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qemu-e2k/block/io.c
Eric Blake 465fe887cc block: Honor BDRV_REQ_FUA during write_zeroes 
The block layer has a couple of cases where it can lose
Force Unit Access semantics when writing a large block of
zeroes, such that the request returns before the zeroes
have been guaranteed to land on underlying media.

SCSI does not support FUA during WRITESAME(10/16); FUA is only
supported if it falls back to WRITE(10/16).  But where the
underlying device is new enough to not need a fallback, it
means that any upper layer request with FUA semantics was
silently ignoring BDRV_REQ_FUA.

Conversely, NBD has situations where it can support FUA but not
ZERO_WRITE; when that happens, the generic block layer fallback
to bdrv_driver_pwritev() (or the older bdrv_co_writev() in qemu
2.6) was losing the FUA flag.

The problem of losing flags unrelated to ZERO_WRITE has been
latent in bdrv_co_do_write_zeroes() since commit aa7bfbff, but
back then, it did not matter because there was no FUA flag.  It
became observable when commit 93f5e6d8 paved the way for flags
that can impact correctness, when we should have been using
bdrv_co_writev_flags() with modified flags.  Compare to commit
9eeb6dd, which got flag manipulation right in
bdrv_co_do_zero_pwritev().

Symptoms: I tested with qemu-io with default writethrough cache
(which is supposed to use FUA semantics on every write), and
targetted an NBD client connected to a server that intentionally
did not advertise NBD_FLAG_SEND_FUA.  When doing 'write 0 512',
the NBD client sent two operations (NBD_CMD_WRITE then
NBD_CMD_FLUSH) to get the fallback FUA semantics; but when doing
'write -z 0 512', the NBD client sent only NBD_CMD_WRITE.

The fix is do to a cleanup bdrv_co_flush() at the end of the
operation if any step in the middle relied on a BDS that does
not natively support FUA for that step (note that we don't
need to flush after every operation, if the operation is broken
into chunks based on bounce-buffer sizing).  Each BDS gains a
new flag .supported_zero_flags, which parallels the use of
.supported_write_flags but only when accessing a zero write
operation (the flags MUST be different, because of SCSI having
different semantics based on WRITE vs. WRITESAME; and also
because BDRV_REQ_MAY_UNMAP only makes sense on zero writes).

Also fix some documentation to describe -ENOTSUP semantics,
particularly since iscsi depends on those semantics.

Down the road, we may want to add a driver where its
.bdrv_co_pwritev() honors all three of BDRV_REQ_FUA,
BDRV_REQ_ZERO_WRITE, and BDRV_REQ_MAY_UNMAP, and advertise
this via bs->supported_write_flags for blocks opened by that
driver; such a driver should NOT supply .bdrv_co_write_zeroes
nor .supported_zero_flags.  But none of the drivers touched
in this patch want to do that (the act of writing zeroes is
different enough from normal writes to deserve a second
callback).

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-12 15:22:09 +02:00

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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 "block/throttle-groups.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_rw_vector(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
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_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags);
/* throttling disk I/O limits */
void bdrv_set_io_limits(BlockDriverState *bs,
ThrottleConfig *cfg)
{
throttle_group_config(bs, cfg);
}
void bdrv_no_throttling_begin(BlockDriverState *bs)
{
if (bs->io_limits_disabled++ == 0) {
throttle_group_restart_bs(bs);
}
}
void bdrv_no_throttling_end(BlockDriverState *bs)
{
assert(bs->io_limits_disabled);
--bs->io_limits_disabled;
}
void bdrv_io_limits_disable(BlockDriverState *bs)
{
assert(bs->throttle_state);
bdrv_no_throttling_begin(bs);
throttle_group_unregister_bs(bs);
bdrv_no_throttling_end(bs);
}
/* should be called before bdrv_set_io_limits if a limit is set */
void bdrv_io_limits_enable(BlockDriverState *bs, const char *group)
{
assert(!bs->throttle_state);
throttle_group_register_bs(bs, group);
}
void bdrv_io_limits_update_group(BlockDriverState *bs, const char *group)
{
/* this bs is not part of any group */
if (!bs->throttle_state) {
return;
}
/* this bs is a part of the same group than the one we want */
if (!g_strcmp0(throttle_group_get_name(bs), group)) {
return;
}
/* need to change the group this bs belong to */
bdrv_io_limits_disable(bs);
