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qemu-e2k/block/block-backend.c
Paolo Bonzini 881a4c553c block: add missing coroutine_fn annotations 
Callers of coroutine_fn must be coroutine_fn themselves, or the call
must be within "if (qemu_in_coroutine())".  Apply coroutine_fn to
functions where this holds.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220922084924.201610-3-pbonzini@redhat.com>
[kwolf: Fixed up coding style]
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-10-07 12:11:40 +02:00

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/*
* QEMU Block backends
*
* Copyright (C) 2014-2016 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 "qemu/osdep.h"
#include "sysemu/block-backend.h"
#include "block/block_int.h"
#include "block/blockjob.h"
#include "block/coroutines.h"
#include "block/throttle-groups.h"
#include "hw/qdev-core.h"
#include "sysemu/blockdev.h"
#include "sysemu/runstate.h"
#include "sysemu/replay.h"
#include "qapi/error.h"
#include "qapi/qapi-events-block.h"
#include "qemu/id.h"
#include "qemu/main-loop.h"
#include "qemu/option.h"
#include "trace.h"
#include "migration/misc.h"
/* Number of coroutines to reserve per attached device model */
#define COROUTINE_POOL_RESERVATION 64
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb);
typedef struct BlockBackendAioNotifier {
void (*attached_aio_context)(AioContext *new_context, void *opaque);
void (*detach_aio_context)(void *opaque);
void *opaque;
QLIST_ENTRY(BlockBackendAioNotifier) list;
} BlockBackendAioNotifier;
struct BlockBackend {
char *name;
int refcnt;
BdrvChild *root;
AioContext *ctx;
DriveInfo *legacy_dinfo; /* null unless created by drive_new() */
QTAILQ_ENTRY(BlockBackend) link; /* for block_backends */
QTAILQ_ENTRY(BlockBackend) monitor_link; /* for monitor_block_backends */
BlockBackendPublic public;
DeviceState *dev; /* attached device model, if any */
const BlockDevOps *dev_ops;
void *dev_opaque;
/* If the BDS tree is removed, some of its options are stored here (which
* can be used to restore those options in the new BDS on insert) */
BlockBackendRootState root_state;
bool enable_write_cache;
/* I/O stats (display with "info blockstats"). */
BlockAcctStats stats;
BlockdevOnError on_read_error, on_write_error;
bool iostatus_enabled;
BlockDeviceIoStatus iostatus;
uint64_t perm;
uint64_t shared_perm;
bool disable_perm;
bool allow_aio_context_change;
bool allow_write_beyond_eof;
/* Protected by BQL */
NotifierList remove_bs_notifiers, insert_bs_notifiers;
QLIST_HEAD(, BlockBackendAioNotifier) aio_notifiers;
int quiesce_counter;
CoQueue queued_requests;
bool disable_request_queuing;
VMChangeStateEntry *vmsh;
bool force_allow_inactivate;
/* Number of in-flight aio requests. BlockDriverState also counts
* in-flight requests but aio requests can exist even when blk->root is
* NULL, so we cannot rely on its counter for that case.
* Accessed with atomic ops.
*/
unsigned int in_flight;
};
typedef struct BlockBackendAIOCB {
BlockAIOCB common;
BlockBackend *blk;
int ret;
} BlockBackendAIOCB;
static const AIOCBInfo block_backend_aiocb_info = {
.get_aio_context = blk_aiocb_get_aio_context,
.aiocb_size = sizeof(BlockBackendAIOCB),
};
static void drive_info_del(DriveInfo *dinfo);
static BlockBackend *bdrv_first_blk(BlockDriverState *bs);
/* All BlockBackends. Protected by BQL. */
static QTAILQ_HEAD(, BlockBackend) block_backends =
QTAILQ_HEAD_INITIALIZER(block_backends);
/*
* All BlockBackends referenced by the monitor and which are iterated through by
* blk_next(). Protected by BQL.
*/
static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
static void blk_root_inherit_options(BdrvChildRole role, bool parent_is_format,
int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
/* We're not supposed to call this function for root nodes */
abort();
}
static void blk_root_drained_begin(BdrvChild *child);
static bool blk_root_drained_poll(BdrvChild *child);
static void blk_root_drained_end(BdrvChild *child, int *drained_end_counter);
static void blk_root_change_media(BdrvChild *child, bool load);
static void blk_root_resize(BdrvChild *child);
static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore, Error **errp);
static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore);
static char *blk_root_get_parent_desc(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
g_autofree char *dev_id = NULL;
if (blk->name) {
return g_strdup_printf("block device '%s'", blk->name);
}
dev_id = blk_get_attached_dev_id(blk);
if (*dev_id) {
return g_strdup_printf("block device '%s'", dev_id);
} else {
/* TODO Callback into the BB owner for something more detailed */
return g_strdup("an unnamed block device");
}
}
static const char *blk_root_get_name(BdrvChild *child)
{
return blk_name(child->opaque);
}
static void blk_vm_state_changed(void *opaque, bool running, RunState state)
{
Error *local_err = NULL;
BlockBackend *blk = opaque;
if (state == RUN_STATE_INMIGRATE) {
return;
}
qemu_del_vm_change_state_handler(blk->vmsh);
blk->vmsh = NULL;
blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
if (local_err) {
error_report_err(local_err);
}
}
/*
* Notifies the user of the BlockBackend that migration has completed. qdev
* devices can tighten their permissions in response (specifically revoke
* shared write permissions that we needed for storage migration).
*
* If an error is returned, the VM cannot be allowed to be resumed.
*/
static void blk_root_activate(BdrvChild *child, Error **errp)
{
BlockBackend *blk = child->opaque;
Error *local_err = NULL;
uint64_t saved_shared_perm;
if (!blk->disable_perm) {
return;
}
blk->disable_perm = false;
/*
* blk->shared_perm contains the permissions we want to share once
* migration is really completely done. For now, we need to share
* all; but we also need to retain blk->shared_perm, which is
* overwritten by a successful blk_set_perm() call. Save it and
* restore it below.
*/
saved_shared_perm = blk->shared_perm;
blk_set_perm(blk, blk->perm, BLK_PERM_ALL, &local_err);
if (local_err) {
error_propagate(errp, local_err);
blk->disable_perm = true;
return;
}
blk->shared_perm = saved_shared_perm;
if (runstate_check(RUN_STATE_INMIGRATE)) {
/* Activation can happen when migration process is still active, for
* example when nbd_server_add is called during non-shared storage
* migration. Defer the shared_perm update to migration completion. */
if (!blk->vmsh) {
blk->vmsh = qemu_add_vm_change_state_handler(blk_vm_state_changed,
blk);
}
return;
}
blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
if (local_err) {
error_propagate(errp, local_err);
blk->disable_perm = true;
return;
}
}
void blk_set_force_allow_inactivate(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
blk->force_allow_inactivate = true;
}
static bool blk_can_inactivate(BlockBackend *blk)
{
/* If it is a guest device, inactivate is ok. */
if (blk->dev || blk_name(blk)[0]) {
return true;
}
/* Inactivating means no more writes to the image can be done,
* even if those writes would be changes invisible to the
* guest. For block job BBs that satisfy this, we can just allow
* it. This is the case for mirror job source, which is required
* by libvirt non-shared block migration. */
if (!(blk->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED))) {
return true;
}
return blk->force_allow_inactivate;
}
static int blk_root_inactivate(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
if (blk->disable_perm) {
return 0;
}
if (!blk_can_inactivate(blk)) {
return -EPERM;
}
blk->disable_perm = true;
if (blk->root) {
bdrv_child_try_set_perm(blk->root, 0, BLK_PERM_ALL, &error_abort);
}
return 0;
}
static void blk_root_attach(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
BlockBackendAioNotifier *notifier;
trace_blk_root_attach(child, blk, child->bs);
QLIST_FOREACH(notifier, &blk->aio_notifiers, list) {
bdrv_add_aio_context_notifier(child->bs,
notifier->attached_aio_context,
notifier->detach_aio_context,
notifier->opaque);
}
}
static void blk_root_detach(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
BlockBackendAioNotifier *notifier;
trace_blk_root_detach(child, blk, child->bs);
QLIST_FOREACH(notifier, &blk->aio_notifiers, list) {
bdrv_remove_aio_context_notifier(child->bs,
notifier->attached_aio_context,
notifier->detach_aio_context,
notifier->opaque);
}
}
static AioContext *blk_root_get_parent_aio_context(BdrvChild *c)
{
BlockBackend *blk = c->opaque;
return blk_get_aio_context(blk);
}
static const BdrvChildClass child_root = {
.inherit_options = blk_root_inherit_options,
.change_media = blk_root_change_media,
.resize = blk_root_resize,
.get_name = blk_root_get_name,
.get_parent_desc = blk_root_get_parent_desc,
.drained_begin = blk_root_drained_begin,
.drained_poll = blk_root_drained_poll,
.drained_end = blk_root_drained_end,
.activate = blk_root_activate,
.inactivate = blk_root_inactivate,
.attach = blk_root_attach,
.detach = blk_root_detach,
.can_set_aio_ctx = blk_root_can_set_aio_ctx,
.set_aio_ctx = blk_root_set_aio_ctx,
.get_parent_aio_context = blk_root_get_parent_aio_context,
};
/*
* Create a new BlockBackend with a reference count of one.
