@@ -958,6 +958,24 @@ fail:
return ret;
}
+void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
+{
+ if (bs->backing_hd) {
+ bdrv_unref(bs->backing_hd);
+ }
+
+ bs->backing_hd = backing_hd;
+ if (!backing_hd) {
+ return;
+ }
+ bdrv_ref(bs->backing_hd);
+
+ 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);
+}
+
/*
* Opens the backing file for a BlockDriverState if not yet open
*
@@ -971,6 +989,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
char backing_filename[PATH_MAX];
int back_flags, ret;
BlockDriver *back_drv = NULL;
+ BlockDriverState *backing_hd;
Error *local_err = NULL;
if (bs->backing_hd != NULL) {
@@ -994,7 +1013,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
sizeof(backing_filename));
}
- bs->backing_hd = bdrv_new("");
+ backing_hd = bdrv_new("");
if (bs->backing_format[0] != '\0') {
back_drv = bdrv_find_format(bs->backing_format);
@@ -1004,20 +1023,18 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT |
BDRV_O_COPY_ON_READ);
- ret = bdrv_open(bs->backing_hd,
+ ret = bdrv_open(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;
+ bdrv_unref(backing_hd);
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;
}
- pstrcpy(bs->backing_file, sizeof(bs->backing_file),
- bs->backing_hd->file->filename);
+ bdrv_set_backing_hd(bs, backing_hd);
return 0;
}
@@ -185,6 +185,7 @@ 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);
+void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd);
int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp);
int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
int flags, BlockDriver *drv, Error **errp);
This is the common but non-trivial steps to assign or change the backing_hd of BDS. Signed-off-by: Fam Zheng <famz@redhat.com> --- block.c | 29 +++++++++++++++++++++++------ include/block/block.h | 1 + 2 files changed, 24 insertions(+), 6 deletions(-)