From bd39e6ed0b88a1473c652c97e731a156cccf16e2 Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Tue, 22 Jul 2014 22:58:43 +0200
Subject: 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>
---
 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 48df0b83c2..55aec6bded 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 df854059be..c8434206b8 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;
diff --git a/qemu-img.texi b/qemu-img.texi
index 688b28d87b..cb689483b6 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.
-- 
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