bdrv_io_limits_enable(bs, group);
}
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;
}
/* 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;
}
bs->bl.opt_transfer_length = bs->file->bs->bl.opt_transfer_length;
bs->bl.max_transfer_length = bs->file->bs->bl.max_transfer_length;
bs->bl.min_mem_alignment = bs->file->bs->bl.min_mem_alignment;
bs->bl.opt_mem_alignment = bs->file->bs->bl.opt_mem_alignment;
bs->bl.max_iov = bs->file->bs->bl.max_iov;
} 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;
}
bs->bl.opt_transfer_length =
MAX(bs->bl.opt_transfer_length,
bs->backing->bs->bl.opt_transfer_length);
bs->bl.max_transfer_length =
MIN_NON_ZERO(bs->bl.max_transfer_length,
bs->backing->bs->bl.max_transfer_length);
bs->bl.opt_mem_alignment =
MAX(bs->bl.opt_mem_alignment,
bs->backing->bs->bl.opt_mem_alignment);
bs->bl.min_mem_alignment =
MAX(bs->bl.min_mem_alignment,
bs->backing->bs->bl.min_mem_alignment);
bs->bl.max_iov =
MIN(bs->bl.max_iov,
bs->backing->bs->bl.max_iov);
}
/* 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 (!QLIST_EMPTY(&bs->tracked_requests)) {
return true;
}
if (!qemu_co_queue_empty(&bs->throttled_reqs[0])) {
return true;
}
if (!qemu_co_queue_empty(&bs->throttled_reqs[1])) {
return true;
}
QLIST_FOREACH(child, &bs->children, next) {
if (bdrv_requests_pending(child->bs)) {
return true;
}
}
return false;
}
static void bdrv_drain_recurse(BlockDriverState *bs)
{
BdrvChild *child;
if (bs->drv && bs->drv->bdrv_drain) {
bs->drv->bdrv_drain(bs);
}
QLIST_FOREACH(child, &bs->children, next) {
bdrv_drain_recurse(child->bs);
}
}
typedef struct {
Coroutine *co;
BlockDriverState *bs;
QEMUBH *bh;
bool done;
} BdrvCoDrainData;
static void bdrv_drain_poll(BlockDriverState *bs)
{
bool busy = true;
while (busy) {
/* Keep iterating */
busy = bdrv_requests_pending(bs);
busy |= aio_poll(bdrv_get_aio_context(bs), busy);
}
}
static void bdrv_co_drain_bh_cb(void *opaque)
{
BdrvCoDrainData *data = opaque;
Coroutine *co = data->co;
qemu_bh_delete(data->bh);
bdrv_drain_poll(data->bs);
data->done = true;
qemu_coroutine_enter(co, NULL);
}
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,
.bh = aio_bh_new(bdrv_get_aio_context(bs), bdrv_co_drain_bh_cb, &data),
};
qemu_bh_schedule(data.bh);
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);
}
/*
* 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)
{
bdrv_no_throttling_begin(bs);
bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
bdrv_co_yield_to_drain(bs);
bdrv_io_unplugged_end(bs);
bdrv_no_throttling_end(bs);
}
void bdrv_drain(BlockDriverState *bs)
{
bdrv_no_throttling_begin(bs);
bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
if (qemu_in_coroutine()) {
bdrv_co_yield_to_drain(bs);
} else {
bdrv_drain_poll(bs);
}
bdrv_io_unplugged_end(bs);
bdrv_no_throttling_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.
*/
void bdrv_drain_all(void)
{
/* Always run first iteration so any pending completion BHs run */
bool busy = true;
BlockDriverState *bs = NULL;
GSList *aio_ctxs = NULL, *ctx;
while ((bs = bdrv_next(bs))) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
if (bs->job) {
block_job_pause(bs->job);
}
bdrv_no_throttling_begin(bs);
bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
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 (busy) {
busy = false;
for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
AioContext *aio_context = ctx->data;
bs = NULL;
aio_context_acquire(aio_context);
while ((bs = bdrv_next(bs))) {
if (aio_context == bdrv_get_aio_context(bs)) {
if (bdrv_requests_pending(bs)) {
busy = true;
aio_poll(aio_context, busy);
}
}
}
busy |= aio_poll(aio_context, false);
aio_context_release(aio_context);
}
}
bs = NULL;
while ((bs = bdrv_next(bs))) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
bdrv_io_unplugged_end(bs);
bdrv_no_throttling_end(bs);
if (bs->job) {
block_job_resume(bs->job);
}
aio_context_release(aio_context);
}
g_slist_free(aio_ctxs);
}
/**
* 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
*/
void bdrv_round_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);
}
}
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->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;
}
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);
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;
}
static int bdrv_check_request(BlockDriverState *bs, int64_t sector_num,
int nb_sectors)
{
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EIO;
}
return bdrv_check_byte_request(bs, sector_num * BDRV_SECTOR_SIZE,