*
* @perm is a bitmasks of BLK_PERM_* constants which describes the permissions
* to request for a block driver node that is attached to this BlockBackend.
* @shared_perm is a bitmask which describes which permissions may be granted
* to other users of the attached node.
* Both sets of permissions can be changed later using blk_set_perm().
*
* Return the new BlockBackend on success, null on failure.
*/
BlockBackend *blk_new(AioContext *ctx, uint64_t perm, uint64_t shared_perm)
{
BlockBackend *blk;
GLOBAL_STATE_CODE();
blk = g_new0(BlockBackend, 1);
blk->refcnt = 1;
blk->ctx = ctx;
blk->perm = perm;
blk->shared_perm = shared_perm;
blk_set_enable_write_cache(blk, true);
blk->on_read_error = BLOCKDEV_ON_ERROR_REPORT;
blk->on_write_error = BLOCKDEV_ON_ERROR_ENOSPC;
block_acct_init(&blk->stats);
qemu_co_queue_init(&blk->queued_requests);
notifier_list_init(&blk->remove_bs_notifiers);
notifier_list_init(&blk->insert_bs_notifiers);
QLIST_INIT(&blk->aio_notifiers);
QTAILQ_INSERT_TAIL(&block_backends, blk, link);
return blk;
}
/*
* Create a new BlockBackend connected to an existing BlockDriverState.
*
* @perm is a bitmasks of BLK_PERM_* constants which describes the
* permissions to request for @bs that is attached to this
* BlockBackend. @shared_perm is a bitmask which describes which
* permissions may be granted to other users of the attached node.
* Both sets of permissions can be changed later using blk_set_perm().
*
* Return the new BlockBackend on success, null on failure.
*/
BlockBackend *blk_new_with_bs(BlockDriverState *bs, uint64_t perm,
uint64_t shared_perm, Error **errp)
{
BlockBackend *blk = blk_new(bdrv_get_aio_context(bs), perm, shared_perm);
GLOBAL_STATE_CODE();
if (blk_insert_bs(blk, bs, errp) < 0) {
blk_unref(blk);
return NULL;
}
return blk;
}
/*
* Creates a new BlockBackend, opens a new BlockDriverState, and connects both.
* The new BlockBackend is in the main AioContext.
*
* Just as with bdrv_open(), after having called this function the reference to
* @options belongs to the block layer (even on failure).
*
* TODO: Remove @filename and @flags; it should be possible to specify a whole
* BDS tree just by specifying the @options QDict (or @reference,
* alternatively). At the time of adding this function, this is not possible,
* though, so callers of this function have to be able to specify @filename and
* @flags.
*/
BlockBackend *blk_new_open(const char *filename, const char *reference,
QDict *options, int flags, Error **errp)
{
BlockBackend *blk;
BlockDriverState *bs;
uint64_t perm = 0;
uint64_t shared = BLK_PERM_ALL;
GLOBAL_STATE_CODE();
/*
* blk_new_open() is mainly used in .bdrv_create implementations and the
* tools where sharing isn't a major concern because the BDS stays private
* and the file is generally not supposed to be used by a second process,
* so we just request permission according to the flags.
*
* The exceptions are xen_disk and blockdev_init(); in these cases, the
* caller of blk_new_open() doesn't make use of the permissions, but they
* shouldn't hurt either. We can still share everything here because the
* guest devices will add their own blockers if they can't share.
*/
if ((flags & BDRV_O_NO_IO) == 0) {
perm |= BLK_PERM_CONSISTENT_READ;
if (flags & BDRV_O_RDWR) {
perm |= BLK_PERM_WRITE;
}
}
if (flags & BDRV_O_RESIZE) {
perm |= BLK_PERM_RESIZE;
}
if (flags & BDRV_O_NO_SHARE) {
shared = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
}
blk = blk_new(qemu_get_aio_context(), perm, shared);
bs = bdrv_open(filename, reference, options, flags, errp);
if (!bs) {
blk_unref(blk);
return NULL;
}
blk->root = bdrv_root_attach_child(bs, "root", &child_root,
BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
perm, shared, blk, errp);
if (!blk->root) {
blk_unref(blk);
return NULL;
}
return blk;
}
static void blk_delete(BlockBackend *blk)
{
assert(!blk->refcnt);
assert(!blk->name);
assert(!blk->dev);
if (blk->public.throttle_group_member.throttle_state) {
blk_io_limits_disable(blk);
}
if (blk->root) {
blk_remove_bs(blk);
}
if (blk->vmsh) {
qemu_del_vm_change_state_handler(blk->vmsh);
blk->vmsh = NULL;
}
assert(QLIST_EMPTY(&blk->remove_bs_notifiers.notifiers));
assert(QLIST_EMPTY(&blk->insert_bs_notifiers.notifiers));
assert(QLIST_EMPTY(&blk->aio_notifiers));
QTAILQ_REMOVE(&block_backends, blk, link);
drive_info_del(blk->legacy_dinfo);
block_acct_cleanup(&blk->stats);
g_free(blk);
}
static void drive_info_del(DriveInfo *dinfo)
{
if (!dinfo) {
return;
}
qemu_opts_del(dinfo->opts);
g_free(dinfo);
}
int blk_get_refcnt(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk ? blk->refcnt : 0;
}
/*
* Increment @blk's reference count.
* @blk must not be null.
*/
void blk_ref(BlockBackend *blk)
{
assert(blk->refcnt > 0);
GLOBAL_STATE_CODE();
blk->refcnt++;
}
/*
* Decrement @blk's reference count.
* If this drops it to zero, destroy @blk.
* For convenience, do nothing if @blk is null.
*/
void blk_unref(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
if (blk) {
assert(blk->refcnt > 0);
if (blk->refcnt > 1) {
blk->refcnt--;
} else {
blk_drain(blk);
/* blk_drain() cannot resurrect blk, nobody held a reference */
assert(blk->refcnt == 1);
blk->refcnt = 0;
blk_delete(blk);
}
}
}
/*
* Behaves similarly to blk_next() but iterates over all BlockBackends, even the
* ones which are hidden (i.e. are not referenced by the monitor).
