[Qemu-devel] [PATCH v3 1/2] qga: Add 'mountpoints' argument to guest-fsfreeze-freeze command

[Tomoki Sekiyama <tomoki.sekiyama@hds.com>]

When an array of mount point paths is specified as 'mountpoints' argument
of guest-fsfreeze-freeze, qemu-ga with this patch will only freeze the file
systems mounted on specified paths in Linux.
This would be useful when the host wants to create partial disk snapshots.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
---
 qga/commands-posix.c |   17 ++++++++++++++++-
 qga/commands-win32.c |    3 ++-
 qga/qapi-schema.json |    4 ++++
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 34ddba0..771f00c 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -714,9 +714,11 @@ GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **errp)
  * Walk list of mounted file systems in the guest, and freeze the ones which
  * are real local file systems.
  */
-int64_t qmp_guest_fsfreeze_freeze(Error **errp)
+int64_t qmp_guest_fsfreeze_freeze(bool has_mountpoints, strList *mountpoints,
+                                  Error **errp)
 {
     int ret = 0, i = 0;
+    strList *list;
     FsMountList mounts;
     struct FsMount *mount;
     Error *local_err = NULL;
@@ -741,6 +743,19 @@ int64_t qmp_guest_fsfreeze_freeze(Error **errp)
     ga_set_frozen(ga_state);
 
     QTAILQ_FOREACH_REVERSE(mount, &mounts, FsMountList, next) {
+        /* To issue fsfreeze in the reverse order of mounts, check if the
+         * mount is listed in the list here */
+        if (has_mountpoints) {
+            for (list = mountpoints; list; list = list->next) {
+                if (strcmp(list->value, mount->dirname) == 0) {
+                    break;
+                }
+            }
+            if (!list) {
+                continue;
+            }
+        }
+
         fd = qemu_open(mount->dirname, O_RDONLY);
         if (fd == -1) {
             error_setg_errno(errp, errno, "failed to open %s", mount->dirname);
diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index d793dd0..0c6296d 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -171,7 +171,8 @@ GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **errp)
  * Freeze local file systems using Volume Shadow-copy Service.
  * The frozen state is limited for up to 10 seconds by VSS.
  */
-int64_t qmp_guest_fsfreeze_freeze(Error **errp)
+int64_t qmp_guest_fsfreeze_freeze(bool has_mountpoints, strList *mountpoints,
+                                  Error **errp)
 {
     int i;
     Error *local_err = NULL;
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index a8cdcb3..31c0dc8 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -378,12 +378,16 @@
 #
 # Sync and freeze all freezable, local guest filesystems
 #
+# @mountpoints: #optional an array of mountpoints of filesystems to be frozen.
+#               If omitted, every mounted filesystem is frozen. (Since: 2.1)
+#
 # Returns: Number of file systems currently frozen. On error, all filesystems
 # will be thawed.
 #
 # Since: 0.15.0
 ##
 { 'command': 'guest-fsfreeze-freeze',
+  'data':    { '*mountpoints': ['str'] },
   'returns': 'int' }
 
 ##