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qemu/block/io.c
Fam Zheng 178bd438af block: Walk bs->children carefully in bdrv_drain_recurse 
The recursive bdrv_drain_recurse may run a block job completion BH that
drops nodes. The coming changes will make that more likely and use-after-free
would happen without this patch

Stash the bs pointer and use bdrv_ref/bdrv_unref in addition to
QLIST_FOREACH_SAFE to prevent such a case from happening.

Since bdrv_unref accesses global state that is not protected by the AioContext
lock, we cannot use bdrv_ref/bdrv_unref unconditionally.  Fortunately the
protection is not needed in IOThread because only main loop can modify a graph
with the AioContext lock held.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170418143044.12187-2-famz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Tested-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-04-18 22:56:28 +08:00

2692 lines
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/*
* Block layer I/O functions
*
* Copyright (c) 2003 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "trace.h"
#include "sysemu/block-backend.h"
#include "block/blockjob.h"
#include "block/block_int.h"
#include "qemu/cutils.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
static BlockAIOCB *bdrv_co_aio_prw_vector(BdrvChild *child,
int64_t offset,
QEMUIOVector *qiov,
BdrvRequestFlags flags,
BlockCompletionFunc *cb,
void *opaque,
bool is_write);
static void coroutine_fn bdrv_co_do_rw(void *opaque);
static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int count, BdrvRequestFlags flags);
void bdrv_parent_drained_begin(BlockDriverState *bs)
{
BdrvChild *c;
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->role->drained_begin) {
c->role->drained_begin(c);
}
}
}
void bdrv_parent_drained_end(BlockDriverState *bs)
{
BdrvChild *c;
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->role->drained_end) {
c->role->drained_end(c);
}
}
}
static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src)
{
dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer);
dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_transfer);
dst->opt_mem_alignment = MAX(dst->opt_mem_alignment,
src->opt_mem_alignment);
dst->min_mem_alignment = MAX(dst->min_mem_alignment,
src->min_mem_alignment);
dst->max_iov = MIN_NON_ZERO(dst->max_iov, src->max_iov);
}
void bdrv_refresh_limits(BlockDriverState *bs, Error **errp)
{
BlockDriver *drv = bs->drv;
Error *local_err = NULL;
memset(&bs->bl, 0, sizeof(bs->bl));
if (!drv) {
return;
}
/* Default alignment based on whether driver has byte interface */
bs->bl.request_alignment = drv->bdrv_co_preadv ? 1 : 512;
/* Take some limits from the children as a default */
if (bs->file) {
bdrv_refresh_limits(bs->file->bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
bdrv_merge_limits(&bs->bl, &bs->file->bs->bl);
} else {
bs->bl.min_mem_alignment = 512;
bs->bl.opt_mem_alignment = getpagesize();
/* Safe default since most protocols use readv()/writev()/etc */
bs->bl.max_iov = IOV_MAX;
}
if (bs->backing) {
bdrv_refresh_limits(bs->backing->bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
bdrv_merge_limits(&bs->bl, &bs->backing->bs->bl);
}
/* Then let the driver override it */
if (drv->bdrv_refresh_limits) {
drv->bdrv_refresh_limits(bs, errp);
}
}
/**
* The copy-on-read flag is actually a reference count so multiple users may
* use the feature without worrying about clobbering its previous state.
* Copy-on-read stays enabled until all users have called to disable it.
*/
void bdrv_enable_copy_on_read(BlockDriverState *bs)
{
bs->copy_on_read++;
}
void bdrv_disable_copy_on_read(BlockDriverState *bs)
{
assert(bs->copy_on_read > 0);
bs->copy_on_read--;
}
/* Check if any requests are in-flight (including throttled requests) */
bool bdrv_requests_pending(BlockDriverState *bs)
{
BdrvChild *child;
if (atomic_read(&bs->in_flight)) {
return true;
}
QLIST_FOREACH(child, &bs->children, next) {
if (bdrv_requests_pending(child->bs)) {
return true;
}
}
return false;
}
static bool bdrv_drain_recurse(BlockDriverState *bs)
{
BdrvChild *child, *tmp;
bool waited;
waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0);
if (bs->drv && bs->drv->bdrv_drain) {
bs->drv->bdrv_drain(bs);
}
QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
BlockDriverState *bs = child->bs;
bool in_main_loop =
qemu_get_current_aio_context() == qemu_get_aio_context();
assert(bs->refcnt > 0);
if (in_main_loop) {
/* In case the recursive bdrv_drain_recurse processes a
* block_job_defer_to_main_loop BH and modifies the graph,
* let's hold a reference to bs until we are done.
*
* IOThread doesn't have such a BH, and it is not safe to call
* bdrv_unref without BQL, so skip doing it there.
*/
bdrv_ref(bs);
}
waited |= bdrv_drain_recurse(bs);
if (in_main_loop) {
bdrv_unref(bs);
}
}
return waited;
}
typedef struct {
Coroutine *co;
BlockDriverState *bs;
bool done;
} BdrvCoDrainData;
static void bdrv_co_drain_bh_cb(void *opaque)
{
BdrvCoDrainData *data = opaque;
Coroutine *co = data->co;
BlockDriverState *bs = data->bs;
bdrv_dec_in_flight(bs);
bdrv_drained_begin(bs);
data->done = true;
aio_co_wake(co);
}
static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs)
{
BdrvCoDrainData data;
/* Calling bdrv_drain() from a BH ensures the current coroutine yields and
* other coroutines run if they were queued from
* qemu_co_queue_run_restart(). */
assert(qemu_in_coroutine());
data = (BdrvCoDrainData) {
.co = qemu_coroutine_self(),
.bs = bs,
.done = false,
};
bdrv_inc_in_flight(bs);
aio_bh_schedule_oneshot(bdrv_get_aio_context(bs),
bdrv_co_drain_bh_cb, &data);
qemu_coroutine_yield();
/* If we are resumed from some other event (such as an aio completion or a
* timer callback), it is a bug in the caller that should be fixed. */
assert(data.done);
}
void bdrv_drained_begin(BlockDriverState *bs)
{
if (qemu_in_coroutine()) {
bdrv_co_yield_to_drain(bs);
return;
}
if (!bs->quiesce_counter++) {
aio_disable_external(bdrv_get_aio_context(bs));
bdrv_parent_drained_begin(bs);
}
bdrv_drain_recurse(bs);
}
void bdrv_drained_end(BlockDriverState *bs)
{
assert(bs->quiesce_counter > 0);
if (--bs->quiesce_counter > 0) {
return;
}
bdrv_parent_drained_end(bs);
aio_enable_external(bdrv_get_aio_context(bs));
}
/*
* Wait for pending requests to complete on a single BlockDriverState subtree,
* and suspend block driver's internal I/O until next request arrives.
*
* Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
* AioContext.
*
* Only this BlockDriverState's AioContext is run, so in-flight requests must
* not depend on events in other AioContexts. In that case, use
* bdrv_drain_all() instead.
*/
void coroutine_fn bdrv_co_drain(BlockDriverState *bs)
{
assert(qemu_in_coroutine());
bdrv_drained_begin(bs);
bdrv_drained_end(bs);
}
void bdrv_drain(BlockDriverState *bs)
{
bdrv_drained_begin(bs);
bdrv_drained_end(bs);
}
/*
* Wait for pending requests to complete across all BlockDriverStates
*
* This function does not flush data to disk, use bdrv_flush_all() for that
* after calling this function.
*
* This pauses all block jobs and disables external clients. It must
* be paired with bdrv_drain_all_end().
*
* NOTE: no new block jobs or BlockDriverStates can be created between
* the bdrv_drain_all_begin() and bdrv_drain_all_end() calls.
*/
void bdrv_drain_all_begin(void)
{
/* Always run first iteration so any pending completion BHs run */
bool waited = true;
BlockDriverState *bs;
BdrvNextIterator it;
BlockJob *job = NULL;
GSList *aio_ctxs = NULL, *ctx;
while ((job = block_job_next(job))) {
AioContext *aio_context = blk_get_aio_context(job->blk);
aio_context_acquire(aio_context);
block_job_pause(job);
aio_context_release(aio_context);
}
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
bdrv_parent_drained_begin(bs);
aio_disable_external(aio_context);
aio_context_release(aio_context);
if (!g_slist_find(aio_ctxs, aio_context)) {
aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
}
}
/* Note that completion of an asynchronous I/O operation can trigger any
* number of other I/O operations on other devices---for example a
* coroutine can submit an I/O request to another device in response to
* request completion. Therefore we must keep looping until there was no
* more activity rather than simply draining each device independently.