*/
BlockBackend *blk_all_next(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk ? QTAILQ_NEXT(blk, link)
: QTAILQ_FIRST(&block_backends);
}
void blk_remove_all_bs(void)
{
BlockBackend *blk = NULL;
GLOBAL_STATE_CODE();
while ((blk = blk_all_next(blk)) != NULL) {
AioContext *ctx = blk_get_aio_context(blk);
aio_context_acquire(ctx);
if (blk->root) {
blk_remove_bs(blk);
}
aio_context_release(ctx);
}
}
/*
* Return the monitor-owned 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)
{
GLOBAL_STATE_CODE();
return blk ? QTAILQ_NEXT(blk, monitor_link)
: QTAILQ_FIRST(&monitor_block_backends);
}
/* Iterates over all top-level BlockDriverStates, i.e. BDSs that are owned by
* the monitor or attached to a BlockBackend */
BlockDriverState *bdrv_next(BdrvNextIterator *it)
{
BlockDriverState *bs, *old_bs;
/* Must be called from the main loop */
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
/* First, return all root nodes of BlockBackends. In order to avoid
* returning a BDS twice when multiple BBs refer to it, we only return it
* if the BB is the first one in the parent list of the BDS. */
if (it->phase == BDRV_NEXT_BACKEND_ROOTS) {
BlockBackend *old_blk = it->blk;
old_bs = old_blk ? blk_bs(old_blk) : NULL;
do {
it->blk = blk_all_next(it->blk);
bs = it->blk ? blk_bs(it->blk) : NULL;
} while (it->blk && (bs == NULL || bdrv_first_blk(bs) != it->blk));
if (it->blk) {
blk_ref(it->blk);
}
blk_unref(old_blk);
if (bs) {
bdrv_ref(bs);
bdrv_unref(old_bs);
return bs;
}
it->phase = BDRV_NEXT_MONITOR_OWNED;
} else {
old_bs = it->bs;
}
/* Then return the monitor-owned BDSes without a BB attached. Ignore all
* BDSes that are attached to a BlockBackend here; they have been handled
* by the above block already */
do {
it->bs = bdrv_next_monitor_owned(it->bs);
bs = it->bs;
} while (bs && bdrv_has_blk(bs));
if (bs) {
bdrv_ref(bs);
}
bdrv_unref(old_bs);
return bs;
}
static void bdrv_next_reset(BdrvNextIterator *it)
{
*it = (BdrvNextIterator) {
.phase = BDRV_NEXT_BACKEND_ROOTS,
};
}
BlockDriverState *bdrv_first(BdrvNextIterator *it)
{
GLOBAL_STATE_CODE();
bdrv_next_reset(it);
return bdrv_next(it);
}
/* Must be called when aborting a bdrv_next() iteration before
* bdrv_next() returns NULL */
void bdrv_next_cleanup(BdrvNextIterator *it)
{
/* Must be called from the main loop */
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
if (it->phase == BDRV_NEXT_BACKEND_ROOTS) {
if (it->blk) {
bdrv_unref(blk_bs(it->blk));
blk_unref(it->blk);
}
} else {
bdrv_unref(it->bs);
}
bdrv_next_reset(it);
}
/*
* Add a BlockBackend into the list of backends referenced by the monitor, with
* the given @name acting as the handle for the monitor.
* Strictly for use by blockdev.c.
*
* @name must not be null or empty.
*
* Returns true on success and false on failure. In the latter case, an Error
* object is returned through @errp.
*/
bool monitor_add_blk(BlockBackend *blk, const char *name, Error **errp)
{
assert(!blk->name);
assert(name && name[0]);
GLOBAL_STATE_CODE();
if (!id_wellformed(name)) {
error_setg(errp, "Invalid device name");
return false;
}
if (blk_by_name(name)) {
error_setg(errp, "Device with id '%s' already exists", name);
return false;
}
if (bdrv_find_node(name)) {
error_setg(errp,
"Device name '%s' conflicts with an existing node name",
name);
return false;
}
blk->name = g_strdup(name);
QTAILQ_INSERT_TAIL(&monitor_block_backends, blk, monitor_link);
return true;
}
/*
* Remove a BlockBackend from the list of backends referenced by the monitor.
* Strictly for use by blockdev.c.
*/
void monitor_remove_blk(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
if (!blk->name) {
return;
}
QTAILQ_REMOVE(&monitor_block_backends, blk, monitor_link);
g_free(blk->name);
blk->name = NULL;
}
/*
* Return @blk's name, a non-null string.
* Returns an empty string iff @blk is not referenced by the monitor.
*/
const char *blk_name(const BlockBackend *blk)
{
IO_CODE();
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 = NULL;
GLOBAL_STATE_CODE();
assert(name);
while ((blk = blk_next(blk)) != NULL) {
if (!strcmp(name, blk->name)) {
return blk;
}
}
return NULL;
}
/*
* Return the BlockDriverState attached to @blk if any, else null.
*/
BlockDriverState *blk_bs(BlockBackend *blk)
{
IO_CODE();
return blk->root ? blk->root->bs : NULL;
}
static BlockBackend *bdrv_first_blk(BlockDriverState *bs)
{
BdrvChild *child;
GLOBAL_STATE_CODE();
QLIST_FOREACH(child, &bs->parents, next_parent) {
if (child->klass == &child_root) {
return child->opaque;
}
}
return NULL;
}
/*
* Returns true if @bs has an associated BlockBackend.
*/
bool bdrv_has_blk(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
return bdrv_first_blk(bs) != NULL;
}
/*
* Returns true if @bs has only BlockBackends as parents.
*/
bool bdrv_is_root_node(BlockDriverState *bs)
{
BdrvChild *c;
GLOBAL_STATE_CODE();
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->klass != &child_root) {
return false;
}
}
return true;
}
/*
* Return @blk's DriveInfo if any, else null.
*/
DriveInfo *blk_legacy_dinfo(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk->legacy_dinfo;
}
/*
* Set @blk's DriveInfo to @dinfo, and return it.
* @blk must not have a DriveInfo set already.
* No other BlockBackend may have the same DriveInfo set.
*/
DriveInfo *blk_set_legacy_dinfo(BlockBackend *blk, DriveInfo *dinfo)
{
assert(!blk->legacy_dinfo);
GLOBAL_STATE_CODE();
return blk->legacy_dinfo = dinfo;
}
/*
* Return the BlockBackend with DriveInfo @dinfo.
* It must exist.
*/
BlockBackend *blk_by_legacy_dinfo(DriveInfo *dinfo)
{
BlockBackend *blk = NULL;
GLOBAL_STATE_CODE();
while ((blk = blk_next(blk)) != NULL) {
if (blk->legacy_dinfo == dinfo) {
return blk;
}
}
abort();
}
/*
* Returns a pointer to the publicly accessible fields of @blk.
*/
BlockBackendPublic *blk_get_public(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return &blk->public;
}
/*
* Returns a BlockBackend given the associated @public fields.
*/
BlockBackend *blk_by_public(BlockBackendPublic *public)
{
GLOBAL_STATE_CODE();
return container_of(public, BlockBackend, public);
}
/*
* Disassociates the currently associated BlockDriverState from @blk.
*/
void blk_remove_bs(BlockBackend *blk)
{
ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
BdrvChild *root;
GLOBAL_STATE_CODE();
notifier_list_notify(&blk->remove_bs_notifiers, blk);
if (tgm->throttle_state) {
BlockDriverState *bs = blk_bs(blk);
/*
* Take a ref in case blk_bs() changes across bdrv_drained_begin(), for
* example, if a temporary filter node is removed by a blockjob.
*/
bdrv_ref(bs);
bdrv_drained_begin(bs);
throttle_group_detach_aio_context(tgm);
throttle_group_attach_aio_context(tgm, qemu_get_aio_context());
bdrv_drained_end(bs);
bdrv_unref(bs);
}
blk_update_root_state(blk);
/* bdrv_root_unref_child() will cause blk->root to become stale and may
* switch to a completion coroutine later on. Let's drain all I/O here
* to avoid that and a potential QEMU crash.
*/
blk_drain(blk);
root = blk->root;
blk->root = NULL;
bdrv_root_unref_child(root);
}
/*
* Associates a new BlockDriverState with @blk.
*/
int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)
{
ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
GLOBAL_STATE_CODE();
bdrv_ref(bs);
blk->root = bdrv_root_attach_child(bs, "root", &child_root,
BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
blk->perm, blk->shared_perm,
blk, errp);
if (blk->root == NULL) {
return -EPERM;
}
notifier_list_notify(&blk->insert_bs_notifiers, blk);
if (tgm->throttle_state) {
throttle_group_detach_aio_context(tgm);
throttle_group_attach_aio_context(tgm, bdrv_get_aio_context(bs));
}
return 0;
}
/*
* Change BlockDriverState associated with @blk.
