[Qemu-devel] [PATCH v2 2/2] block: disable I/O throttling on sync api

[zwu . kernel]

From: Zhi Yong Wu <address@hidden>

Signed-off-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Zhi Yong Wu <address@hidden>
---
 block.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/block.c b/block.c
index 1fbf4dd..f0b4f38 100644
--- a/block.c
+++ b/block.c
@@ -1477,6 +1477,12 @@ static int bdrv_rw_co(BlockDriverState *bs, int64_t 
sector_num, uint8_t *buf,
 
     qemu_iovec_init_external(&qiov, &iov, 1);
 
+    if (bs->io_limits_enabled) {
+        fprintf(stderr, "Disabling I/O throttling on '%s' due "
+                        "to synchronous I/O.\n", bdrv_get_device_name(bs));
+        bdrv_io_limits_disable(bs);
+    }
+
     if (qemu_in_coroutine()) {
         /* Fast-path if already in coroutine context */
         bdrv_rw_co_entry(&rwco);
@@ -1983,10 +1989,14 @@ static int guess_disk_lchs(BlockDriverState *bs,
     struct partition *p;
     uint32_t nr_sects;
     uint64_t nb_sectors;
+    bool enabled;
 
     bdrv_get_geometry(bs, &nb_sectors);
 
+    enabled = bs->io_limits_enabled;
+    bs->io_limits_enabled = false;
     ret = bdrv_read(bs, 0, buf, 1);
+    bs->io_limits_enabled = enabled;
     if (ret < 0)
         return -1;
     /* test msdos magic */
-- 
1.7.6