qcow2 format: keep 'num_free_bytes', and show it upon 'info blockstats' (Uri Lublin)

'num_free_bytes' is the number of non-allocated bytes below highest-allocation.
It's useful, together with the highest-allocation, to figure out how
fragmented the image is, and how likely it will run out-of-space soon.

For example when the highest allocation is high (almost end-of-disk), but 
many bytes (clusters) are free, and can be re-allocated when neeeded, than
we know it's probably not going to reach end-of-disk-space soon.

Added bookkeeping to block-qcow2.c
Export it using BlockDeviceInfo
Show it upon 'info blockstats' if BlockDeviceInfo exists

Signed-off-by: Uri Lublin <uril@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6407 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 1 insertions, 0 deletions

diff --git a/block.h b/block.h
index 4334071961..e1927dd1d7 100644
--- a/block.h
+++ b/block.h
@@ -27,6 +27,7 @@ typedef struct BlockDriverInfo {
     /* offset at which the VM state can be saved (0 if not possible) */
     int64_t vm_state_offset;
     int64_t highest_alloc; /* highest allocated block offset (in bytes) */
+    int64_t num_free_bytes; /* below highest_alloc  */
 } BlockDriverInfo;
 
 typedef struct QEMUSnapshotInfo {