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locks: allow __break_lease to sleep even when break_time is 0 

A fl->fl_break_time of 0 has a special meaning to the lease break code
that basically means "never break the lease". knfsd uses this to ensure
that leases don't disappear out from under it.

Unfortunately, the code in __break_lease can end up passing this value
to wait_event_interruptible as a timeout, which prevents it from going
to sleep at all. This causes __break_lease to spin in a tight loop and
causes soft lockups.

Fix this by ensuring that we pass a minimum value of 1 as a timeout
instead.

Cc: <stable@vger.kernel.org>
Cc: J. Bruce Fields <bfields@fieldses.org>
Reported-by: Terry Barnaby <terry1@beam.ltd.uk>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Jeff Layton 2014-04-15 08:44:12 -04:00 committed by J. Bruce Fields
parent c9eaa447e7
commit 4991a628a7
1 changed files with 3 additions and 4 deletions
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7
fs/locks.c
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@ -1391,11 +1391,10 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
restart:
break_time = flock->fl_break_time;
if (break_time != 0) {
if (break_time != 0)
break_time -= jiffies;
if (break_time == 0)
break_time++;
}
if (break_time == 0)
break_time++;
locks_insert_block(flock, new_fl);
spin_unlock(&inode->i_lock);
error = wait_event_interruptible_timeout(new_fl->fl_wait,