nb_sectors * BDRV_SECTOR_SIZE);
}
typedef struct RwCo {
BlockDriverState *bs;
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->bs, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
} else {
rwco->ret = bdrv_co_pwritev(rwco->bs, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
}
}
/*
* Process a vectored synchronous request using coroutines
*/
static int bdrv_prwv_co(BlockDriverState *bs, int64_t offset,
QEMUIOVector *qiov, bool is_write,
BdrvRequestFlags flags)
{
Coroutine *co;
RwCo rwco = {
.bs = bs,
.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 {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_rw_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
aio_poll(aio_context, true);
}
}
return rwco.ret;
}
/*
* Process a synchronous request using coroutines
*/
static int bdrv_rw_co(BlockDriverState *bs, 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(bs, sector_num << BDRV_SECTOR_BITS,
&qiov, is_write, flags);
}
/* return < 0 if error. See bdrv_write() for the return codes */
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
return bdrv_rw_co(bs, 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(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
}
int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, BdrvRequestFlags flags)
{
return bdrv_rw_co(bs, sector_num, NULL, nb_sectors, true,
BDRV_REQ_ZERO_WRITE | flags);
}
/*
* Completely zero out a block device with the help of bdrv_write_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_write_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(BlockDriverState *bs, BdrvRequestFlags flags)
{
int64_t target_sectors, ret, nb_sectors, sector_num = 0;
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_write_zeroes(bs, sector_num, n, flags);
if (ret < 0) {
error_report("error writing zeroes at sector %" PRId64 ": %s",
sector_num, strerror(-ret));
return ret;
}
sector_num += n;
}
}
int bdrv_pread(BlockDriverState *bs, int64_t offset, void *buf, int bytes)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = bytes,
};
int ret;
if (bytes < 0) {
return -EINVAL;
}
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_prwv_co(bs, offset, &qiov, false, 0);
if (ret < 0) {
return ret;
}
return bytes;
}
int bdrv_pwritev(BlockDriverState *bs, int64_t offset, QEMUIOVector *qiov)
{
int ret;
ret = bdrv_prwv_co(bs, offset, qiov, true, 0);
if (ret < 0) {
return ret;
}
return qiov->size;
}
int bdrv_pwrite(BlockDriverState *bs, 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(bs, 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(BlockDriverState *bs, int64_t offset,
const void *buf, int count)
{
int ret;
ret = bdrv_pwrite(bs, offset, buf, count);
if (ret < 0) {
return ret;
}
ret = bdrv_flush(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;
qemu_coroutine_enter(co->coroutine, NULL);
}
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;
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;
if (drv->bdrv_co_pwritev) {
ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov, 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_co_do_copy_on_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
/* 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_sector_num;
int cluster_nb_sectors;
size_t skip_bytes;
int ret;
/* Cover entire cluster so no additional backing file I/O is required when
* allocating cluster in the image file.
*/
bdrv_round_to_clusters(bs, sector_num, nb_sectors,
&cluster_sector_num, &cluster_nb_sectors);
trace_bdrv_co_do_copy_on_readv(bs, sector_num, nb_sectors,
cluster_sector_num, cluster_nb_sectors);
iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE;
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_sector_num * BDRV_SECTOR_SIZE,
cluster_nb_sectors * BDRV_SECTOR_SIZE,
&bounce_qiov, 0);
if (ret < 0) {
goto err;
}
if (drv->bdrv_co_write_zeroes &&
buffer_is_zero(bounce_buffer, iov.iov_len)) {
ret = bdrv_co_do_write_zeroes(bs, cluster_sector_num,
cluster_nb_sectors, 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_sector_num * BDRV_SECTOR_SIZE,
cluster_nb_sectors * BDRV_SECTOR_SIZE,
&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 = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE;
qemu_iovec_from_buf(qiov, 0, bounce_buffer + skip_bytes,
nb_sectors * BDRV_SECTOR_SIZE);
err:
qemu_vfree(bounce_buffer);
return ret;
}
/*
* Forwards an already correctly aligned request to the BlockDriver. This
* handles copy on read and zeroing after EOF; any other features must be
* implemented by the caller.
