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[Qemu-block] [PULL 04/43] block: Fix harmless off-by-one in bdrv_aligned

From: Kevin Wolf
Subject: [Qemu-block] [PULL 04/43] block: Fix harmless off-by-one in bdrv_aligned_preadv()
Date: Tue, 5 Jul 2016 17:50:13 +0200

From: Eric Blake <address@hidden>

If the amount of data to read ends exactly on the total size
of the bs, then we were wasting time creating a local qiov
to read the data in preparation for what would normally be
appending zeroes beyond the end, even though this corner case
has nothing further to do.

Signed-off-by: Eric Blake <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
Reviewed-by: Fam Zheng <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
 block/io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/io.c b/block/io.c
index 994d3fa..82c9ff0 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1036,7 +1036,7 @@ static int coroutine_fn 
bdrv_aligned_preadv(BlockDriverState *bs,
     max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align);
-    if (bytes < max_bytes) {
+    if (bytes <= max_bytes) {
         ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0);
     } else if (max_bytes > 0) {
         QEMUIOVector local_qiov;

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