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authorJohn Snow <jsnow@redhat.com>2017-07-17 20:34:22 -0400
committerKevin Wolf <kwolf@redhat.com>2017-07-18 15:27:37 +0200
commit6e6e55f5c2e5b520d6506c2716287ba3b5d1bbc8 (patch)
treeed30613055c350d84000cd205b35bd6ffc441054 /qemu-img.texi
parent2a32c6e82ed24d837ce7af346ffc93113f0164b5 (diff)
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qemu-img: Check for backing image if specified during create
Or, rather, force the open of a backing image if one was specified for creation. Using a similar -unsafe option as rebase, allow qemu-img to ignore the backing file validation if possible. It may not always be possible, as in the existing case when a filesize for the new image was not specified. This is accomplished by shifting around the conditionals in bdrv_img_create, such that a backing file is always opened unless we provide BDRV_O_NO_BACKING. qemu-img is adjusted to pass this new flag when -u is provided to create. Sorry for the heinous looking diffstat, but it's mostly whitespace. Inspired by: https://bugzilla.redhat.com/show_bug.cgi?id=1213786 Signed-off-by: John Snow <jsnow@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'qemu-img.texi')
-rw-r--r--qemu-img.texi9
1 files changed, 8 insertions, 1 deletions
diff --git a/qemu-img.texi b/qemu-img.texi
index f11f603..72dabd6 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -233,7 +233,7 @@ If @code{-r} is specified, exit codes representing the image state refer to the
state after (the attempt at) repairing it. That is, a successful @code{-r all}
will yield the exit code 0, independently of the image state before.
-@item create [-f @var{fmt}] [-b @var{backing_file}] [-F @var{backing_fmt}] [-o @var{options}] @var{filename} [@var{size}]
+@item create [-f @var{fmt}] [-b @var{backing_file}] [-F @var{backing_fmt}] [-u] [-o @var{options}] @var{filename} [@var{size}]
Create the new disk image @var{filename} of size @var{size} and format
@var{fmt}. Depending on the file format, you can add one or more @var{options}
@@ -244,6 +244,13 @@ only the differences from @var{backing_file}. No size needs to be specified in
this case. @var{backing_file} will never be modified unless you use the
@code{commit} monitor command (or qemu-img commit).
+Note that a given backing file will be opened to check that it is valid. Use
+the @code{-u} option to enable unsafe backing file mode, which means that the
+image will be created even if the associated backing file cannot be opened. A
+matching backing file must be created or additional options be used to make the
+backing file specification valid when you want to use an image created this
+way.
+
The size can also be specified using the @var{size} option with @code{-o},
it doesn't need to be specified separately in this case.