*/
static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
int64_t align, QEMUIOVector *qiov, int flags)
{
int ret;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
assert(!qiov || bytes == qiov->size);
assert((bs->open_flags & BDRV_O_NO_IO) == 0);
/* 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) {
int pnum;
ret = bdrv_is_allocated(bs, sector_num, nb_sectors, &pnum);
if (ret < 0) {
goto out;
}
if (!ret || pnum != nb_sectors) {
ret = bdrv_co_do_copy_on_readv(bs, sector_num, nb_sectors, qiov);
goto out;
}
}
/* Forward the request to the BlockDriver */
if (!bs->zero_beyond_eof) {
ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0);
} else {
/* Read zeros after EOF */
int64_t total_sectors, max_nb_sectors;
total_sectors = bdrv_nb_sectors(bs);
if (total_sectors < 0) {
ret = total_sectors;
goto out;
}
max_nb_sectors = ROUND_UP(MAX(0, total_sectors - sector_num),
align >> BDRV_SECTOR_BITS);
if (nb_sectors < max_nb_sectors) {
ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0);
} else if (max_nb_sectors > 0) {
QEMUIOVector local_qiov;
qemu_iovec_init(&local_qiov, qiov->niov);
qemu_iovec_concat(&local_qiov, qiov, 0,
max_nb_sectors * BDRV_SECTOR_SIZE);
ret = bdrv_driver_preadv(bs, offset,
max_nb_sectors * BDRV_SECTOR_SIZE,
&local_qiov, 0);
qemu_iovec_destroy(&local_qiov);
} else {
ret = 0;
}
/* Reading beyond end of file is supposed to produce zeroes */
if (ret == 0 && total_sectors < sector_num + nb_sectors) {
uint64_t offset = MAX(0, total_sectors - sector_num);
uint64_t bytes = (sector_num + nb_sectors - offset) *
BDRV_SECTOR_SIZE;
qemu_iovec_memset(qiov, offset * BDRV_SECTOR_SIZE, 0, bytes);
}
}
out:
return ret;
}
/*
* Handle a read request in coroutine context
*/
int coroutine_fn bdrv_co_preadv(BlockDriverState *bs,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->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;
}
/* 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;
}
/* throttling disk I/O */
if (bs->throttle_state) {
throttle_group_co_io_limits_intercept(bs, bytes, false);
}
/* 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(bs, &req, offset, bytes, align,
use_local_qiov ? &local_qiov : qiov,
flags);
tracked_request_end(&req);
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(BlockDriverState *bs,
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(bs, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_readv(bs, sector_num, nb_sectors);
return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov, 0);
}
int coroutine_fn bdrv_co_readv_no_serialising(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_readv_no_serialising(bs, sector_num, nb_sectors);
return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov,
BDRV_REQ_NO_SERIALISING);
}
int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors);
return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov,
BDRV_REQ_COPY_ON_READ);
}
#define MAX_WRITE_ZEROES_BOUNCE_BUFFER 32768
static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
{
BlockDriver *drv = bs->drv;
QEMUIOVector qiov;
struct iovec iov = {0};
int ret = 0;
bool need_flush = false;
int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_write_zeroes,
BDRV_REQUEST_MAX_SECTORS);
while (nb_sectors > 0 && !ret) {
int num = nb_sectors;
/* Align request. Block drivers can expect the "bulk" of the request
* to be aligned.
*/
if (bs->bl.write_zeroes_alignment
&& num > bs->bl.write_zeroes_alignment) {
if (sector_num % bs->bl.write_zeroes_alignment != 0) {
/* Make a small request up to the first aligned sector. */
num = bs->bl.write_zeroes_alignment;
num -= sector_num % bs->bl.write_zeroes_alignment;
} else if ((sector_num + num) % bs->bl.write_zeroes_alignment != 0) {
/* Shorten the request to the last aligned sector. num cannot
* underflow because num > bs->bl.write_zeroes_alignment.
*/
num -= (sector_num + num) % bs->bl.write_zeroes_alignment;
}
}
/* 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_write_zeroes) {
ret = drv->bdrv_co_write_zeroes(bs, sector_num, 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 */
int max_xfer_len = MIN_NON_ZERO(bs->bl.max_transfer_length,
MAX_WRITE_ZEROES_BOUNCE_BUFFER);
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_xfer_len);
iov.iov_len = num * BDRV_SECTOR_SIZE;
if (iov.iov_base == NULL) {
iov.iov_base = qemu_try_blockalign(bs, num * BDRV_SECTOR_SIZE);
if (iov.iov_base == NULL) {
ret = -ENOMEM;
goto fail;
}
memset(iov.iov_base, 0, num * BDRV_SECTOR_SIZE);
}
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_driver_pwritev(bs, sector_num * BDRV_SECTOR_SIZE,
num * BDRV_SECTOR_SIZE, &qiov,
write_flags);
/* Keep bounce buffer around if it is big enough for all
* all future requests.
*/
if (num < max_xfer_len) {
qemu_vfree(iov.iov_base);
iov.iov_base = NULL;
}
}
sector_num += num;
nb_sectors -= 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.
