[Qemu-devel] [PATCHv2 1/2] qemu-img: find the highest offset in use during check

[Federico Simoncelli <fsimonce@redhat.com>]

This patch adds the support for reporting the highest offset in use by
an image. This is particularly useful after a conversion (or a rebase)
where the destination is a block device in order to find the actual
amount of space in use.

Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
---
 block.h                      |    1 +
 block/qcow2-refcount.c       |   10 ++++++++--
 qemu-img.c                   |    4 ++++
 tests/qemu-iotests/026       |    6 +++---
 tests/qemu-iotests/036       |    3 ++-
 tests/qemu-iotests/039       |    2 +-
 tests/qemu-iotests/common.rc |    5 +++--
 7 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/block.h b/block.h
index 722c620..de42e8c 100644
--- a/block.h
+++ b/block.h
@@ -213,6 +213,7 @@ typedef struct BdrvCheckResult {
     int check_errors;
     int corruptions_fixed;
     int leaks_fixed;
+    int64_t highest_offset;
     BlockFragInfo bfi;
 } BdrvCheckResult;
 
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 96224d1..017439d 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1116,7 +1116,7 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
                           BdrvCheckMode fix)
 {
     BDRVQcowState *s = bs->opaque;
-    int64_t size, i;
+    int64_t size, i, highest_cluster;
     int nb_clusters, refcount1, refcount2;
     QCowSnapshot *sn;
     uint16_t *refcount_table;
@@ -1154,7 +1154,7 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
         s->refcount_table_offset,
         s->refcount_table_size * sizeof(uint64_t));
 
-    for(i = 0; i < s->refcount_table_size; i++) {
+    for(i = 0, highest_cluster = 0; i < s->refcount_table_size; i++) {
         uint64_t offset, cluster;
         offset = s->refcount_table[i];
         cluster = offset >> s->cluster_bits;
@@ -1197,6 +1197,11 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
         }
 
         refcount2 = refcount_table[i];
+
+        if (refcount1 > 0 || refcount2 > 0) {
+            highest_cluster = i;
+        }
+
         if (refcount1 != refcount2) {
 
             /* Check if we're allowed to fix the mismatch */
@@ -1231,6 +1236,7 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
         }
     }
 
+    res->highest_offset = (highest_cluster + 1) * s->cluster_size;
     ret = 0;
 
 fail:
diff --git a/qemu-img.c b/qemu-img.c
index e29e01b..45c1ec1 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -470,6 +470,10 @@ static int img_check(int argc, char **argv)
         result.bfi.fragmented_clusters * 100.0 / result.bfi.allocated_clusters);
     }
 
+    if (result.highest_offset > 0) {
+        printf("Highest offset in use: %" PRId64 "\n", result.highest_offset);
+    }
+
     bdrv_delete(bs);
 
     if (ret < 0 || result.check_errors) {
diff --git a/tests/qemu-iotests/026 b/tests/qemu-iotests/026
index 1602ccd..107a3ff 100755
--- a/tests/qemu-iotests/026
+++ b/tests/qemu-iotests/026
@@ -102,7 +102,7 @@ if [ "$event" == "l2_load" ]; then
     $QEMU_IO -c "read $vmstate 0 128k " $BLKDBG_TEST_IMG | _filter_qemu_io
 fi
 
-$QEMU_IMG check $TEST_IMG 2>&1 | grep -v "refcount=1 reference=0"
+_check_test_img 2>&1 | grep -v "refcount=1 reference=0"
 
 done
 done
@@ -147,7 +147,7 @@ echo
 echo "Event: $event; errno: $errno; imm: $imm; once: $once; write $vmstate"
 $QEMU_IO -c "write $vmstate 0 64M" $BLKDBG_TEST_IMG | _filter_qemu_io
 
-$QEMU_IMG check $TEST_IMG 2>&1 | grep -v "refcount=1 reference=0"
+_check_test_img 2>&1 | grep -v "refcount=1 reference=0"
 
 done
 done
@@ -186,7 +186,7 @@ echo
 echo "Event: $event; errno: $errno; imm: $imm; once: $once"
 $QEMU_IO -c "write -b 0 64k" $BLKDBG_TEST_IMG | _filter_qemu_io
 
-$QEMU_IMG check $TEST_IMG 2>&1 | grep -v "refcount=1 reference=0"
+_check_test_img 2>&1 | grep -v "refcount=1 reference=0"
 
 done
 done
diff --git a/tests/qemu-iotests/036 b/tests/qemu-iotests/036
index 329533e..4dbfc57 100755
--- a/tests/qemu-iotests/036
+++ b/tests/qemu-iotests/036
@@ -59,7 +59,8 @@ _make_test_img 64M
 echo
 echo === Repair image ===
 echo
-$QEMU_IMG check -r all $TEST_IMG
+_check_test_img -r all
+
 ./qcow2.py $TEST_IMG dump-header
 
 # success, all done
diff --git a/tests/qemu-iotests/039 b/tests/qemu-iotests/039
index c5ae806..ae35175 100755
--- a/tests/qemu-iotests/039
+++ b/tests/qemu-iotests/039
@@ -86,7 +86,7 @@ $QEMU_IO -r -c "read -P 0x5a 0 512" $TEST_IMG | _filter_qemu_io
 echo
 echo "== Repairing the image file must succeed =="
 
-$QEMU_IMG check -r all $TEST_IMG
+_check_test_img -r all
 
 # The dirty bit must not be set
 ./qcow2.py $TEST_IMG dump-header | grep incompatible_features
diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
index aef5f52..22c0186 100644
--- a/tests/qemu-iotests/common.rc
+++ b/tests/qemu-iotests/common.rc
@@ -161,9 +161,10 @@ _cleanup_test_img()
 
 _check_test_img()
 {
-    $QEMU_IMG check -f $IMGFMT $TEST_IMG 2>&1 | \
+    $QEMU_IMG check "$@" -f $IMGFMT $TEST_IMG 2>&1 | \
         grep -v "fragmented$" | \
-    	sed -e 's/qemu-img\: This image format does not support checks/No errors were found on the image./'
+    	sed -e 's/qemu-img\: This image format does not support checks/No errors were found on the image./' | \
+    	sed -e '/Highest offset in use: [0-9]\+/d'
 }
 
 _img_info()
-- 
1.7.1