[v3,2/2] block: move I/O request processing to block/io.c

diff --git a/block.c b/block.c
index 1f0a4e2..7904098 100644
--- a/block.c
+++ b/block.c
@@ -30,7 +30,6 @@ 
 #include "qapi/qmp/qjson.h"
 #include "sysemu/block-backend.h"
 #include "sysemu/sysemu.h"
-#include "sysemu/qtest.h"
 #include "qemu/notify.h"
 #include "block/coroutine.h"
 #include "block/qapi.h"
@@ -71,36 +70,6 @@  struct BdrvDirtyBitmap {
 
 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
 
-static BlockAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockCompletionFunc *cb, void *opaque);
-static BlockAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockCompletionFunc *cb, void *opaque);
-static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
-                                         int64_t sector_num, int nb_sectors,
-                                         QEMUIOVector *iov);
-static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
-                                         int64_t sector_num, int nb_sectors,
-                                         QEMUIOVector *iov);
-static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
-    BdrvRequestFlags flags);
-static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
-    BdrvRequestFlags flags);
-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);
-
 static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
     QTAILQ_HEAD_INITIALIZER(bdrv_states);
 
@@ -110,10 +79,6 @@  static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
 static QLIST_HEAD(, BlockDriver) bdrv_drivers =
     QLIST_HEAD_INITIALIZER(bdrv_drivers);
 
-static void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
-                           int nr_sectors);
-static void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
-                             int nr_sectors);
 static void bdrv_dirty_bitmap_truncate(BlockDriverState *bs);
 /* If non-zero, use only whitelisted block drivers */
 static int use_bdrv_whitelist;
@@ -138,110 +103,6 @@  int is_windows_drive(const char *filename)
 }
 #endif
 
-/* throttling disk I/O limits */
-void bdrv_set_io_limits(BlockDriverState *bs,
-                        ThrottleConfig *cfg)
-{
-    int i;
-
-    throttle_config(&bs->throttle_state, cfg);
-
-    for (i = 0; i < 2; i++) {
-        qemu_co_enter_next(&bs->throttled_reqs[i]);
-    }
-}
-
-/* this function drain all the throttled IOs */
-static bool bdrv_start_throttled_reqs(BlockDriverState *bs)
-{
-    bool drained = false;
-    bool enabled = bs->io_limits_enabled;
-    int i;
-
-    bs->io_limits_enabled = false;
-
-    for (i = 0; i < 2; i++) {
-        while (qemu_co_enter_next(&bs->throttled_reqs[i])) {
-            drained = true;
-        }
-    }
-
-    bs->io_limits_enabled = enabled;
-
-    return drained;
-}
-
-void bdrv_io_limits_disable(BlockDriverState *bs)
-{
-    bs->io_limits_enabled = false;
-
-    bdrv_start_throttled_reqs(bs);
-
-    throttle_destroy(&bs->throttle_state);
-}
-
-static void bdrv_throttle_read_timer_cb(void *opaque)
-{
-    BlockDriverState *bs = opaque;
-    qemu_co_enter_next(&bs->throttled_reqs[0]);
-}
-
-static void bdrv_throttle_write_timer_cb(void *opaque)
-{
-    BlockDriverState *bs = opaque;
-    qemu_co_enter_next(&bs->throttled_reqs[1]);
-}
-
-/* should be called before bdrv_set_io_limits if a limit is set */
-void bdrv_io_limits_enable(BlockDriverState *bs)
-{
-    int clock_type = QEMU_CLOCK_REALTIME;
-
-    if (qtest_enabled()) {
-        /* For testing block IO throttling only */
-        clock_type = QEMU_CLOCK_VIRTUAL;
-    }
-    assert(!bs->io_limits_enabled);
-    throttle_init(&bs->throttle_state,
-                  bdrv_get_aio_context(bs),
-                  clock_type,
-                  bdrv_throttle_read_timer_cb,
-                  bdrv_throttle_write_timer_cb,
-                  bs);
-    bs->io_limits_enabled = true;
-}
-
-/* This function makes an IO wait if needed
- *
- * @nb_sectors: the number of sectors of the IO
- * @is_write:   is the IO a write
- */
-static void bdrv_io_limits_intercept(BlockDriverState *bs,
-                                     unsigned int bytes,
-                                     bool is_write)
-{
-    /* does this io must wait */
-    bool must_wait = throttle_schedule_timer(&bs->throttle_state, is_write);
-
-    /* if must wait or any request of this type throttled queue the IO */
-    if (must_wait ||
-        !qemu_co_queue_empty(&bs->throttled_reqs[is_write])) {
-        qemu_co_queue_wait(&bs->throttled_reqs[is_write]);
-    }
-
-    /* the IO will be executed, do the accounting */
-    throttle_account(&bs->throttle_state, is_write, bytes);
-
-
-    /* if the next request must wait -> do nothing */
-    if (throttle_schedule_timer(&bs->throttle_state, is_write)) {
-        return;
-    }
-
-    /* else queue next request for execution */
-    qemu_co_queue_next(&bs->throttled_reqs[is_write]);
-}
-
 size_t bdrv_opt_mem_align(BlockDriverState *bs)
 {
     if (!bs || !bs->drv) {
@@ -355,20 +216,7 @@  void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz,
 
