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qemu/block/block-backend.c
Max Reitz e037c09c78 block: Do not poll in bdrv_do_drained_end() 
We should never poll anywhere in bdrv_do_drained_end() (including its
recursive callees like bdrv_drain_invoke()), because it does not cope
well with graph changes.  In fact, it has been written based on the
postulation that no graph changes will happen in it.

Instead, the callers that want to poll must poll, i.e. all currently
globally available wrappers: bdrv_drained_end(),
bdrv_subtree_drained_end(), bdrv_unapply_subtree_drain(), and
bdrv_drain_all_end().  Graph changes there do not matter.

They can poll simply by passing a pointer to a drained_end_counter and
wait until it reaches 0.

This patch also adds a non-polling global wrapper for
bdrv_do_drained_end() that takes a drained_end_counter pointer.  We need
such a variant because now no function called anywhere from
bdrv_do_drained_end() must poll.  This includes
BdrvChildRole.drained_end(), which already must not poll according to
its interface documentation, but bdrv_child_cb_drained_end() just
violates that by invoking bdrv_drained_end() (which does poll).
Therefore, BdrvChildRole.drained_end() must take a *drained_end_counter
parameter, which bdrv_child_cb_drained_end() can pass on to the new
bdrv_drained_end_no_poll() function.

Note that we now have a pattern of all drained_end-related functions
either polling or receiving a *drained_end_counter to let the caller
poll based on that.

A problem with a single poll loop is that when the drained section in
bdrv_set_aio_context_ignore() ends, some nodes in the subgraph may be in
the old contexts, while others are in the new context already.  To let
the collective poll in bdrv_drained_end() work correctly, we must not
hold a lock to the old context, so that the old context can make
progress in case it is different from the current context.

(In the process, remove the comment saying that the current context is
always the old context, because it is wrong.)

In all other places, all nodes in a subtree must be in the same context,
so we can just poll that.  The exception of course is
bdrv_drain_all_end(), but that always runs in the main context, so we
can just poll NULL (like bdrv_drain_all_begin() does).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-07-19 13:19:16 +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/throttle-groups.h"
#include "sysemu/blockdev.h"
#include "sysemu/sysemu.h"
#include "qapi/error.h"
#include "qapi/qapi-events-block.h"
#include "qemu/id.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;
/* the block size for which the guest device expects atomicity */
int guest_block_size;
/* 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;
NotifierList remove_bs_notifiers, insert_bs_notifiers;
QLIST_HEAD(, BlockBackendAioNotifier) aio_notifiers;
int quiesce_counter;
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 */
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() */
static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
static void blk_root_inherit_options(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;
char *dev_id;
if (blk->name) {
return g_strdup(blk->name);
}
dev_id = blk_get_attached_dev_id(blk);
if (*dev_id) {
return dev_id;
} else {
/* TODO Callback into the BB owner for something more detailed */
g_free(dev_id);
return g_strdup("a block device");
}
}
static const char *blk_root_get_name(BdrvChild *child)
{
return blk_name(child->opaque);
}
static void blk_vm_state_changed(void *opaque, int 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;
if (!blk->disable_perm) {
return;
}
blk->disable_perm = false;
blk_set_perm(blk, blk->perm, BLK_PERM_ALL, &local_err);
if (local_err) {
error_propagate(errp, local_err);
blk->disable_perm = true;
return;
}
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)
{
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 const BdrvChildRole 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,
};
/*
* 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;
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);
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;
}
/*
* 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;
/* blk_new_open() is mainly used in .bdrv_create implementations and the
* tools where sharing isn't a concern because the BDS stays private, 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;
}
blk = blk_new(qemu_get_aio_context(), perm, BLK_PERM_ALL);
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, blk->ctx,
perm, BLK_PERM_ALL, 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)
{
return blk ? blk->refcnt : 0;
}
/*
* Increment @blk's reference count.
* @blk must not be null.
*/
void blk_ref(BlockBackend *blk)
{
assert(blk->refcnt > 0);
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)
{
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)
{
return blk ? QTAILQ_NEXT(blk, link)
: QTAILQ_FIRST(&block_backends);
}
void blk_remove_all_bs(void)
{
BlockBackend *blk = NULL;
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)
{
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)
{
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]);
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)
{
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)
{
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;
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)
{
return blk->root ? blk->root->bs : NULL;
}
static BlockBackend *bdrv_first_blk(BlockDriverState *bs)
{
BdrvChild *child;
QLIST_FOREACH(child, &bs->parents, next_parent) {
if (child->role == &child_root) {
return child->opaque;
}
}
return NULL;
}
/*
* Returns true if @bs has an associated BlockBackend.
