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blockdev: Split monitor reference from BB creation

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Before this patch, blk_new() automatically assigned a name to the new
BlockBackend and considered it referenced by the monitor. This patch
removes the implicit monitor_add_blk() call from blk_new() (and
consequently the monitor_remove_blk() call from blk_delete(), too) and
thus blk_new() (and related functions) no longer take a BB name
argument.

In fact, there is only a single point where blk_new()/blk_new_open() is
called and the new BB is monitor-owned, and that is in blockdev_init().
Besides thus relieving us from having to invent names for all of the BBs
we use in qemu-img, this fixes a bug where qemu cannot create a new
image if there already is a monitor-owned BB named "image".

If a BB and its BDS tree are created in a single operation, as of this
patch the BDS tree will be created before the BB is given a name
(whereas it was the other way around before). This results in minor
change to the output of iotest 087, whose reference output is amended
accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2016-03-16 19:54:38 +01:00 • committed by Kevin Wolf
parent e5e785500b
commit efaa7c4eeb
18 changed files with 68 additions and 76 deletions
Download patch file Download diff file Expand all files Collapse all files

26
block/block-backend.c
View file

@ -80,13 +80,11 @@ static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
/*
* Create a new BlockBackend with @name, with a reference count of one.
* @name must not be null or empty.
* Fail if a BlockBackend with this name already exists.
* Create a new BlockBackend with a reference count of one.
* Store an error through @errp on failure, unless it's null.
* Return the new BlockBackend on success, null on failure.
*/
BlockBackend *blk_new(const char *name, Error **errp)
BlockBackend *blk_new(Error **errp)
{
BlockBackend *blk;
@ -94,14 +92,7 @@ BlockBackend *blk_new(const char *name, Error **errp)
blk->refcnt = 1;
notifier_list_init(&blk->remove_bs_notifiers);
notifier_list_init(&blk->insert_bs_notifiers);
QTAILQ_INSERT_TAIL(&block_backends, blk, link);
if (!monitor_add_blk(blk, name, errp)) {
blk_unref(blk);
return NULL;
}
return blk;
}
@ -109,12 +100,12 @@ BlockBackend *blk_new(const char *name, Error **errp)
* Create a new BlockBackend with a new BlockDriverState attached.
* Otherwise just like blk_new(), which see.
*/
BlockBackend *blk_new_with_bs(const char *name, Error **errp)
BlockBackend *blk_new_with_bs(Error **errp)
{
BlockBackend *blk;
BlockDriverState *bs;
blk = blk_new(name, errp);
blk = blk_new(errp);
if (!blk) {
return NULL;
}
@ -137,14 +128,13 @@ BlockBackend *blk_new_with_bs(const char *name, Error **errp)
* though, so callers of this function have to be able to specify @filename and
* @flags.
*/
BlockBackend *blk_new_open(const char *name, const char *filename,
const char *reference, QDict *options, int flags,
Error **errp)
BlockBackend *blk_new_open(const char *filename, const char *reference,
QDict *options, int flags, Error **errp)
{
BlockBackend *blk;
int ret;
blk = blk_new_with_bs(name, errp);
blk = blk_new_with_bs(errp);
if (!blk) {
QDECREF(options);
return NULL;
@ -161,8 +151,6 @@ BlockBackend *blk_new_open(const char *name, const char *filename,
static void blk_delete(BlockBackend *blk)
{
monitor_remove_blk(blk);
assert(!blk->refcnt);
assert(!blk->name);
assert(!blk->dev);