From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Alexandre Derumier <aderumier@odiso.com>
Date: Mon, 6 Apr 2020 12:16:42 +0200
Subject: [PATCH] PVE: [Up] qemu-img dd: add -n skip_create

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
[FE: fix getopt-string + add documentation]
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 docs/tools/qemu-img.rst | 11 ++++++++++-
 qemu-img-cmds.hx        |  4 ++--
 qemu-img.c              | 23 ++++++++++++++---------
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 15aeddc6d8..5e713e231d 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -208,6 +208,10 @@ Parameters to convert subcommand:
 
 Parameters to dd subcommand:
 
+.. option:: -n
+
+  Skip the creation of the target volume
+
 .. program:: qemu-img-dd
 
 .. option:: bs=BLOCK_SIZE
@@ -488,7 +492,7 @@ Command description:
   it doesn't need to be specified separately in this case.
 
 
-.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] if=INPUT of=OUTPUT
+.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [-n] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] if=INPUT of=OUTPUT
 
   dd copies from *INPUT* file to *OUTPUT* file converting it from
   *FMT* format to *OUTPUT_FMT* format.
@@ -499,6 +503,11 @@ Command description:
 
   The size syntax is similar to :manpage:`dd(1)`'s size syntax.
 
+  If the ``-n`` option is specified, the target volume creation will be
+  skipped. This is useful for formats such as ``rbd`` if the target
+  volume has already been created with site specific options that cannot
+  be supplied through ``qemu-img``.
+
 .. option:: info [--object OBJECTDEF] [--image-opts] [-f FMT] [--output=OFMT] [--backing-chain] [-U] FILENAME
 
   Give information about the disk image *FILENAME*. Use it in
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index d1616c045a..b5b0bb4467 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -58,9 +58,9 @@ SRST
 ERST
 
 DEF("dd", img_dd,
-    "dd [--image-opts] [-U] [-f fmt] [-O output_fmt] [bs=block_size] [count=blocks] [skip=blocks] [osize=output_size] if=input of=output")
+    "dd [--image-opts] [-U] [-f fmt] [-O output_fmt] [-n] [bs=block_size] [count=blocks] [skip=blocks] [osize=output_size] if=input of=output")
 SRST
-.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] [osize=OUTPUT_SIZE] if=INPUT of=OUTPUT
+.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [-n] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] [osize=OUTPUT_SIZE] if=INPUT of=OUTPUT
 ERST
 
 DEF("info", img_info,
diff --git a/qemu-img.c b/qemu-img.c
index c1306385a8..59c403373b 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4954,7 +4954,7 @@ static int img_dd(int argc, char **argv)
     const char *fmt = NULL;
     int64_t size = 0, readsize = 0;
     int64_t out_pos, in_pos;
-    bool force_share = false;
+    bool force_share = false, skip_create = false;
     struct DdInfo dd = {
         .flags = 0,
         .count = 0,
@@ -4992,7 +4992,7 @@ static int img_dd(int argc, char **argv)
         { 0, 0, 0, 0 }
     };
 
-    while ((c = getopt_long(argc, argv, ":hf:O:U", long_options, NULL))) {
+    while ((c = getopt_long(argc, argv, ":hf:O:Un", long_options, NULL))) {
         if (c == EOF) {
             break;
         }
@@ -5012,6 +5012,9 @@ static int img_dd(int argc, char **argv)
         case 'h':
             help();
             break;
+        case 'n':
+            skip_create = true;
+            break;
         case 'U':
             force_share = true;
             break;
@@ -5142,13 +5145,15 @@ static int img_dd(int argc, char **argv)
                                 size - in.bsz * in.offset, &error_abort);
         }
 
-        ret = bdrv_create(drv, out.filename, opts, &local_err);
-        if (ret < 0) {
-            error_reportf_err(local_err,
-                              "%s: error while creating output image: ",
-                              out.filename);
-            ret = -1;
-            goto out;
+        if (!skip_create) {
+            ret = bdrv_create(drv, out.filename, opts, &local_err);
+            if (ret < 0) {
+                error_reportf_err(local_err,
+                                  "%s: error while creating output image: ",
+                                  out.filename);
+                ret = -1;
+                goto out;
+            }
         }
 
         /* TODO, we can't honour --image-opts for the target,
