commit be9c9404db7e6992946fa55c75ca61dfb20926eb
author Eric Blake <eblake@redhat.com> Tue Apr 28 15:29:02 2020 -0500
committer Kevin Wolf <kwolf@redhat.com> Fri May 08 13:26:35 2020 +0200
tree d1c974e4a6679cb120caf44aa086c36bb8abf53a
parent fec00559e71c94749deac176f6c4bebf81fbe7b8

ssh: Support BDRV_REQ_ZERO_WRITE for truncate

Our .bdrv_has_zero_init_truncate can detect when the remote side
always zero fills; we can reuse that same knowledge to implement
BDRV_REQ_ZERO_WRITE by ignoring it when the server gives it to us for
free.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200428202905.770727-7-eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/ssh.c

diff --git a/block/ssh.c b/block/ssh.c
index 9eb33df..f9e08a4 100644
--- a/block/ssh.c
+++ b/block/ssh.c
@@ -883,6 +883,10 @@
     /* Go non-blocking. */
     ssh_set_blocking(s->session, 0);
 
+    if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) {
+        bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
+    }
+
     qapi_free_BlockdevOptionsSsh(opts);
 
     return 0;