From dc5f690b97ccdffa79fe7169bb26b0ebf06688bf Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Tue, 13 Jun 2017 22:20:55 +0200 Subject: qemu-img: Expose PreallocMode for resizing Add a --preallocation command line option to qemu-img resize which can be used to set the PreallocMode parameter of blk_truncate(). While touching this code, fix the fact that we did not handle errors returned by blk_getlength(). Signed-off-by: Max Reitz Message-id: 20170613202107.10125-5-mreitz@redhat.com Reviewed-by: Stefan Hajnoczi Signed-off-by: Max Reitz --- qemu-img.texi | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'qemu-img.texi') diff --git a/qemu-img.texi b/qemu-img.texi index a2f45199d2..f11f6036ad 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -529,7 +529,7 @@ 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 +541,11 @@ 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 -- cgit v1.2.1