*/
bool bdrv_has_blk(BlockDriverState *bs)
{
return bdrv_first_blk(bs) != NULL;
}
/*
* Returns true if @bs has only BlockBackends as parents.
*/
bool bdrv_is_root_node(BlockDriverState *bs)
{
BdrvChild *c;
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->role != &child_root) {
return false;
}
}
return true;
}
/*
* Return @blk's DriveInfo if any, else null.
*/
DriveInfo *blk_legacy_dinfo(BlockBackend *blk)
{
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);
return blk->legacy_dinfo = dinfo;
}
/*
* Return the BlockBackend with DriveInfo @dinfo.
* It must exist.
*/
BlockBackend *blk_by_legacy_dinfo(DriveInfo *dinfo)
{
BlockBackend *blk = NULL;
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)
{
return &blk->public;
}
/*
* Returns a BlockBackend given the associated @public fields.
*/
BlockBackend *blk_by_public(BlockBackendPublic *public)
{
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;
BlockDriverState *bs;
notifier_list_notify(&blk->remove_bs_notifiers, blk);
if (tgm->throttle_state) {
bs = blk_bs(blk);
bdrv_drained_begin(bs);
throttle_group_detach_aio_context(tgm);
throttle_group_attach_aio_context(tgm, qemu_get_aio_context());
bdrv_drained_end(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);
bdrv_root_unref_child(blk->root);
blk->root = NULL;
}
/*
* Associates a new BlockDriverState with @blk.
*/
int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)
{
ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
bdrv_ref(bs);
blk->root = bdrv_root_attach_child(bs, "root", &child_root, blk->ctx,
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;
}
/*
* 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;
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)
{
*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)
{
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);
blk->dev = NULL;
blk->dev_ops = NULL;
blk->dev_opaque = NULL;
blk->guest_block_size = 512;
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)
{
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;
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;
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)
{
blk->dev_ops = ops;
blk->dev_opaque = opaque;
/* Are we currently quiesced? Should we enforce this right now? */
if (blk->quiesce_counter && 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)
{
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)
{
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)
{
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)
{
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)
{
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)
{
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)
{
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)
{
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)
{
return blk->iostatus;
}
void blk_iostatus_disable(BlockBackend *blk)
{
blk->iostatus_enabled = false;
}
void blk_iostatus_reset(BlockBackend *blk)
{
if (blk_iostatus_is_enabled(blk)) {
blk->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
}
}
void blk_iostatus_set_err(BlockBackend *blk, int error)
{
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)
{
blk->allow_write_beyond_eof = allow;
}
void blk_set_allow_aio_context_change(BlockBackend *blk, bool allow)
{
blk->allow_aio_context_change = allow;
}
static int blk_check_byte_request(BlockBackend *blk, int64_t offset,
size_t size)
{
int64_t len;
if (size > INT_MAX) {
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 < size) {
return -EIO;
}
}
return 0;
}
int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
int ret;
BlockDriverState *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(blk->root, offset, bytes, qiov, flags);
bdrv_dec_in_flight(bs);
return ret;
}
int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
int ret;
BlockDriverState *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(blk->root, offset, bytes, qiov, flags);
bdrv_dec_in_flight(bs);
return ret;
}
typedef struct BlkRwCo {
BlockBackend *blk;
int64_t offset;
void *iobuf;
int ret;
BdrvRequestFlags flags;
} BlkRwCo;
static void blk_read_entry(void *opaque)
{
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;
rwco->ret = blk_co_preadv(rwco->blk, rwco->offset, qiov->size,
qiov, rwco->flags);
aio_wait_kick();
}
static void blk_write_entry(void *opaque)
{
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;