 void bdrv_register(BlockDriver *bdrv)
 {
-    /* Block drivers without coroutine functions need emulation */
-    if (!bdrv->bdrv_co_readv) {
-        bdrv->bdrv_co_readv = bdrv_co_readv_em;
-        bdrv->bdrv_co_writev = bdrv_co_writev_em;
-
-        /* bdrv_co_readv_em()/brdv_co_writev_em() work in terms of aio, so if
-         * the block driver lacks aio we need to emulate that too.
-         */
-        if (!bdrv->bdrv_aio_readv) {
-            /* add AIO emulation layer */
-            bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
-            bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
-        }
-    }
+    bdrv_setup_io_funcs(bdrv);
 
     QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
 }
@@ -540,54 +388,6 @@  int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
     return ret;
 }
 
-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, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
-            return;
-        }
-        bs->bl.opt_transfer_length = bs->file->bl.opt_transfer_length;
-        bs->bl.max_transfer_length = bs->file->bl.max_transfer_length;
-        bs->bl.opt_mem_alignment = bs->file->bl.opt_mem_alignment;
-    } else {
-        bs->bl.opt_mem_alignment = 512;
-    }
-
-    if (bs->backing_hd) {
-        bdrv_refresh_limits(bs->backing_hd, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
-            return;
-        }
-        bs->bl.opt_transfer_length =
-            MAX(bs->bl.opt_transfer_length,
-                bs->backing_hd->bl.opt_transfer_length);
-        bs->bl.max_transfer_length =
-            MIN_NON_ZERO(bs->bl.max_transfer_length,
-                         bs->backing_hd->bl.max_transfer_length);
-        bs->bl.opt_mem_alignment =
-            MAX(bs->bl.opt_mem_alignment,
-                bs->backing_hd->bl.opt_mem_alignment);
-    }
-
-    /* Then let the driver override it */
-    if (drv->bdrv_refresh_limits) {
-        drv->bdrv_refresh_limits(bs, errp);
-    }
-}
-
 /**
  * Try to get @bs's logical and physical block size.
  * On success, store them in @bsz struct and return 0.
@@ -861,22 +661,6 @@  int bdrv_parse_cache_flags(const char *mode, int *flags)
     return 0;
 }
 
-/**
- * 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--;
-}
-
 /*
  * Returns the flags that a temporary snapshot should get, based on the
  * originally requested flags (the originally requested image will have flags
@@ -1986,108 +1770,6 @@  void bdrv_close_all(void)
     }
 }
 