*/
int blk_replace_bs(BlockBackend *blk, BlockDriverState *new_bs, Error **errp)
{
GLOBAL_STATE_CODE();
return bdrv_replace_child_bs(blk->root, new_bs, errp);
}
/*
* Sets the permission bitmasks that the user of the BlockBackend needs.
*/
int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
Error **errp)
{
int ret;
GLOBAL_STATE_CODE();
if (blk->root && !blk->disable_perm) {
ret = bdrv_child_try_set_perm(blk->root, perm, shared_perm, errp);
if (ret < 0) {
return ret;
}
}
blk->perm = perm;
blk->shared_perm = shared_perm;
return 0;
}
void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm)
{
GLOBAL_STATE_CODE();
*perm = blk->perm;
*shared_perm = blk->shared_perm;
}
/*
* Attach device model @dev to @blk.
* Return 0 on success, -EBUSY when a device model is attached already.
*/
int blk_attach_dev(BlockBackend *blk, DeviceState *dev)
{
GLOBAL_STATE_CODE();
if (blk->dev) {
return -EBUSY;
}
/* While migration is still incoming, we don't need to apply the
* permissions of guest device BlockBackends. We might still have a block
* job or NBD server writing to the image for storage migration. */
if (runstate_check(RUN_STATE_INMIGRATE)) {
blk->disable_perm = true;
}
blk_ref(blk);
blk->dev = dev;
blk_iostatus_reset(blk);
return 0;
}
/*
* Detach device model @dev from @blk.
* @dev must be currently attached to @blk.
*/
void blk_detach_dev(BlockBackend *blk, DeviceState *dev)
{
assert(blk->dev == dev);
GLOBAL_STATE_CODE();
blk->dev = NULL;
blk->dev_ops = NULL;
blk->dev_opaque = NULL;
blk_set_perm(blk, 0, BLK_PERM_ALL, &error_abort);
blk_unref(blk);
}
/*
* Return the device model attached to @blk if any, else null.
*/
DeviceState *blk_get_attached_dev(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk->dev;
}
/* Return the qdev ID, or if no ID is assigned the QOM path, of the block
* device attached to the BlockBackend. */
char *blk_get_attached_dev_id(BlockBackend *blk)
{
DeviceState *dev = blk->dev;
IO_CODE();
if (!dev) {
return g_strdup("");
} else if (dev->id) {
return g_strdup(dev->id);
}
return object_get_canonical_path(OBJECT(dev)) ?: g_strdup("");
}
/*
* Return the BlockBackend which has the device model @dev attached if it
* exists, else null.
*
* @dev must not be null.
*/
BlockBackend *blk_by_dev(void *dev)
{
BlockBackend *blk = NULL;
GLOBAL_STATE_CODE();
assert(dev != NULL);
while ((blk = blk_all_next(blk)) != NULL) {
if (blk->dev == dev) {
return blk;
}
}
return NULL;
}
/*
* Set @blk's device model callbacks to @ops.
* @opaque is the opaque argument to pass to the callbacks.
* This is for use by device models.
*/
void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops,
void *opaque)
{
GLOBAL_STATE_CODE();
blk->dev_ops = ops;
blk->dev_opaque = opaque;
/* Are we currently quiesced? Should we enforce this right now? */
if (blk->quiesce_counter && ops && ops->drained_begin) {
ops->drained_begin(opaque);
}
}
/*
* Notify @blk's attached device model of media change.
*
* If @load is true, notify of media load. This action can fail, meaning that
* the medium cannot be loaded. @errp is set then.
*
* If @load is false, notify of media eject. This can never fail.
*
* Also send DEVICE_TRAY_MOVED events as appropriate.
*/
void blk_dev_change_media_cb(BlockBackend *blk, bool load, Error **errp)
{
GLOBAL_STATE_CODE();
if (blk->dev_ops && blk->dev_ops->change_media_cb) {
bool tray_was_open, tray_is_open;
Error *local_err = NULL;
tray_was_open = blk_dev_is_tray_open(blk);
blk->dev_ops->change_media_cb(blk->dev_opaque, load, &local_err);
if (local_err) {
assert(load == true);
error_propagate(errp, local_err);
return;
}
tray_is_open = blk_dev_is_tray_open(blk);
if (tray_was_open != tray_is_open) {
char *id = blk_get_attached_dev_id(blk);
qapi_event_send_device_tray_moved(blk_name(blk), id, tray_is_open);
g_free(id);
}
}
}
static void blk_root_change_media(BdrvChild *child, bool load)
{
blk_dev_change_media_cb(child->opaque, load, NULL);
}
/*
* Does @blk's attached device model have removable media?
* %true if no device model is attached.
*/
bool blk_dev_has_removable_media(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return !blk->dev || (blk->dev_ops && blk->dev_ops->change_media_cb);
}
/*
* Does @blk's attached device model have a tray?
*/
bool blk_dev_has_tray(BlockBackend *blk)
{
IO_CODE();
return blk->dev_ops && blk->dev_ops->is_tray_open;
}
/*
* Notify @blk's attached device model of a media eject request.
* If @force is true, the medium is about to be yanked out forcefully.
*/
void blk_dev_eject_request(BlockBackend *blk, bool force)
{
GLOBAL_STATE_CODE();
if (blk->dev_ops && blk->dev_ops->eject_request_cb) {
blk->dev_ops->eject_request_cb(blk->dev_opaque, force);
}
}
/*
* Does @blk's attached device model have a tray, and is it open?
*/
bool blk_dev_is_tray_open(BlockBackend *blk)
{
IO_CODE();
if (blk_dev_has_tray(blk)) {
return blk->dev_ops->is_tray_open(blk->dev_opaque);
}
return false;
}
/*
* Does @blk's attached device model have the medium locked?
* %false if the device model has no such lock.
*/
bool blk_dev_is_medium_locked(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
if (blk->dev_ops && blk->dev_ops->is_medium_locked) {
return blk->dev_ops->is_medium_locked(blk->dev_opaque);
}
return false;
}
/*
* Notify @blk's attached device model of a backend size change.