rwco->ret = blk_co_pwritev(rwco->blk, rwco->offset, qiov->size,
qiov, rwco->flags);
aio_wait_kick();
}
static int blk_prw(BlockBackend *blk, int64_t offset, uint8_t *buf,
int64_t bytes, CoroutineEntry co_entry,
BdrvRequestFlags flags)
{
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
BlkRwCo rwco = {
.blk = blk,
.offset = offset,
.iobuf = &qiov,
.flags = flags,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
co_entry(&rwco);
} else {
Coroutine *co = qemu_coroutine_create(co_entry, &rwco);
bdrv_coroutine_enter(blk_bs(blk), co);
BDRV_POLL_WHILE(blk_bs(blk), rwco.ret == NOT_DONE);
}
return rwco.ret;
}
int blk_pread_unthrottled(BlockBackend *blk, int64_t offset, uint8_t *buf,
int count)
{
int ret;
ret = blk_check_byte_request(blk, offset, count);
if (ret < 0) {
return ret;
}
blk_root_drained_begin(blk->root);
ret = blk_pread(blk, offset, buf, count);
blk_root_drained_end(blk->root, NULL);
return ret;
}
int blk_pwrite_zeroes(BlockBackend *blk, int64_t offset,
int bytes, BdrvRequestFlags flags)
{
return blk_prw(blk, offset, NULL, bytes, blk_write_entry,
flags | BDRV_REQ_ZERO_WRITE);
}
int blk_make_zero(BlockBackend *blk, BdrvRequestFlags flags)
{
return bdrv_make_zero(blk->root, flags);
}
void blk_inc_in_flight(BlockBackend *blk)
{
atomic_inc(&blk->in_flight);
}
void blk_dec_in_flight(BlockBackend *blk)
{
atomic_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;
blk_inc_in_flight(blk);
acb = blk_aio_get(&block_backend_aiocb_info, blk, cb, opaque);
acb->blk = blk;
acb->ret = ret;
aio_bh_schedule_oneshot(blk_get_aio_context(blk), error_callback_bh, acb);
return &acb->common;
}
typedef struct BlkAioEmAIOCB {
BlockAIOCB common;
BlkRwCo rwco;
int bytes;
bool has_returned;
} BlkAioEmAIOCB;
static const AIOCBInfo blk_aio_em_aiocb_info = {
.aiocb_size = sizeof(BlkAioEmAIOCB),
};
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, int 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) {
aio_bh_schedule_oneshot(blk_get_aio_context(blk),
blk_aio_complete_bh, acb);
}
return &acb->common;
}
static void 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_preadv(rwco->blk, rwco->offset, acb->bytes,
qiov, rwco->flags);
blk_aio_complete(acb);
}
static void 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_pwritev(rwco->blk, rwco->offset, acb->bytes,
qiov, rwco->flags);
blk_aio_complete(acb);
}
BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
int count, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
{
return blk_aio_prwv(blk, offset, count, NULL, blk_aio_write_entry,
flags | BDRV_REQ_ZERO_WRITE, cb, opaque);
}
int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int count)
{
int ret = blk_prw(blk, offset, buf, count, blk_read_entry, 0);
if (ret < 0) {
return ret;
}
return count;
}
int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count,
BdrvRequestFlags flags)
{
int ret = blk_prw(blk, offset, (void *) buf, count, blk_write_entry,
flags);
if (ret < 0) {
return ret;
}
return count;
}
int64_t blk_getlength(BlockBackend *blk)
{
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_getlength(blk_bs(blk));
}
void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr)
{
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)
{
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)
{
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)
{
return blk_aio_prwv(blk, offset, qiov->size, qiov,
blk_aio_write_entry, flags, cb, opaque);
}
static void blk_aio_flush_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
rwco->ret = blk_co_flush(rwco->blk);
blk_aio_complete(acb);
}
BlockAIOCB *blk_aio_flush(BlockBackend *blk,
BlockCompletionFunc *cb, void *opaque)
{
return blk_aio_prwv(blk, 0, 0, NULL, blk_aio_flush_entry, 0, cb, opaque);
}
static void blk_aio_pdiscard_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
rwco->ret = blk_co_pdiscard(rwco->blk, rwco->offset, acb->bytes);
blk_aio_complete(acb);
}
BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk,
int64_t offset, int bytes,
BlockCompletionFunc *cb, void *opaque)
{
return blk_aio_prwv(blk, offset, bytes, NULL, blk_aio_pdiscard_entry, 0,
cb, opaque);
}
void blk_aio_cancel(BlockAIOCB *acb)
{
bdrv_aio_cancel(acb);
}
void blk_aio_cancel_async(BlockAIOCB *acb)
{
bdrv_aio_cancel_async(acb);
}
int blk_co_ioctl(BlockBackend *blk, unsigned long int req, void *buf)
{