*/
while (waited) {
waited = false;
for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
AioContext *aio_context = ctx->data;
aio_context_acquire(aio_context);
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
if (aio_context == bdrv_get_aio_context(bs)) {
waited |= bdrv_drain_recurse(bs);
}
}
aio_context_release(aio_context);
}
}
g_slist_free(aio_ctxs);
}
void bdrv_drain_all_end(void)
{
BlockDriverState *bs;
BdrvNextIterator it;
BlockJob *job = NULL;
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
aio_enable_external(aio_context);
bdrv_parent_drained_end(bs);
aio_context_release(aio_context);
}
while ((job = block_job_next(job))) {
AioContext *aio_context = blk_get_aio_context(job->blk);
aio_context_acquire(aio_context);
block_job_resume(job);
aio_context_release(aio_context);
}
}
void bdrv_drain_all(void)
{
bdrv_drain_all_begin();
bdrv_drain_all_end();
}
/**
* Remove an active request from the tracked requests list
*
* This function should be called when a tracked request is completing.
*/
static void tracked_request_end(BdrvTrackedRequest *req)
{
if (req->serialising) {
req->bs->serialising_in_flight--;
}
QLIST_REMOVE(req, list);
qemu_co_queue_restart_all(&req->wait_queue);
}
/**
* Add an active request to the tracked requests list
*/
static void tracked_request_begin(BdrvTrackedRequest *req,
BlockDriverState *bs,
int64_t offset,
unsigned int bytes,
enum BdrvTrackedRequestType type)
{
*req = (BdrvTrackedRequest){
.bs = bs,
.offset = offset,
.bytes = bytes,
.type = type,
.co = qemu_coroutine_self(),
.serialising = false,
.overlap_offset = offset,
.overlap_bytes = bytes,
};
qemu_co_queue_init(&req->wait_queue);
QLIST_INSERT_HEAD(&bs->tracked_requests, req, list);
}
static void mark_request_serialising(BdrvTrackedRequest *req, uint64_t align)
{
int64_t overlap_offset = req->offset & ~(align - 1);
unsigned int overlap_bytes = ROUND_UP(req->offset + req->bytes, align)
- overlap_offset;
if (!req->serialising) {
req->bs->serialising_in_flight++;
req->serialising = true;
}
req->overlap_offset = MIN(req->overlap_offset, overlap_offset);
req->overlap_bytes = MAX(req->overlap_bytes, overlap_bytes);
}
/**
* Round a region to cluster boundaries (sector-based)
*/
void bdrv_round_sectors_to_clusters(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
int64_t *cluster_sector_num,
int *cluster_nb_sectors)
{
BlockDriverInfo bdi;
if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) {
*cluster_sector_num = sector_num;
*cluster_nb_sectors = nb_sectors;
} else {
int64_t c = bdi.cluster_size / BDRV_SECTOR_SIZE;
*cluster_sector_num = QEMU_ALIGN_DOWN(sector_num, c);
*cluster_nb_sectors = QEMU_ALIGN_UP(sector_num - *cluster_sector_num +
nb_sectors, c);
}
}
/**
* Round a region to cluster boundaries
*/
void bdrv_round_to_clusters(BlockDriverState *bs,
int64_t offset, unsigned int bytes,
int64_t *cluster_offset,
unsigned int *cluster_bytes)
{
BlockDriverInfo bdi;
if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) {
*cluster_offset = offset;
*cluster_bytes = bytes;
} else {
int64_t c = bdi.cluster_size;
*cluster_offset = QEMU_ALIGN_DOWN(offset, c);
*cluster_bytes = QEMU_ALIGN_UP(offset - *cluster_offset + bytes, c);
}
}
static int bdrv_get_cluster_size(BlockDriverState *bs)
{
BlockDriverInfo bdi;
int ret;
ret = bdrv_get_info(bs, &bdi);
if (ret < 0 || bdi.cluster_size == 0) {
return bs->bl.request_alignment;
} else {
return bdi.cluster_size;
}
}
static bool tracked_request_overlaps(BdrvTrackedRequest *req,
int64_t offset, unsigned int bytes)
{
/* aaaa bbbb */
if (offset >= req->overlap_offset + req->overlap_bytes) {
return false;
}
/* bbbb aaaa */
if (req->overlap_offset >= offset + bytes) {
return false;
}
return true;
}
void bdrv_inc_in_flight(BlockDriverState *bs)
{
atomic_inc(&bs->in_flight);
}
static void dummy_bh_cb(void *opaque)
{
}
void bdrv_wakeup(BlockDriverState *bs)
{
if (bs->wakeup) {
aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
}
}
void bdrv_dec_in_flight(BlockDriverState *bs)
{
atomic_dec(&bs->in_flight);
bdrv_wakeup(bs);
}
static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
{
BlockDriverState *bs = self->bs;
BdrvTrackedRequest *req;
bool retry;
bool waited = false;
if (!bs->serialising_in_flight) {
return false;
}
do {
retry = false;
QLIST_FOREACH(req, &bs->tracked_requests, list) {
if (req == self || (!req->serialising && !self->serialising)) {
continue;
}
if (tracked_request_overlaps(req, self->overlap_offset,
self->overlap_bytes))
{
/* Hitting this means there was a reentrant request, for
* example, a block driver issuing nested requests. This must
* never happen since it means deadlock.
*/
assert(qemu_coroutine_self() != req->co);
/* If the request is already (indirectly) waiting for us, or
* will wait for us as soon as it wakes up, then just go on
* (instead of producing a deadlock in the former case). */
if (!req->waiting_for) {
self->waiting_for = req;
qemu_co_queue_wait(&req->wait_queue, NULL);
self->waiting_for = NULL;
retry = true;
waited = true;
break;
}
}
}
} while (retry);
return waited;
}
static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
size_t size)
{
if (size > BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS) {
return -EIO;
}
if (!bdrv_is_inserted(bs)) {
return -ENOMEDIUM;
}
if (offset < 0) {
return -EIO;
}
return 0;
}
typedef struct RwCo {
BdrvChild *child;
int64_t offset;
QEMUIOVector *qiov;
bool is_write;
int ret;
BdrvRequestFlags flags;
} RwCo;
static void coroutine_fn bdrv_rw_co_entry(void *opaque)
{
RwCo *rwco = opaque;
if (!rwco->is_write) {
rwco->ret = bdrv_co_preadv(rwco->child, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
} else {
rwco->ret = bdrv_co_pwritev(rwco->child, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
}
}
/*
* Process a vectored synchronous request using coroutines
*/
static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
QEMUIOVector *qiov, bool is_write,
BdrvRequestFlags flags)
{
Coroutine *co;
RwCo rwco = {
.child = child,
.offset = offset,
.qiov = qiov,
.is_write = is_write,
.ret = NOT_DONE,
.flags = flags,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_rw_co_entry(&rwco);
} else {
co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco);
bdrv_coroutine_enter(child->bs, co);
BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE);
}
return rwco.ret;
}
/*
* Process a synchronous request using coroutines
*/
static int bdrv_rw_co(BdrvChild *child, int64_t sector_num, uint8_t *buf,
int nb_sectors, bool is_write, BdrvRequestFlags flags)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = nb_sectors * BDRV_SECTOR_SIZE,
};
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EINVAL;
}
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_prwv_co(child, sector_num << BDRV_SECTOR_BITS,
&qiov, is_write, flags);
}
/* return < 0 if error. See bdrv_write() for the return codes */
int bdrv_read(BdrvChild *child, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
return bdrv_rw_co(child, sector_num, buf, nb_sectors, false, 0);
}
/* Return < 0 if error. Important errors are:
-EIO generic I/O error (may happen for all errors)
-ENOMEDIUM No media inserted.
-EINVAL Invalid sector number or nb_sectors
-EACCES Trying to write a read-only device
*/
int bdrv_write(BdrvChild *child, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
return bdrv_rw_co(child, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
}
int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
int count, BdrvRequestFlags flags)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = NULL,
.iov_len = count,
};
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_prwv_co(child, offset, &qiov, true,
BDRV_REQ_ZERO_WRITE | flags);
}
/*
* Completely zero out a block device with the help of bdrv_pwrite_zeroes.
