Re: [Qemu-devel] [PATCH v2 03/17] block: Fix harmless off-by-one in bdrv_aligned_preadv()

[Fam Zheng]

On Tue, 06/14 15:30, Eric Blake wrote:
> 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 
> Reviewed-by: Kevin Wolf 

Reviewed-by: Fam Zheng 

[Qemu-devel] [PATCH v2 03/17] block: Fix harmless off-by-one in bdrv_aligned_preadv()

[Eric Blake]

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 
Reviewed-by: Kevin Wolf 

---
v2: no change, add R-b
---
 block/io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/io.c b/block/io.c
index 9191772..383154f 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1024,7 +1024,7 @@ 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;
-- 
2.5.5