[Xen-devel] [PATCH] [Attempt 2] xl save but leave domain paused

[Ian Murray <murrayie@xxxxxxxxxxx>]

    New feature to allow xl save to leave a domain paused after its
    memory has been saved. This is to allow disk snapshots of domU
    to be taken that exactly correspond to the memory state at save time.
    Once the snapshot(s) have been taken or whatever, the domain can be
    unpaused in the usual manner.

    Usage:
      xl save -p <domid> <filespec>

    Somewhat fixed alignment.
    Re-worked the if statements so they read better - no change to logic.
    Removed spurious empty line.
    Fixed Man page.

    Signed-off-by: Ian Murray <murrayie@xxxxxxxxxxx>
---
 docs/man/xl.pod.1         |    6 +++++-
 tools/libxl/xl_cmdimpl.c  |   20 ++++++++++++++------
 tools/libxl/xl_cmdtable.c |    3 ++-
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/docs/man/xl.pod.1 b/docs/man/xl.pod.1
index 64a118e..5975d7b 100644
--- a/docs/man/xl.pod.1
+++ b/docs/man/xl.pod.1
@@ -504,7 +504,7 @@ Pass VNC password to vncviewer via stdin.
 
 Saves a running domain to a state file so that it can be restored
 later.  Once saved, the domain will no longer be running on the
-system, unless the -c option is used.
+system, unless the -c or -p options are used.
 B<xl restore> restores from this checkpoint file.
 Passing a config file argument allows the user to manually select the VM config
 file used to create the domain.
@@ -515,6 +515,10 @@ file used to create the domain.
 
 Leave domain running after creating the snapshot.
 
+=item B<-p>
+
+Leave domain paused after creating the snapshot.
+
 =back
 
 =item B<sharing> [I<domain-id>]
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 8a478ba..0e2b0b6 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -3266,7 +3266,7 @@ static void save_domain_core_writeconfig(int fd, const 
char *source,
 }
 
 static int save_domain(uint32_t domid, const char *filename, int checkpoint,
-                const char *override_config_file)
+                            int leavepaused, const char *override_config_file)
 {
     int fd;
     uint8_t *config_data;
@@ -3290,11 +3290,15 @@ static int save_domain(uint32_t domid, const char 
*filename, int checkpoint,
     int rc = libxl_domain_suspend(ctx, domid, fd, 0, NULL);
     close(fd);
 
-    if (rc < 0)
+    if (rc < 0) {
         fprintf(stderr, "Failed to save domain, resuming domain\n");
-
-    if (checkpoint || rc < 0)
         libxl_domain_resume(ctx, domid, 1, 0);
+    }
+    else if (leavepaused || checkpoint) {
+        if (leavepaused)
+            libxl_domain_pause(ctx, domid);
+        libxl_domain_resume(ctx, domid, 1, 0);
+    }
     else
         libxl_domain_destroy(ctx, domid, 0);
 
@@ -3838,12 +3842,16 @@ int main_save(int argc, char **argv)
     const char *filename;
     const char *config_filename = NULL;
     int checkpoint = 0;
+    int leavepaused = 0;
     int opt;
 
-    SWITCH_FOREACH_OPT(opt, "c", NULL, "save", 2) {
+    SWITCH_FOREACH_OPT(opt, "cp", NULL, "save", 2) {
     case 'c':
         checkpoint = 1;
         break;
+    case 'p':
+        leavepaused = 1;
+        break;
     }
 
     if (argc-optind > 3) {
@@ -3856,7 +3864,7 @@ int main_save(int argc, char **argv)
     if ( argc - optind >= 3 )
         config_filename = argv[optind + 2];
 
-    save_domain(domid, filename, checkpoint, config_filename);
+    save_domain(domid, filename, checkpoint, leavepaused, config_filename);
     return 0;
 }
 
diff --git a/tools/libxl/xl_cmdtable.c b/tools/libxl/xl_cmdtable.c
index 44b42b0..326a660 100644
--- a/tools/libxl/xl_cmdtable.c
+++ b/tools/libxl/xl_cmdtable.c
@@ -142,7 +142,8 @@ struct cmd_spec cmd_table[] = {
       "Save a domain state to restore later",
       "[options] <Domain> <CheckpointFile> [<ConfigFile>]",
       "-h  Print this help.\n"
-      "-c  Leave domain running after creating the snapshot."
+      "-c  Leave domain running after creating the snapshot.\n"
+      "-p  Leave domain paused after creating the snapshot."
     },
     { "migrate",
       &main_migrate, 0, 1,
-- 
1.7.9.5


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