From 8b8aefb3d6ae2139ea3d4ef6d7dd2c06f57f6075 Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 21 Aug 2018 11:55:55 +0200
Subject: [PATCH] qemu_conf: Introduce metadata_lock_manager

This config option allows users to set and enable lock manager
for domain metadata. The lock manager is going to be used by
security drivers to serialize each other when changing a file
ownership or changing the SELinux label. The only supported lock
manager is 'lockd' for now.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
---
 src/qemu/libvirtd_qemu.aug         |  1 +
 src/qemu/qemu.conf                 |  8 ++++++++
 src/qemu/qemu_conf.c               | 13 +++++++++++++
 src/qemu/qemu_conf.h               |  1 +
 src/qemu/test_libvirtd_qemu.aug.in |  1 +
 5 files changed, 24 insertions(+)

diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug
index ddc4bbfd1d..42e325d4fb 100644
--- a/src/qemu/libvirtd_qemu.aug
+++ b/src/qemu/libvirtd_qemu.aug
@@ -98,6 +98,7 @@ module Libvirtd_qemu =
                  | bool_entry "relaxed_acs_check"
                  | bool_entry "allow_disk_format_probing"
                  | str_entry "lock_manager"
+                 | str_entry "metadata_lock_manager"
 
    let rpc_entry = int_entry "max_queued"
                  | int_entry "keepalive_interval"
diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf
index cd57b3cc69..84492719c4 100644
--- a/src/qemu/qemu.conf
+++ b/src/qemu/qemu.conf
@@ -659,6 +659,14 @@
 #lock_manager = "lockd"
 
 
+# To serialize two or more daemons trying to change metadata on a
+# file (e.g. a file on NFS share), libvirt offers a locking
+# mechanism. Currently, only "lockd" is supported (or no locking
+# at all if unset). Note that this is independent of lock_manager
+# described above.
+#
+#metadata_lock_manager = "lockd"
+
 
 # Set limit of maximum APIs queued on one domain. All other APIs
 # over this threshold will fail on acquiring job lock. Specially,
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 4d69b599fe..8c5f9021f9 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -430,6 +430,7 @@ static void virQEMUDriverConfigDispose(void *obj)
     virStringListFree(cfg->securityDriverNames);
 
     VIR_FREE(cfg->lockManagerName);
+    VIR_FREE(cfg->metadataLockManagerName);
 
     virFirmwareFreeList(cfg->firmwares, cfg->nfirmwares);
 
@@ -840,6 +841,18 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
 
     if (virConfGetValueString(conf, "lock_manager", &cfg->lockManagerName) < 0)
         goto cleanup;
+
+    if (virConfGetValueString(conf, "metadata_lock_manager",
+                              &cfg->metadataLockManagerName) < 0)
+        goto cleanup;
+    if (cfg->metadataLockManagerName &&
+        STRNEQ(cfg->metadataLockManagerName, "lockd")) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("unknown metadata lock manager name %s"),
+                       cfg->metadataLockManagerName);
+        goto cleanup;
+    }
+
     if (virConfGetValueString(conf, "stdio_handler", &stdioHandler) < 0)
         goto cleanup;
     if (stdioHandler) {
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index a8d84efea2..c227ac72cc 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -186,6 +186,7 @@ struct _virQEMUDriverConfig {
     bool autoStartBypassCache;
 
     char *lockManagerName;
+    char *metadataLockManagerName;
 
     int keepAliveInterval;
     unsigned int keepAliveCount;
diff --git a/src/qemu/test_libvirtd_qemu.aug.in b/src/qemu/test_libvirtd_qemu.aug.in
index f1e8806ad2..451e73126e 100644
--- a/src/qemu/test_libvirtd_qemu.aug.in
+++ b/src/qemu/test_libvirtd_qemu.aug.in
@@ -81,6 +81,7 @@ module Test_libvirtd_qemu =
 { "mac_filter" = "1" }
 { "relaxed_acs_check" = "1" }
 { "lock_manager" = "lockd" }
+{ "metadata_lock_manager" = "lockd" }
 { "max_queued" = "0" }
 { "keepalive_interval" = "5" }
 { "keepalive_count" = "5" }