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[libvirt] [PATCH 11/14] Add ability to maintain disk leases indirectly



From: "Daniel P. Berrange" <berrange redhat com>

The default lockd driver behavour is to acquire leases
directly on the disk files. This introduces an alternative
mode, where leases are acquire indirectly on a file that
is based on a SHA256 hash of the disk filename.

Signed-off-by: Daniel P. Berrange <berrange redhat com>
---
 bootstrap.conf                        |   1 +
 src/Makefile.am                       |   4 +-
 src/locking/libvirt_lockd.aug         |   1 +
 src/locking/lock_driver_lockd.c       | 128 +++++++++++++++++++++++++++++++---
 src/locking/lockd.conf                |  22 ++++++
 src/locking/test_libvirt_lockd.aug.in |   1 +
 6 files changed, 148 insertions(+), 9 deletions(-)

diff --git a/bootstrap.conf b/bootstrap.conf
index 59dd258..37a0ae1 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -36,6 +36,7 @@ connect
 configmake
 count-one-bits
 crypto/md5
+crypto/sha256
 dirname-lgpl
 environ
 execinfo
diff --git a/src/Makefile.am b/src/Makefile.am
index 5808653..0a1b98f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1564,7 +1564,7 @@ lockd_la_SOURCES = \
 		$(LOCK_DRIVER_LOCKD_SOURCES) \
 		$(LOCK_PROTOCOL_GENERATED) \
 		$(NULL)
-lockd_la_CFLAGS = $(AM_CFLAGS)
+lockd_la_CFLAGS = -I$(top_srcdir)/src/conf $(AM_CFLAGS)
 lockd_la_LDFLAGS = -module -avoid-version
 lockd_la_LIBADD = ../gnulib/lib/libgnu.la libvirt-net-rpc.la libvirt-net-rpc-client.la
 if WITH_DTRACE_PROBES
@@ -1940,6 +1940,7 @@ EXTRA_DIST += $(SECURITY_DRIVER_APPARMOR_HELPER_SOURCES)
 install-data-local: install-init install-systemd
 if WITH_LIBVIRTD
 	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/lib/libvirt/lockd"
+	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/lib/libvirt/lockd/files"
 	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/run/libvirt/lockd"
 endif
 	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/cache/libvirt"
@@ -1992,6 +1993,7 @@ endif
 
 uninstall-local:: uninstall-init uninstall-systemd
 if WITH_LIBVIRTD
+	rmdir "$(DESTDIR)$(localstatedir)/lib/libvirt/lockd/files" ||:
 	rmdir "$(DESTDIR)$(localstatedir)/lib/libvirt/lockd" ||:
 	rmdir "$(DESTDIR)$(localstatedir)/run/libvirt/lockd" ||:
 endif
diff --git a/src/locking/libvirt_lockd.aug b/src/locking/libvirt_lockd.aug
index 4649644..dafd8f9 100644
--- a/src/locking/libvirt_lockd.aug
+++ b/src/locking/libvirt_lockd.aug
@@ -19,6 +19,7 @@ module Libvirt_lockd =
    (* Each enty in the config is one of the following three ... *)
    let entry = bool_entry "auto_disk_leases"
              | bool_entry "require_lease_for_disks"
+             | str_entry "file_lockspace_dir"
    let comment = [ label "#comment" . del /#[ \t]*/ "# " .  store /([^ \t\n][^\n]*)?/ . del /\n/ "\n" ]
    let empty = [ label "#empty" . eol ]
 
diff --git a/src/locking/lock_driver_lockd.c b/src/locking/lock_driver_lockd.c
index 089b284..aa0f94a 100644
--- a/src/locking/lock_driver_lockd.c
+++ b/src/locking/lock_driver_lockd.c
@@ -32,6 +32,7 @@
 #include "rpc/virnetclient.h"
 #include "lock_protocol.h"
 #include "configmake.h"
+#include "sha256.h"
 
 #define VIR_FROM_THIS VIR_FROM_LOCKING
 
@@ -70,6 +71,8 @@ struct _virLockManagerLockDaemonPrivate {
 struct _virLockManagerLockDaemonDriver {
     bool autoDiskLease;
     bool requireLeaseForDisks;
+
+    char *fileLockSpaceDir;
 };
 
 static virLockManagerLockDaemonDriverPtr driver = NULL;
@@ -120,6 +123,17 @@ static int virLockManagerLockDaemonLoadConfig(const char *configFile)
     CHECK_TYPE("auto_disk_leases", VIR_CONF_LONG);
     if (p) driver->autoDiskLease = p->l;
 
