[Qemu-devel] [PATCH v8 0/4] Improve convert and dd commands

[Qemu-devel] [PATCH v8 0/4] Improve convert and dd commands

[Daniel P. Berrange]

Update to

  v1: https://lists.gnu.org/archive/html/qemu-devel/2017-01/msg05699.html
  v2: https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg00728.html
  v3: https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg04391.html
  v4: https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg02153.html
  v5: https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg04109.html
  v6: https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg00215.html

This series is in response to Max pointing out that you cannot
use 'convert' for an encrypted target image.

The 'convert' and 'dd' commands need to first create the image
and then open it. The bdrv_create() method takes a set of options
for creating the image, which let us provide a key-secret for the
encryption key. When the commands then open the new image, they
don't provide any options, so the image is unable to be opened
due to lack of encryption key. It is also not possible to use
the --image-opts argument to provide structured options in the
target image name - it must be a plain filename to satisfy the
bdrv_create() API contract.

This series addresses these problems to some extent

 - Adds a new --target-image-opts flag which is used to say
   that the target filename is using structured options.
   It is *only* permitted to use this when -n is also set.
   ie the target image must be pre-created so convert/dd
   don't need to run bdrv_create().

 - When --target-image-opts is not used, add special case
   code that identifies options passed to bdrv_create()
   named "*key-secret" and adds them to the options used
   to open the new image

In future it is desirable to make --target-image-opts work even when -n is
*not* given. This requires considerable work to create a new bdrv_create()
API impl.

The first patch fixes a bug in the 'dd' command while the second adds support
for the missing '--object' arg to 'dd', allowing it to reference secrets when
opening files.  The last two patches implement the new features described above
for the 'convert' command.

NB v8 is based against git master once more, since the img_convert changes
previously in block-next have now merged.

Changed in v8:

 - Readd accidentally dropped check for compression (Max)
 - Fix indentation of variable declaration (Max)
 - Fix goto jump target (Max)

Changed in v7:

 - Drop the (accidentally included) revert patch (Eric)

Changed in v6:

 - Fix misc typos (Fam)
 - Resolve messy conflicts wrt max/block-next (Max)

Changed in v5:

 - Fix return value (Max)
 - Misc doc changes (Max)
 - Use error_abort (Max)

Changed in v4:

 - Refactor img_open_new_file in terms of img_open_file (Kevin)

Changed in v3:

 - Drop all patches affecting the 'dd' command except for the clear bug fix
   and the --object support. They can be re-considered once dd is rewritten
   to run ontop of convert.
 - Use consistent return/goto style in dd command (Max)
 - Fix error reporting when using compressed image and skip-create (Max)
 - Unconditionally create QDict when open files (Max)

Changed in v2:

 - Replace dd -n flag with support for conv=nocreat,notrunc
 - Misc typos (Eric, Fam)


Daniel P. Berrange (4):
  qemu-img: add support for --object with 'dd' command
  qemu-img: fix --image-opts usage with dd command
  qemu-img: introduce --target-image-opts for 'convert' command
  qemu-img: copy *key-secret opts when opening newly created files

 qemu-img-cmds.hx |   4 +-
 qemu-img.c       | 145 +++++++++++++++++++++++++++++++++++++++++++------------
 qemu-img.texi    |  12 ++++-
 3 files changed, 126 insertions(+), 35 deletions(-)

-- 
2.9.3

[Qemu-devel] [PATCH v8 1/4] qemu-img: add support for --object with 'dd' command

[Daniel P. Berrange]

The qemu-img dd command added --image-opts support, but missed
the corresponding --object support. This prevented passing
secrets (eg auth passwords) needed by certain disk images.

Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 qemu-img.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/qemu-img.c b/qemu-img.c
index c719636..34f49c2 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4086,6 +4086,7 @@ static int img_dd(int argc, char **argv)
     };
     const struct option long_options[] = {
         { "help", no_argument, 0, 'h'},
+        { "object", required_argument, 0, OPTION_OBJECT},
         { "image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
         { 0, 0, 0, 0 }
     };
@@ -4110,6 +4111,15 @@ static int img_dd(int argc, char **argv)
         case 'h':
             help();
             break;
+        case OPTION_OBJECT: {
+            QemuOpts *opts;
+            opts = qemu_opts_parse_noisily(&qemu_object_opts,
+                                           optarg, true);
+            if (!opts) {
+                ret = -1;
+                goto out;
+            }
+        }   break;
         case OPTION_IMAGE_OPTS:
             image_opts = true;
             break;
@@ -4154,6 +4164,14 @@ static int img_dd(int argc, char **argv)
         ret = -1;
         goto out;
     }
+
+    if (qemu_opts_foreach(&qemu_object_opts,
+                          user_creatable_add_opts_foreach,
+                          NULL, NULL)) {
+        ret = -1;
+        goto out;
+    }
+
     blk1 = img_open(image_opts, in.filename, fmt, 0, false, false);
 
     if (!blk1) {
-- 
2.9.3

[Qemu-devel] [PATCH v8 2/4] qemu-img: fix --image-opts usage with dd command

[Daniel P. Berrange]

