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locks: allow __break_lease to sleep even when break_time is 0

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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 makes __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>
This commit is contained in:
Jeff Layton 2014-04-15 06:17:49 -04:00
parent 55101e2d6c
commit f1c6bb2cb8
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,