raw-posix: Add falloc and full preallocation option

This patch adds a new option preallocation for raw format, and implements
falloc and full preallocation.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Hu Tao 2014-09-10 17:05:48 +08:00 committed by Kevin Wolf
parent ffeaac9b4e
commit 06247428be
3 changed files with 96 additions and 24 deletions

View file

@ -419,6 +419,15 @@ Linux or NTFS on Windows), then only the written sectors will reserve
space. Use @code{qemu-img info} to know the real size used by the
image or @code{ls -ls} on Unix/Linux.
Supported options:
@table @code
@item preallocation
Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
@code{falloc} mode preallocates space for image by calling posix_fallocate().
@code{full} mode preallocates space for image by writing zeros to underlying
storage.
@end table
@item qcow2
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example