* The operation is sped up by checking the block status and only writing
* zeroes to the device if they currently do not return zeroes. Optional
* flags are passed through to bdrv_pwrite_zeroes (e.g. BDRV_REQ_MAY_UNMAP,
* BDRV_REQ_FUA).
*
* Returns < 0 on error, 0 on success. For error codes see bdrv_write().
*/
int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags)
{
int64_t target_sectors, ret, nb_sectors, sector_num = 0;
BlockDriverState *bs = child->bs;
BlockDriverState *file;
int n;
target_sectors = bdrv_nb_sectors(bs);
if (target_sectors < 0) {
return target_sectors;
}
for (;;) {
nb_sectors = MIN(target_sectors - sector_num, BDRV_REQUEST_MAX_SECTORS);
if (nb_sectors <= 0) {
return 0;
}
ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, &file);
if (ret < 0) {
error_report("error getting block status at sector %" PRId64 ": %s",
sector_num, strerror(-ret));
return ret;
}
if (ret & BDRV_BLOCK_ZERO) {
sector_num += n;
continue;
}
ret = bdrv_pwrite_zeroes(child, sector_num << BDRV_SECTOR_BITS,
n << BDRV_SECTOR_BITS, flags);
if (ret < 0) {
error_report("error writing zeroes at sector %" PRId64 ": %s",
sector_num, strerror(-ret));
return ret;
}
sector_num += n;
}
}
int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
{
int ret;
ret = bdrv_prwv_co(child, offset, qiov, false, 0);
if (ret < 0) {
return ret;
}
return qiov->size;
}
int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = bytes,
};
if (bytes < 0) {
return -EINVAL;
}
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_preadv(child, offset, &qiov);
}
int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
{
int ret;
ret = bdrv_prwv_co(child, offset, qiov, true, 0);
if (ret < 0) {
return ret;
}
return qiov->size;
}
int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, int bytes)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *) buf,
.iov_len = bytes,
};
if (bytes < 0) {
return -EINVAL;
}
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_pwritev(child, offset, &qiov);
}
/*
* Writes to the file and ensures that no writes are reordered across this
* request (acts as a barrier)
*
* Returns 0 on success, -errno in error cases.
*/
int bdrv_pwrite_sync(BdrvChild *child, int64_t offset,
const void *buf, int count)
{
int ret;
ret = bdrv_pwrite(child, offset, buf, count);
if (ret < 0) {
return ret;
}
ret = bdrv_flush(child->bs);
if (ret < 0) {
return ret;
}
return 0;
}
typedef struct CoroutineIOCompletion {
Coroutine *coroutine;
int ret;
} CoroutineIOCompletion;
static void bdrv_co_io_em_complete(void *opaque, int ret)
{
CoroutineIOCompletion *co = opaque;
co->ret = ret;
aio_co_wake(co->coroutine);
}
static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
int64_t sector_num;
unsigned int nb_sectors;
assert(!(flags & ~BDRV_REQ_MASK));
if (drv->bdrv_co_preadv) {
return drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags);
}
sector_num = offset >> BDRV_SECTOR_BITS;
nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
if (drv->bdrv_co_readv) {
return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
} else {
BlockAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_readv(bs, sector_num, qiov, nb_sectors,
bdrv_co_io_em_complete, &co);
if (acb == NULL) {
return -EIO;
} else {
qemu_coroutine_yield();
return co.ret;
}
}
}
static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
int64_t sector_num;
unsigned int nb_sectors;
int ret;
assert(!(flags & ~BDRV_REQ_MASK));
if (drv->bdrv_co_pwritev) {
ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov,
flags & bs->supported_write_flags);
flags &= ~bs->supported_write_flags;
goto emulate_flags;
}
sector_num = offset >> BDRV_SECTOR_BITS;
nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
if (drv->bdrv_co_writev_flags) {
ret = drv->bdrv_co_writev_flags(bs, sector_num, nb_sectors, qiov,
flags & bs->supported_write_flags);
flags &= ~bs->supported_write_flags;
} else if (drv->bdrv_co_writev) {
assert(!bs->supported_write_flags);
ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
} else {
BlockAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_writev(bs, sector_num, qiov, nb_sectors,
bdrv_co_io_em_complete, &co);
if (acb == NULL) {
ret = -EIO;
} else {
qemu_coroutine_yield();
ret = co.ret;
}
}
emulate_flags:
if (ret == 0 && (flags & BDRV_REQ_FUA)) {
ret = bdrv_co_flush(bs);
}
return ret;
}
static int coroutine_fn
bdrv_driver_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov)
{
BlockDriver *drv = bs->drv;
if (!drv->bdrv_co_pwritev_compressed) {
return -ENOTSUP;
}
return drv->bdrv_co_pwritev_compressed(bs, offset, bytes, qiov);
}
static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov)
{
BlockDriverState *bs = child->bs;
/* Perform I/O through a temporary buffer so that users who scribble over
* their read buffer while the operation is in progress do not end up
* modifying the image file. This is critical for zero-copy guest I/O
* where anything might happen inside guest memory.
*/
void *bounce_buffer;
BlockDriver *drv = bs->drv;
struct iovec iov;
QEMUIOVector bounce_qiov;
int64_t cluster_offset;
unsigned int cluster_bytes;
size_t skip_bytes;
int ret;
/* FIXME We cannot require callers to have write permissions when all they
* are doing is a read request. If we did things right, write permissions
* would be obtained anyway, but internally by the copy-on-read code. As
* long as it is implemented here rather than in a separat filter driver,
* the copy-on-read code doesn't have its own BdrvChild, however, for which
* it could request permissions. Therefore we have to bypass the permission
* system for the moment. */
// assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
/* Cover entire cluster so no additional backing file I/O is required when
* allocating cluster in the image file.
*/
bdrv_round_to_clusters(bs, offset, bytes, &cluster_offset, &cluster_bytes);
trace_bdrv_co_do_copy_on_readv(bs, offset, bytes,
cluster_offset, cluster_bytes);
iov.iov_len = cluster_bytes;
iov.iov_base = bounce_buffer = qemu_try_blockalign(bs, iov.iov_len);
if (bounce_buffer == NULL) {
ret = -ENOMEM;
goto err;
}
qemu_iovec_init_external(&bounce_qiov, &iov, 1);
ret = bdrv_driver_preadv(bs, cluster_offset, cluster_bytes,
&bounce_qiov, 0);
if (ret < 0) {
goto err;
}
if (drv->bdrv_co_pwrite_zeroes &&
buffer_is_zero(bounce_buffer, iov.iov_len)) {
/* FIXME: Should we (perhaps conditionally) be setting
* BDRV_REQ_MAY_UNMAP, if it will allow for a sparser copy
* that still correctly reads as zero? */
ret = bdrv_co_do_pwrite_zeroes(bs, cluster_offset, cluster_bytes, 0);
} else {
/* This does not change the data on the disk, it is not necessary
* to flush even in cache=writethrough mode.
*/
ret = bdrv_driver_pwritev(bs, cluster_offset, cluster_bytes,
&bounce_qiov, 0);
}
if (ret < 0) {
/* It might be okay to ignore write errors for guest requests. If this
* is a deliberate copy-on-read then we don't want to ignore the error.
* Simply report it in all cases.
*/
goto err;
}
skip_bytes = offset - cluster_offset;
qemu_iovec_from_buf(qiov, 0, bounce_buffer + skip_bytes, bytes);
err:
qemu_vfree(bounce_buffer);
return ret;
}
/*
* Forwards an already correctly aligned request to the BlockDriver. This
* handles copy on read, zeroing after EOF, and fragmentation of large
* reads; any other features must be implemented by the caller.