-/* Check if any requests are in-flight (including throttled requests) */
-static bool bdrv_requests_pending(BlockDriverState *bs)
-{
-    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;
-    }
-    if (bs->file && bdrv_requests_pending(bs->file)) {
-        return true;
-    }
-    if (bs->backing_hd && bdrv_requests_pending(bs->backing_hd)) {
-        return true;
-    }
-    return false;
-}
-
-static bool bdrv_drain_one(BlockDriverState *bs)
-{
-    bool bs_busy;
-
-    bdrv_flush_io_queue(bs);
-    bdrv_start_throttled_reqs(bs);
-    bs_busy = bdrv_requests_pending(bs);
-    bs_busy |= aio_poll(bdrv_get_aio_context(bs), bs_busy);
-    return bs_busy;
-}
-
-/*
- * Wait for pending requests to complete on a single BlockDriverState subtree
- *
- * See the warning in bdrv_drain_all().  This function can only be called if
- * you are sure nothing can generate I/O because you have op blockers
- * installed.
- *
- * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
- * AioContext.
- */
-void bdrv_drain(BlockDriverState *bs)
-{
-    while (bdrv_drain_one(bs)) {
-        /* Keep iterating */
-    }
-}
-
-/*
- * 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.
- *
- * 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 be arbitrarily complex and a constant flow of I/O can come until the
- * coroutine is complete.  Because of this, it is not possible to have a
- * function to drain a single device's I/O queue.
- */
-void bdrv_drain_all(void)
-{
-    /* Always run first iteration so any pending completion BHs run */
-    bool busy = true;
-    BlockDriverState *bs = NULL;
-
-    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);
-        }
-        aio_context_release(aio_context);
-    }
-
-    while (busy) {
-        busy = false;
-        bs = NULL;
-
-        while ((bs = bdrv_next(bs))) {
-            AioContext *aio_context = bdrv_get_aio_context(bs);
-
-            aio_context_acquire(aio_context);
-            busy |= bdrv_drain_one(bs);
-            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);
-        if (bs->job) {
-            block_job_resume(bs->job);
-        }
-        aio_context_release(aio_context);
-    }
-}
-
 /* make a BlockDriverState anonymous by removing from bdrv_state and
  * graph_bdrv_state list.
    Also, NULL terminate the device_name to prevent double remove */
@@ -2409,152 +2091,6 @@  int bdrv_commit_all(void)
     return 0;
 }
 
-/**
- * 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, bool is_write)
-{
-    *req = (BdrvTrackedRequest){
-        .bs = bs,
-        .offset         = offset,
-        .bytes          = bytes,
-        .is_write       = is_write,
-        .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;
-}
-
 /*
  * Return values:
  * 0        - success
@@ -2723,879 +2259,6 @@  exit:
     return ret;
 }
 