The --image-opts flag can only be used to affect the parsing
of the source image. The target image has to be specified in
the traditional style regardless, since it needs to be passed
to the bdrv_create() API which does not support the new style
opts.

Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 qemu-img.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 34f49c2..d8fdcb1 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4239,8 +4239,13 @@ static int img_dd(int argc, char **argv)
         goto out;
     }
 
-    blk2 = img_open(image_opts, out.filename, out_fmt, BDRV_O_RDWR,
-                    false, false);
+    /* TODO, we can't honour --image-opts for the target,
+     * since it needs to be given in a format compatible
+     * with the bdrv_create() call above which does not
+     * support image-opts style.
+     */
+    blk2 = img_open_file(out.filename, out_fmt, BDRV_O_RDWR,
+                         false, false);
 
     if (!blk2) {
         ret = -1;
-- 
2.9.3

[Qemu-devel] [PATCH v8 3/4] qemu-img: introduce --target-image-opts for 'convert' command

[Daniel P. Berrange]

The '--image-opts' flag indicates whether the source filename
includes options. The target filename has to remain in the
plain filename format though, since it needs to be passed to
bdrv_create().  When using --skip-create though, it would be
possible to use image-opts syntax. This adds --target-image-opts
to indicate that the target filename includes options. Currently
this mandates use of the --skip-create flag too.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 qemu-img-cmds.hx |  4 +--
 qemu-img.c       | 83 ++++++++++++++++++++++++++++++++++++++------------------
 qemu-img.texi    | 12 ++++++--
 3 files changed, 69 insertions(+), 30 deletions(-)

diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index bf4ce59..c97572e 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -40,9 +40,9 @@ STEXI
 ETEXI
 
 DEF("convert", img_convert,
-    "convert [--object objectdef] [--image-opts] [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-T src_cache] [-O output_fmt] [-B backing_file] [-o options] [-s snapshot_id_or_name] [-l snapshot_param] [-S sparse_size] [-m num_coroutines] [-W] filename [filename2 [...]] output_filename")
+    "convert [--object objectdef] [--image-opts] [--target-image-opts] [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-T src_cache] [-O output_fmt] [-B backing_file] [-o options] [-s snapshot_id_or_name] [-l snapshot_param] [-S sparse_size] [-m num_coroutines] [-W] filename [filename2 [...]] output_filename")
 STEXI
-@item convert [--object @var{objectdef}] [--image-opts] [-c] [-p] [-q] [-n] [-f @var{fmt}] [-t @var{cache}] [-T @var{src_cache}] [-O @var{output_fmt}] [-B @var{backing_file}] [-o @var{options}] [-s @var{snapshot_id_or_name}] [-l @var{snapshot_param}] [-S @var{sparse_size}] [-m @var{num_coroutines}] [-W] @var{filename} [@var{filename2} [...]] @var{output_filename}
+@item convert [--object @var{objectdef}] [--image-opts] [--target-image-opts] [-c] [-p] [-q] [-n] [-f @var{fmt}] [-t @var{cache}] [-T @var{src_cache}] [-O @var{output_fmt}] [-B @var{backing_file}] [-o @var{options}] [-s @var{snapshot_id_or_name}] [-l @var{snapshot_param}] [-S @var{sparse_size}] [-m @var{num_coroutines}] [-W] @var{filename} [@var{filename2} [...]] @var{output_filename}
 ETEXI
 
 DEF("dd", img_dd,
diff --git a/qemu-img.c b/qemu-img.c
index d8fdcb1..bb79cfb 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -59,6 +59,7 @@ enum {
     OPTION_PATTERN = 260,
     OPTION_FLUSH_INTERVAL = 261,
     OPTION_NO_DRAIN = 262,
+    OPTION_TARGET_IMAGE_OPTS = 263,
 };
 
