autofs-5.0.6 - reinstate singleton mount probe

From: Ian Kent <ikent@redhat.com>

The change to have the kernel process text based mount options can
introduce lengthy timeout waits when attempting a mount to a host
that is not available.

To avoid these waits autofs should probe singleton mounts if it
thinks mount.nfs will pass text options to the kernel (which of
course implies the kernel supports this).
---

 CHANGELOG            |    1 +
 daemon/automount.c   |    7 +++++++
 include/mounts.h     |    1 +
 modules/replicated.c |   18 ++++++++++++++++--
 4 files changed, 25 insertions(+), 2 deletions(-)


diff --git a/CHANGELOG b/CHANGELOG
index 359c293..5a6af1c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -29,6 +29,7 @@
 - ignore duplicate exports in auto.net.
 - add kernel verion check function.
 - add function to check mount.nfs version.
+- reinstate singleton mount probe.
 
 28/06/2011 autofs-5.0.6
 -----------------------
diff --git a/daemon/automount.c b/daemon/automount.c
index c0b4b85..31dd564 100644
--- a/daemon/automount.c
+++ b/daemon/automount.c
@@ -51,6 +51,9 @@ const char *libdir = AUTOFS_LIB_DIR;	/* Location of library modules */
 const char *mapdir = AUTOFS_MAP_DIR;	/* Location of mount maps */
 const char *confdir = AUTOFS_CONF_DIR;	/* Location of autofs config file */
 
+unsigned int nfs_mount_uses_string_options = 0;
+static struct nfs_mount_vers vers, check = {1, 1, 1};
+
 /* autofs fifo name prefix */
 const char *fifodir = AUTOFS_FIFO_DIR "/autofs.fifo";
 
@@ -1273,6 +1276,8 @@ static int do_hup_signal(struct master *master, time_t age)
 	if (status)
 		fatal(status);
 
+	nfs_mount_uses_string_options = check_nfs_mount_version(&vers, &check);
+
 	master_mutex_lock();
 	if (master->reading) {
 		status = pthread_mutex_unlock(&mrc.mutex);
@@ -1936,6 +1941,8 @@ int main(int argc, char *argv[])
 
 	defaults_read_config(0);
 
+	nfs_mount_uses_string_options = check_nfs_mount_version(&vers, &check);
+
 	kpkt_len = get_kpkt_len();
 	timeout = defaults_get_timeout();
 	ghost = defaults_get_browse_mode();
diff --git a/include/mounts.h b/include/mounts.h
index 6a6ebab..9aac90f 100644
--- a/include/mounts.h
+++ b/include/mounts.h
@@ -95,6 +95,7 @@ struct nfs_mount_vers {
 	unsigned int fix;
 };
 int check_nfs_mount_version(struct nfs_mount_vers *, struct nfs_mount_vers *);
+extern unsigned int nfs_mount_uses_string_options;
 
 unsigned int query_kproto_ver(void);
 unsigned int get_kver_major(void);
diff --git a/modules/replicated.c b/modules/replicated.c
index 65634bd..84134b6 100644
--- a/modules/replicated.c
+++ b/modules/replicated.c
@@ -901,6 +901,7 @@ int prune_host_list(unsigned logopt, struct host **list,
 	unsigned int v2_udp_count, v3_udp_count, v4_udp_count;
 	unsigned int max_udp_count, max_tcp_count, max_count;
 	int status;
+	int kern_vers;
 
 	if (!*list)
 		return 0;
@@ -920,9 +921,22 @@ int prune_host_list(unsigned logopt, struct host **list,
 	 * or a single host entry whose proximity isn't local. If so
 	 * return immediately as we don't want to add probe latency for
 	 * the common case of a single filesystem mount request.
+	 *
+	 * But, if the kernel understands text nfs mount options then
+	 * mount.nfs most likely bypasses its probing and lets the kernel
+	 * do all the work. This can lead to long timeouts for hosts that
+	 * are not available so check the kernel version and mount.nfs
+	 * version and probe singleton mounts if the kernel version is
+	 * greater than 2.6.22 and mount.nfs version is greater than 1.1.1.
 	 */
-	if (!this || !this->next)
-		return 1;
+	if (nfs_mount_uses_string_options &&
+	   (kern_vers = linux_version_code()) > KERNEL_VERSION(2, 6, 22)) {
+		if (!this)
+			return 1;
+	} else {
+		if (!this || !this->next)
+			return 1;
+	}
 
 	proximity = this->proximity;
 	while (this) {