*/
static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
bool waited;
int ret;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
assert(!qiov || bytes == qiov->size);
assert((bs->open_flags & BDRV_O_NO_IO) == 0);
waited = wait_serialising_requests(req);
assert(!waited || !req->serialising);
assert(req->overlap_offset <= offset);
assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
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_write_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_write_zeroes(bs, sector_num, nb_sectors, flags);
} else {
bdrv_debug_event(bs, BLKDBG_PWRITEV);
ret = bdrv_driver_pwritev(bs, offset, bytes, qiov, flags);
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE);
bdrv_set_dirty(bs, sector_num, nb_sectors);
if (bs->wr_highest_offset < offset + bytes) {
bs->wr_highest_offset = offset + bytes;
}
if (ret >= 0) {
bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors);
}
return ret;
}
static int coroutine_fn bdrv_co_do_zero_pwritev(BlockDriverState *bs,
int64_t offset,
unsigned int bytes,
BdrvRequestFlags flags,
BdrvTrackedRequest *req)
{
uint8_t *buf = NULL;
QEMUIOVector local_qiov;
struct iovec iov;
uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->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(bs, 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(bs, req, offset & ~(align - 1), 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(bs, req, offset, aligned_bytes,
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(bs, 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(bs, req, offset, 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(BlockDriverState *bs,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BdrvTrackedRequest req;
/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->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;
}
/* throttling disk I/O */
if (bs->throttle_state) {
throttle_group_co_io_limits_intercept(bs, bytes, true);
}
/*
* 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(bs, 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(bs, &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);
}
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(bs, &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(bs, &req, offset, bytes,
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);
return ret;
}
static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
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(bs, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_writev(bs, sector_num, nb_sectors);
return bdrv_co_do_writev(bs, sector_num, nb_sectors, qiov, 0);
}
int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
BdrvRequestFlags flags)
{
trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags);
if (!(bs->open_flags & BDRV_O_UNMAP)) {
flags &= ~BDRV_REQ_MAY_UNMAP;
}
return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
BDRV_REQ_ZERO_WRITE | flags);
}
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;
ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum,
file);
if (ret < 0) {
*pnum = 0;
return ret;
}
if (ret & BDRV_BLOCK_RAW) {
assert(ret & BDRV_BLOCK_OFFSET_VALID);
return bdrv_get_block_status(bs->file->bs, ret >> BDRV_SECTOR_BITS,
*pnum, pnum, file);
}
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);
}
}
}
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 {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_get_block_status_above_co_entry);
qemu_coroutine_enter(co, &data);
while (!data.done) {
aio_poll(aio_context, true);
}
}
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;
}
int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BlockDriver *drv = bs->drv;
int ret;
if (!drv) {
return -ENOMEDIUM;
}
if (!drv->bdrv_write_compressed) {
return -ENOTSUP;
}
ret = bdrv_check_request(bs, sector_num, nb_sectors);
if (ret < 0) {
return ret;
}
assert(QLIST_EMPTY(&bs->dirty_bitmaps));
return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);
}
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,
};
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_writev_vmstate(bs, &qiov, pos);
}
int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
} else if (drv->bdrv_save_vmstate) {
return drv->bdrv_save_vmstate(bs, qiov, pos);
} else if (bs->file) {
return bdrv_writev_vmstate(bs->file->bs, qiov, pos);
}
return -ENOTSUP;
}
int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
int64_t pos, int size)
{
BlockDriver *drv = bs->drv;
if (!drv)
return -ENOMEDIUM;
if (drv->bdrv_load_vmstate)
return drv->bdrv_load_vmstate(bs, buf, pos, size);
if (bs->file)
return bdrv_load_vmstate(bs->file->bs, buf, pos, size);
return -ENOTSUP;
}
/**************************************************************/
/* async I/Os */
BlockAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_readv(bs, sector_num, nb_sectors, opaque);
return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, 0,
cb, opaque, false);
}
BlockAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_writev(bs, sector_num, nb_sectors, opaque);
return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, 0,
cb, opaque, true);
}
BlockAIOCB *bdrv_aio_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_write_zeroes(bs, sector_num, nb_sectors, flags, opaque);
return bdrv_co_aio_rw_vector(bs, sector_num, NULL, nb_sectors,
BDRV_REQ_ZERO_WRITE | flags,
cb, opaque, true);
}
typedef struct MultiwriteCB {
int error;
int num_requests;
int num_callbacks;
struct {
BlockCompletionFunc *cb;
void *opaque;
QEMUIOVector *free_qiov;
} callbacks[];
} MultiwriteCB;
static void multiwrite_user_cb(MultiwriteCB *mcb)
{
int i;
for (i = 0; i < mcb->num_callbacks; i++) {
mcb->callbacks[i].cb(mcb->callbacks[i].opaque, mcb->error);
if (mcb->callbacks[i].free_qiov) {
qemu_iovec_destroy(mcb->callbacks[i].free_qiov);
}
g_free(mcb->callbacks[i].free_qiov);
}
}
static void multiwrite_cb(void *opaque, int ret)
{
MultiwriteCB *mcb = opaque;
trace_multiwrite_cb(mcb, ret);
if (ret < 0 && !mcb->error) {
mcb->error = ret;
}
mcb->num_requests--;
if (mcb->num_requests == 0) {
multiwrite_user_cb(mcb);
g_free(mcb);
}
}
static int multiwrite_req_compare(const void *a, const void *b)
{
const BlockRequest *req1 = a, *req2 = b;
/*
* Note that we can't simply subtract req2->sector from req1->sector
* here as that could overflow the return value.