-
-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_do_preadv(rwco->bs, rwco->offset,
-                                      rwco->qiov->size, rwco->qiov,
-                                      rwco->flags);
-    } else {
-        rwco->ret = bdrv_co_do_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,
-    };
-
-    /**
-     * In sync call context, when the vcpu is blocked, this throttling timer
-     * will not fire; so the I/O throttling function has to be disabled here
-     * if it has been enabled.
-     */
-    if (bs->io_limits_enabled) {
-        fprintf(stderr, "Disabling I/O throttling on '%s' due "
-                        "to synchronous I/O.\n", bdrv_get_device_name(bs));
-        bdrv_io_limits_disable(bs);
-    }
-
-    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);
-}
-
-/* Just like bdrv_read(), but with I/O throttling temporarily disabled */
-int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
-                          uint8_t *buf, int nb_sectors)
-{
-    bool enabled;
-    int ret;
-
-    enabled = bs->io_limits_enabled;
-    bs->io_limits_enabled = false;
-    ret = bdrv_read(bs, sector_num, buf, nb_sectors);
-    bs->io_limits_enabled = enabled;
-    return ret;
-}
-
-/* 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).
- *
- * 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;
-    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);
-        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;
-    }
-
-    /* No flush needed for cache modes that already do it */
-    if (bs->enable_write_cache) {
-        bdrv_flush(bs);
-    }
-
-    return 0;
-}
-
-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 = drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors,
-                             &bounce_qiov);
-    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 = drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors,
-                                  &bounce_qiov);
-    }
-
-    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)
-{
-    BlockDriver *drv = bs->drv;
-    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);
-
-    /* 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));
-    }
-
-    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 = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
-    } 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 = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
-        } 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 = drv->bdrv_co_readv(bs, sector_num, max_nb_sectors,
-                                     &local_qiov);
-
-            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;
-}
-
-static inline uint64_t bdrv_get_align(BlockDriverState *bs)
-{
-    /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
-    return MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
-}
-
-static inline bool bdrv_req_is_aligned(BlockDriverState *bs,
-                                       int64_t offset, size_t bytes)
-{
-    int64_t align = bdrv_get_align(bs);
-    return !(offset & (align - 1) || (bytes & (align - 1)));
-}
-
-/*
- * Handle a read request in coroutine context
- */
-static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
-    BdrvRequestFlags flags)
-{
-    BlockDriver *drv = bs->drv;
-    BdrvTrackedRequest req;
-
-    uint64_t align = bdrv_get_align(bs);
-    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;
-    }
-
-    if (bs->copy_on_read) {
-        flags |= BDRV_REQ_COPY_ON_READ;
-    }
-
-    /* throttling disk I/O */
-    if (bs->io_limits_enabled) {
-        bdrv_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, false);
-    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_do_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_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;
-
-    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);
-        }
-
-        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);
-            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 = drv->bdrv_co_writev(bs, sector_num, num, &qiov);
-
-            /* 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:
-    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);
-
-    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) {
-        BLKDBG_EVENT(bs, BLKDBG_PWRITEV_ZERO);
-        ret = bdrv_co_do_write_zeroes(bs, sector_num, nb_sectors, flags);
-    } else {
-        BLKDBG_EVENT(bs, BLKDBG_PWRITEV);
-        ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
-    }
-    BLKDBG_EVENT(bs, BLKDBG_PWRITEV_DONE);
-
-    if (ret == 0 && !bs->enable_write_cache) {
-        ret = bdrv_co_flush(bs);
-    }
-
-    bdrv_set_dirty(bs, sector_num, nb_sectors);
-
-    block_acct_highest_sector(&bs->stats, sector_num, nb_sectors);
-
-    if (ret >= 0) {
-        bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors);
-    }
-
-    return ret;
-}
-
-/*
- * Handle a write request in coroutine context
- */
-static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
-    BdrvRequestFlags flags)
-{
-    BdrvTrackedRequest req;
-    uint64_t align = bdrv_get_align(bs);
-    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 -EACCES;
-    }
-
-    ret = bdrv_check_byte_request(bs, offset, bytes);
-    if (ret < 0) {
-        return ret;
-    }
-
-    /* throttling disk I/O */
-    if (bs->io_limits_enabled) {
-        bdrv_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, true);
-
-    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);
-
-        BLKDBG_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;
-        }
-        BLKDBG_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);
-
-        BLKDBG_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;
-        }
-        BLKDBG_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);
-    }
-
-    if (use_local_qiov) {
-        /* Local buffer may have non-zero data. */
-        flags &= ~BDRV_REQ_ZERO_WRITE;
-    }
-    ret = bdrv_aligned_pwritev(bs, &req, offset, bytes,
-                               use_local_qiov ? &local_qiov : qiov,
-                               flags);
-
-fail:
-    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_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_do_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)
-{
-    int ret;
-
-    trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags);
-
-    if (!(bs->open_flags & BDRV_O_UNMAP)) {
-        flags &= ~BDRV_REQ_MAY_UNMAP;
-    }
-    if (bdrv_req_is_aligned(bs, sector_num << BDRV_SECTOR_BITS,
-                            nb_sectors << BDRV_SECTOR_BITS)) {
-        ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
-                                BDRV_REQ_ZERO_WRITE | flags);
-    } else {
-        uint8_t *buf;
-        QEMUIOVector local_qiov;
-        size_t bytes = nb_sectors << BDRV_SECTOR_BITS;
-
-        buf = qemu_memalign(bdrv_opt_mem_align(bs), bytes);
-        memset(buf, 0, bytes);
-        qemu_iovec_init(&local_qiov, 1);
-        qemu_iovec_add(&local_qiov, buf, bytes);
-
-        ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, &local_qiov,
-                                BDRV_REQ_ZERO_WRITE | flags);
-        qemu_vfree(buf);
-    }
-    return ret;
-}
-
 /**
  * Truncate file to 'offset' bytes (needed only for file protocols)
  */
@@ -4015,26 +2678,6 @@  int bdrv_get_flags(BlockDriverState *bs)
     return bs->open_flags;
 }
 
-int bdrv_flush_all(void)
-{
-    BlockDriverState *bs = NULL;
-    int result = 0;
-
-    while ((bs = bdrv_next(bs))) {
-        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;
-}
-
 int bdrv_has_zero_init_1(BlockDriverState *bs)
 {
     return 1;
@@ -4087,222 +2730,6 @@  bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
     return false;
 }
 