 typedef enum OutputFormat {
@@ -1889,10 +1890,10 @@ static int convert_do_copy(ImgConvertState *s)
 static int img_convert(int argc, char **argv)
 {
     int c, bs_i, flags, src_flags = 0;
-    const char *fmt = NULL, *out_fmt = "raw", *cache = "unsafe",
+    const char *fmt = NULL, *out_fmt = NULL, *cache = "unsafe",
                *src_cache = BDRV_DEFAULT_CACHE, *out_baseimg = NULL,
                *out_filename, *out_baseimg_param, *snapshot_name = NULL;
-    BlockDriver *drv, *proto_drv;
+    BlockDriver *drv = NULL, *proto_drv = NULL;
     BlockDriverInfo bdi;
     BlockDriverState *out_bs;
     QemuOpts *opts = NULL, *sn_opts = NULL;
@@ -1900,7 +1901,7 @@ static int img_convert(int argc, char **argv)
     char *options = NULL;
     Error *local_err = NULL;
     bool writethrough, src_writethrough, quiet = false, image_opts = false,
-         skip_create = false, progress = false;
+         skip_create = false, progress = false, tgt_image_opts = false;
     int64_t ret = -EINVAL;
 
     ImgConvertState s = (ImgConvertState) {
@@ -1916,6 +1917,7 @@ static int img_convert(int argc, char **argv)
             {"help", no_argument, 0, 'h'},
             {"object", required_argument, 0, OPTION_OBJECT},
             {"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
+            {"target-image-opts", no_argument, 0, OPTION_TARGET_IMAGE_OPTS},
             {0, 0, 0, 0}
         };
         c = getopt_long(argc, argv, ":hf:O:B:ce6o:s:l:S:pt:T:qnm:W",
@@ -2033,9 +2035,16 @@ static int img_convert(int argc, char **argv)
         case OPTION_IMAGE_OPTS:
             image_opts = true;
             break;
+        case OPTION_TARGET_IMAGE_OPTS:
+            tgt_image_opts = true;
+            break;
         }
     }
 
+    if (!out_fmt && !tgt_image_opts) {
+        out_fmt = "raw";
+    }
+
     if (qemu_opts_foreach(&qemu_object_opts,
                           user_creatable_add_opts_foreach,
                           NULL, NULL)) {
@@ -2047,12 +2056,22 @@ static int img_convert(int argc, char **argv)
         goto fail_getopt;
     }
 
+    if (tgt_image_opts && !skip_create) {
+        error_report("--target-image-opts requires use of -n flag");
+        goto fail_getopt;
+    }
+
     s.src_num = argc - optind - 1;
     out_filename = s.src_num >= 1 ? argv[argc - 1] : NULL;
 
     if (options && has_help_option(options)) {
-        ret = print_block_option_help(out_filename, out_fmt);
-        goto fail_getopt;
+        if (out_fmt) {
+            ret = print_block_option_help(out_filename, out_fmt);
+            goto fail_getopt;
+        } else {
+            error_report("Option help requires a format be specified");
+            goto fail_getopt;
+        }
     }
 
     if (s.src_num < 1) {
@@ -2116,22 +2135,22 @@ static int img_convert(int argc, char **argv)
         goto out;
     }
 
-    /* Find driver and parse its options */
-    drv = bdrv_find_format(out_fmt);
-    if (!drv) {
-        error_report("Unknown file format '%s'", out_fmt);
-        ret = -1;
-        goto out;
-    }
+    if (!skip_create) {
+        /* Find driver and parse its options */
+        drv = bdrv_find_format(out_fmt);
+        if (!drv) {
+            error_report("Unknown file format '%s'", out_fmt);
+            ret = -1;
+            goto out;
+        }
 
-    proto_drv = bdrv_find_protocol(out_filename, true, &local_err);
-    if (!proto_drv) {
-        error_report_err(local_err);
-        ret = -1;
-        goto out;
-    }
+        proto_drv = bdrv_find_protocol(out_filename, true, &local_err);
+        if (!proto_drv) {
+            error_report_err(local_err);
+            ret = -1;
+            goto out;
+        }
 
-    if (!skip_create) {
         if (!drv->create_opts) {
             error_report("Format driver '%s' does not support image creation",
                          drv->format_name);
@@ -2188,7 +2207,7 @@ static int img_convert(int argc, char **argv)
         const char *preallocation =
             qemu_opt_get(opts, BLOCK_OPT_PREALLOC);
 
-        if (!drv->bdrv_co_pwritev_compressed) {
+        if (drv && !drv->bdrv_co_pwritev_compressed) {
             error_report("Compression not supported for this file format");
             ret = -1;
             goto out;
@@ -2228,18 +2247,30 @@ static int img_convert(int argc, char **argv)
         goto out;
     }
 
