diff options
| author |   Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> | 2023-10-10 11:40:56 +0000 |
|---|---|---|
| committer | Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> | 2023-10-10 11:40:56 +0000 |
| commit | e02cda008591317b1625707ff8e115a4841aa889 (patch) | |
| tree | aee302e3cf8b59ec2d32ec481be3d1afddfc8968 /block/io.c | |
| parent | cc668e6b7e0ffd8c9d130513d12053cf5eda1d3b (diff) | |
Introduce Virtio-loopback epsilon release:
Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.
Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9
Diffstat (limited to 'block/io.c')
| -rw-r--r-- | block/io.c | 3585 |
1 files changed, 3585 insertions, 0 deletions
diff --git a/block/io.c b/block/io.c new file mode 100644 index 000000000..bb0a254de --- /dev/null +++ b/block/io.c @@ -0,0 +1,3585 @@ +/* + * Block layer I/O functions + * + * Copyright (c) 2003 Fabrice Bellard + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu/osdep.h" +#include "trace.h" +#include "sysemu/block-backend.h" +#include "block/aio-wait.h" +#include "block/blockjob.h" +#include "block/blockjob_int.h" +#include "block/block_int.h" +#include "block/coroutines.h" +#include "block/write-threshold.h" +#include "qemu/cutils.h" +#include "qapi/error.h" +#include "qemu/error-report.h" +#include "qemu/main-loop.h" +#include "sysemu/replay.h" + +/* Maximum bounce buffer for copy-on-read and write zeroes, in bytes */ +#define MAX_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS) + +static void bdrv_parent_cb_resize(BlockDriverState *bs); +static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, + int64_t offset, int64_t bytes, BdrvRequestFlags flags); + +static void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore, + bool ignore_bds_parents) +{ + BdrvChild *c, *next; + + QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) { + if (c == ignore || (ignore_bds_parents && c->klass->parent_is_bds)) { + continue; + } + bdrv_parent_drained_begin_single(c, false); + } +} + +static void bdrv_parent_drained_end_single_no_poll(BdrvChild *c, + int *drained_end_counter) +{ + assert(c->parent_quiesce_counter > 0); + c->parent_quiesce_counter--; + if (c->klass->drained_end) { + c->klass->drained_end(c, drained_end_counter); + } +} + +void bdrv_parent_drained_end_single(BdrvChild *c) +{ + int drained_end_counter = 0; + bdrv_parent_drained_end_single_no_poll(c, &drained_end_counter); + BDRV_POLL_WHILE(c->bs, qatomic_read(&drained_end_counter) > 0); +} + +static void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore, + bool ignore_bds_parents, + int *drained_end_counter) +{ + BdrvChild *c; + + QLIST_FOREACH(c, &bs->parents, next_parent) { + if (c == ignore || (ignore_bds_parents && c->klass->parent_is_bds)) { + continue; + } + bdrv_parent_drained_end_single_no_poll(c, drained_end_counter); + } +} + +static bool bdrv_parent_drained_poll_single(BdrvChild *c) +{ + if (c->klass->drained_poll) { + return c->klass->drained_poll(c); + } + return false; +} + +static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore, + bool ignore_bds_parents) +{ + BdrvChild *c, *next; + bool busy = false; + + QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) { + if (c == ignore || (ignore_bds_parents && c->klass->parent_is_bds)) { + continue; + } + busy |= bdrv_parent_drained_poll_single(c); + } + + return busy; +} + +void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll) +{ + c->parent_quiesce_counter++; + if (c->klass->drained_begin) { + c->klass->drained_begin(c); + } + if (poll) { + BDRV_POLL_WHILE(c->bs, bdrv_parent_drained_poll_single(c)); + } +} + +static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src) +{ + dst->pdiscard_alignment = MAX(dst->pdiscard_alignment, + src->pdiscard_alignment); + dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer); + dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_transfer); + dst->max_hw_transfer = MIN_NON_ZERO(dst->max_hw_transfer, + src->max_hw_transfer); + dst->opt_mem_alignment = MAX(dst->opt_mem_alignment, + src->opt_mem_alignment); + dst->min_mem_alignment = MAX(dst->min_mem_alignment, + src->min_mem_alignment); + dst->max_iov = MIN_NON_ZERO(dst->max_iov, src->max_iov); + dst->max_hw_iov = MIN_NON_ZERO(dst->max_hw_iov, src->max_hw_iov); +} + +typedef struct BdrvRefreshLimitsState { + BlockDriverState *bs; + BlockLimits old_bl; +} BdrvRefreshLimitsState; + +static void bdrv_refresh_limits_abort(void *opaque) +{ + BdrvRefreshLimitsState *s = opaque; + + s->bs->bl = s->old_bl; +} + +static TransactionActionDrv bdrv_refresh_limits_drv = { + .abort = bdrv_refresh_limits_abort, + .clean = g_free, +}; + +/* @tran is allowed to be NULL, in this case no rollback is possible. */ +void bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error **errp) +{ + ERRP_GUARD(); + BlockDriver *drv = bs->drv; + BdrvChild *c; + bool have_limits; + + if (tran) { + BdrvRefreshLimitsState *s = g_new(BdrvRefreshLimitsState, 1); + *s = (BdrvRefreshLimitsState) { + .bs = bs, + .old_bl = bs->bl, + }; + tran_add(tran, &bdrv_refresh_limits_drv, s); + } + + memset(&bs->bl, 0, sizeof(bs->bl)); + + if (!drv) { + return; + } + + /* Default alignment based on whether driver has byte interface */ + bs->bl.request_alignment = (drv->bdrv_co_preadv || + drv->bdrv_aio_preadv || + drv->bdrv_co_preadv_part) ? 1 : 512; + + /* Take some limits from the children as a default */ + have_limits = false; + QLIST_FOREACH(c, &bs->children, next) { + if (c->role & (BDRV_CHILD_DATA | BDRV_CHILD_FILTERED | BDRV_CHILD_COW)) + { + bdrv_refresh_limits(c->bs, tran, errp); + if (*errp) { + return; + } + bdrv_merge_limits(&bs->bl, &c->bs->bl); + have_limits = true; + } + } + + if (!have_limits) { + bs->bl.min_mem_alignment = 512; + bs->bl.opt_mem_alignment = qemu_real_host_page_size; + + /* Safe default since most protocols use readv()/writev()/etc */ + bs->bl.max_iov = IOV_MAX; + } + + /* Then let the driver override it */ + if (drv->bdrv_refresh_limits) { + drv->bdrv_refresh_limits(bs, errp); + if (*errp) { + return; + } + } + + if (bs->bl.request_alignment > BDRV_MAX_ALIGNMENT) { + error_setg(errp, "Driver requires too large request alignment"); + } +} + +/** + * 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) +{ + qatomic_inc(&bs->copy_on_read); +} + +void bdrv_disable_copy_on_read(BlockDriverState *bs) +{ + int old = qatomic_fetch_dec(&bs->copy_on_read); + assert(old >= 1); +} + +typedef struct { + Coroutine *co; + BlockDriverState *bs; + bool done; + bool begin; + bool recursive; + bool poll; + BdrvChild *parent; + bool ignore_bds_parents; + int *drained_end_counter; +} BdrvCoDrainData; + +static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) +{ + BdrvCoDrainData *data = opaque; + BlockDriverState *bs = data->bs; + + if (data->begin) { + bs->drv->bdrv_co_drain_begin(bs); + } else { + bs->drv->bdrv_co_drain_end(bs); + } + + /* Set data->done and decrement drained_end_counter before bdrv_wakeup() */ + qatomic_mb_set(&data->done, true); + if (!data->begin) { + qatomic_dec(data->drained_end_counter); + } + bdrv_dec_in_flight(bs); + + g_free(data); +} + +/* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */ +static void bdrv_drain_invoke(BlockDriverState *bs, bool begin, + int *drained_end_counter) +{ + BdrvCoDrainData *data; + + if (!bs->drv || (begin && !bs->drv->bdrv_co_drain_begin) || + (!begin && !bs->drv->bdrv_co_drain_end)) { + return; + } + + data = g_new(BdrvCoDrainData, 1); + *data = (BdrvCoDrainData) { + .bs = bs, + .done = false, + .begin = begin, + .drained_end_counter = drained_end_counter, + }; + + if (!begin) { + qatomic_inc(drained_end_counter); + } + + /* Make sure the driver callback completes during the polling phase for + * drain_begin. */ + bdrv_inc_in_flight(bs); + data->co = qemu_coroutine_create(bdrv_drain_invoke_entry, data); + aio_co_schedule(bdrv_get_aio_context(bs), data->co); +} + +/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */ +bool bdrv_drain_poll(BlockDriverState *bs, bool recursive, + BdrvChild *ignore_parent, bool ignore_bds_parents) +{ + BdrvChild *child, *next; + + if (bdrv_parent_drained_poll(bs, ignore_parent, ignore_bds_parents)) { + return true; + } + + if (qatomic_read(&bs->in_flight)) { + return true; + } + + if (recursive) { + assert(!ignore_bds_parents); + QLIST_FOREACH_SAFE(child, &bs->children, next, next) { + if (bdrv_drain_poll(child->bs, recursive, child, false)) { + return true; + } + } + } + + return false; +} + +static bool bdrv_drain_poll_top_level(BlockDriverState *bs, bool recursive, + BdrvChild *ignore_parent) +{ + return bdrv_drain_poll(bs, recursive, ignore_parent, false); +} + +static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, + BdrvChild *parent, bool ignore_bds_parents, + bool poll); +static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, + BdrvChild *parent, bool ignore_bds_parents, + int *drained_end_counter); + +static void bdrv_co_drain_bh_cb(void *opaque) +{ + BdrvCoDrainData *data = opaque; + Coroutine *co = data->co; + BlockDriverState *bs = data->bs; + + if (bs) { + AioContext *ctx = bdrv_get_aio_context(bs); + aio_context_acquire(ctx); + bdrv_dec_in_flight(bs); + if (data->begin) { + assert(!data->drained_end_counter); + bdrv_do_drained_begin(bs, data->recursive, data->parent, + data->ignore_bds_parents, data->poll); + } else { + assert(!data->poll); + bdrv_do_drained_end(bs, data->recursive, data->parent, + data->ignore_bds_parents, + data->drained_end_counter); + } + aio_context_release(ctx); + } else { + assert(data->begin); + bdrv_drain_all_begin(); + } + + data->done = true; + aio_co_wake(co); +} + +static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, + bool begin, bool recursive, + BdrvChild *parent, + bool ignore_bds_parents, + bool poll, + int *drained_end_counter) +{ + BdrvCoDrainData data; + Coroutine *self = qemu_coroutine_self(); + AioContext *ctx = bdrv_get_aio_context(bs); + AioContext *co_ctx = qemu_coroutine_get_aio_context(self); + + /* Calling bdrv_drain() from a BH ensures the current coroutine yields and + * other coroutines run if they were queued by aio_co_enter(). */ + + assert(qemu_in_coroutine()); + data = (BdrvCoDrainData) { + .co = self, + .bs = bs, + .done = false, + .begin = begin, + .recursive = recursive, + .parent = parent, + .ignore_bds_parents = ignore_bds_parents, + .poll = poll, + .drained_end_counter = drained_end_counter, + }; + + if (bs) { + bdrv_inc_in_flight(bs); + } + + /* + * Temporarily drop the lock across yield or we would get deadlocks. + * bdrv_co_drain_bh_cb() reaquires the lock as needed. + * + * When we yield below, the lock for the current context will be + * released, so if this is actually the lock that protects bs, don't drop + * it a second time. + */ + if (ctx != co_ctx) { + aio_context_release(ctx); + } + replay_bh_schedule_oneshot_event(ctx, bdrv_co_drain_bh_cb, &data); + + qemu_coroutine_yield(); + /* If we are resumed from some other event (such as an aio completion or a + * timer callback), it is a bug in the caller that should be fixed. */ + assert(data.done); + + /* Reaquire the AioContext of bs if we dropped it */ + if (ctx != co_ctx) { + aio_context_acquire(ctx); + } +} + +void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, + BdrvChild *parent, bool ignore_bds_parents) +{ + assert(!qemu_in_coroutine()); + + /* Stop things in parent-to-child order */ + if (qatomic_fetch_inc(&bs->quiesce_counter) == 0) { + aio_disable_external(bdrv_get_aio_context(bs)); + } + + bdrv_parent_drained_begin(bs, parent, ignore_bds_parents); + bdrv_drain_invoke(bs, true, NULL); +} + +static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, + BdrvChild *parent, bool ignore_bds_parents, + bool poll) +{ + BdrvChild *child, *next; + + if (qemu_in_coroutine()) { + bdrv_co_yield_to_drain(bs, true, recursive, parent, ignore_bds_parents, + poll, NULL); + return; + } + + bdrv_do_drained_begin_quiesce(bs, parent, ignore_bds_parents); + + if (recursive) { + assert(!ignore_bds_parents); + bs->recursive_quiesce_counter++; + QLIST_FOREACH_SAFE(child, &bs->children, next, next) { + bdrv_do_drained_begin(child->bs, true, child, ignore_bds_parents, + false); + } + } + + /* + * Wait for drained requests to finish. + * + * Calling BDRV_POLL_WHILE() only once for the top-level node is okay: The + * call is needed so things in this AioContext can make progress even + * though we don't return to the main AioContext loop - this automatically + * includes other nodes in the same AioContext and therefore all child + * nodes. + */ + if (poll) { + assert(!ignore_bds_parents); + BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, recursive, parent)); + } +} + +void bdrv_drained_begin(BlockDriverState *bs) +{ + bdrv_do_drained_begin(bs, false, NULL, false, true); +} + +void bdrv_subtree_drained_begin(BlockDriverState *bs) +{ + bdrv_do_drained_begin(bs, true, NULL, false, true); +} + +/** + * This function does not poll, nor must any of its recursively called + * functions. The *drained_end_counter pointee will be incremented + * once for every background operation scheduled, and decremented once + * the operation settles. Therefore, the pointer must remain valid + * until the pointee reaches 0. That implies that whoever sets up the + * pointee has to poll until it is 0. + * + * We use atomic operations to access *drained_end_counter, because + * (1) when called from bdrv_set_aio_context_ignore(), the subgraph of + * @bs may contain nodes in different AioContexts, + * (2) bdrv_drain_all_end() uses the same counter for all nodes, + * regardless of which AioContext they are in. + */ +static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, + BdrvChild *parent, bool ignore_bds_parents, + int *drained_end_counter) +{ + BdrvChild *child; + int old_quiesce_counter; + + assert(drained_end_counter != NULL); + + if (qemu_in_coroutine()) { + bdrv_co_yield_to_drain(bs, false, recursive, parent, ignore_bds_parents, + false, drained_end_counter); + return; + } + assert(bs->quiesce_counter > 0); + + /* Re-enable things in child-to-parent order */ + bdrv_drain_invoke(bs, false, drained_end_counter); + bdrv_parent_drained_end(bs, parent, ignore_bds_parents, + drained_end_counter); + + old_quiesce_counter = qatomic_fetch_dec(&bs->quiesce_counter); + if (old_quiesce_counter == 1) { + aio_enable_external(bdrv_get_aio_context(bs)); + } + + if (recursive) { + assert(!ignore_bds_parents); + bs->recursive_quiesce_counter--; + QLIST_FOREACH(child, &bs->children, next) { + bdrv_do_drained_end(child->bs, true, child, ignore_bds_parents, + drained_end_counter); + } + } +} + +void bdrv_drained_end(BlockDriverState *bs) +{ + int drained_end_counter = 0; + bdrv_do_drained_end(bs, false, NULL, false, &drained_end_counter); + BDRV_POLL_WHILE(bs, qatomic_read(&drained_end_counter) > 0); +} + +void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter) +{ + bdrv_do_drained_end(bs, false, NULL, false, drained_end_counter); +} + +void bdrv_subtree_drained_end(BlockDriverState *bs) +{ + int drained_end_counter = 0; + bdrv_do_drained_end(bs, true, NULL, false, &drained_end_counter); + BDRV_POLL_WHILE(bs, qatomic_read(&drained_end_counter) > 0); +} + +void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent) +{ + int i; + + for (i = 0; i < new_parent->recursive_quiesce_counter; i++) { + bdrv_do_drained_begin(child->bs, true, child, false, true); + } +} + +void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent) +{ + int drained_end_counter = 0; + int i; + + for (i = 0; i < old_parent->recursive_quiesce_counter; i++) { + bdrv_do_drained_end(child->bs, true, child, false, + &drained_end_counter); + } + + BDRV_POLL_WHILE(child->bs, qatomic_read(&drained_end_counter) > 0); +} + +/* + * Wait for pending requests to complete on a single BlockDriverState subtree, + * and suspend block driver's internal I/O until next request arrives. + * + * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState + * AioContext. + */ +void coroutine_fn bdrv_co_drain(BlockDriverState *bs) +{ + assert(qemu_in_coroutine()); + bdrv_drained_begin(bs); + bdrv_drained_end(bs); +} + +void bdrv_drain(BlockDriverState *bs) +{ + bdrv_drained_begin(bs); + bdrv_drained_end(bs); +} + +static void bdrv_drain_assert_idle(BlockDriverState *bs) +{ + BdrvChild *child, *next; + + assert(qatomic_read(&bs->in_flight) == 0); + QLIST_FOREACH_SAFE(child, &bs->children, next, next) { + bdrv_drain_assert_idle(child->bs); + } +} + +unsigned int bdrv_drain_all_count = 0; + +static bool bdrv_drain_all_poll(void) +{ + BlockDriverState *bs = NULL; + bool result = false; + + /* bdrv_drain_poll() can't make changes to the graph and we are holding the + * main AioContext lock, so iterating bdrv_next_all_states() is safe. */ + while ((bs = bdrv_next_all_states(bs))) { + AioContext *aio_context = bdrv_get_aio_context(bs); + aio_context_acquire(aio_context); + result |= bdrv_drain_poll(bs, false, NULL, true); + aio_context_release(aio_context); + } + + return result; +} + +/* + * Wait for pending requests to complete across all BlockDriverStates + * + * This function does not flush data to disk, use bdrv_flush_all() for that + * after calling this function. + * + * This pauses all block jobs and disables external clients. It must + * be paired with bdrv_drain_all_end(). + * + * NOTE: no new block jobs or BlockDriverStates can be created between + * the bdrv_drain_all_begin() and