nfsd4: fix hang on fast-booting nfs servers
The last_close field of a cache_detail is initialized to zero, so the
condition
detail->last_close < seconds_since_boot() - 30
may be false even for a cache that was never opened.
However, we want to immediately fail upcalls to caches that were never
opened: in the case of the auth_unix_gid cache, especially, which may
never be opened by mountd (if the --manage-gids option is not set), we
want to fail the upcall immediately. Otherwise client requests will be
dropped unnecessarily on reboot.
Also document these conditions.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index da872f9..ca7c621 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -1091,6 +1091,23 @@
}
}
+static bool cache_listeners_exist(struct cache_detail *detail)
+{
+ if (atomic_read(&detail->readers))
+ return true;
+ if (detail->last_close == 0)
+ /* This cache was never opened */
+ return false;
+ if (detail->last_close < seconds_since_boot() - 30)
+ /*
+ * We allow for the possibility that someone might
+ * restart a userspace daemon without restarting the
+ * server; but after 30 seconds, we give up.
+ */
+ return false;
+ return true;
+}
+
/*
* register an upcall request to user-space and queue it up for read() by the
* upcall daemon.
@@ -1109,10 +1126,9 @@
char *bp;
int len;
- if (atomic_read(&detail->readers) == 0 &&
- detail->last_close < seconds_since_boot() - 30) {
- warn_no_listener(detail);
- return -EINVAL;
+ if (!cache_listeners_exist(detail)) {
+ warn_no_listener(detail);
+ return -EINVAL;
}
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);