[Xen-changelog] [xen master] tools: libxc: fix Remus failover regression

[patchbot@xxxxxxx]

commit ca0354f90a25be9f4e31dafe6e37b012bb2de7ac
Author:     Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
AuthorDate: Mon Jul 28 12:03:27 2014 +0800
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Thu Aug 21 23:29:18 2014 +0100

    tools: libxc: fix Remus failover regression
    
    commit: c2ba706c "tools/libxc: goto correct label on error paths" by Andrew
    Cooper broke Remus in Xen 4.4 or earlier versions that has this commit
    backported.
    
    With Remus, this jump essentially discards the current incomplete checkpoint
    received by the backup and restore backup from the last complete checkpoint.
    This is required for Remus to work and this does not break live migration.  
It
    has been around since Xen 4.0.
    
    CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
    CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    CC: Shriram Rajagopalan <rshriram@xxxxxxxxx>
    Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
    Acked-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 tools/libxc/xc_domain_restore.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index e73e0a2..b9a56d5 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -1783,20 +1783,29 @@ int xc_domain_restore(xc_interface *xch, int io_fd, 
uint32_t dom,
 
     if ( pagebuf_get(xch, ctx, &pagebuf, io_fd, dom) ) {
         PERROR("error when buffering batch, finishing");
-        goto out;
+        /*
+         * Remus: discard the current incomplete checkpoint and restore
+         * backup from the last complete checkpoint.
+         */
+        goto finish;
     }
     memset(&tmptail, 0, sizeof(tmptail));
     tmptail.ishvm = hvm;
     if ( buffer_tail(xch, ctx, &tmptail, io_fd, max_vcpu_id, vcpumap,
                      ext_vcpucontext, vcpuextstate_size) < 0 ) {
         ERROR ("error buffering image tail, finishing");
-        goto out;
+        /*
+         * Remus: discard the current incomplete checkpoint and restore
+         * backup from the last complete checkpoint.
+         */
+        goto finish;
     }
     tailbuf_free(&tailbuf);
     memcpy(&tailbuf, &tmptail, sizeof(tailbuf));
 
     goto loadpages;
 
+  /* With Remus: restore from last complete checkpoint */
   finish:
     if ( hvm )
         goto finish_hvm;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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