+    p = virConfGetValue(conf, "file_lockspace_dir");
+    CHECK_TYPE("file_lockspace_dir", VIR_CONF_STRING);
+    if (p && p->str) {
+        VIR_FREE(driver->fileLockSpaceDir);
+        if (!(driver->fileLockSpaceDir = strdup(p->str))) {
+            virReportOOMError();
+            virConfFree(conf);
+            return -1;
+        }
+    }
+
     p = virConfGetValue(conf, "require_lease_for_disks");
     CHECK_TYPE("require_lease_for_disks", VIR_CONF_LONG);
     if (p)
@@ -288,6 +302,47 @@ error:
 }
 
 
+static int virLockManagerLockDaemonSetupLockspace(const char *path)
+{
+    virNetClientPtr client;
+    virNetClientProgramPtr program = NULL;
+    virLockSpaceProtocolCreateLockSpaceArgs args;
+    int rv = -1;
+    int counter = 0;
+
+    memset(&args, 0, sizeof(args));
+    args.path = (char*)path;
+
+    if (!(client = virLockManagerLockDaemonConnectionNew(getuid() == 0, &program)))
+        return -1;
+
+    if (virNetClientProgramCall(program,
+                                client,
+                                counter++,
+                                VIR_LOCK_SPACE_PROTOCOL_PROC_CREATE_LOCKSPACE,
+                                0, NULL, NULL, NULL,
+                                (xdrproc_t)xdr_virLockSpaceProtocolCreateLockSpaceArgs, (char*)&args,
+                                (xdrproc_t)xdr_void, NULL) < 0) {
+        virErrorPtr err = virGetLastError();
+        if (err && err->code == VIR_ERR_OPERATION_INVALID) {
+            /* The lockspace already exists */
+            virResetLastError();
+            rv = 0;
+        } else {
+            goto cleanup;
+        }
+    }
+
+    rv = 0;
+
+cleanup:
+    virObjectUnref(program);
+    virNetClientClose(client);
+    virObjectUnref(client);
+    return rv;
+}
+
+
 static int virLockManagerLockDaemonDeinit(void);
 
 static int virLockManagerLockDaemonInit(unsigned int version,
@@ -312,6 +367,13 @@ static int virLockManagerLockDaemonInit(unsigned int version,
     if (virLockManagerLockDaemonLoadConfig(configFile) < 0)
         goto error;
 
+    if (driver->autoDiskLease) {
+        if (driver->fileLockSpaceDir &&
+            virLockManagerLockDaemonSetupLockspace(driver->fileLockSpaceDir) < 0)
+            goto error;
+    }
+
+
     return 0;
 
 error:
@@ -324,6 +386,7 @@ static int virLockManagerLockDaemonDeinit(void)
     if (!driver)
         return 0;
 
+    VIR_FREE(driver->fileLockSpaceDir);
     VIR_FREE(driver);
 
     return 0;
@@ -421,6 +484,36 @@ static int virLockManagerLockDaemonNew(virLockManagerPtr lock,
 }
 
 
+static const char hex[] = { '0', '1', '2', '3', '4', '5', '6', '7',
+                            '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+
+static char *virLockManagerLockDaemonDiskLeaseName(const char *path)
+{
+    unsigned char buf[SHA256_DIGEST_SIZE];
+    char *ret;
+    int i;
+
+    if (!(sha256_buffer(path, strlen(path), buf))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("Unable to compute sha256 checksum"));
+        return NULL;
+    }
+
+    if (VIR_ALLOC_N(ret, (SHA256_DIGEST_SIZE * 2) + 1) < 0) {
+        virReportOOMError();
+        return NULL;
+    }
+
+    for (i = 0 ; i < SHA256_DIGEST_SIZE ; i++) {
+        ret[i*2] = hex[(buf[i] >> 4) & 0xf];
+        ret[(i*2)+1] = hex[buf[i] & 0xf];
+    }
+    ret[(SHA256_DIGEST_SIZE * 2) + 1] = '\0';
+
+    return ret;
+}
+
+
 static int virLockManagerLockDaemonAddResource(virLockManagerPtr lock,
                                                unsigned int type,
                                                const char *name,
@@ -429,8 +522,9 @@ static int virLockManagerLockDaemonAddResource(virLockManagerPtr lock,
                                                unsigned int flags)
 {
     virLockManagerLockDaemonPrivatePtr priv = lock->privateData;
-    char *newName;
+    char *newName = NULL;
     char *newLockspace = NULL;
+    bool autoCreate = false;
 
