block/qcow2: Add qcow2_refcount_area()

This function creates a collection of self-describing refcount
structures (including a new refcount table) at the end of a qcow2 image
file. Optionally, these structures can also describe a number of
additional clusters beyond themselves; this will be important for
preallocated truncation, which will place the data clusters and L2
tables there.

For now, we can use this function to replace the part of
alloc_refcount_block() that grows the refcount table (from which it is
actually derived).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20170613202107.10125-13-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2017-06-13 22:21:03 +02:00
parent 95b98f343b
commit 12cc30a8cb
4 changed files with 208 additions and 93 deletions

View file

@ -1,6 +1,6 @@
No errors were found on the image.
7292415/33554432 = 21.73% allocated, 0.00% fragmented, 0.00% compressed clusters
Image end offset: 4296152064
Image end offset: 4296217088
.
----------------------------------------------------------------------
Ran 1 tests