bdrv_drain_all_end() calls. + */ +void bdrv_drain_all_begin(void) +{ + BlockDriverState *bs = NULL; + + if (qemu_in_coroutine()) { + bdrv_co_yield_to_drain(NULL, true, false, NULL, true, true, NULL); + return; + } + + /* + * bdrv queue is managed by record/replay, + * waiting for finishing the I/O requests may + * be infinite + */ + if (replay_events_enabled()) { + return; + } + + /* AIO_WAIT_WHILE() with a NULL context can only be called from the main + * loop AioContext, so make sure we're in the main context. */ + assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + assert(bdrv_drain_all_count < INT_MAX); + bdrv_drain_all_count++; + + /* Quiesce all nodes, without polling in-flight requests yet. The graph + * cannot change during this loop. */ + while ((bs = bdrv_next_all_states(bs))) { + AioContext *aio_context = bdrv_get_aio_context(bs); + + aio_context_acquire(aio_context); + bdrv_do_drained_begin(bs, false, NULL, true, false); + aio_context_release(aio_context); + } + + /* Now poll the in-flight requests */ + AIO_WAIT_WHILE(NULL, bdrv_drain_all_poll()); + + while ((bs = bdrv_next_all_states(bs))) { + bdrv_drain_assert_idle(bs); + } +} + +void bdrv_drain_all_end_quiesce(BlockDriverState *bs) +{ + int drained_end_counter = 0; + + g_assert(bs->quiesce_counter > 0); + g_assert(!bs->refcnt); + + while (bs->quiesce_counter) { + bdrv_do_drained_end(bs, false, NULL, true, &drained_end_counter); + } + BDRV_POLL_WHILE(bs, qatomic_read(&drained_end_counter) > 0); +} + +void bdrv_drain_all_end(void) +{ + BlockDriverState *bs = NULL; + int drained_end_counter = 0; + + /* + * bdrv queue is managed by record/replay, + * waiting for finishing the I/O requests may + * be endless + */ + if (replay_events_enabled()) { + return; + } + + while ((bs = bdrv_next_all_states(bs))) { + AioContext *aio_context = bdrv_get_aio_context(bs); + + aio_context_acquire(aio_context); + bdrv_do_drained_end(bs, false, NULL, true, &drained_end_counter); + aio_context_release(aio_context); + } + + assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + AIO_WAIT_WHILE(NULL, qatomic_read(&drained_end_counter) > 0); + + assert(bdrv_drain_all_count > 0); + bdrv_drain_all_count--; +} + +void bdrv_drain_all(void) +{ + bdrv_drain_all_begin(); + bdrv_drain_all_end(); +} + +/** + * Remove an active request from the tracked requests list + * + * This function should be called when a tracked request is completing. + */ +static void tracked_request_end(BdrvTrackedRequest *req) +{ + if (req->serialising) { + qatomic_dec(&req->bs->serialising_in_flight); + } + + qemu_co_mutex_lock(&req->bs->reqs_lock); + QLIST_REMOVE(req, list); + qemu_co_queue_restart_all(&req->wait_queue); + qemu_co_mutex_unlock(&req->bs->reqs_lock); +} + +/** + * Add an active request to the tracked requests list + */ +static void tracked_request_begin(BdrvTrackedRequest *req, + BlockDriverState *bs, + int64_t offset, + int64_t bytes, + enum BdrvTrackedRequestType type) +{ + bdrv_check_request(offset, bytes, &error_abort); + + *req = (BdrvTrackedRequest){ + .bs = bs, + .offset = offset, + .bytes = bytes, + .type = type, + .co = qemu_coroutine_self(), + .serialising = false, + .overlap_offset = offset, + .overlap_bytes = bytes, + }; + + qemu_co_queue_init(&req->wait_queue); + + qemu_co_mutex_lock(&bs->reqs_lock); + QLIST_INSERT_HEAD(&bs->tracked_requests, req, list); + qemu_co_mutex_unlock(&bs->reqs_lock); +} + +static bool tracked_request_overlaps(BdrvTrackedRequest *req, + int64_t offset, int64_t bytes) +{ + bdrv_check_request(offset, bytes, &error_abort); + + /* aaaa bbbb */ + if (offset >= req->overlap_offset + req->overlap_bytes) { + return false; + } + /* bbbb aaaa */ + if (req->overlap_offset >= offset + bytes) { + return false; + } + return true; +} + +/* Called with self->bs->reqs_lock held */ +static BdrvTrackedRequest * +bdrv_find_conflicting_request(BdrvTrackedRequest *self) +{ + BdrvTrackedRequest *req; + + QLIST_FOREACH(req, &self->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) { + return req; + } + } + } + + return NULL; +} + +/* Called with self->bs->reqs_lock held */ +static bool coroutine_fn +bdrv_wait_serialising_requests_locked(BdrvTrackedRequest *self) +{ + BdrvTrackedRequest *req; + bool waited = false; + + while ((req = bdrv_find_conflicting_request(self))) { + self->waiting_for = req; + qemu_co_queue_wait(&req->wait_queue, &self->bs->reqs_lock); + self->waiting_for = NULL; + waited = true; + } + + return waited; +} + +/* Called with req->bs->reqs_lock held */ +static void tracked_request_set_serialising(BdrvTrackedRequest *req, + uint64_t align) +{ + int64_t overlap_offset = req->offset & ~(align - 1); + int64_t overlap_bytes = + ROUND_UP(req->offset + req->bytes, align) - overlap_offset; + + bdrv_check_request(req->offset, req->bytes, &error_abort); + + if (!req->serialising) { + qatomic_inc(&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); +} + +/** + * Return the tracked request on @bs for the current coroutine, or + * NULL if there is none. + */ +BdrvTrackedRequest *coroutine_fn bdrv_co_get_self_request(BlockDriverState *bs) +{ + BdrvTrackedRequest *req; + Coroutine *self = qemu_coroutine_self(); + + QLIST_FOREACH(req, &bs->tracked_requests, list) { + if (req->co == self) { + return req; + } + } + + return NULL; +} + +/** + * Round a region to cluster boundaries + */ +void bdrv_round_to_clusters(BlockDriverState *bs, + int64_t offset, int64_t bytes, + int64_t *cluster_offset, + int64_t *cluster_bytes) +{ + BlockDriverInfo bdi; + + if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) { + *cluster_offset = offset; + *cluster_bytes = bytes; + } else { + int64_t c = bdi.cluster_size; + *cluster_offset = QEMU_ALIGN_DOWN(offset, c); + *cluster_bytes = QEMU_ALIGN_UP(offset - *cluster_offset + bytes, c); + } +} + +static int bdrv_get_cluster_size(BlockDriverState *bs) +{ + BlockDriverInfo bdi; + int ret; + + ret = bdrv_get_info(bs, &bdi); + if (ret < 0 || bdi.cluster_size == 0) { + return bs->bl.request_alignment; + } else { + return bdi.cluster_size; + } +} + +void bdrv_inc_in_flight(BlockDriverState *bs) +{ + qatomic_inc(&bs->in_flight); +} + +void bdrv_wakeup(BlockDriverState *bs) +{ + aio_wait_kick(); +} + +void bdrv_dec_in_flight(BlockDriverState *bs) +{ + qatomic_dec(&bs->in_flight); + bdrv_wakeup(bs); +} + +static bool coroutine_fn bdrv_wait_serialising_requests(BdrvTrackedRequest *self) +{ + BlockDriverState *bs = self->bs; + bool waited = false; + + if (!qatomic_read(&bs->serialising_in_flight)) { + return false; + } + + qemu_co_mutex_lock(&bs->reqs_lock); + waited = bdrv_wait_serialising_requests_locked(self); + qemu_co_mutex_unlock(&bs->reqs_lock); + + return waited; +} + +bool coroutine_fn bdrv_make_request_serialising(BdrvTrackedRequest *req, + uint64_t align) +{ + bool waited; + + qemu_co_mutex_lock(&req->bs->reqs_lock); + + tracked_request_set_serialising(req, align); + waited = bdrv_wait_serialising_requests_locked(req); + + qemu_co_mutex_unlock(&req->bs->reqs_lock); + + return waited; +} + +int bdrv_check_qiov_request(int64_t offset, int64_t bytes, + QEMUIOVector *qiov, size_t qiov_offset, + Error **errp) +{ + /* + * Check generic offset/bytes correctness + */ + + if (offset < 0) { + error_setg(errp, "offset is negative: %" PRIi64, offset); + return -EIO; + } + + if (bytes < 0) { + error_setg(errp, "bytes is negative: %" PRIi64, bytes); + return -EIO; + } + + if (bytes > BDRV_MAX_LENGTH) { + error_setg(errp, "bytes(%" PRIi64 ") exceeds maximum(%" PRIi64 ")", + bytes, BDRV_MAX_LENGTH); + return -EIO; + } + + if (offset > BDRV_MAX_LENGTH) { + error_setg(errp, "offset(%" PRIi64 ") exceeds maximum(%" PRIi64 ")", + offset, BDRV_MAX_LENGTH); + return -EIO; + } + + if (offset > BDRV_MAX_LENGTH - bytes) { + error_setg(errp, "sum of offset(%" PRIi64 ") and bytes(%" PRIi64 ") " + "exceeds maximum(%" PRIi64 ")", offset, bytes, + BDRV_MAX_LENGTH); + return -EIO; + } + + if (!qiov) { + return 0; + } + + /* + * Check qiov and qiov_offset + */ + + if (qiov_offset > qiov->size) { + error_setg(errp, "qiov_offset(%zu) overflow io vector size(%zu)", + qiov_offset, qiov->size); + return -EIO; + } + + if (bytes > qiov->size - qiov_offset) { + error_setg(errp, "bytes(%" PRIi64 ") + qiov_offset(%zu) overflow io " + "vector size(%zu)", bytes, qiov_offset, qiov->size); + return -EIO; + } + + return 0; +} + +int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp) +{ + return bdrv_check_qiov_request(offset, bytes, NULL, 0, errp); +} + +static int bdrv_check_request32(int64_t offset, int64_t bytes, + QEMUIOVector *qiov, size_t qiov_offset) +{ + int ret = bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, NULL); + if (ret < 0) { + return