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_co_ioctl(blk_bs(blk), req, buf);
}
static void blk_ioctl_entry(void *opaque)
{
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;
rwco->ret = blk_co_ioctl(rwco->blk, rwco->offset,
qiov->iov[0].iov_base);
aio_wait_kick();
}
int blk_ioctl(BlockBackend *blk, unsigned long int req, void *buf)
{
return blk_prw(blk, req, buf, 0, blk_ioctl_entry, 0);
}
static void blk_aio_ioctl_entry(void *opaque)
{
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;
rwco->ret = blk_co_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)
{
return blk_aio_prwv(blk, req, 0, buf, blk_aio_ioctl_entry, 0, cb, opaque);
}
int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int bytes)
{
int ret = blk_check_byte_request(blk, offset, bytes);
if (ret < 0) {
return ret;
}
return bdrv_co_pdiscard(blk->root, offset, bytes);
}
int blk_co_flush(BlockBackend *blk)
{
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_co_flush(blk_bs(blk));
}
static void blk_flush_entry(void *opaque)
{
BlkRwCo *rwco = opaque;
rwco->ret = blk_co_flush(rwco->blk);
aio_wait_kick();
}
int blk_flush(BlockBackend *blk)
{
return blk_prw(blk, 0, NULL, 0, blk_flush_entry, 0);
}
void blk_drain(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
bdrv_drained_begin(bs);
}
/* We may have -ENOMEDIUM completions in flight */
AIO_WAIT_WHILE(blk_get_aio_context(blk),
atomic_mb_read(&blk->in_flight) > 0);
if (bs) {
bdrv_drained_end(bs);
}
}
void blk_drain_all(void)
{
BlockBackend *blk = NULL;
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, atomic_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)
{
blk->on_read_error = on_read_error;
blk->on_write_error = on_write_error;
}
BlockdevOnError blk_get_on_error(BlockBackend *blk, bool is_read)
{
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);
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);
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);
}
}
bool blk_is_read_only(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
return bdrv_is_read_only(bs);
} else {
return blk->root_state.read_only;
}
}
bool blk_is_sg(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
if (!bs) {
return false;
}
return bdrv_is_sg(bs);
}
bool blk_enable_write_cache(BlockBackend *blk)
{
return blk->enable_write_cache;
}
void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
{
blk->enable_write_cache = wce;
}
void blk_invalidate_cache(BlockBackend *blk, Error **errp)
{
BlockDriverState *bs = blk_bs(blk);
if (!bs) {
error_setg(errp, "Device '%s' has no medium", blk->name);
return;
}
bdrv_invalidate_cache(bs, errp);
}
bool blk_is_inserted(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
return bs && bdrv_is_inserted(bs);
}
bool blk_is_available(BlockBackend *blk)
{
return blk_is_inserted(blk) && !blk_dev_is_tray_open(blk);
}
void blk_lock_medium(BlockBackend *blk, bool locked)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
bdrv_lock_medium(bs, locked);
}
}
void blk_eject(BlockBackend *blk, bool eject_flag)
{
BlockDriverState *bs = blk_bs(blk);
char *id;
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);
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);
return bs ? bs->bl.request_alignment : BDRV_SECTOR_SIZE;
}
/* 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 = 0;
if (bs) {
max = bs->bl.max_transfer;
}
return MIN_NON_ZERO(max, INT_MAX);
}
int blk_get_max_iov(BlockBackend *blk)
{
return blk->root->bs->bl.max_iov;
}
void blk_set_guest_block_size(BlockBackend *blk, int align)
{
blk->guest_block_size = align;
}
void *blk_try_blockalign(BlockBackend *blk, size_t size)
{
return qemu_try_blockalign(blk ? blk_bs(blk) : NULL, size);
}
void *blk_blockalign(BlockBackend *blk, size_t size)
{
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);
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);
if (bs) {
bdrv_op_unblock(bs, op, reason);
}
}
void blk_op_block_all(BlockBackend *blk, Error *reason)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
bdrv_op_block_all(bs, reason);
}
}
void blk_op_unblock_all(BlockBackend *blk, Error *reason)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
bdrv_op_unblock_all(bs, reason);
}
}
AioContext *blk_get_aio_context(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
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) {
if (update_root_node) {
ret = bdrv_child_try_set_aio_context(bs, new_context, blk->root,
