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authorDong Jia Shi <bjsdjshi@linux.vnet.ibm.com>2017-04-05 11:19:09 +0200
committerMax Reitz <mreitz@redhat.com>2017-04-11 15:33:00 +0200
commit7a9e51198c24a576275cf509a110d24d7c6ca664 (patch)
treebabdbdcd2c8a486836005c78066c3fc3b8e8ed48
parentaa388ddc36e8032f41cd17bef88cc3ebaeba77c9 (diff)
block: pass the right options for BlockDriver.bdrv_open()
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 <mreitz@redhat.com> Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> Message-id: 20170405091909.36357-2-bjsdjshi@linux.vnet.ibm.com Signed-off-by: Max Reitz <mreitz@redhat.com>
-rw-r--r--block/snapshot.c26
1 files 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;
}