*/
static void blk_root_resize(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
if (blk->dev_ops && blk->dev_ops->resize_cb) {
blk->dev_ops->resize_cb(blk->dev_opaque);
}
}
void blk_iostatus_enable(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
blk->iostatus_enabled = true;
blk->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
}
/* The I/O status is only enabled if the drive explicitly
* enables it _and_ the VM is configured to stop on errors */
bool blk_iostatus_is_enabled(const BlockBackend *blk)
{
IO_CODE();
return (blk->iostatus_enabled &&
(blk->on_write_error == BLOCKDEV_ON_ERROR_ENOSPC ||
blk->on_write_error == BLOCKDEV_ON_ERROR_STOP ||
blk->on_read_error == BLOCKDEV_ON_ERROR_STOP));
}
BlockDeviceIoStatus blk_iostatus(const BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk->iostatus;
}
void blk_iostatus_disable(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
blk->iostatus_enabled = false;
}
void blk_iostatus_reset(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
if (blk_iostatus_is_enabled(blk)) {
blk->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
}
}
void blk_iostatus_set_err(BlockBackend *blk, int error)
{
IO_CODE();
assert(blk_iostatus_is_enabled(blk));
if (blk->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
blk->iostatus = error == ENOSPC ? BLOCK_DEVICE_IO_STATUS_NOSPACE :
BLOCK_DEVICE_IO_STATUS_FAILED;
}
}
void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow)
{
IO_CODE();
blk->allow_write_beyond_eof = allow;
}
void blk_set_allow_aio_context_change(BlockBackend *blk, bool allow)
{
IO_CODE();
blk->allow_aio_context_change = allow;
}
void blk_set_disable_request_queuing(BlockBackend *blk, bool disable)
{
IO_CODE();
blk->disable_request_queuing = disable;
}
static int blk_check_byte_request(BlockBackend *blk, int64_t offset,
int64_t bytes)
{
int64_t len;
if (bytes < 0) {
return -EIO;
}
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
if (offset < 0) {
return -EIO;
}
if (!blk->allow_write_beyond_eof) {
len = blk_getlength(blk);
if (len < 0) {
return len;
}
if (offset > len || len - offset < bytes) {
return -EIO;
}
}
return 0;
}
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static void coroutine_fn blk_wait_while_drained(BlockBackend *blk)
{
assert(blk->in_flight > 0);
if (blk->quiesce_counter && !blk->disable_request_queuing) {
blk_dec_in_flight(blk);
qemu_co_queue_wait(&blk->queued_requests, NULL);
blk_inc_in_flight(blk);
}
}
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_co_do_preadv_part(BlockBackend *blk, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
int ret;
BlockDriverState *bs;
IO_CODE();
blk_wait_while_drained(blk);
/* Call blk_bs() only after waiting, the graph may have changed */
bs = blk_bs(blk);
trace_blk_co_preadv(blk, bs, offset, bytes, flags);
ret = blk_check_byte_request(blk, offset, bytes);
if (ret < 0) {
return ret;
}
bdrv_inc_in_flight(bs);
/* throttling disk I/O */
if (blk->public.throttle_group_member.throttle_state) {
throttle_group_co_io_limits_intercept(&blk->public.throttle_group_member,
bytes, false);
}
ret = bdrv_co_preadv_part(blk->root, offset, bytes, qiov, qiov_offset,
flags);
bdrv_dec_in_flight(bs);
return ret;
}
int coroutine_fn blk_co_pread(BlockBackend *blk, int64_t offset, int64_t bytes,
void *buf, BdrvRequestFlags flags)
{
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
IO_OR_GS_CODE();
assert(bytes <= SIZE_MAX);
return blk_co_preadv(blk, offset, bytes, &qiov, flags);
}
int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
int64_t bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
int ret;
IO_OR_GS_CODE();
blk_inc_in_flight(blk);
ret = blk_co_do_preadv_part(blk, offset, bytes, qiov, 0, flags);
blk_dec_in_flight(blk);
return ret;
}
int coroutine_fn blk_co_preadv_part(BlockBackend *blk, int64_t offset,
int64_t bytes, QEMUIOVector *qiov,
size_t qiov_offset, BdrvRequestFlags flags)
{
int ret;
IO_OR_GS_CODE();
blk_inc_in_flight(blk);
ret = blk_co_do_preadv_part(blk, offset, bytes, qiov, qiov_offset, flags);
blk_dec_in_flight(blk);
return ret;
}
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_co_do_pwritev_part(BlockBackend *blk, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
int ret;
BlockDriverState *bs;
IO_CODE();
blk_wait_while_drained(blk);
/* Call blk_bs() only after waiting, the graph may have changed */
bs = blk_bs(blk);
trace_blk_co_pwritev(blk, bs, offset, bytes, flags);
ret = blk_check_byte_request(blk, offset, bytes);
if (ret < 0) {
return ret;
}
bdrv_inc_in_flight(bs);
/* throttling disk I/O */
if (blk->public.throttle_group_member.throttle_state) {
throttle_group_co_io_limits_intercept(&blk->public.throttle_group_member,
bytes, true);
}
if (!blk->enable_write_cache) {
flags |= BDRV_REQ_FUA;
}
ret = bdrv_co_pwritev_part(blk->root, offset, bytes, qiov, qiov_offset,
flags);
bdrv_dec_in_flight(bs);
return ret;
}
int coroutine_fn blk_co_pwritev_part(BlockBackend *blk, int64_t offset,
int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
int ret;
IO_OR_GS_CODE();
blk_inc_in_flight(blk);
ret = blk_co_do_pwritev_part(blk, offset, bytes, qiov, qiov_offset, flags);
blk_dec_in_flight(blk);
return ret;
}
int coroutine_fn blk_co_pwrite(BlockBackend *blk, int64_t offset, int64_t bytes,
const void *buf, BdrvRequestFlags flags)
{
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
IO_OR_GS_CODE();
assert(bytes <= SIZE_MAX);
return blk_co_pwritev(blk, offset, bytes, &qiov, flags);
}
int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
int64_t bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
IO_OR_GS_CODE();
return blk_co_pwritev_part(blk, offset, bytes, qiov, 0, flags);
}
typedef struct BlkRwCo {
BlockBackend *blk;
int64_t offset;
void *iobuf;
int ret;
BdrvRequestFlags flags;
} BlkRwCo;
int blk_make_zero(BlockBackend *blk, BdrvRequestFlags flags)
{
GLOBAL_STATE_CODE();
return bdrv_make_zero(blk->root, flags);
}
void blk_inc_in_flight(BlockBackend *blk)
{
IO_CODE();
qatomic_inc(&blk->in_flight);
}
void blk_dec_in_flight(BlockBackend *blk)
{
IO_CODE();
qatomic_dec(&blk->in_flight);
aio_wait_kick();
}
static void error_callback_bh(void *opaque)
{
struct BlockBackendAIOCB *acb = opaque;
blk_dec_in_flight(acb->blk);
acb->common.cb(acb->common.opaque, acb->ret);
qemu_aio_unref(acb);
}
BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
BlockCompletionFunc *cb,
void *opaque, int ret)
{
struct BlockBackendAIOCB *acb;
IO_CODE();
blk_inc_in_flight(blk);
acb = blk_aio_get(&block_backend_aiocb_info, blk, cb, opaque);
acb->blk = blk;
acb->ret = ret;
replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
error_callback_bh, acb);
return &acb->common;
}
typedef struct BlkAioEmAIOCB {
BlockAIOCB common;
BlkRwCo rwco;
int64_t bytes;
bool has_returned;
} BlkAioEmAIOCB;
static AioContext *blk_aio_em_aiocb_get_aio_context(BlockAIOCB *acb_)
{
BlkAioEmAIOCB *acb = container_of(acb_, BlkAioEmAIOCB, common);
return blk_get_aio_context(acb->rwco.blk);
}
static const AIOCBInfo blk_aio_em_aiocb_info = {
.aiocb_size = sizeof(BlkAioEmAIOCB),
.get_aio_context = blk_aio_em_aiocb_get_aio_context,
};
static void blk_aio_complete(BlkAioEmAIOCB *acb)
{
if (acb->has_returned) {
acb->common.cb(acb->common.opaque, acb->rwco.ret);
blk_dec_in_flight(acb->rwco.blk);
qemu_aio_unref(acb);
}
}
static void blk_aio_complete_bh(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
assert(acb->has_returned);
blk_aio_complete(acb);
}
static BlockAIOCB *blk_aio_prwv(BlockBackend *blk, int64_t offset,
int64_t bytes,
void *iobuf, CoroutineEntry co_entry,
BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
{
BlkAioEmAIOCB *acb;
Coroutine *co;
blk_inc_in_flight(blk);
acb = blk_aio_get(&blk_aio_em_aiocb_info, blk, cb, opaque);
acb->rwco = (BlkRwCo) {
.blk = blk,
.offset = offset,
.iobuf = iobuf,