*/
static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child,
BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
int64_t align, QEMUIOVector *qiov, int flags)
{
BlockDriverState *bs = child->bs;
int64_t total_bytes, max_bytes;
int ret = 0;
uint64_t bytes_remaining = bytes;
int max_transfer;
assert(is_power_of_2(align));
assert((offset & (align - 1)) == 0);
assert((bytes & (align - 1)) == 0);
assert(!qiov || bytes == qiov->size);
assert((bs->open_flags & BDRV_O_NO_IO) == 0);
max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX),
align);
/* TODO: We would need a per-BDS .supported_read_flags and
* potential fallback support, if we ever implement any read flags
* to pass through to drivers. For now, there aren't any
* passthrough flags. */
assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_READ)));
/* Handle Copy on Read and associated serialisation */
if (flags & BDRV_REQ_COPY_ON_READ) {
/* If we touch the same cluster it counts as an overlap. This
* guarantees that allocating writes will be serialized and not race
* with each other for the same cluster. For example, in copy-on-read
* it ensures that the CoR read and write operations are atomic and
* guest writes cannot interleave between them. */
mark_request_serialising(req, bdrv_get_cluster_size(bs));
}
if (!(flags & BDRV_REQ_NO_SERIALISING)) {
wait_serialising_requests(req);
}
if (flags & BDRV_REQ_COPY_ON_READ) {
int64_t start_sector = offset >> BDRV_SECTOR_BITS;
int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
unsigned int nb_sectors = end_sector - start_sector;
int pnum;
ret = bdrv_is_allocated(bs, start_sector, nb_sectors, &pnum);
if (ret < 0) {
goto out;
}
if (!ret || pnum != nb_sectors) {
ret = bdrv_co_do_copy_on_readv(child, offset, bytes, qiov);
goto out;
}
}
/* Forward the request to the BlockDriver, possibly fragmenting it */
total_bytes = bdrv_getlength(bs);
if (total_bytes < 0) {
ret = total_bytes;
goto out;
}
max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align);
if (bytes <= max_bytes && bytes <= max_transfer) {
ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0);
goto out;
}
while (bytes_remaining) {
int num;
if (max_bytes) {
QEMUIOVector local_qiov;
num = MIN(bytes_remaining, MIN(max_bytes, max_transfer));
assert(num);
qemu_iovec_init(&local_qiov, qiov->niov);
qemu_iovec_concat(&local_qiov, qiov, bytes - bytes_remaining, num);
ret = bdrv_driver_preadv(bs, offset + bytes - bytes_remaining,
num, &local_qiov, 0);
max_bytes -= num;
qemu_iovec_destroy(&local_qiov);
} else {
num = bytes_remaining;
ret = qemu_iovec_memset(qiov, bytes - bytes_remaining, 0,
bytes_remaining);
}
if (ret < 0) {
goto out;
}
bytes_remaining -= num;
}
out:
return ret < 0 ? ret : 0;
}
/*
* Handle a read request in coroutine context
*/
int coroutine_fn bdrv_co_preadv(BdrvChild *child,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BlockDriverState *bs = child->bs;
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
uint64_t align = bs->bl.request_alignment;
uint8_t *head_buf = NULL;
uint8_t *tail_buf = NULL;
QEMUIOVector local_qiov;
bool use_local_qiov = false;
int ret;
if (!drv) {
return -ENOMEDIUM;
}
ret = bdrv_check_byte_request(bs, offset, bytes);
if (ret < 0) {
return ret;
}
bdrv_inc_in_flight(bs);
/* Don't do copy-on-read if we read data before write operation */
if (bs->copy_on_read && !(flags & BDRV_REQ_NO_SERIALISING)) {
flags |= BDRV_REQ_COPY_ON_READ;
}
/* Align read if necessary by padding qiov */
if (offset & (align - 1)) {
head_buf = qemu_blockalign(bs, align);
qemu_iovec_init(&local_qiov, qiov->niov + 2);
qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1));
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
bytes += offset & (align - 1);
offset = offset & ~(align - 1);
}
if ((offset + bytes) & (align - 1)) {
if (!use_local_qiov) {
qemu_iovec_init(&local_qiov, qiov->niov + 1);
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
}
tail_buf = qemu_blockalign(bs, align);
qemu_iovec_add(&local_qiov, tail_buf,
align - ((offset + bytes) & (align - 1)));
bytes = ROUND_UP(bytes, align);
}
tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_READ);
ret = bdrv_aligned_preadv(child, &req, offset, bytes, align,
use_local_qiov ? &local_qiov : qiov,
flags);
tracked_request_end(&req);
bdrv_dec_in_flight(bs);
if (use_local_qiov) {
qemu_iovec_destroy(&local_qiov);
qemu_vfree(head_buf);
qemu_vfree(tail_buf);
}
return ret;
}
static int coroutine_fn bdrv_co_do_readv(BdrvChild *child,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EINVAL;
}
return bdrv_co_preadv(child, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
int coroutine_fn bdrv_co_readv(BdrvChild *child, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_readv(child->bs, sector_num, nb_sectors);
return bdrv_co_do_readv(child, sector_num, nb_sectors, qiov, 0);
}
/* Maximum buffer for write zeroes fallback, in bytes */
#define MAX_WRITE_ZEROES_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS)
static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int count, BdrvRequestFlags flags)
{
BlockDriver *drv = bs->drv;
QEMUIOVector qiov;
struct iovec iov = {0};
int ret = 0;
bool need_flush = false;
int head = 0;
int tail = 0;
int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX);
int alignment = MAX(bs->bl.pwrite_zeroes_alignment,
bs->bl.request_alignment);
int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer,
MAX_WRITE_ZEROES_BOUNCE_BUFFER);
assert(alignment % bs->bl.request_alignment == 0);
head = offset % alignment;
tail = (offset + count) % alignment;
max_write_zeroes = QEMU_ALIGN_DOWN(max_write_zeroes, alignment);
assert(max_write_zeroes >= bs->bl.request_alignment);
while (count > 0 && !ret) {
int num = count;
/* Align request. Block drivers can expect the "bulk" of the request
* to be aligned, and that unaligned requests do not cross cluster
* boundaries.
*/
if (head) {
/* Make a small request up to the first aligned sector. For
* convenience, limit this request to max_transfer even if
* we don't need to fall back to writes. */
num = MIN(MIN(count, max_transfer), alignment - head);
head = (head + num) % alignment;
assert(num < max_write_zeroes);
} else if (tail && num > alignment) {
/* Shorten the request to the last aligned sector. */
num -= tail;
}
/* limit request size */
if (num > max_write_zeroes) {
num = max_write_zeroes;
}
ret = -ENOTSUP;
/* First try the efficient write zeroes operation */
if (drv->bdrv_co_pwrite_zeroes) {
ret = drv->bdrv_co_pwrite_zeroes(bs, offset, num,
flags & bs->supported_zero_flags);
if (ret != -ENOTSUP && (flags & BDRV_REQ_FUA) &&
!(bs->supported_zero_flags & BDRV_REQ_FUA)) {
need_flush = true;
}
} else {
assert(!bs->supported_zero_flags);
}
if (ret == -ENOTSUP) {
/* Fall back to bounce buffer if write zeroes is unsupported */
BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE;
if ((flags & BDRV_REQ_FUA) &&
!(bs->supported_write_flags & BDRV_REQ_FUA)) {
/* No need for bdrv_driver_pwrite() to do a fallback
* flush on each chunk; use just one at the end */
write_flags &= ~BDRV_REQ_FUA;
need_flush = true;
}
num = MIN(num, max_transfer);
iov.iov_len = num;
if (iov.iov_base == NULL) {
iov.iov_base = qemu_try_blockalign(bs, num);
if (iov.iov_base == NULL) {
ret = -ENOMEM;
goto fail;
}
memset(iov.iov_base, 0, num);
}
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_driver_pwritev(bs, offset, num, &qiov, write_flags);
/* Keep bounce buffer around if it is big enough for all
* all future requests.
*/
if (num < max_transfer) {
qemu_vfree(iov.iov_base);
iov.iov_base = NULL;
}
}
offset += num;
count -= num;
}
fail:
if (ret == 0 && need_flush) {
ret = bdrv_co_flush(bs);
}
qemu_vfree(iov.iov_base);
return ret;
}
/*
* Forwards an already correctly aligned write request to the BlockDriver,
* after possibly fragmenting it.