*/
if (req1->sector > req2->sector) {
return 1;
} else if (req1->sector < req2->sector) {
return -1;
} else {
return 0;
}
}
/*
* Takes a bunch of requests and tries to merge them. Returns the number of
* requests that remain after merging.
*/
static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs,
int num_reqs, MultiwriteCB *mcb)
{
int i, outidx;
// Sort requests by start sector
qsort(reqs, num_reqs, sizeof(*reqs), &multiwrite_req_compare);
// Check if adjacent requests touch the same clusters. If so, combine them,
// filling up gaps with zero sectors.
outidx = 0;
for (i = 1; i < num_reqs; i++) {
int merge = 0;
int64_t oldreq_last = reqs[outidx].sector + reqs[outidx].nb_sectors;
// Handle exactly sequential writes and overlapping writes.
if (reqs[i].sector <= oldreq_last) {
merge = 1;
}
if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1 >
bs->bl.max_iov) {
merge = 0;
}
if (bs->bl.max_transfer_length && reqs[outidx].nb_sectors +
reqs[i].nb_sectors > bs->bl.max_transfer_length) {
merge = 0;
}
if (merge) {
size_t size;
QEMUIOVector *qiov = g_malloc0(sizeof(*qiov));
qemu_iovec_init(qiov,
reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1);
// Add the first request to the merged one. If the requests are
// overlapping, drop the last sectors of the first request.
size = (reqs[i].sector - reqs[outidx].sector) << 9;
qemu_iovec_concat(qiov, reqs[outidx].qiov, 0, size);
// We should need to add any zeros between the two requests
assert (reqs[i].sector <= oldreq_last);
// Add the second request
qemu_iovec_concat(qiov, reqs[i].qiov, 0, reqs[i].qiov->size);
// Add tail of first request, if necessary
if (qiov->size < reqs[outidx].qiov->size) {
qemu_iovec_concat(qiov, reqs[outidx].qiov, qiov->size,
reqs[outidx].qiov->size - qiov->size);
}
reqs[outidx].nb_sectors = qiov->size >> 9;
reqs[outidx].qiov = qiov;
mcb->callbacks[i].free_qiov = reqs[outidx].qiov;
} else {
outidx++;
reqs[outidx].sector = reqs[i].sector;
reqs[outidx].nb_sectors = reqs[i].nb_sectors;
reqs[outidx].qiov = reqs[i].qiov;
}
}
if (bs->blk) {
block_acct_merge_done(blk_get_stats(bs->blk), BLOCK_ACCT_WRITE,
num_reqs - outidx - 1);
}
return outidx + 1;
}
/*
* Submit multiple AIO write requests at once.
*
* On success, the function returns 0 and all requests in the reqs array have
* been submitted. In error case this function returns -1, and any of the
* requests may or may not be submitted yet. In particular, this means that the
* callback will be called for some of the requests, for others it won't. The
* caller must check the error field of the BlockRequest to wait for the right
* callbacks (if error != 0, no callback will be called).
*
* The implementation may modify the contents of the reqs array, e.g. to merge
* requests. However, the fields opaque and error are left unmodified as they
* are used to signal failure for a single request to the caller.
*/
int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
{
MultiwriteCB *mcb;
int i;
/* don't submit writes if we don't have a medium */
if (bs->drv == NULL) {
for (i = 0; i < num_reqs; i++) {
reqs[i].error = -ENOMEDIUM;
}
return -1;
}
if (num_reqs == 0) {
return 0;
}
// Create MultiwriteCB structure
mcb = g_malloc0(sizeof(*mcb) + num_reqs * sizeof(*mcb->callbacks));
mcb->num_requests = 0;
mcb->num_callbacks = num_reqs;
for (i = 0; i < num_reqs; i++) {
mcb->callbacks[i].cb = reqs[i].cb;
mcb->callbacks[i].opaque = reqs[i].opaque;
}
// Check for mergable requests
num_reqs = multiwrite_merge(bs, reqs, num_reqs, mcb);
trace_bdrv_aio_multiwrite(mcb, mcb->num_callbacks, num_reqs);
/* Run the aio requests. */
mcb->num_requests = num_reqs;
for (i = 0; i < num_reqs; i++) {
bdrv_co_aio_rw_vector(bs, reqs[i].sector, reqs[i].qiov,
reqs[i].nb_sectors, reqs[i].flags,
multiwrite_cb, mcb,
true);
}
return 0;
}
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) {
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 BlockAIOCBCoroutine {
BlockAIOCB common;
BlockRequest req;
bool is_write;
bool need_bh;
bool *done;
QEMUBH* bh;
} BlockAIOCBCoroutine;
static const AIOCBInfo bdrv_em_co_aiocb_info = {
.aiocb_size = sizeof(BlockAIOCBCoroutine),
};
static void bdrv_co_complete(BlockAIOCBCoroutine *acb)
{
if (!acb->need_bh) {
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);