.flags = flags,
.ret = NOT_DONE,
};
acb->bytes = bytes;
acb->has_returned = false;
co = qemu_coroutine_create(co_entry, acb);
bdrv_coroutine_enter(blk_bs(blk), co);
acb->has_returned = true;
if (acb->rwco.ret != NOT_DONE) {
replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
blk_aio_complete_bh, acb);
}
return &acb->common;
}
static void coroutine_fn blk_aio_read_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
QEMUIOVector *qiov = rwco->iobuf;
assert(qiov->size == acb->bytes);
rwco->ret = blk_co_do_preadv_part(rwco->blk, rwco->offset, acb->bytes, qiov,
0, rwco->flags);
blk_aio_complete(acb);
}
static void coroutine_fn blk_aio_write_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
QEMUIOVector *qiov = rwco->iobuf;
assert(!qiov || qiov->size == acb->bytes);
rwco->ret = blk_co_do_pwritev_part(rwco->blk, rwco->offset, acb->bytes,
qiov, 0, rwco->flags);
blk_aio_complete(acb);
}
BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
int64_t bytes, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
{
IO_CODE();
return blk_aio_prwv(blk, offset, bytes, NULL, blk_aio_write_entry,
flags | BDRV_REQ_ZERO_WRITE, cb, opaque);
}
int64_t blk_getlength(BlockBackend *blk)
{
IO_CODE();
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_getlength(blk_bs(blk));
}
void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr)
{
IO_CODE();
if (!blk_bs(blk)) {
*nb_sectors_ptr = 0;
} else {
bdrv_get_geometry(blk_bs(blk), nb_sectors_ptr);
}
}
int64_t blk_nb_sectors(BlockBackend *blk)
{
IO_CODE();
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_nb_sectors(blk_bs(blk));
}
BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
QEMUIOVector *qiov, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
{
IO_CODE();
assert((uint64_t)qiov->size <= INT64_MAX);
return blk_aio_prwv(blk, offset, qiov->size, qiov,
blk_aio_read_entry, flags, cb, opaque);
}
BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
QEMUIOVector *qiov, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
{
IO_CODE();
assert((uint64_t)qiov->size <= INT64_MAX);
return blk_aio_prwv(blk, offset, qiov->size, qiov,
blk_aio_write_entry, flags, cb, opaque);
}
void blk_aio_cancel(BlockAIOCB *acb)
{
GLOBAL_STATE_CODE();
bdrv_aio_cancel(acb);
}
void blk_aio_cancel_async(BlockAIOCB *acb)
{
IO_CODE();
bdrv_aio_cancel_async(acb);
}
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_co_do_ioctl(BlockBackend *blk, unsigned long int req, void *buf)
{
IO_CODE();
blk_wait_while_drained(blk);
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_co_ioctl(blk_bs(blk), req, buf);
}
int coroutine_fn blk_co_ioctl(BlockBackend *blk, unsigned long int req,
void *buf)
{
int ret;
IO_OR_GS_CODE();
blk_inc_in_flight(blk);
ret = blk_co_do_ioctl(blk, req, buf);
blk_dec_in_flight(blk);
return ret;
}
static void coroutine_fn blk_aio_ioctl_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
rwco->ret = blk_co_do_ioctl(rwco->blk, rwco->offset, rwco->iobuf);
blk_aio_complete(acb);
}
BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
BlockCompletionFunc *cb, void *opaque)
{
IO_CODE();
return blk_aio_prwv(blk, req, 0, buf, blk_aio_ioctl_entry, 0, cb, opaque);
}
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_co_do_pdiscard(BlockBackend *blk, int64_t offset, int64_t bytes)
{
int ret;
IO_CODE();
blk_wait_while_drained(blk);
ret = blk_check_byte_request(blk, offset, bytes);
if (ret < 0) {
return ret;
}
return bdrv_co_pdiscard(blk->root, offset, bytes);
}
static void coroutine_fn blk_aio_pdiscard_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
rwco->ret = blk_co_do_pdiscard(rwco->blk, rwco->offset, acb->bytes);
blk_aio_complete(acb);
}
BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk,
int64_t offset, int64_t bytes,
BlockCompletionFunc *cb, void *opaque)
{
IO_CODE();
return blk_aio_prwv(blk, offset, bytes, NULL, blk_aio_pdiscard_entry, 0,
cb, opaque);
}
int coroutine_fn blk_co_pdiscard(BlockBackend *blk, int64_t offset,
int64_t bytes)
{
int ret;
IO_OR_GS_CODE();
blk_inc_in_flight(blk);
ret = blk_co_do_pdiscard(blk, offset, bytes);
blk_dec_in_flight(blk);
return ret;
}
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn blk_co_do_flush(BlockBackend *blk)
{
blk_wait_while_drained(blk);
IO_CODE();
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_co_flush(blk_bs(blk));
}
static void coroutine_fn blk_aio_flush_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
rwco->ret = blk_co_do_flush(rwco->blk);
blk_aio_complete(acb);
}
BlockAIOCB *blk_aio_flush(BlockBackend *blk,
BlockCompletionFunc *cb, void *opaque)
{
IO_CODE();
return blk_aio_prwv(blk, 0, 0, NULL, blk_aio_flush_entry, 0, cb, opaque);
}
int coroutine_fn blk_co_flush(BlockBackend *blk)
{
int ret;
IO_OR_GS_CODE();
blk_inc_in_flight(blk);
ret = blk_co_do_flush(blk);
blk_dec_in_flight(blk);
return ret;
}
void blk_drain(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (bs) {
bdrv_ref(bs);
bdrv_drained_begin(bs);
}
/* We may have -ENOMEDIUM completions in flight */
AIO_WAIT_WHILE(blk_get_aio_context(blk),
qatomic_mb_read(&blk->in_flight) > 0);
if (bs) {
bdrv_drained_end(bs);
bdrv_unref(bs);
}
}
void blk_drain_all(void)
{
BlockBackend *blk = NULL;
GLOBAL_STATE_CODE();
bdrv_drain_all_begin();
while ((blk = blk_all_next(blk)) != NULL) {
AioContext *ctx = blk_get_aio_context(blk);
aio_context_acquire(ctx);
/* We may have -ENOMEDIUM completions in flight */
AIO_WAIT_WHILE(ctx, qatomic_mb_read(&blk->in_flight) > 0);
aio_context_release(ctx);
}
bdrv_drain_all_end();
}
void blk_set_on_error(BlockBackend *blk, BlockdevOnError on_read_error,
BlockdevOnError on_write_error)
{
GLOBAL_STATE_CODE();
blk->on_read_error = on_read_error;
blk->on_write_error = on_write_error;
}
BlockdevOnError blk_get_on_error(BlockBackend *blk, bool is_read)
{
IO_CODE();
return is_read ? blk->on_read_error : blk->on_write_error;
}
BlockErrorAction blk_get_error_action(BlockBackend *blk, bool is_read,
int error)
{
BlockdevOnError on_err = blk_get_on_error(blk, is_read);
IO_CODE();
switch (on_err) {
case BLOCKDEV_ON_ERROR_ENOSPC:
return (error == ENOSPC) ?
BLOCK_ERROR_ACTION_STOP : BLOCK_ERROR_ACTION_REPORT;
case BLOCKDEV_ON_ERROR_STOP:
return BLOCK_ERROR_ACTION_STOP;
case BLOCKDEV_ON_ERROR_REPORT:
return BLOCK_ERROR_ACTION_REPORT;
case BLOCKDEV_ON_ERROR_IGNORE:
return BLOCK_ERROR_ACTION_IGNORE;
case BLOCKDEV_ON_ERROR_AUTO:
default:
abort();
}
}
static void send_qmp_error_event(BlockBackend *blk,
BlockErrorAction action,
bool is_read, int error)
{
IoOperationType optype;
BlockDriverState *bs = blk_bs(blk);
optype = is_read ? IO_OPERATION_TYPE_READ : IO_OPERATION_TYPE_WRITE;
qapi_event_send_block_io_error(blk_name(blk), !!bs,
bs ? bdrv_get_node_name(bs) : NULL, optype,
action, blk_iostatus_is_enabled(blk),
error == ENOSPC, strerror(error));
}
/* This is done by device models because, while the block layer knows
* about the error, it does not know whether an operation comes from
* the device or the block layer (from a job, for example).
*/
void blk_error_action(BlockBackend *blk, BlockErrorAction action,
bool is_read, int error)
{
assert(error >= 0);
IO_CODE();
if (action == BLOCK_ERROR_ACTION_STOP) {
/* First set the iostatus, so that "info block" returns an iostatus
* that matches the events raised so far (an additional error iostatus
* is fine, but not a lost one).
*/
blk_iostatus_set_err(blk, error);
/* Then raise the request to stop the VM and the event.
* qemu_system_vmstop_request_prepare has two effects. First,
* it ensures that the STOP event always comes after the
* BLOCK_IO_ERROR event. Second, it ensures that even if management
* can observe the STOP event and do a "cont" before the STOP
* event is issued, the VM will not stop. In this case, vm_start()
* also ensures that the STOP/RESUME pair of events is emitted.
