[Qemu-devel] [PATCH v2 2/3] vmdk: Reduce the max bound for L1 table size

[Sam Eiderman <shmuel.eiderman@oracle.com>]

512M of L1 entries is a very loose bound, only 32M are required to store
the maximal supported VMDK file size of 2TB.

Fixed qemu-iotest 59# - now failure occures before on impossible L1
table size.

Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
Reviewed-by: Eyal Moscovici <eyal.moscovici@oracle.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Arbel Moshe <arbel.moshe@oracle.com>
Signed-off-by: Sam Eiderman <shmuel.eiderman@oracle.com>
---
 block/vmdk.c               | 13 +++++++------
 tests/qemu-iotests/059.out |  2 +-
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 0f2e453bf5..931eb2759c 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -425,15 +425,16 @@ static int vmdk_add_extent(BlockDriverState *bs,
         error_setg(errp, "Invalid granularity, image may be corrupt");
         return -EFBIG;
     }
-    if (l1_size > 512 * 1024 * 1024) {
+    if (l1_size > 32 * 1024 * 1024) {
         /*
          * Although with big capacity and small l1_entry_sectors, we can get a
          * big l1_size, we don't want unbounded value to allocate the table.
-         * Limit it to 512M, which is:
-         *     16PB - for default "Hosted Sparse Extent" (VMDK4)
-         *            cluster size: 64KB, L2 table size: 512 entries
-         *     1PB  - for default "ESXi Host Sparse Extent" (VMDK3/vmfsSparse)
-         *            cluster size: 512B, L2 table size: 4096 entries
+         * Limit it to 32M, which is enough to store:
+         *     8TB  - for both VMDK3 & VMDK4 with
+         *            minimal cluster size: 512B
+         *            minimal L2 table size: 512 entries
+         *            8 TB is still more than the maximal value supported for
+         *            VMDK3 & VMDK4 which is 2TB.
          */
         error_setg(errp, "L1 size too big");
         return -EFBIG;
diff --git a/tests/qemu-iotests/059.out b/tests/qemu-iotests/059.out
index f51394ae8e..4fab42a28c 100644
--- a/tests/qemu-iotests/059.out
+++ b/tests/qemu-iotests/059.out
@@ -2358,5 +2358,5 @@ Offset          Length          Mapped to       File
 0x140000000     0x10000         0x50000         TEST_DIR/t-s003.vmdk
 
 === Testing afl image with a very large capacity ===
-qemu-img: Can't get image size 'TEST_DIR/afl9.IMGFMT': File too large
+qemu-img: Could not open 'TEST_DIR/afl9.IMGFMT': L1 size too big
 *** done
-- 
2.13.3