qemu_bh_delete(acb->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;
acb->bh = aio_bh_new(bdrv_get_aio_context(bs), bdrv_co_em_bh, acb);
qemu_bh_schedule(acb->bh);
}
}
/* Invoke bdrv_co_do_readv/bdrv_co_do_writev */
static void coroutine_fn bdrv_co_do_rw(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
if (!acb->is_write) {
acb->req.error = bdrv_co_do_readv(bs, acb->req.sector,
acb->req.nb_sectors, acb->req.qiov, acb->req.flags);
} else {
acb->req.error = bdrv_co_do_writev(bs, acb->req.sector,
acb->req.nb_sectors, acb->req.qiov, acb->req.flags);
}
bdrv_co_complete(acb);
}
static BlockAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BdrvRequestFlags flags,
BlockCompletionFunc *cb,
void *opaque,
bool is_write)
{
Coroutine *co;
BlockAIOCBCoroutine *acb;
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
acb->req.sector = sector_num;
acb->req.nb_sectors = nb_sectors;
acb->req.qiov = qiov;
acb->req.flags = flags;
acb->is_write = is_write;
co = qemu_coroutine_create(bdrv_co_do_rw);
qemu_coroutine_enter(co, acb);
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;
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);
qemu_coroutine_enter(co, acb);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
static void coroutine_fn bdrv_aio_discard_co_entry(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
acb->req.error = bdrv_co_discard(bs, acb->req.sector, acb->req.nb_sectors);
bdrv_co_complete(acb);
}
BlockAIOCB *bdrv_aio_discard(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
Coroutine *co;
BlockAIOCBCoroutine *acb;
trace_bdrv_aio_discard(bs, sector_num, nb_sectors, opaque);
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
acb->req.sector = sector_num;
acb->req.nb_sectors = nb_sectors;
co = qemu_coroutine_create(bdrv_aio_discard_co_entry);
qemu_coroutine_enter(co, acb);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
void *qemu_aio_get(const AIOCBInfo *aiocb_info, BlockDriverState *bs,
BlockCompletionFunc *cb, void *opaque)
{
BlockAIOCB *acb;
acb = g_malloc(aiocb_info->aiocb_size);
acb->aiocb_info = aiocb_info;
acb->bs = bs;
acb->cb = cb;
acb->opaque = opaque;
acb->refcnt = 1;
return acb;
}
void qemu_aio_ref(void *p)
{
BlockAIOCB *acb = p;
acb->refcnt++;
}
void qemu_aio_unref(void *p)
{
BlockAIOCB *acb = p;
assert(acb->refcnt > 0);
if (--acb->refcnt == 0) {
g_free(acb);
}
}
/**************************************************************/
/* Coroutine block device emulation */
static void coroutine_fn bdrv_flush_co_entry(void *opaque)
{
RwCo *rwco = opaque;
rwco->ret = bdrv_co_flush(rwco->bs);
}
int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{
int ret;
BdrvTrackedRequest req;
if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
bdrv_is_sg(bs)) {
return 0;
}
tracked_request_begin(&req, bs, 0, 0, BDRV_TRACKED_FLUSH);
/* 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;
}
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:
tracked_request_end(&req);
return ret;
}
int bdrv_flush(BlockDriverState *bs)
{
Coroutine *co;
RwCo rwco = {
.bs = bs,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_flush_co_entry(&rwco);
} else {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_flush_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
aio_poll(aio_context, true);
}
}
return rwco.ret;
}
typedef struct DiscardCo {
BlockDriverState *bs;
int64_t sector_num;
int nb_sectors;
int ret;
} DiscardCo;
static void coroutine_fn bdrv_discard_co_entry(void *opaque)
{
DiscardCo *rwco = opaque;
rwco->ret = bdrv_co_discard(rwco->bs, rwco->sector_num, rwco->nb_sectors);
}
int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
int nb_sectors)
{
BdrvTrackedRequest req;
int max_discard, ret;
if (!bs->drv) {
return -ENOMEDIUM;
}
ret = bdrv_check_request(bs, sector_num, nb_sectors);
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_discard && !bs->drv->bdrv_aio_discard) {
return 0;
}
tracked_request_begin(&req, bs, sector_num, nb_sectors,
BDRV_TRACKED_DISCARD);
bdrv_set_dirty(bs, sector_num, nb_sectors);
max_discard = MIN_NON_ZERO(bs->bl.max_discard, BDRV_REQUEST_MAX_SECTORS);
while (nb_sectors > 0) {
int ret;
int num = nb_sectors;
/* align request */
if (bs->bl.discard_alignment &&
num >= bs->bl.discard_alignment &&
sector_num % bs->bl.discard_alignment) {
if (num > bs->bl.discard_alignment) {