*/
static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
int64_t align, QEMUIOVector *qiov, int flags)
{
BlockDriverState *bs = child->bs;
BlockDriver *drv = bs->drv;
bool waited;
int ret;
int64_t start_sector = offset >> BDRV_SECTOR_BITS;
int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
uint64_t bytes_remaining = bytes;
int max_transfer;
assert(is_power_of_2(align));
assert((offset & (align - 1)) == 0);
assert((bytes & (align - 1)) == 0);
assert(!qiov || bytes == qiov->size);
assert((bs->open_flags & BDRV_O_NO_IO) == 0);
assert(!(flags & ~BDRV_REQ_MASK));
max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX),
align);
waited = wait_serialising_requests(req);
assert(!waited || !req->serialising);
assert(req->overlap_offset <= offset);
assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
/* FIXME: Block migration uses the BlockBackend of the guest device at a
* point when it has not yet taken write permissions. This will be
* fixed by a future patch, but for now we have to bypass this
* assertion for block migration to work. */
// assert(child->perm & BLK_PERM_WRITE);
/* FIXME: Because of the above, we also cannot guarantee that all format
* BDS take the BLK_PERM_RESIZE permission on their file BDS, since
* they are not obligated to do so if they do not have any parent
* that has taken the permission to write to them. */
// assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE);
ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
!(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes &&
qemu_iovec_is_zero(qiov)) {
flags |= BDRV_REQ_ZERO_WRITE;
if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
flags |= BDRV_REQ_MAY_UNMAP;
}
}
if (ret < 0) {
/* Do nothing, write notifier decided to fail this request */
} else if (flags & BDRV_REQ_ZERO_WRITE) {
bdrv_debug_event(bs, BLKDBG_PWRITEV_ZERO);
ret = bdrv_co_do_pwrite_zeroes(bs, offset, bytes, flags);
} else if (flags & BDRV_REQ_WRITE_COMPRESSED) {
ret = bdrv_driver_pwritev_compressed(bs, offset, bytes, qiov);
} else if (bytes <= max_transfer) {
bdrv_debug_event(bs, BLKDBG_PWRITEV);
ret = bdrv_driver_pwritev(bs, offset, bytes, qiov, flags);
} else {
bdrv_debug_event(bs, BLKDBG_PWRITEV);
while (bytes_remaining) {
int num = MIN(bytes_remaining, max_transfer);
QEMUIOVector local_qiov;
int local_flags = flags;
assert(num);
if (num < bytes_remaining && (flags & BDRV_REQ_FUA) &&
!(bs->supported_write_flags & BDRV_REQ_FUA)) {
/* If FUA is going to be emulated by flush, we only
* need to flush on the last iteration */
local_flags &= ~BDRV_REQ_FUA;
}
qemu_iovec_init(&local_qiov, qiov->niov);
qemu_iovec_concat(&local_qiov, qiov, bytes - bytes_remaining, num);
ret = bdrv_driver_pwritev(bs, offset + bytes - bytes_remaining,
num, &local_qiov, local_flags);
qemu_iovec_destroy(&local_qiov);
if (ret < 0) {
break;
}
bytes_remaining -= num;
}
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE);
++bs->write_gen;
bdrv_set_dirty(bs, start_sector, end_sector - start_sector);
if (bs->wr_highest_offset < offset + bytes) {
bs->wr_highest_offset = offset + bytes;
}
if (ret >= 0) {
bs->total_sectors = MAX(bs->total_sectors, end_sector);
ret = 0;
}
return ret;
}
static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child,
int64_t offset,
unsigned int bytes,
BdrvRequestFlags flags,
BdrvTrackedRequest *req)
{
BlockDriverState *bs = child->bs;
uint8_t *buf = NULL;
QEMUIOVector local_qiov;
struct iovec iov;
uint64_t align = bs->bl.request_alignment;
unsigned int head_padding_bytes, tail_padding_bytes;
int ret = 0;
head_padding_bytes = offset & (align - 1);
tail_padding_bytes = align - ((offset + bytes) & (align - 1));
assert(flags & BDRV_REQ_ZERO_WRITE);
if (head_padding_bytes || tail_padding_bytes) {
buf = qemu_blockalign(bs, align);
iov = (struct iovec) {
.iov_base = buf,
.iov_len = align,
};
qemu_iovec_init_external(&local_qiov, &iov, 1);
}
if (head_padding_bytes) {
uint64_t zero_bytes = MIN(bytes, align - head_padding_bytes);
/* RMW the unaligned part before head. */
mark_request_serialising(req, align);
wait_serialising_requests(req);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
ret = bdrv_aligned_preadv(child, req, offset & ~(align - 1), align,
align, &local_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD);
memset(buf + head_padding_bytes, 0, zero_bytes);
ret = bdrv_aligned_pwritev(child, req, offset & ~(align - 1), align,
align, &local_qiov,
flags & ~BDRV_REQ_ZERO_WRITE);
if (ret < 0) {
goto fail;
}
offset += zero_bytes;
bytes -= zero_bytes;
}
assert(!bytes || (offset & (align - 1)) == 0);
if (bytes >= align) {
/* Write the aligned part in the middle. */
uint64_t aligned_bytes = bytes & ~(align - 1);
ret = bdrv_aligned_pwritev(child, req, offset, aligned_bytes, align,
NULL, flags);
if (ret < 0) {
goto fail;
}
bytes -= aligned_bytes;
offset += aligned_bytes;
}
assert(!bytes || (offset & (align - 1)) == 0);
if (bytes) {
assert(align == tail_padding_bytes + bytes);
/* RMW the unaligned part after tail. */
mark_request_serialising(req, align);
wait_serialising_requests(req);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
ret = bdrv_aligned_preadv(child, req, offset, align,
align, &local_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
memset(buf, 0, bytes);
ret = bdrv_aligned_pwritev(child, req, offset, align, align,
&local_qiov, flags & ~BDRV_REQ_ZERO_WRITE);
}
fail:
qemu_vfree(buf);
return ret;
}
/*
* Handle a write request in coroutine context
*/
int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BlockDriverState *bs = child->bs;
BdrvTrackedRequest req;
uint64_t align = bs->bl.request_alignment;
uint8_t *head_buf = NULL;
uint8_t *tail_buf = NULL;
QEMUIOVector local_qiov;
bool use_local_qiov = false;
int ret;
if (!bs->drv) {
return -ENOMEDIUM;
}
if (bs->read_only) {
return -EPERM;
}
assert(!(bs->open_flags & BDRV_O_INACTIVE));
ret = bdrv_check_byte_request(bs, offset, bytes);
if (ret < 0) {
return ret;
}
bdrv_inc_in_flight(bs);
/*
* Align write if necessary by performing a read-modify-write cycle.
* Pad qiov with the read parts and be sure to have a tracked request not
* only for bdrv_aligned_pwritev, but also for the reads of the RMW cycle.
*/
tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE);
if (!qiov) {
ret = bdrv_co_do_zero_pwritev(child, offset, bytes, flags, &req);
goto out;
}
if (offset & (align - 1)) {
QEMUIOVector head_qiov;
struct iovec head_iov;
mark_request_serialising(&req, align);
wait_serialising_requests(&req);
head_buf = qemu_blockalign(bs, align);
head_iov = (struct iovec) {
.iov_base = head_buf,
.iov_len = align,
};
qemu_iovec_init_external(&head_qiov, &head_iov, 1);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
ret = bdrv_aligned_preadv(child, &req, offset & ~(align - 1), align,
align, &head_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD);
qemu_iovec_init(&local_qiov, qiov->niov + 2);
qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1));
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
bytes += offset & (align - 1);
offset = offset & ~(align - 1);
/* We have read the tail already if the request is smaller
* than one aligned block.
