@@ -961,13 +961,22 @@ fail:
void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
{
if (bs->backing_hd) {
+ assert(error_is_set(&bs->backing_blocker));
+ bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
bdrv_unref(bs->backing_hd);
+ } else if (backing_hd) {
+ error_setg(&bs->backing_blocker,
+ "device is used as backing hd of '%s'",
+ bs->device_name);
}
bs->backing_hd = backing_hd;
if (!backing_hd) {
bs->backing_file[0] = '\0';
bs->backing_format[0] = '\0';
+ if (error_is_set(&bs->backing_blocker)) {
+ error_free(bs->backing_blocker);
+ }
return;
}
pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename);
@@ -975,6 +984,10 @@ void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
backing_hd->drv ? backing_hd->drv->format_name : "");
bdrv_ref(bs->backing_hd);
+ bdrv_op_block_all(bs->backing_hd, bs->backing_blocker);
+ /* Otherwise we won't be able to commit due to check in bdrv_commit */
+ bdrv_op_unblock(bs->backing_hd, BLOCK_OP_TYPE_COMMIT,
+ bs->backing_blocker);
pstrcpy(bs->backing_file, sizeof(bs->backing_file),
bs->backing_hd->file->filename);
pstrcpy(bs->backing_format, sizeof(bs->backing_format),
@@ -1481,8 +1494,7 @@ void bdrv_close(BlockDriverState *bs)
if (bs->drv) {
if (bs->backing_hd) {
- bdrv_unref(bs->backing_hd);
- bs->backing_hd = NULL;
+ bdrv_set_backing_hd(bs, NULL);
}
bs->drv->bdrv_close(bs);
g_free(bs->opaque);
@@ -341,6 +341,9 @@ struct BlockDriverState {
BlockJob *job;
QDict *options;
+
+ /* The error object in use for blocking operations on backing_hd */
+ Error *backing_blocker;
};
int get_tmp_filename(char *filename, int size);
This makes use of op_blocker and blocks all the operations except for commit target, on each BlockDriverState->backing_hd. Signed-off-by: Fam Zheng <famz@redhat.com> --- block.c | 16 ++++++++++++++-- include/block/block_int.h | 3 +++ 2 files changed, 17 insertions(+), 2 deletions(-)