2005, Jeff Moyer wrote: >> Hi, Ian, list, >> >> I have a bug filed against autofs when ghosting is enabled. The best way >> to describe the bug is to walk through the reproducer, I guess. >> >> Take the following maps, for example: >> >> auto.master >> /sbox auto.sbox >> >> auto.sbox: >> src segfault:/sbox/src/ >> >> Let's say that there is a file, id3_0.12.orig.tar.gz, in segfault:/sbox/src/. >> >> To reproduce the problem, stop the nfs service on the server. >> >> On the client, do an 'ls /sbox/src/id3_012.orig.tar.gz'. This will fail, >> as well it should. However, if we look in the logs, we find this: >> >> automount[1182]: handle_packet_missing: token 1, name src >> automount[1182]: attempting to mount entry /sbox/src >> ... >> automount[1481]: mount(nfs): calling mkdir_path /sbox/src >> automount[1481]: mount(nfs): calling mount -t nfs -s-o tcp,intr,timeo=600,rsize=8192,wsize=8192,retrans=5 segfault:/sbox/src /sbox/src >> automount[1481]: >> mount: RPC: Program not registered >> automount[1481]: mount(nfs): add_bad_host: segfault:/sbox/src >> automount[1481]: mount(nfs): nfs: mount failure segfault:/sbox/src on /sbox/src >> automount[1481]: failed to mount /sbox/src >> ... >> automount[1182]: send_fail: token=1 >> automount[1182]: handle_packet: type = 0 >> automount[1182]: handle_packet_missing: token 2, name src/id3_0.12.orig.tar.gz >> automount[1182]: attempting to mount entry /sbox/src/id3_0.12.orig.tar.gz >> >> Noteworthy are these last two lines! Even though the mount failed, we are >> continuing the lookup. The culprit is here, in cached_lookup: >> >> if (!dentry->d_op->d_revalidate(dentry, flags) && !d_invalidate(dentry)) { >> dput(dentry); >> dentry = NULL; >> } >> >> d_revalidate points to autofs4_revalidate, which calls try_to_fill_dentry, >> which will return a status of 0. Since ghosting is enabled, >> d_invalidate(dentry) will return -EBUSY, and so we return the dentry to raven> the >> caller, which then continues the lookup. >> >> Ian, I'm not really sure how we can address this issue without VFS >> changes. Any ideas? >>
raven> I'm aware of this problem. raven> I'm not sure how to deal with it yet. raven> The case above is probably not that difficult to solve but if the last raven> component is a directory it's hard to work out it's a problem.
Ugh. If you're thinking what I think you're thinking, that's an ugly hack.
raven> There's more information here than I've gathhered so far.
>> Oh, also note that, once the nfs service is started up again on the server, >> the lookup of a specific file name will still fail! In this case, the >> daemon won't even be called.
raven> I'll have to check this out. raven> It could be helpful.
Well, I've provided a reproducer. If you'd like log output from the kernel side, let me know. I can certainly provide that.
-Jeff - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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