-typedef struct BdrvCoGetBlockStatusData {
-    BlockDriverState *bs;
-    BlockDriverState *base;
-    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.
- */
-static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
-                                                     int64_t sector_num,
-                                                     int nb_sectors, int *pnum)
-{
-    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;
-    }
-
-    ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum);
-    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, ret >> BDRV_SECTOR_BITS,
-                                     *pnum, pnum);
-    }
-
-    if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
-        ret |= BDRV_BLOCK_ALLOCATED;
-    }
-
-    if (!(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO)) {
-        if (bdrv_unallocated_blocks_are_zero(bs)) {
-            ret |= BDRV_BLOCK_ZERO;
-        } else if (bs->backing_hd) {
-            BlockDriverState *bs2 = bs->backing_hd;
-            int64_t nb_sectors2 = bdrv_nb_sectors(bs2);
-            if (nb_sectors2 >= 0 && sector_num >= nb_sectors2) {
-                ret |= BDRV_BLOCK_ZERO;
-            }
-        }
-    }
-
-    if (bs->file &&
-        (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
-        (ret & BDRV_BLOCK_OFFSET_VALID)) {
-        int file_pnum;
-
-        ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
-                                        *pnum, &file_pnum);
-        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;
-}
-
-/* Coroutine wrapper for bdrv_get_block_status() */
-static void coroutine_fn bdrv_get_block_status_co_entry(void *opaque)
-{
-    BdrvCoGetBlockStatusData *data = opaque;
-    BlockDriverState *bs = data->bs;
-
-    data->ret = bdrv_co_get_block_status(bs, data->sector_num, data->nb_sectors,
-                                         data->pnum);
-    data->done = true;
-}
-
-/*
- * Synchronous wrapper around bdrv_co_get_block_status().
- *
- * See bdrv_co_get_block_status() for details.
- */
-int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
-                              int nb_sectors, int *pnum)
-{
-    Coroutine *co;
-    BdrvCoGetBlockStatusData data = {
-        .bs = bs,
-        .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_co_entry(&data);
-    } else {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
-
-        co = qemu_coroutine_create(bdrv_get_block_status_co_entry);
-        qemu_coroutine_enter(co, &data);
-        while (!data.done) {
-            aio_poll(aio_context, true);
-        }
-    }
-    return data.ret;
-}
-
-int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
-                                   int nb_sectors, int *pnum)
-{
-    int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
-    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 = intermediate->backing_hd;
-    }
-
-    *pnum = n;
-    return 0;
-}
-
 const char *bdrv_get_encrypted_filename(BlockDriverState *bs)
 {
     if (bs->backing_hd && bs->backing_hd->encrypted)
@@ -4319,28 +2746,6 @@  void bdrv_get_backing_filename(BlockDriverState *bs,
     pstrcpy(filename, filename_size, bs->backing_file);
 }
 
-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_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BlockDriver *drv = bs->drv;
@@ -4361,47 +2766,6 @@  ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs)
     return NULL;
 }
 
-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, 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, buf, pos, size);
-    return -ENOTSUP;
-}
-
 void bdrv_debug_event(BlockDriverState *bs, BlkDebugEvent event)
 {
     if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) {
@@ -4548,477 +2912,6 @@  int bdrv_get_backing_file_depth(BlockDriverState *bs)
     return 1 + bdrv_get_backing_file_depth(bs->backing_hd);
 }
 
-/**************************************************************/
-/* 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 > IOV_MAX) {
-            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;
-        }
-    }
-
-    block_acct_merge_done(&bs->stats, 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 BlockAIOCBSync {
-    BlockAIOCB common;
-    QEMUBH *bh;
-    int ret;
-    /* vector translation state */
-    QEMUIOVector *qiov;
-    uint8_t *bounce;
-    int is_write;
-} BlockAIOCBSync;
-
-static const AIOCBInfo bdrv_em_aiocb_info = {
-    .aiocb_size         = sizeof(BlockAIOCBSync),
-};
-
-static void bdrv_aio_bh_cb(void *opaque)
-{
-    BlockAIOCBSync *acb = opaque;
-
-    if (!acb->is_write && acb->ret >= 0) {
-        qemu_iovec_from_buf(acb->qiov, 0, acb->bounce, acb->qiov->size);
-    }
-    qemu_vfree(acb->bounce);
-    acb->common.cb(acb->common.opaque, acb->ret);
-    qemu_bh_delete(acb->bh);
-    acb->bh = NULL;
-    qemu_aio_unref(acb);
-}
-
-static BlockAIOCB *bdrv_aio_rw_vector(BlockDriverState *bs,
-                                      int64_t sector_num,
-                                      QEMUIOVector *qiov,
-                                      int nb_sectors,
-                                      BlockCompletionFunc *cb,
-                                      void *opaque,
-                                      int is_write)
-
-{
-    BlockAIOCBSync *acb;
-
-    acb = qemu_aio_get(&bdrv_em_aiocb_info, bs, cb, opaque);
-    acb->is_write = is_write;
-    acb->qiov = qiov;
-    acb->bounce = qemu_try_blockalign(bs, qiov->size);
-    acb->bh = aio_bh_new(bdrv_get_aio_context(bs), bdrv_aio_bh_cb, acb);
-
-    if (acb->bounce == NULL) {
-        acb->ret = -ENOMEM;
-    } else if (is_write) {
-        qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);
-        acb->ret = bs->drv->bdrv_write(bs, sector_num, acb->bounce, nb_sectors);
-    } else {
-        acb->ret = bs->drv->bdrv_read(bs, sector_num, acb->bounce, nb_sectors);
-    }
-
-    qemu_bh_schedule(acb->bh);
-
-    return &acb->common;
-}
-
-static BlockAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockCompletionFunc *cb, void *opaque)
-{
-    return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
-}
-
-static BlockAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockCompletionFunc *cb, void *opaque)
-{
-    return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
-}
-
-
-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 bdrv_init(void)
 {
     module_call_init(MODULE_INIT_BLOCK);
@@ -5030,161 +2923,6 @@  void bdrv_init_with_whitelist(void)
     bdrv_init();
 }
 
