[Qemu-devel] [PATCH 12/15] block: add -drive stream=on|off

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

This patch adds the -drive stream=on|off command-line option:

  stream=on|off
  stream is "on" or "off" and enables background copying of backing file
  contents into the image file until the backing file is no longer
  needed.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 blockdev.c      |   12 +++++++++++-
 hmp-commands.hx |    3 ++-
 qemu-config.c   |    4 ++++
 qemu-options.hx |    5 ++++-
 4 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index a044830..20947e2 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -432,7 +432,7 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
     const char *devaddr;
     DriveInfo *dinfo;
     int snapshot = 0;
-    int copy_on_read;
+    int copy_on_read, stream;
     int ret;
 
     translation = BIOS_ATA_TRANSLATION_AUTO;
@@ -450,6 +450,7 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
     snapshot = qemu_opt_get_bool(opts, "snapshot", 0);
     ro = qemu_opt_get_bool(opts, "readonly", 0);
     copy_on_read = qemu_opt_get_bool(opts, "copy-on-read", 0);
+    stream = qemu_opt_get_bool(opts, "stream", 0);
 
     file = qemu_opt_get(opts, "file");
     serial = qemu_opt_get(opts, "serial");
@@ -737,6 +738,15 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
         goto err;
     }
 
+    if (stream) {
+        const char *device_name = bdrv_get_device_name(dinfo->bdrv);
+
+        if (!stream_start(device_name)) {
+            fprintf(stderr, "qemu: warning: stream_start failed for '%s'\n",
+                    device_name);
+        }
+    }
+
     if (bdrv_key_required(dinfo->bdrv))
         autostart = 0;
     return dinfo;
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 2470c3f..b4dd8c08 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -909,7 +909,8 @@ ETEXI
                       "[,unit=m][,media=d][,index=i]\n"
                       "[,cyls=c,heads=h,secs=s[,trans=t]]\n"
                       "[,snapshot=on|off][,cache=on|off]\n"
-                      "[,readonly=on|off][,copy-on-read=on|off]",
+                      "[,readonly=on|off][,copy-on-read=on|off]"
+                      "[,stream=on|off]",
         .help       = "add drive to PCI storage controller",
         .mhandler.cmd = drive_hot_add,
     },
diff --git a/qemu-config.c b/qemu-config.c
index 2e5ee3c..f1b9045 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -88,6 +88,10 @@ static QemuOptsList qemu_drive_opts = {
             .name = "copy-on-read",
             .type = QEMU_OPT_BOOL,
             .help = "copy read data from backing file into image file",
+        },{
+            .name = "stream",
+            .type = QEMU_OPT_BOOL,
+            .help = "copy backing file data into image file while guest runs",
         },
         { /* end of list */ }
     },
diff --git a/qemu-options.hx b/qemu-options.hx
index b7e52fe..d54dd86 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -135,7 +135,7 @@ DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"
     "       [,cache=writethrough|writeback|none|unsafe][,format=f]\n"
     "       [,serial=s][,addr=A][,id=name][,aio=threads|native]\n"
-    "       [,readonly=on|off][,copy-on-read=on|off]\n"
+    "       [,readonly=on|off][,copy-on-read=on|off][,stream=on|off]\n"
     "                use 'file' as a drive image\n", QEMU_ARCH_ALL)
 STEXI
 @item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
@@ -186,6 +186,9 @@ Open drive @option{file} as read-only. Guest write attempts will fail.
 @item copy-on-read=@var{copy-on-read}
 @var{copy-on-read} is "on" or "off" and enables whether to copy read backing
 file sectors into the image file.
+@item stream=@var{stream}
+@var{stream} is "on" or "off" and enables background copying of backing file
+contents into the image file until the backing file is no longer needed.
 @end table
 
 By default, writethrough caching is used for all block device.  This means that
-- 
1.7.5.4