*/
qemu_system_vmstop_request_prepare();
send_qmp_error_event(blk, action, is_read, error);
qemu_system_vmstop_request(RUN_STATE_IO_ERROR);
} else {
send_qmp_error_event(blk, action, is_read, error);
}
}
/*
* Returns true if the BlockBackend can support taking write permissions
* (because its root node is not read-only).
*/
bool blk_supports_write_perm(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (bs) {
return !bdrv_is_read_only(bs);
} else {
return blk->root_state.open_flags & BDRV_O_RDWR;
}
}
/*
* Returns true if the BlockBackend can be written to in its current
* configuration (i.e. if write permission have been requested)
*/
bool blk_is_writable(BlockBackend *blk)
{
IO_CODE();
return blk->perm & BLK_PERM_WRITE;
}
bool blk_is_sg(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (!bs) {
return false;
}
return bdrv_is_sg(bs);
}
bool blk_enable_write_cache(BlockBackend *blk)
{
IO_CODE();
return blk->enable_write_cache;
}
void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
{
GLOBAL_STATE_CODE();
blk->enable_write_cache = wce;
}
void blk_activate(BlockBackend *blk, Error **errp)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (!bs) {
error_setg(errp, "Device '%s' has no medium", blk->name);
return;
}
bdrv_activate(bs, errp);
}
bool blk_is_inserted(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
IO_CODE();
return bs && bdrv_is_inserted(bs);
}
bool blk_is_available(BlockBackend *blk)
{
IO_CODE();
return blk_is_inserted(blk) && !blk_dev_is_tray_open(blk);
}
void blk_lock_medium(BlockBackend *blk, bool locked)
{
BlockDriverState *bs = blk_bs(blk);
IO_CODE();
if (bs) {
bdrv_lock_medium(bs, locked);
}
}
void blk_eject(BlockBackend *blk, bool eject_flag)
{
BlockDriverState *bs = blk_bs(blk);
char *id;
IO_CODE();
if (bs) {
bdrv_eject(bs, eject_flag);
}
/* Whether or not we ejected on the backend,
* the frontend experienced a tray event. */
id = blk_get_attached_dev_id(blk);
qapi_event_send_device_tray_moved(blk_name(blk), id,
eject_flag);
g_free(id);
}
int blk_get_flags(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (bs) {
return bdrv_get_flags(bs);
} else {
return blk->root_state.open_flags;
}
}
/* Returns the minimum request alignment, in bytes; guaranteed nonzero */
uint32_t blk_get_request_alignment(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
IO_CODE();
return bs ? bs->bl.request_alignment : BDRV_SECTOR_SIZE;
}
/* Returns the maximum hardware transfer length, in bytes; guaranteed nonzero */
uint64_t blk_get_max_hw_transfer(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
uint64_t max = INT_MAX;
IO_CODE();
if (bs) {
max = MIN_NON_ZERO(max, bs->bl.max_hw_transfer);
max = MIN_NON_ZERO(max, bs->bl.max_transfer);
}
return ROUND_DOWN(max, blk_get_request_alignment(blk));
}
/* Returns the maximum transfer length, in bytes; guaranteed nonzero */
uint32_t blk_get_max_transfer(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
uint32_t max = INT_MAX;
IO_CODE();
if (bs) {
max = MIN_NON_ZERO(max, bs->bl.max_transfer);
}
return ROUND_DOWN(max, blk_get_request_alignment(blk));
}
int blk_get_max_hw_iov(BlockBackend *blk)
{
IO_CODE();
return MIN_NON_ZERO(blk->root->bs->bl.max_hw_iov,
blk->root->bs->bl.max_iov);
}
int blk_get_max_iov(BlockBackend *blk)
{
IO_CODE();
return blk->root->bs->bl.max_iov;
}
void *blk_try_blockalign(BlockBackend *blk, size_t size)
{
IO_CODE();
return qemu_try_blockalign(blk ? blk_bs(blk) : NULL, size);
}
void *blk_blockalign(BlockBackend *blk, size_t size)
{
IO_CODE();
return qemu_blockalign(blk ? blk_bs(blk) : NULL, size);
}
bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (!bs) {
return false;
}
return bdrv_op_is_blocked(bs, op, errp);
}
void blk_op_unblock(BlockBackend *blk, BlockOpType op, Error *reason)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (bs) {
bdrv_op_unblock(bs, op, reason);
}
}
void blk_op_block_all(BlockBackend *blk, Error *reason)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (bs) {
bdrv_op_block_all(bs, reason);
}
}
void blk_op_unblock_all(BlockBackend *blk, Error *reason)
{
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (bs) {
bdrv_op_unblock_all(bs, reason);
}
}
AioContext *blk_get_aio_context(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
IO_CODE();
if (bs) {
AioContext *ctx = bdrv_get_aio_context(blk_bs(blk));
assert(ctx == blk->ctx);
}
return blk->ctx;
}
static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb)
{
BlockBackendAIOCB *blk_acb = DO_UPCAST(BlockBackendAIOCB, common, acb);
return blk_get_aio_context(blk_acb->blk);
}
static int blk_do_set_aio_context(BlockBackend *blk, AioContext *new_context,
bool update_root_node, Error **errp)
{
BlockDriverState *bs = blk_bs(blk);
ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
int ret;
if (bs) {
bdrv_ref(bs);
if (update_root_node) {
ret = bdrv_child_try_set_aio_context(bs, new_context, blk->root,
errp);
if (ret < 0) {
bdrv_unref(bs);
return ret;
}
}
if (tgm->throttle_state) {
bdrv_drained_begin(bs);
throttle_group_detach_aio_context(tgm);
throttle_group_attach_aio_context(tgm, new_context);
bdrv_drained_end(bs);
}
bdrv_unref(bs);
}
blk->ctx = new_context;
return 0;
}
int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
Error **errp)
{
GLOBAL_STATE_CODE();
return blk_do_set_aio_context(blk, new_context, true, errp);
}
static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore, Error **errp)
{
BlockBackend *blk = child->opaque;
if (blk->allow_aio_context_change) {
return true;
}
/* Only manually created BlockBackends that are not attached to anything
* can change their AioContext without updating their user. */
if (!blk->name || blk->dev) {
/* TODO Add BB name/QOM path */
error_setg(errp, "Cannot change iothread of active block backend");
return false;
}
return true;
}
static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore)
{
BlockBackend *blk = child->opaque;
blk_do_set_aio_context(blk, ctx, false, &error_abort);
}
void blk_add_aio_context_notifier(BlockBackend *blk,
void (*attached_aio_context)(AioContext *new_context, void *opaque),
void (*detach_aio_context)(void *opaque), void *opaque)
{
BlockBackendAioNotifier *notifier;
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
notifier = g_new(BlockBackendAioNotifier, 1);
notifier->attached_aio_context = attached_aio_context;
notifier->detach_aio_context = detach_aio_context;
notifier->opaque = opaque;
QLIST_INSERT_HEAD(&blk->aio_notifiers, notifier, list);
if (bs) {
bdrv_add_aio_context_notifier(bs, attached_aio_context,
detach_aio_context, opaque);
}
}
void blk_remove_aio_context_notifier(BlockBackend *blk,
void (*attached_aio_context)(AioContext *,
void *),
void (*detach_aio_context)(void *),
void *opaque)
{
BlockBackendAioNotifier *notifier;
BlockDriverState *bs = blk_bs(blk);
GLOBAL_STATE_CODE();
if (bs) {
bdrv_remove_aio_context_notifier(bs, attached_aio_context,
detach_aio_context, opaque);
}
QLIST_FOREACH(notifier, &blk->aio_notifiers, list) {
if (notifier->attached_aio_context == attached_aio_context &&
notifier->detach_aio_context == detach_aio_context &&
notifier->opaque == opaque) {
QLIST_REMOVE(notifier, list);
g_free(notifier);
return;
}
}
abort();
}
void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify)
{
GLOBAL_STATE_CODE();
notifier_list_add(&blk->remove_bs_notifiers, notify);
}
