From 4b6c9d80b06057886e35650b904fe332ae14d0bd Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 4 Dec 2013 12:13:10 +0100
Subject: [PATCH 19/37] block: Make zero-after-EOF work with larger alignment

Message-id: <1392117622-28812-20-git-send-email-kwolf@redhat.com>
Patchwork-id: 57184
O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 19/37] block: Make zero-after-EOF work with larger alignment
Bugzilla: 748906
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>

Odd file sizes could make bdrv_aligned_preadv() shorten the request in
non-aligned ways. Fix it by rounding to the required alignment instead
of 512 bytes.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
(cherry picked from commit ec746e10cb2e6276a8d2e036454792fe0674864a)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
---
 block.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index feeab4e..6317321 100644
--- a/block.c
+++ b/block.c
@@ -2748,7 +2748,7 @@ err:
  */
 static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
     BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
-    QEMUIOVector *qiov, int flags)
+    int64_t align, QEMUIOVector *qiov, int flags)
 {
     BlockDriver *drv = bs->drv;
     int ret;
@@ -2796,7 +2796,8 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
         }
 
         total_sectors = DIV_ROUND_UP(len, BDRV_SECTOR_SIZE);
-        max_nb_sectors = MAX(0, total_sectors - sector_num);
+        max_nb_sectors = MAX(0, ROUND_UP(total_sectors - sector_num,
+                                         align >> BDRV_SECTOR_BITS));
         if (max_nb_sectors > 0) {
             ret = drv->bdrv_co_readv(bs, sector_num,
                                      MIN(nb_sectors, max_nb_sectors), qiov);
@@ -2882,7 +2883,7 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
     }
 
     tracked_request_begin(&req, bs, offset, bytes, false);
-    ret = bdrv_aligned_preadv(bs, &req, offset, bytes,
+    ret = bdrv_aligned_preadv(bs, &req, offset, bytes, align,
                               use_local_qiov ? &local_qiov : qiov,
                               flags);
     tracked_request_end(&req);
-- 
1.7.1