Signed-off-by: Fam Zheng <f...@redhat.com>
---
block.c | 31 ++++++++++++++++++++++++++++---
block/mirror.c | 2 +-
include/block/block.h | 3 ++-
include/block/block_int.h | 3 +++
4 files changed, 34 insertions(+), 5 deletions(-)
diff --git a/block.c b/block.c
index c2ab6d8..d633f2b 100644
--- a/block.c
+++ b/block.c
@@ -959,18 +959,39 @@ fail:
/*
* Opens the backing file for a BlockDriverState if not yet open
*
+ * If backing_bs is not NULL or empty, find the BDS by name and reference it as
+ * the backing_hd, in this case options is ignored.
+ *
* options is a QDict of options to pass to the block drivers, or NULL for an
* empty set of options. The reference to the QDict is transferred to this
* function (even on failure), so if the caller intends to reuse the
dictionary,
* it needs to use QINCREF() before calling bdrv_file_open.
*/
-int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
+int bdrv_open_backing_file(BlockDriverState *bs, const char *backing_bs,
+ QDict *options, Error **errp)
{
char backing_filename[PATH_MAX];
int back_flags, ret;
BlockDriver *back_drv = NULL;
Error *local_err = NULL;
+ if (backing_bs && *backing_bs != '\0') {
+ bs->backing_hd = bdrv_find(backing_bs);
+ if (!bs->backing_hd) {
+ error_setg(errp, "Backing device not found: %s", backing_bs);
+ return -ENOENT;
+ }
+ bdrv_ref(bs->backing_hd);
+ assert(!bs->backing_blocker);
+ error_setg(&bs->backing_blocker,
+ "device is used as backing hd of '%s'",
+ bs->device_name);
+ bdrv_op_block_all(bs->backing_hd, bs->backing_blocker);
+ pstrcpy(bs->backing_file, sizeof(bs->backing_file),
+ bs->backing_hd->filename);
+ pstrcpy(bs->backing_format, sizeof(bs->backing_format),
+ bs->backing_hd->drv->format_name);
+ }
if (bs->backing_hd != NULL) {
QDECREF(options);
return 0;
@@ -1166,9 +1187,11 @@ int bdrv_open(BlockDriverState *bs, const char
*filename, QDict *options,
/* If there is a backing file, use it */
if ((flags & BDRV_O_NO_BACKING) == 0) {
QDict *backing_options;
-
qdict_extract_subqdict(options, &backing_options, "backing.");
- ret = bdrv_open_backing_file(bs, backing_options, &local_err);
+ ret = bdrv_open_backing_file(bs, qdict_get_try_str(options, "backing"),
+ backing_options, &local_err);
+
+ qdict_del(options, "backing");
if (ret < 0) {
goto close_and_fail;
}
@@ -1461,6 +1484,8 @@ void bdrv_close(BlockDriverState *bs)
if (bs->drv) {
if (bs->backing_hd) {
+ bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
+ error_free(bs->backing_blocker);
bdrv_unref(bs->backing_hd);
bs->backing_hd = NULL;
}
diff --git a/block/mirror.c b/block/mirror.c
index 7b95acf..ce0103a 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -508,7 +508,7 @@ static void mirror_complete(BlockJob *job, Error **errp)
Error *local_err = NULL;
int ret;
- ret = bdrv_open_backing_file(s->target, NULL, &local_err);
+ ret = bdrv_open_backing_file(s->target, NULL, NULL, &local_err);
if (ret < 0) {
char backing_filename[PATH_MAX];
bdrv_get_full_backing_filename(s->target, backing_filename,
diff --git a/include/block/block.h b/include/block/block.h
index 173c09a..e6ec03e 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -157,7 +157,8 @@ int bdrv_parse_cache_flags(const char *mode, int *flags);
int bdrv_parse_discard_flags(const char *mode, int *flags);
int bdrv_file_open(BlockDriverState **pbs, const char *filename,
QDict *options, int flags, Error **errp);
-int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp);
+int bdrv_open_backing_file(BlockDriverState *bs, const char *backing_bs,
+ QDict *options, Error **errp);
int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
int flags, BlockDriver *drv, Error **errp);
BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 60edc80..6db30c9 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -316,6 +316,9 @@ struct BlockDriverState {
BlockJob *job;
QDict *options;
+
+ /* For backing reference, block the operations of named backing device */
+ Error *backing_blocker;
};
int get_tmp_filename(char *filename, int size);
--
1.8.4.2
