/* * 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 -EPERM; } 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 -EPERM; } 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); } }