-    /* XXX we should allow --image-opts to trigger use of
-     * img_open() here, but then we have trouble with
-     * the bdrv_create() call which takes different params.
-     * Not critical right now, so fix can wait...
-     */
-    s.target = img_open_file(out_filename, out_fmt, flags, writethrough, quiet);
+    if (skip_create) {
+        s.target = img_open(tgt_image_opts, out_filename, out_fmt,
+                            flags, writethrough, quiet);
+    } else {
+        /* TODO ultimately we should allow --target-image-opts
+         * to be used even when -n is not given.
+         * That has to wait for bdrv_create to be improved
+         * to allow filenames in option syntax
+         */
+        s.target = img_open_file(out_filename, out_fmt, flags,
+                                 writethrough, quiet);
+    }
     if (!s.target) {
         ret = -1;
         goto out;
     }
     out_bs = blk_bs(s.target);
 
+    if (s.compressed && !out_bs->drv->bdrv_co_pwritev_compressed) {
+        error_report("Compression not supported for this file format");
+        ret = -1;
+        goto out;
+    }
+
     /* increase bufsectors from the default 4096 (2M) if opt_transfer
      * or discard_alignment of the out_bs is greater. Limit to 32768 (16MB)
      * as maximum. */
diff --git a/qemu-img.texi b/qemu-img.texi
index 50a2364..5b925ec 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -45,9 +45,17 @@ keys.
 
 @item --image-opts
 
-Indicates that the @var{filename} parameter is to be interpreted as a
+Indicates that the source @var{filename} parameter is to be interpreted as a
 full option string, not a plain filename. This parameter is mutually
-exclusive with the @var{-f} and @var{-F} parameters.
+exclusive with the @var{-f} parameter.
+
+@item --target-image-opts
+
+Indicates that the @var{output_filename} parameter(s) are to be interpreted as
+a full option string, not a plain filename. This parameter is mutually
+exclusive with the @var{-O} parameters. It is currently required to also use
+the @var{-n} parameter to skip image creation. This restriction may be relaxed
+in a future release.
 
 @item fmt
 is the disk image format. It is guessed automatically in most cases. See below
-- 
2.9.3

[Qemu-devel] [PATCH v8 4/4] qemu-img: copy *key-secret opts when opening newly created files

[Daniel P. Berrange]

The qemu-img dd/convert commands will create an image file and
then try to open it. Historically it has been possible to open
new files without passing any options. With encrypted files
though, the *key-secret options are mandatory, so we need to
provide those options when opening the newly created file.

Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 qemu-img.c | 41 +++++++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index bb79cfb..c865982 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -305,15 +305,17 @@ static BlockBackend *img_open_opts(const char *optstr,
 }
 
 static BlockBackend *img_open_file(const char *filename,
+                                   QDict *options,
                                    const char *fmt, int flags,
                                    bool writethrough, bool quiet)
 {
     BlockBackend *blk;
     Error *local_err = NULL;
-    QDict *options = NULL;
 
     if (fmt) {
-        options = qdict_new();
+        if (!options) {
+            options = qdict_new();
+        }
         qdict_put(options, "driver", qstring_from_str(fmt));
     }
 
@@ -332,6 +334,33 @@ static BlockBackend *img_open_file(const char *filename,
 }
 
 
+static int img_add_key_secrets(void *opaque,
+                               const char *name, const char *value,
+                               Error **errp)
+{
+    QDict *options = opaque;
+
+    if (g_str_has_suffix(name, "key-secret")) {
+        qdict_put(options, name, qstring_from_str(value));
+    }
+
+    return 0;
+}
+
+static BlockBackend *img_open_new_file(const char *filename,
+                                       QemuOpts *create_opts,
+                                       const char *fmt, int flags,
+                                       bool writethrough, bool quiet)
+{
+    QDict *options = NULL;
+
+    options = qdict_new();
+    qemu_opt_foreach(create_opts, img_add_key_secrets, options, &error_abort);
+
+    return img_open_file(filename, options, fmt, flags, writethrough, quiet);
+}
+
+
 static BlockBackend *img_open(bool image_opts,
                               const char *filename,
                               const char *fmt, int flags, bool writethrough,
@@ -351,7 +380,7 @@ static BlockBackend *img_open(bool image_opts,
         }
         blk = img_open_opts(filename, opts, flags, writethrough, quiet);
     } else {
-        blk = img_open_file(filename, fmt, flags, writethrough, quiet);
+        blk = img_open_file(filename, NULL, fmt, flags, writethrough, quiet);
     }
     return blk;
 }
@@ -2256,8 +2285,8 @@ static int img_convert(int argc, char **argv)
          * That has to wait for bdrv_create to be improved
          * to allow filenames in option syntax
          */
-        s.target = img_open_file(out_filename, out_fmt, flags,
-                                 writethrough, quiet);
+        s.target = img_open_new_file(out_filename, opts, out_fmt,
+                                     flags, writethrough, quiet);
     }
     if (!s.target) {
         ret = -1;
@@ -4275,7 +4304,7 @@ static int img_dd(int argc, char **argv)
      * with the bdrv_create() call above which does not
      * support image-opts style.
      */
-    blk2 = img_open_file(out.filename, out_fmt, BDRV_O_RDWR,
+    blk2 = img_open_file(out.filename, NULL, out_fmt, BDRV_O_RDWR,
                          false, false);
 
