nfs: Don't busy-wait on SIGKILL in __nfs_iocounter_wait

commit 92a56555bd576c61b27a5cab9f38a33a1e9a1df5 upstream.

If a SIGKILL is sent to a task waiting in __nfs_iocounter_wait,
it will busy-wait or soft lockup in its while loop.
nfs_wait_bit_killable won't sleep, and the loop won't exit on
the error return.

Stop the busy-wait by breaking out of the loop when
nfs_wait_bit_killable returns an error.

Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
[ kamal: backport to 3.13-stable: context ]
Cc: Moritz Mühlenhoff <muehlenhoff@univention.de>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 2ffebf2..27d7f27 100644 (file)
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -113,7 +113,7 @@ __nfs_iocounter_wait(struct nfs_io_counter *c)
                if (atomic_read(&c->io_count) == 0)
                        break;
                ret = nfs_wait_bit_killable(&c->flags);
-       } while (atomic_read(&c->io_count) != 0);
+       } while (atomic_read(&c->io_count) != 0 && !ret);
        finish_wait(wq, &q.wait);
        return ret;
 }