Signed-off-by: Fam Zheng <f...@redhat.com>
---
block.c | 109 +++++++++++++++++++++++++++++-----------------
block/mirror.c | 2 +-
include/block/block.h | 3 +-
include/block/block_int.h | 3 ++
4 files changed, 76 insertions(+), 41 deletions(-)
diff --git a/block.c b/block.c
index 45410ef..6fda85f 100644
--- a/block.c
+++ b/block.c
@@ -959,63 +959,87 @@ 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 (bs->backing_hd != NULL) {
- QDECREF(options);
- return 0;
- }
+ 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);
+ } else {
+ if (bs->backing_hd != NULL) {
+ QDECREF(options);
+ return 0;
+ }
- /* NULL means an empty set of options */
- if (options == NULL) {
- options = qdict_new();
- }
+ /* NULL means an empty set of options */
+ if (options == NULL) {
+ options = qdict_new();
+ }
- bs->open_flags &= ~BDRV_O_NO_BACKING;
- if (qdict_haskey(options, "file.filename")) {
- backing_filename[0] = '\0';
- } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
- QDECREF(options);
- return 0;
- } else {
- bdrv_get_full_backing_filename(bs, backing_filename,
- sizeof(backing_filename));
- }
+ bs->open_flags &= ~BDRV_O_NO_BACKING;
+ if (qdict_haskey(options, "file.filename")) {
+ backing_filename[0] = '\0';
+ } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
+ QDECREF(options);
+ return 0;
+ } else {
+ bdrv_get_full_backing_filename(bs, backing_filename,
+ sizeof(backing_filename));
+ }
- bs->backing_hd = bdrv_new("");
+ bs->backing_hd = bdrv_new("");
- if (bs->backing_format[0] != '\0') {
- back_drv = bdrv_find_format(bs->backing_format);
- }
+ if (bs->backing_format[0] != '\0') {
+ back_drv = bdrv_find_format(bs->backing_format);
+ }
- /* backing files always opened read-only */
- back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT |
- BDRV_O_COPY_ON_READ);
+ /* backing files always opened read-only */
+ back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT |
+ BDRV_O_COPY_ON_READ);
- ret = bdrv_open(bs->backing_hd,
- *backing_filename ? backing_filename : NULL, options,
- back_flags, back_drv, &local_err);
- if (ret < 0) {
- bdrv_unref(bs->backing_hd);
- bs->backing_hd = NULL;
- bs->open_flags |= BDRV_O_NO_BACKING;
- error_setg(errp, "Could not open backing file: %s",
- error_get_pretty(local_err));
- error_free(local_err);
- return ret;
+ ret = bdrv_open(bs->backing_hd,
+ *backing_filename ? backing_filename : NULL, options,
+ back_flags, back_drv, &local_err);
+ if (ret < 0) {
+ bdrv_unref(bs->backing_hd);
+ bs->backing_hd = NULL;
+ bs->open_flags |= BDRV_O_NO_BACKING;
+ error_setg(errp, "Could not open backing file: %s",
+ error_get_pretty(local_err));
+ error_free(local_err);
+ return ret;
+ }
}
+ assert(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);
+ /* 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),
+ bs->backing_hd->drv->format_name);
return 0;
}
@@ -1166,9 +1190,11 @@ 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;
}
@@ -1461,9 +1487,14 @@ void bdrv_close(BlockDriverState *bs)
if (bs->drv) {
if (bs->backing_hd) {
+ assert(bs->backing_blocker);
+ bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
bdrv_unref(bs->backing_hd);
bs->backing_hd = NULL;
}
+ if (bs->backing_blocker) {
+ error_free(bs->backing_blocker);
+ }
bs->drv->bdrv_close(bs);
g_free(bs->opaque);
#ifdef _WIN32
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 693d305..67da5d5 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 d8cef85..ffea9ee 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -317,6 +317,9 @@ 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
