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[Qemu-block] [PULL 1/3] block: pass the right options for BlockDriver.bd
From: |
Max Reitz |
Subject: |
[Qemu-block] [PULL 1/3] block: pass the right options for BlockDriver.bdrv_open() |
Date: |
Tue, 11 Apr 2017 15:44:33 +0200 |
From: Dong Jia Shi <address@hidden>
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 <address@hidden>
Signed-off-by: Dong Jia Shi <address@hidden>
Message-id: address@hidden
Signed-off-by: Max Reitz <address@hidden>
---
block/snapshot.c | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/block/snapshot.c b/block/snapshot.c
index bf5c2ca5e1..06b1185d27 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;
}
--
2.12.2