errp);
if (ret < 0) {
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);
}
}
blk->ctx = new_context;
return 0;
}
int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
Error **errp)
{
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);
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);
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)
{
notifier_list_add(&blk->remove_bs_notifiers, notify);
}
void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify)
{
notifier_list_add(&blk->insert_bs_notifiers, notify);
}
void blk_io_plug(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
bdrv_io_plug(bs);
}
}
void blk_io_unplug(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
bdrv_io_unplug(bs);
}
}
BlockAcctStats *blk_get_stats(BlockBackend *blk)
{
return &blk->stats;
}
void *blk_aio_get(const AIOCBInfo *aiocb_info, BlockBackend *blk,
BlockCompletionFunc *cb, void *opaque)
{
return qemu_aio_get(aiocb_info, blk_bs(blk), cb, opaque);
}
int coroutine_fn blk_co_pwrite_zeroes(BlockBackend *blk, int64_t offset,
int bytes, BdrvRequestFlags flags)
{
return blk_co_pwritev(blk, offset, bytes, NULL,
flags | BDRV_REQ_ZERO_WRITE);
}
int blk_pwrite_compressed(BlockBackend *blk, int64_t offset, const void *buf,
int count)
{
return blk_prw(blk, offset, (void *) buf, count, blk_write_entry,
BDRV_REQ_WRITE_COMPRESSED);
}
int blk_truncate(BlockBackend *blk, int64_t offset, PreallocMode prealloc,
Error **errp)
{
if (!blk_is_available(blk)) {
error_setg(errp, "No medium inserted");
return -ENOMEDIUM;
}
return bdrv_truncate(blk->root, offset, prealloc, errp);
}
static void blk_pdiscard_entry(void *opaque)
{
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;
rwco->ret = blk_co_pdiscard(rwco->blk, rwco->offset, qiov->size);
aio_wait_kick();
}
int blk_pdiscard(BlockBackend *blk, int64_t offset, int bytes)
{
return blk_prw(blk, offset, NULL, bytes, blk_pdiscard_entry, 0);
}
int blk_save_vmstate(BlockBackend *blk, const uint8_t *buf,
int64_t pos, int size)
{
int ret;
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)
{
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)
{
if (!blk_is_available(blk)) {
return -ENOMEDIUM;
}
return bdrv_probe_blocksizes(blk_bs(blk), bsz);
}
int blk_probe_geometry(BlockBackend *blk, HDGeometry *geo)
{
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)
{
assert(blk->root);
blk->root_state.open_flags = blk->root->bs->open_flags;
blk->root_state.read_only = blk->root->bs->read_only;
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)
{
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)
{
int bs_flags;
bs_flags = blk->root_state.read_only ? 0 : BDRV_O_RDWR;
bs_flags |= blk->root_state.open_flags & ~BDRV_O_RDWR;
return bs_flags;
}
BlockBackendRootState *blk_get_root_state(BlockBackend *blk)
{
return &blk->root_state;
}
int blk_commit_all(void)
{
BlockBackend *blk = NULL;
while ((blk = blk_all_next(blk)) != NULL) {
AioContext *aio_context = blk_get_aio_context(blk);
aio_context_acquire(aio_context);
if (blk_is_inserted(blk) && blk->root->bs->backing) {
int ret = bdrv_commit(blk->root->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)
{
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);
if (bs) {
bdrv_drained_begin(bs);
}
throttle_group_unregister_tgm(tgm);
if (bs) {
bdrv_drained_end(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);
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)
{
/* 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;
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 (atomic_fetch_inc(&blk->public.throttle_group_member.io_limits_disabled) == 0) {
throttle_group_restart_tgm(&blk->public.throttle_group_member);
}
}
static bool blk_root_drained_poll(BdrvChild *child)
{
BlockBackend *blk = child->opaque;
assert(blk->quiesce_counter);
return !!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);
atomic_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);
}
}
}
void blk_register_buf(BlockBackend *blk, void *host, size_t size)
{
bdrv_register_buf(blk_bs(blk), host, size);
}
void blk_unregister_buf(BlockBackend *blk, void *host)
{
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,
int bytes, BdrvRequestFlags read_flags,
BdrvRequestFlags write_flags)
{
int r;
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)
{
return blk->root;
}
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