From 94789223da7e51599209395f167a95026e707ab8 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Thu, 5 Dec 2013 12:29:59 +0100
Subject: [PATCH 28/37] block: Make bdrv_pread() a bdrv_prwv_co() wrapper

Message-id: <1392117622-28812-29-git-send-email-kwolf@redhat.com>
Patchwork-id: 57193
O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 28/37] block: Make bdrv_pread() a bdrv_prwv_co() wrapper
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>

Instead of implementing the alignment adjustment here, use the now
existing functionality of bdrv_co_do_preadv().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
(cherry picked from commit a3ef65718506fb94cb9e5a903ef9bf9ad8fbe6de)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 49 +++++++++++++------------------------------------
 1 file changed, 13 insertions(+), 36 deletions(-)
---
 block.c |   51 ++++++++++++++-------------------------------------
 1 files changed, 14 insertions(+), 37 deletions(-)

diff --git a/block.c b/block.c
index 3b5b706..e76dec6 100644
--- a/block.c
+++ b/block.c
@@ -2566,49 +2566,26 @@ int bdrv_make_zero(BlockDriverState *bs, BdrvRequestFlags flags)
     }
 }
 
-int bdrv_pread(BlockDriverState *bs, int64_t offset,
-               void *buf, int count1)
+int bdrv_pread(BlockDriverState *bs, int64_t offset, void *buf, int bytes)
 {
-    uint8_t tmp_buf[BDRV_SECTOR_SIZE];
-    int len, nb_sectors, count;
-    int64_t sector_num;
+    QEMUIOVector qiov;
+    struct iovec iov = {
+        .iov_base = (void *)buf,
+        .iov_len = bytes,
+    };
     int ret;
 
-    count = count1;
-    /* first read to align to sector start */
-    len = (BDRV_SECTOR_SIZE - offset) & (BDRV_SECTOR_SIZE - 1);
-    if (len > count)
-        len = count;
-    sector_num = offset >> BDRV_SECTOR_BITS;
-    if (len > 0) {
-        if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
-            return ret;
-        memcpy(buf, tmp_buf + (offset & (BDRV_SECTOR_SIZE - 1)), len);
-        count -= len;
-        if (count == 0)
-            return count1;
-        sector_num++;
-        buf += len;
+    if (bytes < 0) {
+        return -EINVAL;
     }
 
-    /* read the sectors "in place" */
-    nb_sectors = count >> BDRV_SECTOR_BITS;
-    if (nb_sectors > 0) {
-        if ((ret = bdrv_read(bs, sector_num, buf, nb_sectors)) < 0)
-            return ret;
-        sector_num += nb_sectors;
-        len = nb_sectors << BDRV_SECTOR_BITS;
-        buf += len;
-        count -= len;
+    qemu_iovec_init_external(&qiov, &iov, 1);
+    ret = bdrv_prwv_co(bs, offset, &qiov, false, 0);
+    if (ret < 0) {
+        return ret;
     }
 
-    /* add data from the last sector */
-    if (count > 0) {
-        if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
-            return ret;
-        memcpy(buf, tmp_buf, count);
-    }
-    return count1;
+    return bytes;
 }
 
 int bdrv_pwritev(BlockDriverState *bs, int64_t offset, QEMUIOVector *qiov)
-- 
1.7.1