qemu/xen_disk-Add-suse-specific-flush-disable.patch

From: Bruce Rogers <brogers@suse.com>
Date: Wed, 9 Mar 2016 15:18:11 -0700
Subject: xen_disk: Add suse specific flush disable handling and map to QEMU
 equiv

Add code to read the suse specific suse-diskcache-disable-flush flag out
of xenstore, and set the equivalent flag within QEMU.

Patch taken from Xen's patch queue, Olaf Hering being the original author.
[bsc#879425]

[BR: minor edits to pass qemu's checkpatch script]
[BR: With qdevification of xen-block, code has changed significantly]
Signed-off-by: Bruce Rogers <brogers@suse.com>
Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 hw/block/xen-block.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index b1a3fa9b6a91f7748ce54d77cad6..f6b66a0428eaa37db4c1bbe7e2c4 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -729,6 +729,8 @@ static XenBlockDrive *xen_block_drive_create(const char *id,
     const char *mode = qdict_get_try_str(opts, "mode");
     const char *direct_io_safe = qdict_get_try_str(opts, "direct-io-safe");
     const char *discard_enable = qdict_get_try_str(opts, "discard-enable");
+    const char *suse_diskcache_disable_flush = qdict_get_try_str(opts,
+                                               "suse-diskcache-disable-flush");
     char *driver = NULL;
     char *filename = NULL;
     XenBlockDrive *drive = NULL;
@@ -797,6 +799,16 @@ static XenBlockDrive *xen_block_drive_create(const char *id,
         }
     }
 
+    if (suse_diskcache_disable_flush) {
+        unsigned long value;
+        if (!qemu_strtoul(suse_diskcache_disable_flush, NULL, 2, &value) && !!value) {
+            QDict *cache_qdict = qdict_new();
+
+            qdict_put_bool(cache_qdict, "no-flush", true);
+            qdict_put_obj(file_layer, "cache", QOBJECT(cache_qdict));
+        }
+    }
+
     /*
      * It is necessary to turn file locking off as an emulated device
      * may have already opened the same image file.