ret; + } + + if (bytes > BDRV_REQUEST_MAX_BYTES) { + return -EIO; + } + + return 0; +} + +int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, + int64_t bytes, BdrvRequestFlags flags) +{ + return bdrv_pwritev(child, offset, bytes, NULL, + BDRV_REQ_ZERO_WRITE | flags); +} + +/* + * Completely zero out a block device with the help of bdrv_pwrite_zeroes. + * The operation is sped up by checking the block status and only writing + * zeroes to the device if they currently do not return zeroes. Optional + * flags are passed through to bdrv_pwrite_zeroes (e.g. BDRV_REQ_MAY_UNMAP, + * BDRV_REQ_FUA). + * + * Returns < 0 on error, 0 on success. For error codes see bdrv_pwrite(). + */ +int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags) +{ + int ret; + int64_t target_size, bytes, offset = 0; + BlockDriverState *bs = child->bs; + + target_size = bdrv_getlength(bs); + if (target_size < 0) { + return target_size; + } + + for (;;) { + bytes = MIN(target_size - offset, BDRV_REQUEST_MAX_BYTES); + if (bytes <= 0) { + return 0; + } + ret = bdrv_block_status(bs, offset, bytes, &bytes, NULL, NULL); + if (ret < 0) { + return ret; + } + if (ret & BDRV_BLOCK_ZERO) { + offset += bytes; + continue; + } + ret = bdrv_pwrite_zeroes(child, offset, bytes, flags); + if (ret < 0) { + return ret; + } + offset += bytes; + } +} + +/* See bdrv_pwrite() for the return codes */ +int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int64_t bytes) +{ + int ret; + QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes); + + if (bytes < 0) { + return -EINVAL; + } + + ret = bdrv_preadv(child, offset, bytes, &qiov, 0); + + return ret < 0 ? ret : bytes; +} + +/* Return no. of bytes on success or < 0 on error. Important errors are: + -EIO generic I/O error (may happen for all errors) + -ENOMEDIUM No media inserted. + -EINVAL Invalid offset or number of bytes + -EACCES Trying to write a read-only device +*/ +int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, + int64_t bytes) +{ + int ret; + QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes); + + if (bytes < 0) { + return -EINVAL; + } + + ret = bdrv_pwritev(child, offset, bytes, &qiov, 0); + + return ret < 0 ? ret : bytes; +} + +/* + * Writes to the file and ensures that no writes are reordered across this + * request (acts as a barrier) + * + * Returns 0 on success, -errno in error cases. + */ +int bdrv_pwrite_sync(BdrvChild *child, int64_t offset, + const void *buf, int64_t count) +{ + int ret; + + ret = bdrv_pwrite(child, offset, buf, count); + if (ret < 0) { + return ret; + } + + ret = bdrv_flush(child->bs); + if (ret < 0) { + return ret; + } + + return 0; +} + +typedef struct CoroutineIOCompletion { + Coroutine *coroutine; + int ret; +} CoroutineIOCompletion; + +static void bdrv_co_io_em_complete(void *opaque, int ret) +{ + CoroutineIOCompletion *co = opaque; + + co->ret = ret; + aio_co_wake(co->coroutine); +} + +static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs, + int64_t offset, int64_t bytes, + QEMUIOVector *qiov, + size_t qiov_offset, int flags) +{ + BlockDriver *drv = bs->drv; + int64_t sector_num; + unsigned int nb_sectors; + QEMUIOVector local_qiov; + int ret; + + bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); + assert(!(flags & ~BDRV_REQ_MASK)); + assert(!(flags & BDRV_REQ_NO_FALLBACK)); + + if (!drv) { + return -ENOMEDIUM; + } + + if (drv->bdrv_co_preadv_part) { + return drv->bdrv_co_preadv_part(bs, offset, bytes, qiov, qiov_offset, + flags); + } + + if (qiov_offset > 0 || bytes != qiov->size) { + qemu_iovec_init_slice(&local_qiov, qiov, qiov_offset, bytes); + qiov = &local_qiov; + } + + if (drv->bdrv_co_preadv) { + ret = drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags); + goto out; + } + + if (drv->bdrv_aio_preadv) { + BlockAIOCB *acb; + CoroutineIOCompletion co = { + .coroutine = qemu_coroutine_self(), + }; + + acb = drv->bdrv_aio_preadv(bs, offset, bytes, qiov, flags, + bdrv_co_io_em_complete, &co); + if (acb == NULL) { + ret = -EIO; + goto out; + } else { + qemu_coroutine_yield(); + ret = co.ret; + goto out; + } + } + + sector_num = offset >> BDRV_SECTOR_BITS; + nb_sectors = bytes >> BDRV_SECTOR_BITS; + + assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)); + assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE)); + assert(bytes <= BDRV_REQUEST_MAX_BYTES); + assert(drv->bdrv_co_readv); + + ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov); + +out: + if (qiov == &local_qiov) { + qemu_iovec_destroy(&local_qiov); + } + + return ret; +} + +static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs, + int64_t offset, int64_t bytes, + QEMUIOVector *qiov, + size_t qiov_offset, + BdrvRequestFlags flags) +{ + BlockDriver *drv = bs->drv; + int64_t sector_num; + unsigned int nb_sectors; + QEMUIOVector local_qiov; + int ret; + + bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); + assert(!(flags & ~BDRV_REQ_MASK)); + assert(!(flags & BDRV_REQ_NO_FALLBACK)); + + if (!drv) { + return -ENOMEDIUM; + } + + if (drv->bdrv_co_pwritev_part) { + ret = drv->bdrv_co_pwritev_part(bs, offset, bytes, qiov, qiov_offset, + flags & bs->supported_write_flags); + flags &= ~bs->supported_write_flags; + goto emulate_flags; + } + + if (qiov_offset > 0 || bytes != qiov->size) { + qemu_iovec_init_slice(&local_qiov, qiov, qiov_offset, bytes); + qiov = &local_qiov; + } + + if (drv->bdrv_co_pwritev) { + ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov, + flags & bs->supported_write_flags); + flags &= ~bs->supported_write_flags; + goto emulate_flags; + } + + if (drv->bdrv_aio_pwritev) { + BlockAIOCB *acb; + CoroutineIOCompletion co = { + .coroutine = qemu_coroutine_self(), + }; + + acb = drv->bdrv_aio_pwritev(bs, offset, bytes, qiov, + flags & bs->supported_write_flags, + bdrv_co_io_em_complete, &co); + flags &= ~bs->supported_write_flags; + if (acb == NULL) { + ret = -EIO; + } else { + qemu_coroutine_yield(); + ret = co.ret; + } + goto emulate_flags; + } + + sector_num = offset >> BDRV_SECTOR_BITS; + nb_sectors = bytes >> BDRV_SECTOR_BITS; + + assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)); + assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE)); + assert(bytes <= BDRV_REQUEST_MAX_BYTES); + + assert(drv->bdrv_co_writev); + ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov, + flags & bs->supported_write_flags); + flags &= ~bs->supported_write_flags; + +emulate_flags: + if (ret == 0 && (flags & BDRV_REQ_FUA)) { + ret = bdrv_co_flush(bs); + } + + if (qiov == &local_qiov) { + qemu_iovec_destroy(&local_qiov); + } + + return ret; +} + +static int coroutine_fn +bdrv_driver_pwritev_compressed(BlockDriverState *bs, int64_t offset, + int64_t bytes, QEMUIOVector *qiov, + size_t qiov_offset) +{ + BlockDriver *drv = bs->drv; + QEMUIOVector local_qiov; + int ret; + + bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); + + if (!drv) { + return -ENOMEDIUM; + } + + if (!block_driver_can_compress(drv)) { + return -ENOTSUP; + } + + if (drv->bdrv_co_pwritev_compressed_part) { + return drv->bdrv_co_pwritev_compressed_part(bs, offset, bytes, + qiov, qiov_offset); + } + + if (qiov_offset == 0) { + return drv->bdrv_co_pwritev_compressed(bs, offset, bytes, qiov); + } + + qemu_iovec_init_slice(&local_qiov, qiov, qiov_offset, bytes); + ret = drv->bdrv_co_pwritev_compressed(bs, offset, bytes, &local_qiov); + qemu_iovec_destroy(&local_qiov); + + return ret; +} + +static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, + int64_t offset, int64_t bytes, QEMUIOVector *qiov, + size_t qiov_offset, int flags) +{ + BlockDriverState *bs = child->bs; + + /* Perform I/O through a temporary buffer so that users who scribble over + * their read buffer while the operation is in progress do not end up + * modifying the image file. This is critical for zero-copy guest I/O + * where anything might happen inside guest memory. + */ + void *bounce_buffer = NULL; + + BlockDriver *drv = bs->drv; + int64_t cluster_offset; + int64_t cluster_bytes; + int64_t skip_bytes; + int ret; + int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, + BDRV_REQUEST_MAX_BYTES); + int64_t progress = 0; + bool skip_write; + + bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); + + if (!drv) { + return -ENOMEDIUM; + } + + /* + * Do not write anything when the BDS is inactive. That is not + * allowed, and it would not help. + */ + skip_write = (bs->open_flags & BDRV_O_INACTIVE); + + /* FIXME We cannot require callers to have write permissions when all they + * are doing is a read request. If we did things right, write permissions + * would be obtained anyway, but internally by the copy-on-read code. As + * long as it is implemented here rather than in a separate filter