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/*
* QEMU Block backends
*
* Copyright (C) 2014 Red Hat, Inc.
*
* Authors:
* Markus Armbruster <armbru@redhat.com>,
*
* This work is licensed under the terms of the GNU LGPL, version 2.1
* or later. See the COPYING.LIB file in the top-level directory.
*/
#include "sysemu/block-backend.h"
#include "block/block_int.h"
struct BlockBackend {
char *name;
int refcnt;
BlockDriverState *bs;
QTAILQ_ENTRY(BlockBackend) link; /* for blk_backends */
};
/* All the BlockBackends (except for hidden ones) */
static QTAILQ_HEAD(, BlockBackend) blk_backends =
QTAILQ_HEAD_INITIALIZER(blk_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.
* 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;
assert(name && name[0]);
if (blk_by_name(name)) {
error_setg(errp, "Device with id '%s' already exists", name);
return NULL;
}
blk = g_new0(BlockBackend, 1);
blk->name = g_strdup(name);
blk->refcnt = 1;
QTAILQ_INSERT_TAIL(&blk_backends, blk, link);
return blk;
}
/*
* Create a new BlockBackend with a new BlockDriverState attached.
* Both have a reference count of one. Caller owns *both* references.
* TODO Let caller own only the BlockBackend reference
* Otherwise just like blk_new(), which see.
*/
BlockBackend *blk_new_with_bs(const char *name, Error **errp)
{
BlockBackend *blk;
BlockDriverState *bs;
blk = blk_new(name, errp);
if (!blk) {
return NULL;
}
bs = bdrv_new_root(name, errp);
if (!bs) {
blk_unref(blk);
return NULL;
}
blk->bs = bs;
bs->blk = blk;
return blk;
}
static void blk_delete(BlockBackend *blk)
{
assert(!blk->refcnt);
if (blk->bs) {
blk->bs->blk = NULL;
blk->bs = NULL;
}
/* Avoid double-remove after blk_hide_on_behalf_of_do_drive_del() */
if (blk->name[0]) {
QTAILQ_REMOVE(&blk_backends, blk, link);
}
g_free(blk->name);
g_free(blk);
}
/*
* Increment @blk's reference count.
* @blk must not be null.
*/
void blk_ref(BlockBackend *blk)
{
blk->refcnt++;
}
/*
* Decrement @blk's reference count.
* If this drops it to zero, destroy @blk.
* For convenience, do nothing if @blk is null.
* Does *not* touch the attached BlockDriverState's reference count.
* TODO Decrement it!
*/
void blk_unref(BlockBackend *blk)
{
if (blk) {
assert(blk->refcnt > 0);
if (!--blk->refcnt) {
blk_delete(blk);
}
}
}
/*
* Return the BlockBackend after @blk.
* If @blk is null, return the first one.
* Else, return @blk's next sibling, which may be null.
*
* To iterate over all BlockBackends, do
* for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
* ...
* }
*/
BlockBackend *blk_next(BlockBackend *blk)
{
return blk ? QTAILQ_NEXT(blk, link) : QTAILQ_FIRST(&blk_backends);
}
/*
* Return @blk's name, a non-null string.
* Wart: the name is empty iff @blk has been hidden with
* blk_hide_on_behalf_of_do_drive_del().
*/
const char *blk_name(BlockBackend *blk)
{
return blk->name;
}
/*
* Return the BlockBackend with name @name if it exists, else null.
* @name must not be null.
*/
BlockBackend *blk_by_name(const char *name)
{
BlockBackend *blk;
assert(name);
QTAILQ_FOREACH(blk, &blk_backends, link) {
if (!strcmp(name, blk->name)) {
return blk;
}
}
return NULL;
}
/*
* Return the BlockDriverState attached to @blk if any, else null.
*/
BlockDriverState *blk_bs(BlockBackend *blk)
{
return blk->bs;
}
/*
* Hide @blk.
* @blk must not have been hidden already.
* Make attached BlockDriverState, if any, anonymous.
* Once hidden, @blk is invisible to all functions that don't receive
* it as argument. For example, blk_by_name() won't return it.
* Strictly for use by do_drive_del().
* TODO get rid of it!
*/
void blk_hide_on_behalf_of_do_drive_del(BlockBackend *blk)
{
QTAILQ_REMOVE(&blk_backends, blk, link);
blk->name[0] = 0;
if (blk->bs) {
bdrv_make_anon(blk->bs);
}
}
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