void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify)
{
GLOBAL_STATE_CODE();
notifier_list_add(&blk->insert_bs_notifiers, notify);
}
void blk_io_plug(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
IO_CODE();
if (bs) {
bdrv_io_plug(bs);
}
}
void blk_io_unplug(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
IO_CODE();
if (bs) {
bdrv_io_unplug(bs);
}
}
BlockAcctStats *blk_get_stats(BlockBackend *blk)
{
IO_CODE();
return &blk->stats;
}
void *blk_aio_get(const AIOCBInfo *aiocb_info, BlockBackend *blk,
BlockCompletionFunc *cb, void *opaque)
{
IO_CODE();
return qemu_aio_get(aiocb_info, blk_bs(blk), cb, opaque);
}
int coroutine_fn blk_co_pwrite_zeroes(BlockBackend *blk, int64_t offset,
int64_t bytes, BdrvRequestFlags flags)
{
IO_OR_GS_CODE();
return blk_co_pwritev(blk, offset, bytes, NULL,
flags | BDRV_REQ_ZERO_WRITE);
}
int coroutine_fn blk_co_pwrite_compressed(BlockBackend *blk, int64_t offset,
int64_t bytes, const void *buf)
{
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
IO_OR_GS_CODE();
return blk_co_pwritev_part(blk, offset, bytes, &qiov, 0,
BDRV_REQ_WRITE_COMPRESSED);
}
int coroutine_fn blk_co_truncate(BlockBackend *blk, int64_t offset, bool exact,
PreallocMode prealloc, BdrvRequestFlags flags,
Error **errp)
{
IO_OR_GS_CODE();
if (!blk_is_available(blk)) {
error_setg(errp, "No medium inserted");
return -ENOMEDIUM;
}
return bdrv_co_truncate(blk->root, offset, exact, prealloc, flags, errp);
}
int blk_save_vmstate(BlockBackend *blk, const uint8_t *buf,
int64_t pos, int size)
{
int ret;
GLOBAL_STATE_CODE();
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
ret = bdrv_save_vmstate(blk_bs(blk), buf, pos, size);
if (ret < 0) {
return ret;
}
if (ret == size && !blk->enable_write_cache) {
ret = bdrv_flush(blk_bs(blk));
}
return ret < 0 ? ret : size;
}
int blk_load_vmstate(BlockBackend *blk, uint8_t *buf, int64_t pos, int size)
{
GLOBAL_STATE_CODE();
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_load_vmstate(blk_bs(blk), buf, pos, size);
}
int blk_probe_blocksizes(BlockBackend *blk, BlockSizes *bsz)
{
GLOBAL_STATE_CODE();
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_probe_blocksizes(blk_bs(blk), bsz);
}
int blk_probe_geometry(BlockBackend *blk, HDGeometry *geo)
{
GLOBAL_STATE_CODE();
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_probe_geometry(blk_bs(blk), geo);
}
/*
* Updates the BlockBackendRootState object with data from the currently
* attached BlockDriverState.
*/
void blk_update_root_state(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
assert(blk->root);
blk->root_state.open_flags = blk->root->bs->open_flags;
blk->root_state.detect_zeroes = blk->root->bs->detect_zeroes;
}
/*
* Returns the detect-zeroes setting to be used for bdrv_open() of a
* BlockDriverState which is supposed to inherit the root state.
*/
bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk->root_state.detect_zeroes;
}
/*
* Returns the flags to be used for bdrv_open() of a BlockDriverState which is
* supposed to inherit the root state.
*/
int blk_get_open_flags_from_root_state(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk->root_state.open_flags;
}
BlockBackendRootState *blk_get_root_state(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return &blk->root_state;
}
int blk_commit_all(void)
{
BlockBackend *blk = NULL;
GLOBAL_STATE_CODE();
while ((blk = blk_all_next(blk)) != NULL) {
AioContext *aio_context = blk_get_aio_context(blk);
BlockDriverState *unfiltered_bs = bdrv_skip_filters(blk_bs(blk));
aio_context_acquire(aio_context);
if (blk_is_inserted(blk) && bdrv_cow_child(unfiltered_bs)) {
int ret;
ret = bdrv_commit(unfiltered_bs);
if (ret < 0) {
aio_context_release(aio_context);
return ret;
}
}
aio_context_release(aio_context);
}
return 0;
}
/* throttling disk I/O limits */
void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg)
{
GLOBAL_STATE_CODE();
throttle_group_config(&blk->public.throttle_group_member, cfg);
}
void blk_io_limits_disable(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
assert(tgm->throttle_state);
GLOBAL_STATE_CODE();
if (bs) {
bdrv_ref(bs);
bdrv_drained_begin(bs);
}
throttle_group_unregister_tgm(tgm);
if (bs) {
bdrv_drained_end(bs);
bdrv_unref(bs);
}
}
/* should be called before blk_set_io_limits if a limit is set */
void blk_io_limits_enable(BlockBackend *blk, const char *group)
{
assert(!blk->public.throttle_group_member.throttle_state);
GLOBAL_STATE_CODE();
throttle_group_register_tgm(&blk->public.throttle_group_member,
group, blk_get_aio_context(blk));
}
void blk_io_limits_update_group(BlockBackend *blk, const char *group)
{
GLOBAL_STATE_CODE();
/* this BB is not part of any group */
if (!blk->public.throttle_group_member.throttle_state) {
return;
}
/* this BB is a part of the same group than the one we want */
if (!g_strcmp0(throttle_group_get_name(&blk->public.throttle_group_member),
group)) {
return;
}
/* need to change the group this bs belong to */
blk_io_limits_disable(blk);
blk_io_limits_enable(blk, group);
}
static void blk_root_drained_begin(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
if (++blk->quiesce_counter == 1) {
if (blk->dev_ops && blk->dev_ops->drained_begin) {
blk->dev_ops->drained_begin(blk->dev_opaque);
}
}
/* Note that blk->root may not be accessible here yet if we are just
* attaching to a BlockDriverState that is drained. Use child instead. */
if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
throttle_group_restart_tgm(tgm);
}
}
static bool blk_root_drained_poll(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
bool busy = false;
assert(blk->quiesce_counter);
if (blk->dev_ops && blk->dev_ops->drained_poll) {
busy = blk->dev_ops->drained_poll(blk->dev_opaque);
}
return busy || !!blk->in_flight;
}
static void blk_root_drained_end(BdrvChild *child, int *drained_end_counter)
{
BlockBackend *blk = child->opaque;
assert(blk->quiesce_counter);
assert(blk->public.throttle_group_member.io_limits_disabled);
qatomic_dec(&blk->public.throttle_group_member.io_limits_disabled);
if (--blk->quiesce_counter == 0) {
if (blk->dev_ops && blk->dev_ops->drained_end) {
blk->dev_ops->drained_end(blk->dev_opaque);
}
while (qemu_co_enter_next(&blk->queued_requests, NULL)) {
/* Resume all queued requests */
}
}
}
void blk_register_buf(BlockBackend *blk, void *host, size_t size)
{
GLOBAL_STATE_CODE();
bdrv_register_buf(blk_bs(blk), host, size);
}
void blk_unregister_buf(BlockBackend *blk, void *host)
{
GLOBAL_STATE_CODE();
bdrv_unregister_buf(blk_bs(blk), host);
}
int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
BlockBackend *blk_out, int64_t off_out,
int64_t bytes, BdrvRequestFlags read_flags,
BdrvRequestFlags write_flags)
{
int r;
IO_CODE();
r = blk_check_byte_request(blk_in, off_in, bytes);
if (r) {
return r;
}
r = blk_check_byte_request(blk_out, off_out, bytes);
if (r) {
return r;
}
return bdrv_co_copy_range(blk_in->root, off_in,
blk_out->root, off_out,
bytes, read_flags, write_flags);
}
const BdrvChild *blk_root(BlockBackend *blk)
{
GLOBAL_STATE_CODE();
return blk->root;
}
int blk_make_empty(BlockBackend *blk, Error **errp)
{
GLOBAL_STATE_CODE();
if (!blk_is_available(blk)) {
error_setg(errp, "No medium inserted");
return -ENOMEDIUM;
}
return bdrv_make_empty(blk->root, errp);
}
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