driver, + * the copy-on-read code doesn't have its own BdrvChild, however, for which + * it could request permissions. Therefore we have to bypass the permission + * system for the moment. */ + // assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); + + /* Cover entire cluster so no additional backing file I/O is required when + * allocating cluster in the image file. Note that this value may exceed + * BDRV_REQUEST_MAX_BYTES (even when the original read did not), which + * is one reason we loop rather than doing it all at once. + */ + bdrv_round_to_clusters(bs, offset, bytes, &cluster_offset, &cluster_bytes); + skip_bytes = offset - cluster_offset; + + trace_bdrv_co_do_copy_on_readv(bs, offset, bytes, + cluster_offset, cluster_bytes); + + while (cluster_bytes) { + int64_t pnum; + + if (skip_write) { + ret = 1; /* "already allocated", so nothing will be copied */ + pnum = MIN(cluster_bytes, max_transfer); + } else { + ret = bdrv_is_allocated(bs, cluster_offset, + MIN(cluster_bytes, max_transfer), &pnum); + if (ret < 0) { + /* + * Safe to treat errors in querying allocation as if + * unallocated; we'll probably fail again soon on the + * read, but at least that will set a decent errno. + */ + pnum = MIN(cluster_bytes, max_transfer); + } + + /* Stop at EOF if the image ends in the middle of the cluster */ + if (ret == 0 && pnum == 0) { + assert(progress >= bytes); + break; + } + + assert(skip_bytes < pnum); + } + + if (ret <= 0) { + QEMUIOVector local_qiov; + + /* Must copy-on-read; use the bounce buffer */ + pnum = MIN(pnum, MAX_BOUNCE_BUFFER); + if (!bounce_buffer) { + int64_t max_we_need = MAX(pnum, cluster_bytes - pnum); + int64_t max_allowed = MIN(max_transfer, MAX_BOUNCE_BUFFER); + int64_t bounce_buffer_len = MIN(max_we_need, max_allowed); + + bounce_buffer = qemu_try_blockalign(bs, bounce_buffer_len); + if (!bounce_buffer) { + ret = -ENOMEM; + goto err; + } + } + qemu_iovec_init_buf(&local_qiov, bounce_buffer, pnum); + + ret = bdrv_driver_preadv(bs, cluster_offset, pnum, + &local_qiov, 0, 0); + if (ret < 0) { + goto err; + } + + bdrv_debug_event(bs, BLKDBG_COR_WRITE); + if (drv->bdrv_co_pwrite_zeroes && + buffer_is_zero(bounce_buffer, pnum)) { + /* FIXME: Should we (perhaps conditionally) be setting + * BDRV_REQ_MAY_UNMAP, if it will allow for a sparser copy + * that still correctly reads as zero? */ + ret = bdrv_co_do_pwrite_zeroes(bs, cluster_offset, pnum, + BDRV_REQ_WRITE_UNCHANGED); + } else { + /* This does not change the data on the disk, it is not + * necessary to flush even in cache=writethrough mode. + */ + ret = bdrv_driver_pwritev(bs, cluster_offset, pnum, + &local_qiov, 0, + BDRV_REQ_WRITE_UNCHANGED); + } + + 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; + } + + if (!(flags & BDRV_REQ_PREFETCH)) { + qemu_iovec_from_buf(qiov, qiov_offset + progress, + bounce_buffer + skip_bytes, + MIN(pnum - skip_bytes, bytes - progress)); + } + } else if (!(flags & BDRV_REQ_PREFETCH)) { + /* Read directly into the destination */ + ret = bdrv_driver_preadv(bs, offset + progress, + MIN(pnum - skip_bytes, bytes - progress), + qiov, qiov_offset + progress, 0); + if (ret < 0) { + goto err; + } + } + + cluster_offset += pnum; + cluster_bytes -= pnum; + progress += pnum - skip_bytes; + skip_bytes = 0; + } + ret = 0; + +err: + qemu_vfree(bounce_buffer); + return ret; +} + +/* + * Forwards an already correctly aligned request to the BlockDriver. This + * handles copy on read, zeroing after EOF, and fragmentation of large + * reads; any other features must be implemented by the caller. + */ +static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child, + BdrvTrackedRequest *req, int64_t offset, int64_t bytes, + int64_t align, QEMUIOVector *qiov, size_t qiov_offset, int flags) +{ + BlockDriverState *bs = child->bs; + int64_t total_bytes, max_bytes; + int ret = 0; + int64_t bytes_remaining = bytes; + int max_transfer; + + bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); + assert(is_power_of_2(align)); + assert((offset & (align - 1)) == 0); + assert((bytes & (align - 1)) == 0); + assert((bs->open_flags & BDRV_O_NO_IO) == 0); + max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX), + align); + + /* TODO: We would need a per-BDS .supported_read_flags and + * potential fallback support, if we ever implement any read flags + * to pass through to drivers. For now, there aren't any + * passthrough flags. */ + assert(!(flags & ~(BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH))); + + /* 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. */ + bdrv_make_request_serialising(req, bdrv_get_cluster_size(bs)); + } else { + bdrv_wait_serialising_requests(req); + } + + if (flags & BDRV_REQ_COPY_ON_READ) { + int64_t pnum; + + /* The flag BDRV_REQ_COPY_ON_READ has reached its addressee */ + flags &= ~BDRV_REQ_COPY_ON_READ; + + ret = bdrv_is_allocated(bs, offset, bytes, &pnum); + if (ret < 0) { + goto out; + } + + if (!ret || pnum != bytes) { + ret = bdrv_co_do_copy_on_readv(child, offset, bytes, + qiov, qiov_offset, flags); + goto out; + } else if (flags & BDRV_REQ_PREFETCH) { + goto out; + } + } + + /* Forward the request to the BlockDriver, possibly fragmenting it */ + total_bytes = bdrv_getlength(bs); + if (total_bytes < 0) { + ret = total_bytes; + goto out; + } + + assert(!(flags & ~bs->supported_read_flags)); + + max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align); + if (bytes <= max_bytes && bytes <= max_transfer) { + ret = bdrv_driver_preadv(bs, offset, bytes, qiov, qiov_offset, flags); + goto out; + } + + while (bytes_remaining) { + int64_t num; + + if (max_bytes) { + num = MIN(bytes_remaining, MIN(max_bytes, max_transfer)); + assert(num); + + ret = bdrv_driver_preadv(bs, offset + bytes - bytes_remaining, + num, qiov, + qiov_offset + bytes - bytes_remaining, + flags); + max_bytes -= num; + } else { + num = bytes_remaining; + ret = qemu_iovec_memset(qiov, qiov_offset + bytes - bytes_remaining, + 0, bytes_remaining); + } + if (ret < 0) { + goto out; + } + bytes_remaining -= num; + } + +out: + return ret < 0 ? ret : 0; +} + +/* + * Request padding + * + * |<---- align ----->| |<----- align ---->| + * |<- head ->|<------------- bytes ------------->|<-- tail -->| + * | | | | | | + * -*----------$-------*-------- ... --------*-----$------------*--- + * | | | | | | + * | offset | | end | + * ALIGN_DOWN(offset) ALIGN_UP(offset) ALIGN_DOWN(end) ALIGN_UP(end) + * [buf ... ) [tail_buf ) + * + * @buf is an aligned allocation needed to store @head and @tail paddings. @head + * is placed at the beginning of @buf and @tail at the @end. + * + * @tail_buf is a pointer to sub-buffer, corresponding to align-sized chunk + * around tail, if tail exists. + * + * @merge_reads is true for small requests, + * if @buf_len == @head + bytes + @tail. In this case it is possible that both + * head and tail exist but @buf_len == align and @tail_buf == @buf. + */ +typedef struct BdrvRequestPadding { + uint8_t *buf; + size_t buf_len; + uint8_t *tail_buf; + size_t head; + size_t tail; + bool merge_reads; + QEMUIOVector local_qiov; +} BdrvRequestPadding; + +static bool bdrv_init_padding(BlockDriverState *bs, + int64_t offset, int64_t bytes, + BdrvRequestPadding *pad) +{ + int64_t align = bs->bl.request_alignment; + int64_t sum; + + bdrv_check_request(offset, bytes, &error_abort); + assert(align <= INT_MAX); /* documented in block/block_int.h */ + assert(align <= SIZE_MAX / 2); /* so we can allocate the buffer */ + + memset(pad, 0, sizeof(*pad)); + + pad->head = offset & (align - 1); + pad->tail = ((offset + bytes) & (align - 1)); + if (pad->tail) { + pad->tail = align - pad->tail; + } + + if (!pad->head && !pad->tail) { + return false; + } + + assert(bytes); /* Nothing good in aligning zero-length requests */ + + sum = pad->head + bytes + pad->tail; + pad->buf_len = (sum > align && pad->head && pad->tail) ? 