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[PATCHv3,19/20] qemu-img: conditionally zero out target on convert

Message ID 1380029714-5239-20-git-send-email-pl@kamp.de
State New
Headers show

Commit Message

Peter Lieven Sept. 24, 2013, 1:35 p.m. UTC 
If the target has_zero_init = 0, but supports efficiently
writing zeroes by unmapping we call bdrv_zeroize to
avoid fully allocating the target. Ihis currently
is designed especially for iscsi.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
---
 qemu-img.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/qemu-img.c b/qemu-img.c
index c6eff15..2a41942 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1353,7 +1353,7 @@  static int img_convert(int argc, char **argv)
         }
     }
 
-    flags = BDRV_O_RDWR;
+    flags = min_sparse ? (BDRV_O_RDWR | BDRV_O_UNMAP) : BDRV_O_RDWR;
     ret = bdrv_parse_cache_flags(cache, &flags);
     if (ret < 0) {
         error_report("Invalid cache option: %s", cache);
@@ -1469,6 +1469,14 @@  static int img_convert(int argc, char **argv)
     } else {
         int has_zero_init = min_sparse ? bdrv_has_zero_init(out_bs) : 0;
 
+        if (!has_zero_init && bdrv_has_discard_write_zeroes(out_bs)) {
+            ret = bdrv_zeroize(out_bs, BDRV_REQ_MAY_UNMAP);
+            if (ret < 0) {
+                goto out;
+            }
+            has_zero_init = 1;
+        }
+
         sector_num = 0; // total number of sectors converted so far
         nb_sectors = total_sectors - sector_num;
         if (nb_sectors != 0) {