*/
if (bytes < align) {
qemu_iovec_add(&local_qiov, head_buf + bytes, align - bytes);
bytes = align;
}
}
if ((offset + bytes) & (align - 1)) {
QEMUIOVector tail_qiov;
struct iovec tail_iov;
size_t tail_bytes;
bool waited;
mark_request_serialising(&req, align);
waited = wait_serialising_requests(&req);
assert(!waited || !use_local_qiov);
tail_buf = qemu_blockalign(bs, align);
tail_iov = (struct iovec) {
.iov_base = tail_buf,
.iov_len = align,
};
qemu_iovec_init_external(&tail_qiov, &tail_iov, 1);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
ret = bdrv_aligned_preadv(child, &req, (offset + bytes) & ~(align - 1),
align, align, &tail_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
if (!use_local_qiov) {
qemu_iovec_init(&local_qiov, qiov->niov + 1);
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
}
tail_bytes = (offset + bytes) & (align - 1);
qemu_iovec_add(&local_qiov, tail_buf + tail_bytes, align - tail_bytes);
bytes = ROUND_UP(bytes, align);
}
ret = bdrv_aligned_pwritev(child, &req, offset, bytes, align,
use_local_qiov ? &local_qiov : qiov,
flags);
fail:
if (use_local_qiov) {
qemu_iovec_destroy(&local_qiov);
}
qemu_vfree(head_buf);
qemu_vfree(tail_buf);
out:
tracked_request_end(&req);
bdrv_dec_in_flight(bs);
return ret;
}
static int coroutine_fn bdrv_co_do_writev(BdrvChild *child,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EINVAL;
}
return bdrv_co_pwritev(child, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
int coroutine_fn bdrv_co_writev(BdrvChild *child, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_writev(child->bs, sector_num, nb_sectors);
return bdrv_co_do_writev(child, sector_num, nb_sectors, qiov, 0);
}
int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
int count, BdrvRequestFlags flags)
{
trace_bdrv_co_pwrite_zeroes(child->bs, offset, count, flags);
if (!(child->bs->open_flags & BDRV_O_UNMAP)) {
flags &= ~BDRV_REQ_MAY_UNMAP;
}
return bdrv_co_pwritev(child, offset, count, NULL,
BDRV_REQ_ZERO_WRITE | flags);
}
/*
* Flush ALL BDSes regardless of if they are reachable via a BlkBackend or not.
*/
int bdrv_flush_all(void)
{
BdrvNextIterator it;
BlockDriverState *bs = NULL;
int result = 0;
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
int ret;
aio_context_acquire(aio_context);
ret = bdrv_flush(bs);
if (ret < 0 && !result) {
result = ret;
}
aio_context_release(aio_context);
}
return result;
}
typedef struct BdrvCoGetBlockStatusData {
BlockDriverState *bs;
BlockDriverState *base;
BlockDriverState **file;
int64_t sector_num;
int nb_sectors;
int *pnum;
int64_t ret;
bool done;
} BdrvCoGetBlockStatusData;
/*
* Returns the allocation status of the specified sectors.
* Drivers not implementing the functionality are assumed to not support
* backing files, hence all their sectors are reported as allocated.
*
* If 'sector_num' is beyond the end of the disk image the return value is 0
* and 'pnum' is set to 0.
*
* 'pnum' is set to the number of sectors (including and immediately following
* the specified sector) that are known to be in the same
* allocated/unallocated state.
*
* 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
* beyond the end of the disk image it will be clamped.
*
* If returned value is positive and BDRV_BLOCK_OFFSET_VALID bit is set, 'file'
* points to the BDS which the sector range is allocated in.
*/
static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum,
BlockDriverState **file)
{
int64_t total_sectors;
int64_t n;
int64_t ret, ret2;
total_sectors = bdrv_nb_sectors(bs);
if (total_sectors < 0) {
return total_sectors;
}
if (sector_num >= total_sectors) {
*pnum = 0;
return 0;
}
n = total_sectors - sector_num;
if (n < nb_sectors) {
nb_sectors = n;
}
if (!bs->drv->bdrv_co_get_block_status) {
*pnum = nb_sectors;
ret = BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED;
if (bs->drv->protocol_name) {
ret |= BDRV_BLOCK_OFFSET_VALID | (sector_num * BDRV_SECTOR_SIZE);
}
return ret;
}
*file = NULL;
bdrv_inc_in_flight(bs);
ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum,
file);
if (ret < 0) {
*pnum = 0;
goto out;
}
if (ret & BDRV_BLOCK_RAW) {
assert(ret & BDRV_BLOCK_OFFSET_VALID);
ret = bdrv_get_block_status(*file, ret >> BDRV_SECTOR_BITS,
*pnum, pnum, file);
goto out;
}
if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
ret |= BDRV_BLOCK_ALLOCATED;
} else {
if (bdrv_unallocated_blocks_are_zero(bs)) {
ret |= BDRV_BLOCK_ZERO;
} else if (bs->backing) {
BlockDriverState *bs2 = bs->backing->bs;
int64_t nb_sectors2 = bdrv_nb_sectors(bs2);
if (nb_sectors2 >= 0 && sector_num >= nb_sectors2) {
ret |= BDRV_BLOCK_ZERO;
}
}
}
if (*file && *file != bs &&
(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
(ret & BDRV_BLOCK_OFFSET_VALID)) {
BlockDriverState *file2;
int file_pnum;
ret2 = bdrv_co_get_block_status(*file, ret >> BDRV_SECTOR_BITS,
*pnum, &file_pnum, &file2);
if (ret2 >= 0) {
/* Ignore errors. This is just providing extra information, it
* is useful but not necessary.
*/
if (!file_pnum) {
/* !file_pnum indicates an offset at or beyond the EOF; it is
* perfectly valid for the format block driver to point to such
* offsets, so catch it and mark everything as zero */
ret |= BDRV_BLOCK_ZERO;
} else {
/* Limit request to the range reported by the protocol driver */
*pnum = file_pnum;
ret |= (ret2 & BDRV_BLOCK_ZERO);
}
}
}
out:
bdrv_dec_in_flight(bs);
return ret;
}
static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors,
int *pnum,
BlockDriverState **file)
{
BlockDriverState *p;
int64_t ret = 0;
assert(bs != base);
for (p = bs; p != base; p = backing_bs(p)) {
ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum, file);
if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
break;
}
/* [sector_num, pnum] unallocated on this layer, which could be only
* the first part of [sector_num, nb_sectors]. */
nb_sectors = MIN(nb_sectors, *pnum);
}
return ret;
}
/* Coroutine wrapper for bdrv_get_block_status_above() */
static void coroutine_fn bdrv_get_block_status_above_co_entry(void *opaque)
{
BdrvCoGetBlockStatusData *data = opaque;
data->ret = bdrv_co_get_block_status_above(data->bs, data->base,
data->sector_num,
data->nb_sectors,
data->pnum,
data->file);
data->done = true;
}
/*
* Synchronous wrapper around bdrv_co_get_block_status_above().
*
* See bdrv_co_get_block_status_above() for details.
*/
int64_t bdrv_get_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors, int *pnum,
BlockDriverState **file)
{
Coroutine *co;
BdrvCoGetBlockStatusData data = {
.bs = bs,
.base = base,
.file = file,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.pnum = pnum,
.done = false,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_get_block_status_above_co_entry(&data);
} else {
co = qemu_coroutine_create(bdrv_get_block_status_above_co_entry,
&data);
bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, !data.done);
}
return data.ret;
}
int64_t bdrv_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum,
BlockDriverState **file)
{
return bdrv_get_block_status_above(bs, backing_bs(bs),
sector_num, nb_sectors, pnum, file);
}
int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
BlockDriverState *file;
int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum,
&file);
if (ret < 0) {
return ret;
}
return !!(ret & BDRV_BLOCK_ALLOCATED);
}
/*
* Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
*
* Return true if the given sector is allocated in any image between
* BASE and TOP (inclusive). BASE can be NULL to check if the given
* sector is allocated in any image of the chain. Return false otherwise.
*
* 'pnum' is set to the number of sectors (including and immediately following
* the specified sector) that are known to be in the same
* allocated/unallocated state.
*
*/
int bdrv_is_allocated_above(BlockDriverState *top,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors, int *pnum)
{
BlockDriverState *intermediate;
int ret, n = nb_sectors;
intermediate = top;
while (intermediate && intermediate != base) {
int pnum_inter;
ret = bdrv_is_allocated(intermediate, sector_num, nb_sectors,
&pnum_inter);
if (ret < 0) {
return ret;
} else if (ret) {
*pnum = pnum_inter;
return 1;
}
/*
* [sector_num, nb_sectors] is unallocated on top but intermediate
* might have
*
* [sector_num+x, nr_sectors] allocated.
