From 0eafc492bacb5b6370ab8650f8540eb9a8ee772a Mon Sep 17 00:00:00 2001
From: Alex Bligh <alex@alex.org.uk>
Date: Fri, 5 Apr 2013 23:37:19 +0000
Subject: [PATCH] Xen PV backend: Move call to bdrv_new from blk_init to
 blk_connect

This commit delays the point at which bdrv_new (and hence blk_open
on the underlying device) is called from blk_init to blk_connect.
This ensures that in an inbound live migrate, the block device is
not opened until it has been closed at the other end. This is in
preparation for supporting devices with open/close consistency
without using O_DIRECT. This commit does NOT itself change O_DIRECT
semantics.

upstream-commit-id: 86f425db3b1c4b6c4a2927eaec35627f9ab2e703

Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 hw/xen_disk.c | 69 +++++++++++++++++++++++++++++----------------------
 1 file changed, 39 insertions(+), 30 deletions(-)

diff --git a/hw/xen_disk.c b/hw/xen_disk.c
index a402ac8e5..3cecf8d16 100644
--- a/hw/xen_disk.c
+++ b/hw/xen_disk.c
@@ -560,7 +560,7 @@ static void blk_alloc(struct XenDevice *xendev)
 static int blk_init(struct XenDevice *xendev)
 {
     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
-    int index, qflags, info = 0;
+    int info = 0;
 
     /* read xenstore entries */
     if (blkdev->params == NULL) {
@@ -603,18 +603,49 @@ static int blk_init(struct XenDevice *xendev)
     }
 
     /* read-only ? */
-    qflags = BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NATIVE_AIO;
-    if (strcmp(blkdev->mode, "w") == 0) {
-        qflags |= BDRV_O_RDWR;
-    } else {
+    if (strcmp(blkdev->mode, "w")) {
         info  |= VDISK_READONLY;
     }
-
+    
     /* cdrom ? */
     if (blkdev->devtype && !strcmp(blkdev->devtype, "cdrom")) {
         info  |= VDISK_CDROM;
     }
+    
+    blkdev->file_blk  = BLOCK_SIZE;
+
+    /* fill info
+     * blk_connect supplies sector-size and sectors
+     */
+    xenstore_write_be_int(&blkdev->xendev, "feature-barrier", 1);
+    xenstore_write_be_int(&blkdev->xendev, "info",            info);
+    return 0;
+
+out_error:
+    g_free(blkdev->params);
+    blkdev->params = NULL;
+    g_free(blkdev->mode);
+    blkdev->mode = NULL;
+    g_free(blkdev->type);
+    blkdev->type = NULL;
+    g_free(blkdev->dev);
+    blkdev->dev = NULL;
+    g_free(blkdev->devtype);
+    blkdev->devtype = NULL;
+    return -1;
+}
+
+static int blk_connect(struct XenDevice *xendev)
+{
+    struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
+    int index, qflags;
 
+    /* read-only ? */
+    qflags = BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NATIVE_AIO;
+    if (strcmp(blkdev->mode, "w") == 0) {
+        qflags |= BDRV_O_RDWR;
+    }
+    
     /* init qemu block driver */
     index = (blkdev->xendev.dev - 202 * 256) / 16;
     blkdev->dinfo = drive_get(IF_XEN, 0, index);
@@ -630,7 +661,7 @@ static int blk_init(struct XenDevice *xendev)
             }
         }
         if (!blkdev->bs) {
-            goto out_error;
+            return -1;
         }
     } else {
         /* setup via qemu cmdline -> already setup for us */
@@ -638,7 +669,6 @@ static int blk_init(struct XenDevice *xendev)
         blkdev->bs = blkdev->dinfo->bdrv;
     }
     bdrv_attach_dev_nofail(blkdev->bs, blkdev);
-    blkdev->file_blk  = BLOCK_SIZE;
     blkdev->file_size = bdrv_getlength(blkdev->bs);
     if (blkdev->file_size < 0) {
         xen_be_printf(&blkdev->xendev, 1, "bdrv_getlength: %d (%s) | drv %s\n",
@@ -652,31 +682,10 @@ static int blk_init(struct XenDevice *xendev)
                   blkdev->type, blkdev->fileproto, blkdev->filename,
                   blkdev->file_size, blkdev->file_size >> 20);
 
-    /* fill info */
-    xenstore_write_be_int(&blkdev->xendev, "feature-barrier", 1);
-    xenstore_write_be_int(&blkdev->xendev, "info",            info);
+    /* Fill in number of sector size and number of sectors */
     xenstore_write_be_int(&blkdev->xendev, "sector-size",     blkdev->file_blk);
     xenstore_write_be_int(&blkdev->xendev, "sectors",
                           blkdev->file_size / blkdev->file_blk);
-    return 0;
-
-out_error:
-    g_free(blkdev->params);
-    blkdev->params = NULL;
-    g_free(blkdev->mode);
-    blkdev->mode = NULL;
-    g_free(blkdev->type);
-    blkdev->type = NULL;
-    g_free(blkdev->dev);
-    blkdev->dev = NULL;
-    g_free(blkdev->devtype);
-    blkdev->devtype = NULL;
-    return -1;
-}
-
-static int blk_connect(struct XenDevice *xendev)
-{
-    struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
 
     if (xenstore_read_fe_int(&blkdev->xendev, "ring-ref", &blkdev->ring_ref) == -1) {
         return -1;
-- 
2.39.5