Fcntl(..., F GETLK, ...) does not return correct info about a read lock which is set on server

From Linux NFS

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Revision as of 19:30, 29 July 2011

About

• Kernel version: 2.6.22-rc1 and higher
• Bug 23892
• Reported by: Alexander Morozov (November 28, 2010)
• Fixed by: Florain Mickler (January 23, 2010)

How to reproduce

• Environment:

Debian Lenny with kernel 2.6.37-rc3 i686
nfs-common         1:1.1.2-6lenny2
nfs-kernel-server  1:1.1.2-6lenny2
172.22.0.10 is a server
172.22.0.11 is a client

• /etc/exports on a server:

/srv/test  172.22.0.11(rw,sync,no_subtree_check)

• Steps to reproduce:

client# mount -t nfs 172.22.0.10:/srv/test /srv/test

server$ cd /srv/test
server$ ./linlock r file
press Ctrl-C...

client$ cd /srv/test
client$ ./linlock w file
fcntl: Resource temporary unavailable
client$ ./lockinfo file
F_UNLCK SEEK_SET start 0 len 0

• ./linlock tool set read (r) or write (w) lock on a file.
• ./lockinfo shows what F_GETLK returns. This test shows that a client can not set a write lock on a read lock of server but F_GETLK tells that file is not locked.
• The bug does not occur if client with 2.6.21 kernel.
• The bug occurs if client with 2.6.22-rc1 and higher.