-void *qemu_aio_get(const AIOCBInfo *aiocb_info, BlockDriverState *bs,
-                   BlockCompletionFunc *cb, void *opaque)
-{
-    BlockAIOCB *acb;
-
-    acb = g_slice_alloc(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_slice_free1(acb->aiocb_info->aiocb_size, acb);
-    }
-}
-
-/**************************************************************/
-/* Coroutine block device emulation */
-
-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_co_io_em(BlockDriverState *bs, int64_t sector_num,
-                                      int nb_sectors, QEMUIOVector *iov,
-                                      bool is_write)
-{
-    CoroutineIOCompletion co = {
-        .coroutine = qemu_coroutine_self(),
-    };
-    BlockAIOCB *acb;
-
-    if (is_write) {
-        acb = bs->drv->bdrv_aio_writev(bs, sector_num, iov, nb_sectors,
-                                       bdrv_co_io_em_complete, &co);
-    } else {
-        acb = bs->drv->bdrv_aio_readv(bs, sector_num, iov, nb_sectors,
-                                      bdrv_co_io_em_complete, &co);
-    }
-
-    trace_bdrv_co_io_em(bs, sector_num, nb_sectors, is_write, acb);
-    if (!acb) {
-        return -EIO;
-    }
-    qemu_coroutine_yield();
-
-    return co.ret;
-}
-
-static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
-                                         int64_t sector_num, int nb_sectors,
-                                         QEMUIOVector *iov)
-{
-    return bdrv_co_io_em(bs, sector_num, nb_sectors, iov, false);
-}
-
-static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
-                                         int64_t sector_num, int nb_sectors,
-                                         QEMUIOVector *iov)
-{
-    return bdrv_co_io_em(bs, sector_num, nb_sectors, iov, true);
-}
-
-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;
-
-    if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
-        return 0;
-    }
-
-    /* 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) {
-            return ret;
-        }
-    }
-
-    /* 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) {
-        return ret;
-    }
-
-    /* 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:
-    return bdrv_co_flush(bs->file);
-}
-
 void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
 {
     Error *local_err = NULL;
@@ -5234,143 +2972,6 @@  void bdrv_invalidate_cache_all(Error **errp)
     }
 }
 
-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)
-{
-    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 -EROFS;
-    }
-
-    bdrv_reset_dirty(bs, sector_num, nb_sectors);
-
-    /* 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;
-    }
-
-    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) {
-                return -EIO;
-            } else {
-                qemu_coroutine_yield();
-                ret = co.ret;
-            }
-        }
-        if (ret && ret != -ENOTSUP) {
-            return ret;
-        }
-
-        sector_num += num;
-        nb_sectors -= num;
-    }
-    return 0;
-}
-
-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;
-}
-
 /**************************************************************/
 /* removable device support */
 
@@ -5436,87 +3037,11 @@  void bdrv_lock_medium(BlockDriverState *bs, bool locked)
     }
 }
 