num = bs->bl.discard_alignment;
}
num -= sector_num % bs->bl.discard_alignment;
}
/* limit request size */
if (num > max_discard) {
num = max_discard;
}
if (bs->drv->bdrv_co_discard) {
ret = bs->drv->bdrv_co_discard(bs, sector_num, num);
} else {
BlockAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_discard(bs, sector_num, nb_sectors,
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;
}
sector_num += num;
nb_sectors -= num;
}
ret = 0;
out:
tracked_request_end(&req);
return ret;
}
int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
{
Coroutine *co;
DiscardCo rwco = {
.bs = bs,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_discard_co_entry(&rwco);
} else {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_discard_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
aio_poll(aio_context, true);
}
}
return rwco.ret;
}
typedef struct {
CoroutineIOCompletion *co;
QEMUBH *bh;
} BdrvIoctlCompletionData;
static void bdrv_ioctl_bh_cb(void *opaque)
{
BdrvIoctlCompletionData *data = opaque;
bdrv_co_io_em_complete(data->co, -ENOTSUP);
qemu_bh_delete(data->bh);
}
static int bdrv_co_do_ioctl(BlockDriverState *bs, int req, void *buf)
{
BlockDriver *drv = bs->drv;
BdrvTrackedRequest tracked_req;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
BlockAIOCB *acb;
tracked_request_begin(&tracked_req, bs, 0, 0, BDRV_TRACKED_IOCTL);
if (!drv || !drv->bdrv_aio_ioctl) {
co.ret = -ENOTSUP;
goto out;
}
acb = drv->bdrv_aio_ioctl(bs, req, buf, bdrv_co_io_em_complete, &co);
if (!acb) {
BdrvIoctlCompletionData *data = g_new(BdrvIoctlCompletionData, 1);
data->bh = aio_bh_new(bdrv_get_aio_context(bs),
bdrv_ioctl_bh_cb, data);
data->co = &co;
qemu_bh_schedule(data->bh);
}
qemu_coroutine_yield();
out:
tracked_request_end(&tracked_req);
return co.ret;
}
typedef struct {
BlockDriverState *bs;
int req;
void *buf;
int ret;
} BdrvIoctlCoData;
static void coroutine_fn bdrv_co_ioctl_entry(void *opaque)
{
BdrvIoctlCoData *data = opaque;
data->ret = bdrv_co_do_ioctl(data->bs, data->req, data->buf);
}
/* needed for generic scsi interface */
int bdrv_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
{
BdrvIoctlCoData data = {
.bs = bs,
.req = req,
.buf = buf,
.ret = -EINPROGRESS,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_co_ioctl_entry(&data);
} else {
Coroutine *co = qemu_coroutine_create(bdrv_co_ioctl_entry);
qemu_coroutine_enter(co, &data);
while (data.ret == -EINPROGRESS) {
aio_poll(bdrv_get_aio_context(bs), true);
}
}
return data.ret;
}
static void coroutine_fn bdrv_co_aio_ioctl_entry(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
acb->req.error = bdrv_co_do_ioctl(acb->common.bs,
acb->req.req, acb->req.buf);
bdrv_co_complete(acb);
}
BlockAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
unsigned long int req, void *buf,
BlockCompletionFunc *cb, void *opaque)
{
BlockAIOCBCoroutine *acb = qemu_aio_get(&bdrv_em_co_aiocb_info,
bs, cb, opaque);
Coroutine *co;
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
acb->req.req = req;
acb->req.buf = buf;
co = qemu_coroutine_create(bdrv_co_aio_ioctl_entry);
qemu_coroutine_enter(co, acb);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
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 && bs->io_plug_disabled == 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 && bs->io_plug_disabled == 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);
}
}
void bdrv_io_unplugged_begin(BlockDriverState *bs)
{
BdrvChild *child;
if (bs->io_plug_disabled++ == 0 && 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_unplugged_begin(child->bs);
}
}
void bdrv_io_unplugged_end(BlockDriverState *bs)
{
BdrvChild *child;
assert(bs->io_plug_disabled);
QLIST_FOREACH(child, &bs->children, next) {
bdrv_io_unplugged_end(child->bs);
}
if (--bs->io_plug_disabled == 0 && bs->io_plugged > 0) {
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_io_plug) {
drv->bdrv_io_plug(bs);
}
}
}
void bdrv_drained_begin(BlockDriverState *bs)
{
if (!bs->quiesce_counter++) {
aio_disable_external(bdrv_get_aio_context(bs));
}
bdrv_drain(bs);
}
void bdrv_drained_end(BlockDriverState *bs)
{
assert(bs->quiesce_counter > 0);
if (--bs->quiesce_counter > 0) {
return;
}
aio_enable_external(bdrv_get_aio_context(bs));
}
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