From d9b7b05703399fbc9b87553d7f164ffba1db4aa4 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 16 Jan 2015 18:23:41 +0100 Subject: block: Allow references for backing files For bs->file, using references to existing BDSes has been possible for a while already. This patch enables the same for bs->backing. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz --- block.c | 48 +++++++++++++++++++++++++++++------------------- 1 file changed, 29 insertions(+), 19 deletions(-) (limited to 'block.c') diff --git a/block.c b/block.c index 57bf8fc23a..84b9bf439b 100644 --- a/block.c +++ b/block.c @@ -1182,30 +1182,43 @@ out: /* * Opens the backing file for a BlockDriverState if not yet open * - * 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. + * bdref_key specifies the key for the image's BlockdevRef in the options QDict. + * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict + * itself, all options starting with "${bdref_key}." are considered part of the + * BlockdevRef. + * + * TODO Can this be unified with bdrv_open_image()? */ -int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) +int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, + const char *bdref_key, Error **errp) { char *backing_filename = g_malloc0(PATH_MAX); + char *bdref_key_dot; + const char *reference = NULL; int ret = 0; BlockDriverState *backing_hd; + QDict *options; + QDict *tmp_parent_options = NULL; Error *local_err = NULL; if (bs->backing != NULL) { - QDECREF(options); goto free_exit; } /* NULL means an empty set of options */ - if (options == NULL) { - options = qdict_new(); + if (parent_options == NULL) { + tmp_parent_options = qdict_new(); + parent_options = tmp_parent_options; } bs->open_flags &= ~BDRV_O_NO_BACKING; - if (qdict_haskey(options, "file.filename")) { + + bdref_key_dot = g_strdup_printf("%s.", bdref_key); + qdict_extract_subqdict(parent_options, &options, bdref_key_dot); + g_free(bdref_key_dot); + + reference = qdict_get_try_str(parent_options, bdref_key); + if (reference || qdict_haskey(options, "file.filename")) { backing_filename[0] = '\0'; } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { QDECREF(options); @@ -1228,19 +1241,16 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) goto free_exit; } - backing_hd = bdrv_new(); - if (bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) { qdict_put(options, "driver", qstring_from_str(bs->backing_format)); } - assert(bs->backing == NULL); + backing_hd = NULL; ret = bdrv_open_inherit(&backing_hd, *backing_filename ? backing_filename : NULL, - NULL, options, 0, bs, &child_backing, &local_err); + reference, options, 0, bs, &child_backing, + &local_err); if (ret < 0) { - bdrv_unref(backing_hd); - backing_hd = NULL; bs->open_flags |= BDRV_O_NO_BACKING; error_setg(errp, "Could not open backing file: %s", error_get_pretty(local_err)); @@ -1253,8 +1263,11 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) bdrv_set_backing_hd(bs, backing_hd); bdrv_unref(backing_hd); + qdict_del(parent_options, bdref_key); + free_exit: g_free(backing_filename); + QDECREF(tmp_parent_options); return ret; } @@ -1537,10 +1550,7 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename, /* 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, options, "backing", &local_err); if (ret < 0) { goto close_and_fail; } -- cgit v1.2.3