2 * align : align; + pad->buf = qemu_blockalign(bs, pad->buf_len); + pad->merge_reads = sum == pad->buf_len; + if (pad->tail) { + pad->tail_buf = pad->buf + pad->buf_len - align; + } + + return true; +} + +static int bdrv_padding_rmw_read(BdrvChild *child, + BdrvTrackedRequest *req, + BdrvRequestPadding *pad, + bool zero_middle) +{ + QEMUIOVector local_qiov; + BlockDriverState *bs = child->bs; + uint64_t align = bs->bl.request_alignment; + int ret; + + assert(req->serialising && pad->buf); + + if (pad->head || pad->merge_reads) { + int64_t bytes = pad->merge_reads ? pad->buf_len : align; + + qemu_iovec_init_buf(&local_qiov, pad->buf, bytes); + + if (pad->head) { + bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD); + } + if (pad->merge_reads && pad->tail) { + bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL); + } + ret = bdrv_aligned_preadv(child, req, req->overlap_offset, bytes, + align, &local_qiov, 0, 0); + if (ret < 0) { + return ret; + } + if (pad->head) { + bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD); + } + if (pad->merge_reads && pad->tail) { + bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL); + } + + if (pad->merge_reads) { + goto zero_mem; + } + } + + if (pad->tail) { + qemu_iovec_init_buf(&local_qiov, pad->tail_buf, align); + + bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL); + ret = bdrv_aligned_preadv( + child, req, + req->overlap_offset + req->overlap_bytes - align, + align, align, &local_qiov, 0, 0); + if (ret < 0) { + return ret; + } + bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL); + } + +zero_mem: + if (zero_middle) { + memset(pad->buf + pad->head, 0, pad->buf_len - pad->head - pad->tail); + } + + return 0; +} + +static void bdrv_padding_destroy(BdrvRequestPadding *pad) +{ + if (pad->buf) { + qemu_vfree(pad->buf); + qemu_iovec_destroy(&pad->local_qiov); + } + memset(pad, 0, sizeof(*pad)); +} + +/* + * bdrv_pad_request + * + * Exchange request parameters with padded request if needed. Don't include RMW + * read of padding, bdrv_padding_rmw_read() should be called separately if + * needed. + * + * Request parameters (@qiov, &qiov_offset, &offset, &bytes) are in-out: + * - on function start they represent original request + * - on failure or when padding is not needed they are unchanged + * - on success when padding is needed they represent padded request + */ +static int bdrv_pad_request(BlockDriverState *bs, + QEMUIOVector **qiov, size_t *qiov_offset, + int64_t *offset, int64_t *bytes, + BdrvRequestPadding *pad, bool *padded) +{ + int ret; + + bdrv_check_qiov_request(*offset, *bytes, *qiov, *qiov_offset, &error_abort); + + if (!bdrv_init_padding(bs, *offset, *bytes, pad)) { + if (padded) { + *padded = false; + } + return 0; + } + + ret = qemu_iovec_init_extended(&pad->local_qiov, pad->buf, pad->head, + *qiov, *qiov_offset, *bytes, + pad->buf + pad->buf_len - pad->tail, + pad->tail); + if (ret < 0) { + bdrv_padding_destroy(pad); + return ret; + } + *bytes += pad->head + pad->tail; + *offset -= pad->head; + *qiov = &pad->local_qiov; + *qiov_offset = 0; + if (padded) { + *padded = true; + } + + return 0; +} + +int coroutine_fn bdrv_co_preadv(BdrvChild *child, + int64_t offset, int64_t bytes, QEMUIOVector *qiov, + BdrvRequestFlags flags) +{ + return bdrv_co_preadv_part(child, offset, bytes, qiov, 0, flags); +} + +int coroutine_fn bdrv_co_preadv_part(BdrvChild *child, + int64_t offset, int64_t bytes, + QEMUIOVector *qiov, size_t qiov_offset, + BdrvRequestFlags flags) +{ + BlockDriverState *bs = child->bs; + BdrvTrackedRequest req; + BdrvRequestPadding pad; + int ret; + + trace_bdrv_co_preadv_part(bs, offset, bytes, flags); + + if (!bdrv_is_inserted(bs)) { + return -ENOMEDIUM; + } + + ret = bdrv_check_request32(offset, bytes, qiov, qiov_offset); + if (ret < 0) { + return ret; + } + + if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) { + /* + * Aligning zero request is nonsense. Even if driver has special meaning + * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass + * it to driver due to request_alignment. + * + * Still, no reason to return an error if someone do unaligned + * zero-length read occasionally. + */ + return 0; + } + + bdrv_inc_in_flight(bs); + + /* Don't do copy-on-read if we read data before write operation */ + if (qatomic_read(&bs->copy_on_read)) { + flags |= BDRV_REQ_COPY_ON_READ; + } + + ret = bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad, + NULL); + if (ret < 0) { + goto fail; + } + + tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_READ); + ret = bdrv_aligned_preadv(child, &req, offset, bytes, + bs->bl.request_alignment, + qiov, qiov_offset, flags); + tracked_request_end(&req); + bdrv_padding_destroy(&pad); + +fail: + bdrv_dec_in_flight(bs); + + return ret; +} + +static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, + int64_t offset, int64_t bytes, BdrvRequestFlags flags) +{ + BlockDriver *drv = bs->drv; + QEMUIOVector qiov; + void *buf = NULL; + int ret = 0; + bool need_flush = false; + int head = 0; + int tail = 0; + + int64_t max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, + INT64_MAX); + int alignment = MAX(bs->bl.pwrite_zeroes_alignment, + bs->bl.request_alignment); + int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER); + + bdrv_check_request(offset, bytes, &error_abort); + + if (!drv) { + return -ENOMEDIUM; + } + + if ((flags & ~bs->supported_zero_flags) & BDRV_REQ_NO_FALLBACK) { + return -ENOTSUP; + } + + /* Invalidate the cached block-status data range if this write overlaps */ + bdrv_bsc_invalidate_range(bs, offset, bytes); + + assert(alignment % bs->bl.request_alignment == 0); + head = offset % alignment; + tail = (offset + bytes) % alignment; + max_write_zeroes = QEMU_ALIGN_DOWN(max_write_zeroes, alignment); + assert(max_write_zeroes >= bs->bl.request_alignment); + + while (bytes > 0 && !ret) { + int64_t num = bytes; + + /* Align request. Block drivers can expect the "bulk" of the request + * to be aligned, and that unaligned requests do not cross cluster + * boundaries. + */ + if (head) { + /* Make a small request up to the first aligned sector. For + * convenience, limit this request to max_transfer even if + * we don't need to fall back to writes. */ + num = MIN(MIN(bytes, max_transfer), alignment - head); + head = (head + num) % alignment; + assert(num < max_write_zeroes); + } else if (tail && num > alignment) { + /* Shorten the request to the last aligned sector. */ + num -= tail; + } + + /* limit request size */ + if (num > max_write_zeroes) { + num = max_write_zeroes; + } + + ret = -ENOTSUP; + /* First try the efficient write zeroes operation */ + if (drv->bdrv_co_pwrite_zeroes) { + ret = drv->bdrv_co_pwrite_zeroes(bs, offset, num, + flags & bs->supported_zero_flags); + if (ret != -ENOTSUP && (flags & BDRV_REQ_FUA) && + !(bs->supported_zero_flags & BDRV_REQ_FUA)) { + need_flush = true; + } + } else { + assert(!bs->supported_zero_flags); + } + + if (ret == -ENOTSUP && !(flags & BDRV_REQ_NO_FALLBACK)) { + /* Fall back to bounce buffer if write zeroes is unsupported */ + BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE; + + if ((flags & BDRV_REQ_FUA) && + !(bs->supported_write_flags & BDRV_REQ_FUA)) { + /* No need for bdrv_driver_pwrite() to do a fallback + * flush on each chunk; use just one at the end */ + write_flags &= ~BDRV_REQ_FUA; + need_flush = true; + } + num = MIN(num, max_transfer); + if (buf == NULL) { + buf = qemu_try_blockalign0(bs, num); + if (buf == NULL) { + ret = -ENOMEM; + goto fail; + } + } + qemu_iovec_init_buf(&qiov, buf, num); + + ret = bdrv_driver_pwritev(bs, offset, num, &qiov, 0, write_flags); + + /* Keep bounce buffer around if it is big enough for all + * all future requests. + */ + if (num < max_transfer) { + qemu_vfree(buf); + buf = NULL; + } + } + + offset += num; + bytes -= num; + } + +fail: + if (ret == 0 && need_flush) { + ret = bdrv_co_flush(bs); + } + qemu_vfree(buf); + return ret; +} + +static inline int coroutine_fn +bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, int64_t bytes, + BdrvTrackedRequest *req, int flags) +{ + BlockDriverState *bs = child->bs; + + bdrv_check_request(offset, bytes, &error_abort); + + if (bdrv_is_read_only(bs)) { + return -EPERM; + } + + assert(!(bs->open_flags & BDRV_O_INACTIVE)); + assert((bs->open_flags & BDRV_O_NO_IO) == 0); + assert(!(flags & ~BDRV_REQ_MASK)); + assert(!((flags & BDRV_REQ_NO_WAIT) && !