     virCheckFlags(VIR_LOCK_MANAGER_RESOURCE_READONLY |
                   VIR_LOCK_MANAGER_RESOURCE_SHARED, -1);
@@ -451,10 +545,22 @@ static int virLockManagerLockDaemonAddResource(virLockManagerPtr lock,
                 priv->hasRWDisks = true;
             return 0;
         }
-        if (!(newLockspace = strdup(""))) {
-            virReportOOMError();
-            return -1;
+
+        if (driver->fileLockSpaceDir) {
+            if (!(newLockspace = strdup(driver->fileLockSpaceDir)))
+                goto no_memory;
+            if (!(newName = virLockManagerLockDaemonDiskLeaseName(name)))
+                goto no_memory;
+            autoCreate = true;
+            VIR_DEBUG("Using indirect lease %s for %s", newName, name);
+        } else {
+            if (!(newLockspace = strdup("")))
+                goto no_memory;
+            if (!(newName = strdup(name)))
+                goto no_memory;
+            VIR_DEBUG("Using direct lease for %s", name);
         }
+
         break;
     case VIR_LOCK_MANAGER_RESOURCE_TYPE_LEASE: {
         size_t i;
@@ -488,6 +594,9 @@ static int virLockManagerLockDaemonAddResource(virLockManagerPtr lock,
             virReportOOMError();
             return -1;
         }
+        if (!(newName = strdup(name)))
+            goto no_memory;
+
     }   break;
     default:
         virReportError(VIR_ERR_INTERNAL_ERROR,
@@ -496,9 +605,6 @@ static int virLockManagerLockDaemonAddResource(virLockManagerPtr lock,
         return -1;
     }
 
-    if (!(newName = strdup(name)))
-        goto no_memory;
-
     if (VIR_EXPAND_N(priv->resources, priv->nresources, 1) < 0)
         goto no_memory;
 
@@ -509,10 +615,15 @@ static int virLockManagerLockDaemonAddResource(virLockManagerPtr lock,
         priv->resources[priv->nresources-1].flags |=
             VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_SHARED;
 
+    if (autoCreate)
+        priv->resources[priv->nresources-1].flags |=
+            VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_AUTOCREATE;
+
     return 0;
 
 no_memory:
     virReportOOMError();
+    VIR_FREE(newLockspace);
     VIR_FREE(newName);
     return -1;
 }
@@ -521,6 +632,7 @@ no_memory:
 static int virLockManagerLockDaemonAcquire(virLockManagerPtr lock,
                                            const char *state ATTRIBUTE_UNUSED,
                                            unsigned int flags,
+                                           virDomainLockFailureAction action ATTRIBUTE_UNUSED,
                                            int *fd)
 {
     virNetClientPtr client = NULL;
@@ -555,7 +667,7 @@ static int virLockManagerLockDaemonAcquire(virLockManagerPtr lock,
             memset(&args, 0, sizeof(args));
 
             if (priv->resources[i].lockspace)
-            args.path = priv->resources[i].lockspace;
+                args.path = priv->resources[i].lockspace;
             args.name = priv->resources[i].name;
             args.flags = priv->resources[i].flags;
 
diff --git a/src/locking/lockd.conf b/src/locking/lockd.conf
index 0b885c5..7545fd9 100644
--- a/src/locking/lockd.conf
+++ b/src/locking/lockd.conf
@@ -16,3 +16,25 @@
 # to enabled, otherwise it defaults to disabled.
 #
 #require_lease_for_disks = 1
+
+
+#
+# The default lockd behaviour is to use the "direct"
+# lockspace, where the locks are acquired against the
+# actual file paths associated with the <disk> devices.
+#
+# Setting a directory here causes lockd to use "indirect"
+# lockspace, where a hash of the <disk> file path is
+# used to create a file in the lockspace directory. The
+# locks are then held on these hash files instead.
+#
+# This can be useful if the file paths refer to block
+# devices which are shared, since /dev fcntl() locks
+# don't propagate across hosts. It is also useful if
+# the filesystem does not support fcntl() locks.
+#
+# Typically this directory would be located on a shared
+# filesystem visible to all hosts accessing the same
+# storage.
+#
+#file_lockspace_dir = "/var/lib/libvirt/lockd/files"
diff --git a/src/locking/test_libvirt_lockd.aug.in b/src/locking/test_libvirt_lockd.aug.in
index 5be0d99..2e65af6 100644
--- a/src/locking/test_libvirt_lockd.aug.in
+++ b/src/locking/test_libvirt_lockd.aug.in
@@ -4,3 +4,4 @@ module Test_libvirt_lockd =
    test Libvirt_lockd.lns get conf =
 { "auto_disk_leases" = "0" }
 { "require_lease_for_disks" = "1" }
+{ "file_lockspace_dir" = "/var/lib/libvirt/lockd/files" }
-- 
1.7.11.7


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