-/* needed for generic scsi interface */
-
-int bdrv_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
-{
-    BlockDriver *drv = bs->drv;
-
-    if (drv && drv->bdrv_ioctl)
-        return drv->bdrv_ioctl(bs, req, buf);
-    return -ENOTSUP;
-}
-
-BlockAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
-        unsigned long int req, void *buf,
-        BlockCompletionFunc *cb, void *opaque)
-{
-    BlockDriver *drv = bs->drv;
-
-    if (drv && drv->bdrv_aio_ioctl)
-        return drv->bdrv_aio_ioctl(bs, req, buf, cb, opaque);
-    return NULL;
-}
-
 void bdrv_set_guest_block_size(BlockDriverState *bs, int align)
 {
     bs->guest_block_size = align;
 }
 
-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_opt_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;
-}
-
 BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs, const char *name)
 {
     BdrvDirtyBitmap *bm;
@@ -5787,8 +3312,8 @@  void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap)
     hbitmap_reset(bitmap->bitmap, 0, bitmap->size);
 }
 
-static void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
-                           int nr_sectors)
+void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
+                    int nr_sectors)
 {
     BdrvDirtyBitmap *bitmap;
     QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
@@ -5799,8 +3324,8 @@  static void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
     }
 }
 
-static void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
-                             int nr_sectors)
+void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
+                      int nr_sectors)
 {
     BdrvDirtyBitmap *bitmap;
     QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
@@ -6238,12 +3763,6 @@  void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
     abort();
 }
 
-void bdrv_add_before_write_notifier(BlockDriverState *bs,
-                                    NotifierWithReturn *notifier)
-{
-    notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
-}
-
 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
                        BlockDriverAmendStatusCB *status_cb)
 {
@@ -6344,36 +3863,6 @@  out:
     return to_replace_bs;
 }
 
-void bdrv_io_plug(BlockDriverState *bs)
-{
-    BlockDriver *drv = bs->drv;
-    if (drv && drv->bdrv_io_plug) {
-        drv->bdrv_io_plug(bs);
-    } else if (bs->file) {
-        bdrv_io_plug(bs->file);
-    }
-}
-
-void bdrv_io_unplug(BlockDriverState *bs)
-{
-    BlockDriver *drv = bs->drv;
-    if (drv && drv->bdrv_io_unplug) {
-        drv->bdrv_io_unplug(bs);
-    } else if (bs->file) {
-        bdrv_io_unplug(bs->file);
-    }
-}
-
-void bdrv_flush_io_queue(BlockDriverState *bs)
-{
-    BlockDriver *drv = bs->drv;
-    if (drv && drv->bdrv_flush_io_queue) {
-        drv->bdrv_flush_io_queue(bs);
-    } else if (bs->file) {
-        bdrv_flush_io_queue(bs->file);
-    }
-}
-
 static bool append_open_options(QDict *d, BlockDriverState *bs)
 {
     const QDictEntry *entry;
diff --git a/block/Makefile.objs b/block/Makefile.objs
index db2933e..66c3690 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -9,7 +9,7 @@  block-obj-y += block-backend.o snapshot.o qapi.o
 block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o
 block-obj-$(CONFIG_POSIX) += raw-posix.o
 block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
-block-obj-y += null.o mirror.o
+block-obj-y += null.o mirror.o io.o
 
 block-obj-y += nbd.o nbd-client.o sheepdog.o
 block-obj-$(CONFIG_LIBISCSI) += iscsi.o
diff --git a/include/block/block_int.h b/include/block/block_int.h
index e0d5561..db29b74 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -439,6 +439,14 @@  extern BlockDriver bdrv_file;
 extern BlockDriver bdrv_raw;
 extern BlockDriver bdrv_qcow2;
 
+/**
+ * bdrv_setup_io_funcs:
+ *
+ * Prepare a #BlockDriver for I/O request processing by populating
+ * unimplemented coroutine and AIO interfaces with generic wrapper functions
+ * that fall back to implemented interfaces.
+ */
+void bdrv_setup_io_funcs(BlockDriver *bdrv);
 
 int get_tmp_filename(char *filename, int size);
 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
@@ -626,4 +634,8 @@  bool blk_dev_is_tray_open(BlockBackend *blk);
 bool blk_dev_is_medium_locked(BlockBackend *blk);
 void blk_dev_resize_cb(BlockBackend *blk);
 
+void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors);
+void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
+                      int nr_sectors);
+
 #endif /* BLOCK_INT_H */