From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:51704)
	by lists.gnu.org with esmtp (Exim 4.71) (envelope-from <hch@lst.de>)
	id 1Qz9cI-0006h2-QP
	for qemu-devel@nongnu.org; Thu, 01 Sep 2011 11:55:47 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <hch@lst.de>) id 1Qz9cH-0001j5-Lm
	for qemu-devel@nongnu.org; Thu, 01 Sep 2011 11:55:46 -0400
Received: from verein.lst.de ([213.95.11.211]:33334 helo=newverein.lst.de)
	by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from <hch@lst.de>)
	id 1Qz9cH-0001iq-Gv
	for qemu-devel@nongnu.org; Thu, 01 Sep 2011 11:55:45 -0400
Date: Thu, 1 Sep 2011 17:55:43 +0200
From: Christoph Hellwig <hch@lst.de>
Message-ID: <20110901155543.GA11219@lst.de>
References: <20110901132755.GG14462@redhat.com> <20110901140526.GA9388@lst.de>
	<20110901143034.GJ14462@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20110901143034.GJ14462@redhat.com>
Subject: Re: [Qemu-devel] QEMU online guest disk resize wrt host block
	devices
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, qemu-devel@nongnu.org

Please try the attached (untested) patch:


Index: qemu/block/raw-posix.c
===================================================================
--- qemu.orig/block/raw-posix.c	2011-09-01 17:37:42.579651525 +0200
+++ qemu/block/raw-posix.c	2011-09-01 17:43:28.882967337 +0200
@@ -645,10 +645,23 @@ static void raw_close(BlockDriverState *
 static int raw_truncate(BlockDriverState *bs, int64_t offset)
 {
     BDRVRawState *s = bs->opaque;
-    if (s->type != FTYPE_FILE)
-        return -ENOTSUP;
-    if (ftruncate(s->fd, offset) < 0)
+    struct stat st;
+
+    if (fstat(s->fd, &st))
         return -errno;
+
+    if (S_ISREG(st.st_mode)) {
+        if (ftruncate(s->fd, offset) < 0)
+            return -errno;
+    } else if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) {
+       if (offset > raw_getlength(bs)) {
+           return -EINVAL;
+       }
+       return 0;
+
+    } else {
+        return -ENOTSUP;
+    }
     return 0;
 }
 
@@ -1167,6 +1180,7 @@ static BlockDriver bdrv_host_device = {
 
     .bdrv_read          = raw_read,
     .bdrv_write         = raw_write,
+    .bdrv_truncate = raw_truncate,
     .bdrv_getlength	= raw_getlength,
     .bdrv_get_allocated_file_size
                         = raw_get_allocated_file_size,
@@ -1288,6 +1302,7 @@ static BlockDriver bdrv_host_floppy = {
 
     .bdrv_read          = raw_read,
     .bdrv_write         = raw_write,
+    .bdrv_truncate = raw_truncate,
     .bdrv_getlength	= raw_getlength,
     .bdrv_get_allocated_file_size
                         = raw_get_allocated_file_size,
@@ -1389,6 +1404,7 @@ static BlockDriver bdrv_host_cdrom = {
 
     .bdrv_read          = raw_read,
     .bdrv_write         = raw_write,
+    .bdrv_truncate = raw_truncate,
     .bdrv_getlength     = raw_getlength,
     .bdrv_get_allocated_file_size
                         = raw_get_allocated_file_size,
@@ -1510,6 +1526,7 @@ static BlockDriver bdrv_host_cdrom = {
 
     .bdrv_read          = raw_read,
     .bdrv_write         = raw_write,
+    .bdrv_truncate = raw_truncate,
     .bdrv_getlength     = raw_getlength,
     .bdrv_get_allocated_file_size
                         = raw_get_allocated_file_size,