[Qemu-devel] [PATCH v2 2/2] qemu-img: Allow cache mode specification for amend

[Max Reitz <mreitz@redhat.com>]

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>
---
 qemu-img-cmds.hx |  4 ++--
 qemu-img.c       | 19 +++++++++++++++----
 qemu-img.texi    |  2 +-
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 48df0b8..55aec6b 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -70,8 +70,8 @@ STEXI
 ETEXI
 
 DEF("amend", img_amend,
-    "amend [-q] [-f fmt] -o options filename")
+    "amend [-q] [-f fmt] [-t cache] -o options filename")
 STEXI
-@item amend [-q] [-f @var{fmt}] -o @var{options} @var{filename}
+@item amend [-q] [-f @var{fmt}] [-t @var{cache}] -o @var{options} @var{filename}
 @end table
 ETEXI
diff --git a/qemu-img.c b/qemu-img.c
index 9f3909c..ef74ae4 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2738,12 +2738,14 @@ 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;
         }
@@ -2770,6 +2772,9 @@ static int img_amend(int argc, char **argv)
             case 'f':
                 fmt = optarg;
                 break;
+            case 't':
+                cache = optarg;
+                break;
             case 'q':
                 quiet = true;
                 break;
@@ -2792,8 +2797,14 @@ 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;
diff --git a/qemu-img.texi b/qemu-img.texi
index 688b28d..cb68948 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -397,7 +397,7 @@ After using this command to grow a disk image, you must use file system and
 partitioning tools inside the VM to actually begin using the new space on the
 device.
 
-@item amend [-f @var{fmt}] -o @var{options} @var{filename}
+@item amend [-f @var{fmt}] [-t @var{cache}] -o @var{options} @var{filename}
 
 Amends the image format specific @var{options} for the image file
 @var{filename}. Not all file formats support this operation.
-- 
2.0.1