docker: Add test_fail and prep_fail

[qemu.git] / qemu-img.texi

diff --git a/qemu-img.texi b/qemu-img.texi
index a2f45199d222cfa27f41aba3680d442d095ebf8f..72dabd6b3e632a3a74c8f8f8ce185b80239df34d 100644 (file)
--- 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.
 
@@ -529,7 +536,7 @@ qemu-img rebase -b base.img diff.qcow2
 At this point, @code{modified.img} can be discarded, since
 @code{base.img + diff.qcow2} contains the same information.
 
-@item resize @var{filename} [+ | -]@var{size}
+@item resize [--preallocation=@var{prealloc}] @var{filename} [+ | -]@var{size}
 
 Change the disk image as if it had been created with @var{size}.
 
@@ -541,6 +548,11 @@ 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.
 
+When growing an image, the @code{--preallocation} option may be used to specify
+how the additional image area should be allocated on the host.  See the format
+description in the @code{NOTES} section which values are allowed.  Using this
+option may result in slightly more data being allocated than necessary.
+
 @item amend [-p] [-f @var{fmt}] [-t @var{cache}] -o @var{options} @var{filename}
 
 Amends the image format specific @var{options} for the image file