From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41365) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cvh69-0001A9-6A for qemu-devel@nongnu.org; Wed, 05 Apr 2017 05:19:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cvh64-0000i0-T1 for qemu-devel@nongnu.org; Wed, 05 Apr 2017 05:19:29 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:51330) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cvh64-0000gI-Kc for qemu-devel@nongnu.org; Wed, 05 Apr 2017 05:19:24 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v359J1gW057527 for ; Wed, 5 Apr 2017 05:19:22 -0400 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0a-001b2d01.pphosted.com with ESMTP id 29mr5sdbrq-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 05 Apr 2017 05:19:22 -0400 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 5 Apr 2017 03:19:20 -0600 From: Dong Jia Shi Date: Wed, 5 Apr 2017 11:19:09 +0200 In-Reply-To: <20170405091909.36357-1-bjsdjshi@linux.vnet.ibm.com> References: <20170405091909.36357-1-bjsdjshi@linux.vnet.ibm.com> Message-Id: <20170405091909.36357-2-bjsdjshi@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH v4 1/1] block: pass the right options for BlockDriver.bdrv_open() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org, kwolf@redhat.com, mreitz@redhat.com Cc: qemu-devel@nongnu.org, bjsdjshi@linux.vnet.ibm.com, cornelia.huck@de.ibm.com, borntraeger@de.ibm.com raw_open() expects the caller always passing in the right actual @options parameter. But when trying to applying snapshot on a RBD image, bdrv_snapshot_goto() calls raw_open() (by calling the bdrv_open callback on the BlockDriver) with a NULL @options, and that will result in a Segmentation fault. For the other non-raw format drivers, it also makes sense to passing in the actual options, althought they don't trigger the problem so far. Let's prepare a @options by adding the "file" key-value pair to a copy of the actual options that were given for the node (i.e. bs->options), and pass it to the callback. BlockDriver.bdrv_open() expects bs->file to be NULL and just overwrites it with the result from bdrv_open_child(). That means we should actually make sure it's NULL because otherwise the child BDS will have a reference count that is 1 too high. So we unconditionally invoke bdrv_unref_child() before calling BlockDriver.bdrv_open(), and we wrap everything in bdrv_ref()/bdrv_unref() so the BDS isn't deleted in the meantime. Suggested-by: Max Reitz Signed-off-by: Dong Jia Shi --- block/snapshot.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/block/snapshot.c b/block/snapshot.c index bf5c2ca..06b1185 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -27,6 +27,7 @@ #include "block/block_int.h" #include "qapi/error.h" #include "qapi/qmp/qerror.h" +#include "qapi/qmp/qstring.h" QemuOptsList internal_snapshot_opts = { .name = "snapshot", @@ -189,14 +190,33 @@ int bdrv_snapshot_goto(BlockDriverState *bs, } if (bs->file) { + BlockDriverState *file; + QDict *options = qdict_clone_shallow(bs->options); + QDict *file_options; + + file = bs->file->bs; + /* Prevent it from getting deleted when detached from bs */ + bdrv_ref(file); + + qdict_extract_subqdict(options, &file_options, "file."); + QDECREF(file_options); + qdict_put(options, "file", qstring_from_str(bdrv_get_node_name(file))); + drv->bdrv_close(bs); - ret = bdrv_snapshot_goto(bs->file->bs, snapshot_id); - open_ret = drv->bdrv_open(bs, NULL, bs->open_flags, NULL); + bdrv_unref_child(bs, bs->file); + bs->file = NULL; + + ret = bdrv_snapshot_goto(file, snapshot_id); + open_ret = drv->bdrv_open(bs, options, bs->open_flags, NULL); + QDECREF(options); if (open_ret < 0) { - bdrv_unref(bs->file->bs); + bdrv_unref(file); bs->drv = NULL; return open_ret; } + + assert(bs->file->bs == file); + bdrv_unref(file); return ret; } -- 2.10.2