*/
if (n > pnum_inter &&
(intermediate == top ||
sector_num + pnum_inter < intermediate->total_sectors)) {
n = pnum_inter;
}
intermediate = backing_bs(intermediate);
}
*pnum = n;
return 0;
}
typedef struct BdrvVmstateCo {
BlockDriverState *bs;
QEMUIOVector *qiov;
int64_t pos;
bool is_read;
int ret;
} BdrvVmstateCo;
static int coroutine_fn
bdrv_co_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
bool is_read)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
} else if (drv->bdrv_load_vmstate) {
return is_read ? drv->bdrv_load_vmstate(bs, qiov, pos)
: drv->bdrv_save_vmstate(bs, qiov, pos);
} else if (bs->file) {
return bdrv_co_rw_vmstate(bs->file->bs, qiov, pos, is_read);
}
return -ENOTSUP;
}
static void coroutine_fn bdrv_co_rw_vmstate_entry(void *opaque)
{
BdrvVmstateCo *co = opaque;
co->ret = bdrv_co_rw_vmstate(co->bs, co->qiov, co->pos, co->is_read);
}
static inline int
bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
bool is_read)
{
if (qemu_in_coroutine()) {
return bdrv_co_rw_vmstate(bs, qiov, pos, is_read);
} else {
BdrvVmstateCo data = {
.bs = bs,
.qiov = qiov,
.pos = pos,
.is_read = is_read,
.ret = -EINPROGRESS,
};
Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data);
bdrv_coroutine_enter(bs, co);
while (data.ret == -EINPROGRESS) {
aio_poll(bdrv_get_aio_context(bs), true);
}
return data.ret;
}
}
int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
int64_t pos, int size)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *) buf,
.iov_len = size,
};
int ret;
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_writev_vmstate(bs, &qiov, pos);
if (ret < 0) {
return ret;
}
return size;
}
int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
{
return bdrv_rw_vmstate(bs, qiov, pos, false);
}
int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
int64_t pos, int size)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = buf,
.iov_len = size,
};
int ret;
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_readv_vmstate(bs, &qiov, pos);
if (ret < 0) {
return ret;
}
return size;
}
int bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
{
return bdrv_rw_vmstate(bs, qiov, pos, true);
}
/**************************************************************/
/* async I/Os */
BlockAIOCB *bdrv_aio_readv(BdrvChild *child, int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_readv(child->bs, sector_num, nb_sectors, opaque);
assert(nb_sectors << BDRV_SECTOR_BITS == qiov->size);
return bdrv_co_aio_prw_vector(child, sector_num << BDRV_SECTOR_BITS, qiov,
0, cb, opaque, false);
}
BlockAIOCB *bdrv_aio_writev(BdrvChild *child, int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_writev(child->bs, sector_num, nb_sectors, opaque);
assert(nb_sectors << BDRV_SECTOR_BITS == qiov->size);
return bdrv_co_aio_prw_vector(child, sector_num << BDRV_SECTOR_BITS, qiov,
0, cb, opaque, true);
}
void bdrv_aio_cancel(BlockAIOCB *acb)
{
qemu_aio_ref(acb);
bdrv_aio_cancel_async(acb);
while (acb->refcnt > 1) {
if (acb->aiocb_info->get_aio_context) {
aio_poll(acb->aiocb_info->get_aio_context(acb), true);
} else if (acb->bs) {
/* qemu_aio_ref and qemu_aio_unref are not thread-safe, so
* assert that we're not using an I/O thread. Thread-safe
* code should use bdrv_aio_cancel_async exclusively.
*/
assert(bdrv_get_aio_context(acb->bs) == qemu_get_aio_context());
aio_poll(bdrv_get_aio_context(acb->bs), true);
} else {
abort();
}
}
qemu_aio_unref(acb);
}
/* Async version of aio cancel. The caller is not blocked if the acb implements
* cancel_async, otherwise we do nothing and let the request normally complete.
* In either case the completion callback must be called. */
void bdrv_aio_cancel_async(BlockAIOCB *acb)
{
if (acb->aiocb_info->cancel_async) {
acb->aiocb_info->cancel_async(acb);
}
}
/**************************************************************/
/* async block device emulation */
typedef struct BlockRequest {
union {
/* Used during read, write, trim */
struct {
int64_t offset;
int bytes;
int flags;
QEMUIOVector *qiov;
};
/* Used during ioctl */
struct {
int req;
void *buf;
};
};
BlockCompletionFunc *cb;
void *opaque;
int error;
} BlockRequest;
typedef struct BlockAIOCBCoroutine {
BlockAIOCB common;
BdrvChild *child;
BlockRequest req;
bool is_write;
bool need_bh;
bool *done;
} BlockAIOCBCoroutine;
static const AIOCBInfo bdrv_em_co_aiocb_info = {
.aiocb_size = sizeof(BlockAIOCBCoroutine),
};
static void bdrv_co_complete(BlockAIOCBCoroutine *acb)
{
if (!acb->need_bh) {
bdrv_dec_in_flight(acb->common.bs);
acb->common.cb(acb->common.opaque, acb->req.error);
qemu_aio_unref(acb);
}
}
static void bdrv_co_em_bh(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
assert(!acb->need_bh);
bdrv_co_complete(acb);
}
static void bdrv_co_maybe_schedule_bh(BlockAIOCBCoroutine *acb)
{
acb->need_bh = false;
if (acb->req.error != -EINPROGRESS) {
BlockDriverState *bs = acb->common.bs;
aio_bh_schedule_oneshot(bdrv_get_aio_context(bs), bdrv_co_em_bh, acb);
}
}
/* Invoke bdrv_co_do_readv/bdrv_co_do_writev */
static void coroutine_fn bdrv_co_do_rw(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
if (!acb->is_write) {
acb->req.error = bdrv_co_preadv(acb->child, acb->req.offset,
acb->req.qiov->size, acb->req.qiov, acb->req.flags);
} else {
acb->req.error = bdrv_co_pwritev(acb->child, acb->req.offset,
acb->req.qiov->size, acb->req.qiov, acb->req.flags);
}
bdrv_co_complete(acb);
}
static BlockAIOCB *bdrv_co_aio_prw_vector(BdrvChild *child,
int64_t offset,
QEMUIOVector *qiov,
BdrvRequestFlags flags,
BlockCompletionFunc *cb,
void *opaque,
bool is_write)
{
Coroutine *co;
BlockAIOCBCoroutine *acb;
/* Matched by bdrv_co_complete's bdrv_dec_in_flight. */
bdrv_inc_in_flight(child->bs);
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, child->bs, cb, opaque);
acb->child = child;
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
acb->req.offset = offset;
acb->req.qiov = qiov;
acb->req.flags = flags;
acb->is_write = is_write;
co = qemu_coroutine_create(bdrv_co_do_rw, acb);
bdrv_coroutine_enter(child->bs, co);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
static void coroutine_fn bdrv_aio_flush_co_entry(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
acb->req.error = bdrv_co_flush(bs);
bdrv_co_complete(acb);
}
BlockAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_flush(bs, opaque);
Coroutine *co;
BlockAIOCBCoroutine *acb;
/* Matched by bdrv_co_complete's bdrv_dec_in_flight. */
bdrv_inc_in_flight(bs);
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
co = qemu_coroutine_create(bdrv_aio_flush_co_entry, acb);
bdrv_coroutine_enter(bs, co);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
/**************************************************************/
/* Coroutine block device emulation */
typedef struct FlushCo {
BlockDriverState *bs;
int ret;
} FlushCo;
static void coroutine_fn bdrv_flush_co_entry(void *opaque)
{
FlushCo *rwco = opaque;
rwco->ret = bdrv_co_flush(rwco->bs);
}
int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{
int current_gen;
int ret = 0;
bdrv_inc_in_flight(bs);
if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
bdrv_is_sg(bs)) {
goto early_exit;
}
current_gen = bs->write_gen;
/* Wait until any previous flushes are completed */
while (bs->active_flush_req) {
qemu_co_queue_wait(&bs->flush_queue, NULL);
}
bs->active_flush_req = true;
/* Write back all layers by calling one driver function */
if (bs->drv->bdrv_co_flush) {
ret = bs->drv->bdrv_co_flush(bs);
goto out;
}
/* Write back cached data to the OS even with cache=unsafe */
BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_OS);
if (bs->drv->bdrv_co_flush_to_os) {
ret = bs->drv->bdrv_co_flush_to_os(bs);
if (ret < 0) {
goto out;
}
}
/* But don't actually force it to the disk with cache=unsafe */
if (bs->open_flags & BDRV_O_NO_FLUSH) {
goto flush_parent;
}
/* Check if we really need to flush anything */
if (bs->flushed_gen == current_gen) {
goto flush_parent;
}
BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
if (bs->drv->bdrv_co_flush_to_disk) {
ret = bs->drv->bdrv_co_flush_to_disk(bs);
} else if (bs->drv->bdrv_aio_flush) {
BlockAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_flush(bs, bdrv_co_io_em_complete, &co);
if (acb == NULL) {
ret = -EIO;
} else {
qemu_coroutine_yield();
ret = co.ret;
}
} else {
/*
* Some block drivers always operate in either writethrough or unsafe
* mode and don't support bdrv_flush therefore. Usually qemu doesn't
* know how the server works (because the behaviour is hardcoded or
* depends on server-side configuration), so we can't ensure that
* everything is safe on disk. Returning an error doesn't work because
* that would break guests even if the server operates in writethrough
* mode.
