qemu-img: Allow cache mode specification for amend

qemu-img amend may extensively modify the target image, depending on the
options to be amended (e.g. conversion to qcow2 compat level 0.10 from
1.1 for an image with many unallocated zero clusters). Therefore it
makes sense to allow the user to specify the cache mode to be used.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 15 insertions, 4 deletions

diff --git a/qemu-img.c b/qemu-img.c
index df85405..c843420 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2778,12 +2778,14 @@ static int img_amend(int argc, char **argv)
     char *options = NULL;
     QemuOptsList *create_opts = NULL;
     QemuOpts *opts = NULL;
-    const char *fmt = NULL, *filename;
+    const char *fmt = NULL, *filename, *cache;
+    int flags;
     bool quiet = false;
     BlockDriverState *bs = NULL;
 
+    cache = BDRV_DEFAULT_CACHE;
     for (;;) {
-        c = getopt(argc, argv, "hqf:o:");
+        c = getopt(argc, argv, "ho:f:t:q");
         if (c == -1) {
             break;
         }
@@ -2810,6 +2812,9 @@ static int img_amend(int argc, char **argv)
             case 'f':
                 fmt = optarg;
                 break;
+            case 't':
+                cache = optarg;
+                break;
             case 'q':
                 quiet = true;
                 break;
@@ -2832,8 +2837,14 @@ static int img_amend(int argc, char **argv)
         error_exit("Expecting one image file name");
     }
 
-    bs = bdrv_new_open("image", filename, fmt,
-                       BDRV_O_FLAGS | BDRV_O_RDWR, true, quiet);
+    flags = BDRV_O_FLAGS | BDRV_O_RDWR;
+    ret = bdrv_parse_cache_flags(cache, &flags);
+    if (ret < 0) {
+        error_report("Invalid cache option: %s", cache);
+        goto out;
+    }
+
+    bs = bdrv_new_open("image", filename, fmt, flags, true, quiet);
     if (!bs) {
         error_report("Could not open image '%s'", filename);
         ret = -1;