linux/fs/lockd
NeilBrown 2ec197db1a lockd: send correct lock when granting a delayed lock.
If an NFS client attempts to get a lock (using NLM) and the lock is
not available, the server will remember the request and when the lock
becomes available it will send a GRANT request to the client to
provide the lock.

If the client already held an adjacent lock, the GRANT callback will
report the union of the existing and new locks, which can confuse the
client.

This happens because __posix_lock_file (called by vfs_lock_file)
updates the passed-in file_lock structure when adjacent or
over-lapping locks are found.

To avoid this problem we take a copy of the two fields that can
be changed (fl_start and fl_end) before the call and restore them
afterwards.
An alternate would be to allocate a 'struct file_lock', initialise it,
use locks_copy_lock() to take a copy, then locks_release_private()
after the vfs_lock_file() call.  But that is a lot more work.

Reported-by: Olaf Kirch <okir@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

--
v1 had a couple of issues (large on-stack struct and didn't really work properly).
This version is much better tested.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2014-02-13 14:55:02 -05:00
..
Makefile lockd: Introduce new-style XDR functions for NLMv4 2010-12-16 12:37:23 -05:00
clnt4xdr.c lockd: Remove unnecessary BUG_ON()s in the xdr client code 2012-11-04 14:43:39 -05:00
clntlock.c LOCKD: Don't call utsname()->nodename from nlmclnt_setlockargs 2013-08-05 15:03:46 -04:00
clntproc.c LOCKD: Don't call utsname()->nodename from nlmclnt_setlockargs 2013-08-05 15:03:46 -04:00
clntxdr.c lockd: Remove unnecessary BUG_ON()s in the xdr client code 2012-11-04 14:43:39 -05:00
grace.c LockD: pass actual network namespace to grace period management functions 2012-07-27 16:49:22 -04:00
host.c Merge branch 'for-3.9' of git://linux-nfs.org/~bfields/linux 2013-02-28 18:02:55 -08:00
mon.c sunrpc: move address copy/cmp/convert routines and prototypes from clnt.h to addr.h 2013-02-05 09:41:14 -05:00
netns.h lockd: per-net NSM client creation and destruction helpers introduced 2012-10-01 15:27:34 -07:00
svc.c drivers: avoid parsing names as kthread_run() format strings 2013-07-03 16:07:41 -07:00
svc4proc.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-08-01 10:26:23 -07:00
svclock.c lockd: send correct lock when granting a delayed lock. 2014-02-13 14:55:02 -05:00
svcproc.c NLM: nlm_lookup_file() may return NLMv4-specific error codes 2012-10-17 10:14:14 -04:00
svcshare.c lockd: fix sparse warning in svcshare.c 2008-04-23 16:13:39 -04:00
svcsubs.c locks: protect most of the file_lock handling with i_lock 2013-06-29 12:57:42 +04:00
xdr.c lockd: Move nlmdbg_cookie2a() to svclock.c 2010-12-16 12:37:24 -05:00
xdr4.c lockd: Introduce new-style XDR functions for NLMv4 2010-12-16 12:37:23 -05:00