linux-kernel - Re: nfs: lock stuck after interrupt

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Date:	Sun, 20 Apr 2008 14:45:15 -0400
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	trond.myklebust@....uio.no, eshel@...aden.ibm.com, neilb@...e.de,
	akpm@...ux-foundation.org, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: nfs: lock stuck after interrupt

On Thu, Apr 17, 2008 at 07:44:08PM +0200, Miklos Szeredi wrote:
> 1) on server lock file X
> 2) on client lock file X
>      blocks
> 3) on client send interrupt to process doing locking
>      locking syscall restarted, continues blocking
> 4) on server release lock on file X
>      on client lock is acquired
> 5) on client release lock on file X
> 6) on client lock file X
>      blocks
> 
> Everything up to the last step is fine, but something goes wrong
> during the final unlock.  Stopping the nfs-server removes the stray
> lock.
> 
> Here's a trace on the server:
> 
> lockd: request from 192.168.1.1, port=862
> lockd: LOCK          called
> lockd: nlm_lookup_host(192.168.1.2->192.168.1.1, p=6, v=4, my role=server, name=tucsk)
> lockd: get host tucsk
> lockd: nsm_monitor(tucsk)
> lockd: nlm_lookup_file (02000001 00006200 00000002 0001783d 7f54ef79 00017801 d06c5915 00000000)
> lockd: creating file for (02000001 00006200 00000002 0001783d 7f54ef79 00017801 d06c5915 00000000)
> lockd: found file 0ad074c0 (count 0)
> lockd: nlmsvc_lock(ubda/96317, ty=1, pi=1, 0-99, bl=1)
> lockd: nlm_lookup_host(192.168.1.2->192.168.1.1, p=6, v=4, my role=server, name=tucsk)
> lockd: get host tucsk
> lockd: nlmsvc_lookup_block f=0ad074c0 pd=1 0-99 ty=1
> lockd: get host tucsk
> lockd: created block 0aeabf80...
> lockd: vfs_lock_file returned 1

Why is vfs_lock_file returning 1?  It should be 0 or -ERRNO.

--b.

> lockd: nlmsvc_insert_block(0aeabf80, -1)
> lockd: release host tucsk
> lockd: nlmsvc_lock returned 50331648
> lockd: LOCK         status 3
> lockd: release host tucsk
> lockd: nlm_release_file(0ad074c0, ct = 2)
> lockd: request from 192.168.1.1, port=862
> lockd: CANCEL        called
> lockd: nlm_lookup_host(192.168.1.2->192.168.1.1, p=6, v=4, my role=server, name=tucsk)
> lockd: get host tucsk
> lockd: nlm_lookup_file (02000001 00006200 00000002 0001783d 7f54ef79 00017801 d06c5915 00000000)
> lockd: found file 0ad074c0 (count 1)
> lockd: nlmsvc_cancel(ubda/96317, pi=1, 0-99)
> lockd: nlmsvc_lookup_block f=0ad074c0 pd=1 0-99 ty=1
> lockd: check f=0ad074c0 pd=1 0-99 ty=1 cookie=36120000
> lockd: unlinking block 0aeabf80...
> lockd: freeing block 0aeabf80...
> lockd: release host tucsk
> lockd: nlm_release_file(0ad074c0, ct = 2)
> lockd: CANCEL        status 0
> lockd: release host tucsk
> lockd: nlm_release_file(0ad074c0, ct = 1)
> lockd: closing file ubda/96317
> lockd: request from 192.168.1.1, port=862
> lockd: LOCK          called
> lockd: nlm_lookup_host(192.168.1.2->192.168.1.1, p=6, v=4, my role=server, name=tucsk)
> lockd: get host tucsk
> lockd: nsm_monitor(tucsk)
> lockd: nlm_lookup_file (02000001 00006200 00000002 0001783d 7f54ef79 00017801 d06c5915 00000000)
> lockd: creating file for (02000001 00006200 00000002 0001783d 7f54ef79 00017801 d06c5915 00000000)
> lockd: found file 0ad074c0 (count 0)
> lockd: nlmsvc_lock(ubda/96317, ty=1, pi=2, 0-99, bl=1)
> lockd: nlm_lookup_host(192.168.1.2->192.168.1.1, p=6, v=4, my role=server, name=tucsk)
> lockd: get host tucsk
> lockd: nlmsvc_lookup_block f=0ad074c0 pd=2 0-99 ty=1
> lockd: get host tucsk
> lockd: created block 0aeab240...
> lockd: vfs_lock_file returned 0
> lockd: freeing block 0aeab240...
> lockd: release host tucsk
> lockd: nlm_release_file(0ad074c0, ct = 2)
> lockd: release host tucsk
> lockd: nlmsvc_lock returned 0
> lockd: LOCK         status 0
> lockd: release host tucsk
> lockd: nlm_release_file(0ad074c0, ct = 1)
> lockd: request from 192.168.1.1, port=862
> lockd: UNLOCK        called
> lockd: nlm_lookup_host(192.168.1.2->192.168.1.1, p=6, v=4, my role=server, name=tucsk)
> lockd: get host tucsk
> lockd: nlm_lookup_file (02000001 00006200 00000002 0001783d 7f54ef79 00017801 d06c5915 00000000)
> lockd: found file 0ad074c0 (count 0)
> lockd: nlmsvc_unlock(ubda/96317, pi=3, 0-9223372036854775807)
> lockd: nlmsvc_cancel(ubda/96317, pi=3, 0-9223372036854775807)
> lockd: nlmsvc_lookup_block f=0ad074c0 pd=3 0-9223372036854775807 ty=2
> lockd: UNLOCK        status 0
> lockd: release host tucsk
> lockd: nlm_release_file(0ad074c0, ct = 1)
> 
> 
> Everything looks normal, yet...
> 
> This is 100% reproducable for me (ext3 exported over nfs, server and
> client: 2.6-git).
> 
> Miklos
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