(flags & BDRV_REQ_SERIALISING))); + + if (flags & BDRV_REQ_SERIALISING) { + QEMU_LOCK_GUARD(&bs->reqs_lock); + + tracked_request_set_serialising(req, bdrv_get_cluster_size(bs)); + + if ((flags & BDRV_REQ_NO_WAIT) && bdrv_find_conflicting_request(req)) { + return -EBUSY; + } + + bdrv_wait_serialising_requests_locked(req); + } else { + bdrv_wait_serialising_requests(req); + } + + assert(req->overlap_offset <= offset); + assert(offset + bytes <= req->overlap_offset + req->overlap_bytes); + assert(offset + bytes <= bs->total_sectors * BDRV_SECTOR_SIZE || + child->perm & BLK_PERM_RESIZE); + + switch (req->type) { + case BDRV_TRACKED_WRITE: + case BDRV_TRACKED_DISCARD: + if (flags & BDRV_REQ_WRITE_UNCHANGED) { + assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); + } else { + assert(child->perm & BLK_PERM_WRITE); + } + bdrv_write_threshold_check_write(bs, offset, bytes); + return 0; + case BDRV_TRACKED_TRUNCATE: + assert(child->perm & BLK_PERM_RESIZE); + return 0; + default: + abort(); + } +} + +static inline void coroutine_fn +bdrv_co_write_req_finish(BdrvChild *child, int64_t offset, int64_t bytes, + BdrvTrackedRequest *req, int ret) +{ + int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE); + BlockDriverState *bs = child->bs; + + bdrv_check_request(offset, bytes, &error_abort); + + qatomic_inc(&bs->write_gen); + + /* + * Discard cannot extend the image, but in error handling cases, such as + * when reverting a qcow2 cluster allocation, the discarded range can pass + * the end of image file, so we cannot assert about BDRV_TRACKED_DISCARD + * here. Instead, just skip it, since semantically a discard request + * beyond EOF cannot expand the image anyway. + */ + if (ret == 0 && + (req->type == BDRV_TRACKED_TRUNCATE || + end_sector > bs->total_sectors) && + req->type != BDRV_TRACKED_DISCARD) { + bs->total_sectors = end_sector; + bdrv_parent_cb_resize(bs); + bdrv_dirty_bitmap_truncate(bs, end_sector << BDRV_SECTOR_BITS); + } + if (req->bytes) { + switch (req->type) { + case BDRV_TRACKED_WRITE: + stat64_max(&bs->wr_highest_offset, offset + bytes); + /* fall through, to set dirty bits */ + case BDRV_TRACKED_DISCARD: + bdrv_set_dirty(bs, offset, bytes); + break; + default: + break; + } + } +} + +/* + * Forwards an already correctly aligned write request to the BlockDriver, + * after possibly fragmenting it. + */ +static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child, + BdrvTrackedRequest *req, int64_t offset, int64_t bytes, + int64_t align, QEMUIOVector *qiov, size_t qiov_offset, + BdrvRequestFlags flags) +{ + BlockDriverState *bs = child->bs; + BlockDriver *drv = bs->drv; + int ret; + + int64_t bytes_remaining = bytes; + int max_transfer; + + bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); + + if (!drv) { + return -ENOMEDIUM; + } + + if (bdrv_has_readonly_bitmaps(bs)) { + return -EPERM; + } + + assert(is_power_of_2(align)); + assert((offset & (align - 1)) == 0); + assert((bytes & (align - 1)) == 0); + max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX), + align); + + ret = bdrv_co_write_req_prepare(child, offset, bytes, req, flags); + + if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF && + !(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes && + qemu_iovec_is_zero(qiov, qiov_offset, bytes)) { + flags |= BDRV_REQ_ZERO_WRITE; + if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) { + flags |= BDRV_REQ_MAY_UNMAP; + } + } + + if (ret < 0) { + /* Do nothing, write notifier decided to fail this request */ + } else if (flags & BDRV_REQ_ZERO_WRITE) { + bdrv_debug_event(bs, BLKDBG_PWRITEV_ZERO); + ret = bdrv_co_do_pwrite_zeroes(bs, offset, bytes, flags); + } else if (flags & BDRV_REQ_WRITE_COMPRESSED) { + ret = bdrv_driver_pwritev_compressed(bs, offset, bytes, + qiov, qiov_offset); + } else if (bytes <= max_transfer) { + bdrv_debug_event(bs, BLKDBG_PWRITEV); + ret = bdrv_driver_pwritev(bs, offset, bytes, qiov, qiov_offset, flags); + } else { + bdrv_debug_event(bs, BLKDBG_PWRITEV); + while (bytes_remaining) { + int num = MIN(bytes_remaining, max_transfer); + int local_flags = flags; + + assert(num); + if (num < bytes_remaining && (flags & BDRV_REQ_FUA) && + !(bs->supported_write_flags & BDRV_REQ_FUA)) { + /* If FUA is going to be emulated by flush, we only + * need to flush on the last iteration */ + local_flags &= ~BDRV_REQ_FUA; + } + + ret = bdrv_driver_pwritev(bs, offset + bytes - bytes_remaining, + num, qiov, + qiov_offset + bytes - bytes_remaining, + local_flags); + if (ret < 0) { + break; + } + bytes_remaining -= num; + } + } + bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE); + + if (ret >= 0) { + ret = 0; + } + bdrv_co_write_req_finish(child, offset, bytes, req, ret); + + return ret; +} + +static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child, + int64_t offset, + int64_t bytes, + BdrvRequestFlags flags, + BdrvTrackedRequest *req) +{ + BlockDriverState *bs = child->bs; + QEMUIOVector local_qiov; + uint64_t align = bs->bl.request_alignment; + int ret = 0; + bool padding; + BdrvRequestPadding pad; + + padding = bdrv_init_padding(bs, offset, bytes, &pad); + if (padding) { + bdrv_make_request_serialising(req, align); + + bdrv_padding_rmw_read(child, req, &pad, true); + + if (pad.head || pad.merge_reads) { + int64_t aligned_offset = offset & ~(align - 1); + int64_t write_bytes = pad.merge_reads ? pad.buf_len : align; + + qemu_iovec_init_buf(&local_qiov, pad.buf, write_bytes); + ret = bdrv_aligned_pwritev(child, req, aligned_offset, write_bytes, + align, &local_qiov, 0, + flags & ~BDRV_REQ_ZERO_WRITE); + if (ret < 0 || pad.merge_reads) { + /* Error or all work is done */ + goto out; + } + offset += write_bytes - pad.head; + bytes -= write_bytes - pad.head; + } + } + + assert(!bytes || (offset & (align - 1)) == 0); + if (bytes >= align) { + /* Write the aligned part in the middle. */ + int64_t aligned_bytes = bytes & ~(align - 1); + ret = bdrv_aligned_pwritev(child, req, offset, aligned_bytes, align, + NULL, 0, flags); + if (ret < 0) { + goto out; + } + bytes -= aligned_bytes; + offset += aligned_bytes; + } + + assert(!bytes || (offset & (align - 1)) == 0); + if (bytes) { + assert(align == pad.tail + bytes); + + qemu_iovec_init_buf(&local_qiov, pad.tail_buf, align); + ret = bdrv_aligned_pwritev(child, req, offset, align, align, + &local_qiov, 0, + flags & ~BDRV_REQ_ZERO_WRITE); + } + +out: + bdrv_padding_destroy(&pad); + + return ret; +} + +/* + * Handle a write request in coroutine context + */ +int coroutine_fn bdrv_co_pwritev(BdrvChild *child, + int64_t offset, int64_t bytes, QEMUIOVector *qiov, + BdrvRequestFlags flags) +{ + return bdrv_co_pwritev_part(child, offset, bytes, qiov, 0, flags); +} + +int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child, + int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset, + BdrvRequestFlags flags) +{ + BlockDriverState *bs = child->bs; + BdrvTrackedRequest req; + uint64_t align = bs->bl.request_alignment; + BdrvRequestPadding pad; + int ret; + bool padded = false; + + trace_bdrv_co_pwritev_part(child->bs, offset, bytes, flags); + + if (!bdrv_is_inserted(bs)) { + return -ENOMEDIUM; + } + + if (flags & BDRV_REQ_ZERO_WRITE) { + ret = bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, NULL); + } else { + ret = bdrv_check_request32(offset, bytes, qiov, qiov_offset); + } + if (ret < 0) { + return ret; + } + + /* If the request is misaligned then we can't make it efficient */ + if ((flags & BDRV_REQ_NO_FALLBACK) && + !QEMU_IS_ALIGNED(offset | bytes, align)) + { + return -ENOTSUP; + } + + if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) { + /* + * Aligning zero request is nonsense. Even if driver has special meaning + * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass + * it to driver due to request_alignment. + * + * Still, no reason to return an error if someone do unaligned + * zero-length write occasionally. + */ + return 0; + } + + if (!(flags & BDRV_REQ_ZERO_WRITE)) { + /* + * Pad request for following read-modify-write cycle. + * bdrv_co_do_zero_pwritev() does aligning by itself, so, we do + * alignment only if there is no ZERO flag. + */ + ret = bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad, + &padded); + if (ret < 0) { + return ret; + } + } + + bdrv_inc_in_flight(bs); + tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE); + + if (flags & BDRV_REQ_ZERO_WRITE) { + assert(!padded); + ret = bdrv_co_do_zero_pwritev(child, offset, bytes, flags, &req); + goto out; + } + + if (padded) { + /* + * Request was unaligned to request_alignment and therefore + * padded. We are going to do read-modify-write, and must + * serialize the request to prevent interactions of the + * widened region with other transactions. + */ + bdrv_make_request_serialising(&req, align); + bdrv_padding_rmw_read(child, &req, &pad, false); + } + + ret = bdrv_aligned_pwritev(child, &req, offset, bytes, align, + qiov, qiov_offset, flags); + + bdrv_padding_destroy(&pad); + +out: + tracked_request_end(&req); + bdrv_dec_in_flight(bs); + + return ret; +} + +int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset, + int64_t bytes, BdrvRequestFlags flags) +{ + trace_bdrv_co_pwrite_zeroes(child->bs, offset, bytes, flags); + + if (!