diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/Makefile.objs | 2 | ||||
| -rw-r--r-- | block/io.c | 2540 |
2 files changed, 2541 insertions, 1 deletions
diff --git a/block/Makefile.objs b/block/Makefile.objs index 179e71d235..0d8c2a4ab6 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/block/io.c b/block/io.c new file mode 100644 index 0000000000..1ce62c4fbc --- /dev/null +++ b/block/io.c @@ -0,0 +1,2540 @@ +/* + * 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 "trace.h" +#include "sysemu/qtest.h" +#include "block/blockjob.h" +#include "block/block_int.h" + +#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); + +/* 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]); +} + +void bdrv_setup_io_funcs(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; + } + } +} + +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); + } +} + +/** + * 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) */ +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); + } +} + +/** + * 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; +} + +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; +} + +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; +} + +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; +} + +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, 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; +} + +/**************************************************************/ +/* 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 *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); +} + +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; +} + +/* 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 *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; +} + +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) +{ + 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); + } +} |