On 05/26/2017 11:55 AM, Max Reitz wrote: > Add a --preallocation command line option to qemu-img resize which can > be used to set the PreallocMode parameter of blk_truncate(). > > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > qemu-img.c | 33 ++++++++++++++++++++++++++++++--- > qemu-img.texi | 7 ++++++- > 2 files changed, 36 insertions(+), 4 deletions(-)
> @@ -3553,8 +3566,16 @@ static int img_resize(int argc, char **argv) > goto out; > } > > + current_size = blk_getlength(blk); > + if (current_size < 0) { > + error_report("Failed to inquire current image length: %s", > + strerror(-current_size)); > + ret = -1; > + goto out; > + } > + > if (relative) { > - total_size = blk_getlength(blk) + n * relative; > + total_size = current_size + n * relative; You snuck in a bug fix here (reporting failure, rather than using a bogus total_size, if querying the size fails). Please mention that in the commit message. > @@ -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 more data being allocated than necessary. Should we tone it down a bit by saying 'slightly more data'? (We'd rather over-estimate than fall short, but our over-estimation will probably be < 1% off, and not something drastic like an order of magnitude off). With the improved commit message, Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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