Re: [PATCH for-5.0] qcow2: Check request size in qcow2_co_pwritev_compressed_part()

[Andrey Shinkevich]

________________________________________
From: Alberto Garcia <address@hidden>
Sent: Friday, April 3, 2020 7:57 PM
To: address@hidden
Cc: Alberto Garcia; address@hidden; Andrey Shinkevich; Max Reitz; Kevin Wolf; 
Vladimir Sementsov-Ogievskiy; Pavel Butsykin
Subject: [PATCH for-5.0] qcow2: Check request size in 
qcow2_co_pwritev_compressed_part()

When issuing a compressed write request the number of bytes must be a
multiple of the cluster size.

With the current code such requests are allowed and we hit an
assertion:

   $ qemu-img create -f qcow2 img.qcow2 1M
   $ qemu-io -c 'write -c 0 32k' img.qcow2

   qemu-io: block/qcow2.c:4257: qcow2_co_pwritev_compressed_task:
   Assertion `bytes == s->cluster_size || (bytes < s->cluster_size &&
              (offset + bytes == bs->total_sectors << BDRV_SECTOR_BITS))' 
failed.
   Aborted

This patch fixes a regression introduced in 0d483dce38

The condition that QEMU supports writing compressed data of the size equal to 
one cluster was introduced with earlier patches.

Andrey

Signed-off-by: Alberto Garcia <address@hidden>
---
 block/qcow2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 2bb536b014..923ad428f0 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -4345,7 +4345,7 @@ qcow2_co_pwritev_compressed_part(BlockDriverState *bs,
         return bdrv_co_truncate(bs->file, len, false, PREALLOC_MODE_OFF, NULL);
     }

-    if (offset_into_cluster(s, offset)) {
+    if (offset_into_cluster(s, offset | bytes)) {
         return -EINVAL;
     }

--
2.20.1