On Tue, Jun 13, 2017 at 05:07:13PM +0200, Alberto Garcia wrote: > On Tue 13 Jun 2017 03:33:26 PM CEST, Stefan Hajnoczi <stefa...@redhat.com> > wrote: > > Use qcow2_calc_prealloc_size() to get the required file size. > > > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > > Reviewed-by: Alberto Garcia <be...@igalia.com> > > You kept my R-b here but one of the changes was in this patch:
Sorry, I forgot to remove it when making the change.
> > + info = g_new(BlockMeasureInfo, 1);
> > + info->fully_allocated =
> > + qcow2_calc_prealloc_size(virtual_size, cluster_size,
> > + ctz32(refcount_bits));
> > + if (DIV_ROUND_UP(info->fully_allocated, cluster_size) > INT_MAX) {
> > + g_free(info);
> > + error_setg(&local_err, "The image size is too large "
> > + "(try using a larger cluster size)");
> > + goto err;
> > + }
>
> This has the opposite problem than the previous version: valid image
> sizes are now rejected by the 'measure' command.
>
> $ qemu-img create -f qcow2 img.qcow2 1P
> Formatting 'img.qcow2', fmt=qcow2 size=1125899906842624 encryption=off
> cluster_size=65536 lazy_refcounts=off refcount_bits=16
>
> $ build/qemu-img measure -O qcow2 --size 1P
> qemu-img: The image size is too large (try using a larger cluster size)
Hmm...if host file size (not virtual disk size) is 1P then qemu-img
check fails:
int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix)
{
int64_t size, highest_cluster, nb_clusters;
...
size = bdrv_getlength(bs->file->bs);
if (size < 0) {
res->check_errors++;
return size;
}
nb_clusters = size_to_clusters(s, size);
if (nb_clusters > INT_MAX) {
res->check_errors++;
return -EFBIG;
}
This is also where I got the limit from. It was introduced in:
commit 0abe740f1de899737242bcba1fb4a9857f7a3087
Author: Kevin Wolf <kw...@redhat.com>
Date: Wed Mar 26 13:05:52 2014 +0100
qcow2: Protect against some integer overflows in bdrv_check
At that point the code used ints so the overflow check was necessary.
Now the code uses 64-bit types so INT_MAX is obsolete.
I will send a separate patch to fix qemu-img check.
> The actual limit is:
>
> #define QCOW_MAX_L1_SIZE 0x2000000
>
> That's 4194304 entries, each one can address cluster_size^2 / 8 bytes
>
> So using that formula, here is the maximum virtual size depending on the
> cluster size:
>
> |--------------+------------------|
> | Cluster size | Max virtual size |
> |--------------+------------------|
> | 512 bytes | 128 GB |
> | 1 KB | 512 GB |
> | 2 KB | 2 TB |
> | 4 KB | 8 TB |
> | 8 KB | 32 TB |
> | 16 KB | 128 TB |
> | 32 KB | 512 TB |
> | 64 KB | 2 PB |
> | 128 KB | 8 PB |
> | 256 KB | 32 PB |
> | 512 KB | 128 PB |
> | 1 MB | 512 PB |
> | 2 MB | 2 EB |
> |--------------+------------------|
>
> I just created a 2 EB image and it works fine, Linux can detect it
> without problems, I can create a file system, etc.
>
> If you specify a larger size, qcow2_grow_l1_table() fails with -EFIB.
Thanks, will fix!
Stefan
signature.asc
Description: PGP signature