*
* Let's hope the user knows what he's doing.
*/
ret = 0;
}
if (ret < 0) {
goto out;
}
/* Now flush the underlying protocol. It will also have BDRV_O_NO_FLUSH
* in the case of cache=unsafe, so there are no useless flushes.
*/
flush_parent:
ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
out:
/* Notify any pending flushes that we have completed */
if (ret == 0) {
bs->flushed_gen = current_gen;
}
bs->active_flush_req = false;
/* Return value is ignored - it's ok if wait queue is empty */
qemu_co_queue_next(&bs->flush_queue);
early_exit:
bdrv_dec_in_flight(bs);
return ret;
}
int bdrv_flush(BlockDriverState *bs)
{
Coroutine *co;
FlushCo flush_co = {
.bs = bs,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_flush_co_entry(&flush_co);
} else {
co = qemu_coroutine_create(bdrv_flush_co_entry, &flush_co);
bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, flush_co.ret == NOT_DONE);
}
return flush_co.ret;
}
typedef struct DiscardCo {
BlockDriverState *bs;
int64_t offset;
int count;
int ret;
} DiscardCo;
static void coroutine_fn bdrv_pdiscard_co_entry(void *opaque)
{
DiscardCo *rwco = opaque;
rwco->ret = bdrv_co_pdiscard(rwco->bs, rwco->offset, rwco->count);
}
int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
int count)
{
BdrvTrackedRequest req;
int max_pdiscard, ret;
int head, tail, align;
if (!bs->drv) {
return -ENOMEDIUM;
}
ret = bdrv_check_byte_request(bs, offset, count);
if (ret < 0) {
return ret;
} else if (bs->read_only) {
return -EPERM;
}
assert(!(bs->open_flags & BDRV_O_INACTIVE));
/* Do nothing if disabled. */
if (!(bs->open_flags & BDRV_O_UNMAP)) {
return 0;
}
if (!bs->drv->bdrv_co_pdiscard && !bs->drv->bdrv_aio_pdiscard) {
return 0;
}
/* Discard is advisory, but some devices track and coalesce
* unaligned requests, so we must pass everything down rather than
* round here. Still, most devices will just silently ignore
* unaligned requests (by returning -ENOTSUP), so we must fragment
* the request accordingly. */
align = MAX(bs->bl.pdiscard_alignment, bs->bl.request_alignment);
assert(align % bs->bl.request_alignment == 0);
head = offset % align;
tail = (offset + count) % align;
bdrv_inc_in_flight(bs);
tracked_request_begin(&req, bs, offset, count, BDRV_TRACKED_DISCARD);
ret = notifier_with_return_list_notify(&bs->before_write_notifiers, &req);
if (ret < 0) {
goto out;
}
max_pdiscard = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_pdiscard, INT_MAX),
align);
assert(max_pdiscard >= bs->bl.request_alignment);
while (count > 0) {
int ret;
int num = count;
if (head) {
/* Make small requests to get to alignment boundaries. */
num = MIN(count, align - head);
if (!QEMU_IS_ALIGNED(num, bs->bl.request_alignment)) {
num %= bs->bl.request_alignment;
}
head = (head + num) % align;
assert(num < max_pdiscard);
} else if (tail) {
if (num > align) {
/* Shorten the request to the last aligned cluster. */
num -= tail;
} else if (!QEMU_IS_ALIGNED(tail, bs->bl.request_alignment) &&
tail > bs->bl.request_alignment) {
tail %= bs->bl.request_alignment;
num -= tail;
}
}
/* limit request size */
if (num > max_pdiscard) {
num = max_pdiscard;
}
if (bs->drv->bdrv_co_pdiscard) {
ret = bs->drv->bdrv_co_pdiscard(bs, offset, num);
} else {
BlockAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_pdiscard(bs, offset, num,
bdrv_co_io_em_complete, &co);
if (acb == NULL) {
ret = -EIO;
goto out;
} else {
qemu_coroutine_yield();
ret = co.ret;
}
}
if (ret && ret != -ENOTSUP) {
goto out;
}
offset += num;
count -= num;
}
ret = 0;
out:
++bs->write_gen;
bdrv_set_dirty(bs, req.offset >> BDRV_SECTOR_BITS,
req.bytes >> BDRV_SECTOR_BITS);
tracked_request_end(&req);
bdrv_dec_in_flight(bs);
return ret;
}
int bdrv_pdiscard(BlockDriverState *bs, int64_t offset, int count)
{
Coroutine *co;
DiscardCo rwco = {
.bs = bs,
.offset = offset,
.count = count,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_pdiscard_co_entry(&rwco);
} else {
co = qemu_coroutine_create(bdrv_pdiscard_co_entry, &rwco);
bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, rwco.ret == NOT_DONE);
}
return rwco.ret;
}
int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf)
{
BlockDriver *drv = bs->drv;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
BlockAIOCB *acb;
bdrv_inc_in_flight(bs);
if (!drv || (!drv->bdrv_aio_ioctl && !drv->bdrv_co_ioctl)) {
co.ret = -ENOTSUP;
goto out;
}
if (drv->bdrv_co_ioctl) {
co.ret = drv->bdrv_co_ioctl(bs, req, buf);
} else {
acb = drv->bdrv_aio_ioctl(bs, req, buf, bdrv_co_io_em_complete, &co);
if (!acb) {
co.ret = -ENOTSUP;
goto out;
}
qemu_coroutine_yield();
}
out:
bdrv_dec_in_flight(bs);
return co.ret;
}
void *qemu_blockalign(BlockDriverState *bs, size_t size)
{
return qemu_memalign(bdrv_opt_mem_align(bs), size);
}
void *qemu_blockalign0(BlockDriverState *bs, size_t size)
{
return memset(qemu_blockalign(bs, size), 0, size);
}
void *qemu_try_blockalign(BlockDriverState *bs, size_t size)
{
size_t align = bdrv_opt_mem_align(bs);
/* Ensure that NULL is never returned on success */
assert(align > 0);
if (size == 0) {
size = align;
}
return qemu_try_memalign(align, size);
}
void *qemu_try_blockalign0(BlockDriverState *bs, size_t size)
{
void *mem = qemu_try_blockalign(bs, size);
if (mem) {
memset(mem, 0, size);
}
return mem;
}
/*
* Check if all memory in this vector is sector aligned.
*/
bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov)
{
int i;
size_t alignment = bdrv_min_mem_align(bs);
for (i = 0; i < qiov->niov; i++) {
if ((uintptr_t) qiov->iov[i].iov_base % alignment) {
return false;
}
if (qiov->iov[i].iov_len % alignment) {
return false;
}
}
return true;
}
void bdrv_add_before_write_notifier(BlockDriverState *bs,
NotifierWithReturn *notifier)
{
notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
}
void bdrv_io_plug(BlockDriverState *bs)
{
BdrvChild *child;
QLIST_FOREACH(child, &bs->children, next) {
bdrv_io_plug(child->bs);
}
if (bs->io_plugged++ == 0) {
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_io_plug) {
drv->bdrv_io_plug(bs);
}
}
}
void bdrv_io_unplug(BlockDriverState *bs)
{
BdrvChild *child;
assert(bs->io_plugged);
if (--bs->io_plugged == 0) {
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_io_unplug) {
drv->bdrv_io_unplug(bs);
}
}
QLIST_FOREACH(child, &bs->children, next) {
bdrv_io_unplug(child->bs);
}
}
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