     if (!blk2) {
-- 
2.9.3

Re: [Qemu-devel] [PATCH v8 3/4] qemu-img: introduce --target-image-opts for 'convert' command

[Fam Zheng]

On Tue, 05/09 10:48, Daniel P. Berrange wrote:
> The '--image-opts' flag indicates whether the source filename
> includes options. The target filename has to remain in the
> plain filename format though, since it needs to be passed to
> bdrv_create().  When using --skip-create though, it would be
> possible to use image-opts syntax. This adds --target-image-opts
> to indicate that the target filename includes options. Currently
> this mandates use of the --skip-create flag too.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

Reviewed-by: Fam Zheng <famz@redhat.com>

Re: [Qemu-devel] [PATCH v8 0/4] Improve convert and dd commands

[Max Reitz]

[-- Attachment #1: Type: text/plain, Size: 3203 bytes --]

On 2017-05-09 11:48, Daniel P. Berrange wrote:
> Update to
> 
>   v1: https://lists.gnu.org/archive/html/qemu-devel/2017-01/msg05699.html
>   v2: https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg00728.html
>   v3: https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg04391.html
>   v4: https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg02153.html
>   v5: https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg04109.html
>   v6: https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg00215.html
> 
> This series is in response to Max pointing out that you cannot
> use 'convert' for an encrypted target image.
> 
> The 'convert' and 'dd' commands need to first create the image
> and then open it. The bdrv_create() method takes a set of options
> for creating the image, which let us provide a key-secret for the
> encryption key. When the commands then open the new image, they
> don't provide any options, so the image is unable to be opened
> due to lack of encryption key. It is also not possible to use
> the --image-opts argument to provide structured options in the
> target image name - it must be a plain filename to satisfy the
> bdrv_create() API contract.
> 
> This series addresses these problems to some extent
> 
>  - Adds a new --target-image-opts flag which is used to say
>    that the target filename is using structured options.
>    It is *only* permitted to use this when -n is also set.
>    ie the target image must be pre-created so convert/dd
>    don't need to run bdrv_create().
> 
>  - When --target-image-opts is not used, add special case
>    code that identifies options passed to bdrv_create()
>    named "*key-secret" and adds them to the options used
>    to open the new image
> 
> In future it is desirable to make --target-image-opts work even when -n is
> *not* given. This requires considerable work to create a new bdrv_create()
> API impl.
> 
> The first patch fixes a bug in the 'dd' command while the second adds support
> for the missing '--object' arg to 'dd', allowing it to reference secrets when
> opening files.  The last two patches implement the new features described above
> for the 'convert' command.
> 
> NB v8 is based against git master once more, since the img_convert changes
> previously in block-next have now merged.

Changes from the previous version look good, but unfortunately here's
the "but": The image locking series has brought even more changes to
qemu-img. :-(

I tried resolving them, but the following backport-diff didn't look like
I should proceed:

001/4:[----] [-C] 'qemu-img: add support for --object with 'dd' command'
002/4:[0004] [FC] 'qemu-img: fix --image-opts usage with dd command'
003/4:[0015] [FC] 'qemu-img: introduce --target-image-opts for 'convert'
command'
004/4:[0024] [FC] 'qemu-img: copy *key-secret opts when opening newly
created files'

The fun is increased by the fact that the locking series has
(inadvertently) removed the -B documentation from convert, so there is
another conflict looming in the future...

(Or you just inadvertently add it back. Then we'd have resolved the
issue altogether...)

Max


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 498 bytes --]

Re: [Qemu-devel] [PATCH v8 0/4] Improve convert and dd commands

[Fam Zheng]

On Fri, 05/12 19:41, Max Reitz wrote:
> The fun is increased by the fact that the locking series has
> (inadvertently) removed the -B documentation from convert, so there is
> another conflict looming in the future...

Sorry about the mistake there..

I've posted a patch for that:

[Qemu-devel] [PATCH] qemu-img: Fix documentation of convert

Fam