(child->bs->open_flags & BDRV_O_UNMAP)) { + flags &= ~BDRV_REQ_MAY_UNMAP; + } + + return bdrv_co_pwritev(child, offset, bytes, NULL, + BDRV_REQ_ZERO_WRITE | flags); +} + +/* + * Flush ALL BDSes regardless of if they are reachable via a BlkBackend or not. + */ +int bdrv_flush_all(void) +{ + BdrvNextIterator it; + BlockDriverState *bs = NULL; + int result = 0; + + /* + * bdrv queue is managed by record/replay, + * creating new flush request for stopping + * the VM may break the determinism + */ + if (replay_events_enabled()) { + return result; + } + + for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { + AioContext *aio_context = bdrv_get_aio_context(bs); + int ret; + + aio_context_acquire(aio_context); + ret = bdrv_flush(bs); + if (ret < 0 && !result) { + result = ret; + } + aio_context_release(aio_context); + } + + return result; +} + +/* + * 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 'want_zero' is true, the caller is querying for mapping + * purposes, with a focus on valid BDRV_BLOCK_OFFSET_VALID, _DATA, and + * _ZERO where possible; otherwise, the result favors larger 'pnum', + * with a focus on accurate BDRV_BLOCK_ALLOCATED. + * + * If 'offset' is beyond the end of the disk image the return value is + * BDRV_BLOCK_EOF and 'pnum' is set to 0. + * + * 'bytes' is the max value 'pnum' should be set to. If bytes goes + * beyond the end of the disk image it will be clamped; if 'pnum' is set to + * the end of the image, then the returned value will include BDRV_BLOCK_EOF. + * + * 'pnum' is set to the number of bytes (including and immediately + * following the specified offset) that are easily known to be in the + * same allocated/unallocated state. Note that a second call starting + * at the original offset plus returned pnum may have the same status. + * The returned value is non-zero on success except at end-of-file. + * + * Returns negative errno on failure. Otherwise, if the + * BDRV_BLOCK_OFFSET_VALID bit is set, 'map' and 'file' (if non-NULL) are + * set to the host mapping and BDS corresponding to the guest offset. + */ +static int coroutine_fn bdrv_co_block_status(BlockDriverState *bs, + bool want_zero, + int64_t offset, int64_t bytes, + int64_t *pnum, int64_t *map, + BlockDriverState **file) +{ + int64_t total_size; + int64_t n; /* bytes */ + int ret; + int64_t local_map = 0; + BlockDriverState *local_file = NULL; + int64_t aligned_offset, aligned_bytes; + uint32_t align; + bool has_filtered_child; + + assert(pnum); + *pnum = 0; + total_size = bdrv_getlength(bs); + if (total_size < 0) { + ret = total_size; + goto early_out; + } + + if (offset >= total_size) { + ret = BDRV_BLOCK_EOF; + goto early_out; + } + if (!bytes) { + ret = 0; + goto early_out; + } + + n = total_size - offset; + if (n < bytes) { + bytes = n; + } + + /* Must be non-NULL or bdrv_getlength() would have failed */ + assert(bs->drv); + has_filtered_child = bdrv_filter_child(bs); + if (!bs->drv->bdrv_co_block_status && !has_filtered_child) { + *pnum = bytes; + ret = BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED; + if (offset + bytes == total_size) { + ret |= BDRV_BLOCK_EOF; + } + if (bs->drv->protocol_name) { + ret |= BDRV_BLOCK_OFFSET_VALID; + local_map = offset; + local_file = bs; + } + goto early_out; + } + + bdrv_inc_in_flight(bs); + + /* Round out to request_alignment boundaries */ + align = bs->bl.request_alignment; + aligned_offset = QEMU_ALIGN_DOWN(offset, align); + aligned_bytes = ROUND_UP(offset + bytes, align) - aligned_offset; + + if (bs->drv->bdrv_co_block_status) { + /* + * Use the block-status cache only for protocol nodes: Format + * drivers are generally quick to inquire the status, but protocol + * drivers often need to get information from outside of qemu, so + * we do not have control over the actual implementation. There + * have been cases where inquiring the status took an unreasonably + * long time, and we can do nothing in qemu to fix it. + * This is especially problematic for images with large data areas, + * because finding the few holes in them and giving them special + * treatment does not gain much performance. Therefore, we try to + * cache the last-identified data region. + * + * Second, limiting ourselves to protocol nodes allows us to assume + * the block status for data regions to be DATA | OFFSET_VALID, and + * that the host offset is the same as the guest offset. + * + * Note that it is possible that external writers zero parts of + * the cached regions without the cache being invalidated, and so + * we may report zeroes as data. This is not catastrophic, + * however, because reporting zeroes as data is fine. + */ + if (QLIST_EMPTY(&bs->children) && + bdrv_bsc_is_data(bs, aligned_offset, pnum)) + { + ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID; + local_file = bs; + local_map = aligned_offset; + } else { + ret = bs->drv->bdrv_co_block_status(bs, want_zero, aligned_offset, + aligned_bytes, pnum, &local_map, + &local_file); + + /* + * Note that checking QLIST_EMPTY(&bs->children) is also done when + * the cache is queried above. Technically, we do not need to check + * it here; the worst that can happen is that we fill the cache for + * non-protocol nodes, and then it is never used. However, filling + * the cache requires an RCU update, so double check here to avoid + * such an update if possible. + */ + if (ret == (BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID) && + QLIST_EMPTY(&bs->children)) + { + /* + * When a protocol driver reports BLOCK_OFFSET_VALID, the + * returned local_map value must be the same as the offset we + * have passed (aligned_offset), and local_bs must be the node + * itself. + * Assert this, because we follow this rule when reading from + * the cache (see the `local_file = bs` and + * `local_map = aligned_offset` assignments above), and the + * result the cache delivers must be the same as the driver + * would deliver. + */ + assert(local_file == bs); + assert(local_map == aligned_offset); + bdrv_bsc_fill(bs, aligned_offset, *pnum); + } + } + } else { + /* Default code for filters */ + + local_file = bdrv_filter_bs(bs); + assert(local_file); + + *pnum = aligned_bytes; + local_map = aligned_offset; + ret = BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID; + } + if (ret < 0) { + *pnum = 0; + goto out; + } + + /* + * The driver's result must be a non-zero multiple of request_alignment. + * Clamp pnum and adjust map to original request. + */ + assert(*pnum && QEMU_IS_ALIGNED(*pnum, align) && + align > offset - aligned_offset); + if (ret & BDRV_BLOCK_RECURSE) { + assert(ret & BDRV_BLOCK_DATA); + assert(ret & BDRV_BLOCK_OFFSET_VALID); + assert(!(ret & BDRV_BLOCK_ZERO)); + } + + *pnum -= offset - aligned_offset; + if (*pnum > bytes) { + *pnum = bytes; + } + if (ret & BDRV_BLOCK_OFFSET_VALID) { + local_map += offset - aligned_offset; + } + + if (ret & BDRV_BLOCK_RAW) { + assert(ret & BDRV_BLOCK_OFFSET_VALID && local_file); + ret = bdrv_co_block_status(local_file, want_zero, local_map, + *pnum, pnum, &local_map, &local_file); + goto out; + } + + if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) { + ret |= BDRV_BLOCK_ALLOCATED; + } else if (bs->drv->supports_backing) { + BlockDriverState *cow_bs = bdrv_cow_bs(bs); + + if (!cow_bs) { + ret |= BDRV_BLOCK_ZERO; + } else if (want_zero) { + int64_t size2 = bdrv_getlength(cow_bs); + + if (size2 >= 0 && offset >= size2) { + ret |= BDRV_BLOCK_ZERO; + } + } + } + + if (want_zero && ret & BDRV_BLOCK_RECURSE && + local_file && local_file != bs && + (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) && + (ret & BDRV_BLOCK_OFFSET_VALID)) { + int64_t file_pnum; + int ret2; + + ret2 = bdrv_co_block_status(local_file, want_zero, local_map, + *pnum, &file_pnum, NULL, NULL); + if (ret2 >= 0) { + /* Ignore errors. This is just providing extra information, it + * is useful but not necessary. + */ + if (ret2 & BDRV_BLOCK_EOF && + (!file_pnum || ret2 & BDRV_BLOCK_ZERO)) { + /* + * It is valid for the format block driver to read + * beyond the end of the underlying file's current + * size; such areas read as zero. + */ + ret |= BDRV_BLOCK_ZERO; + } else { + /* Limit request to the range reported by the protocol driver */ + *pnum = file_pnum; + ret |= (ret2 & BDRV_BLOCK_ZERO); + } + } + } + +out: + bdrv_dec_in_flight(bs); + if (ret >= 0 && offset + *pnum == total_size) { + ret |= BDRV_BLOCK_EOF; + } +early_out: + if (file) { + *file = local_file; + } + if (map) { + *map = local_map; + } + return ret; +} + +int coroutine_fn +bdrv_co_common_block_status_above(BlockDriverState *bs, + BlockDriverState *base, + bool include_base, + bool want_zero, + int64_t offset, + int64_t bytes, + int64_t *pnum, + int64_t *map, + BlockDriverState **file, + int *depth) +{ + int ret; + BlockDriverState *p; + int64_t eof = 0; + int dummy; + + assert(!include_base || base); /* Can't include NULL base */ + + if (!depth) { + depth = &dummy; + } + *depth = 0; + + if (!include_base && bs == base) { + *pnum = bytes; + return 0; + } + + ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file); + ++*depth; + if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) { + return ret; + } + + if (ret & BDRV_BLOCK_EOF) { + eof = offset + *pnum; + } + + assert(*pnum <= bytes); + bytes = *pnum; + + for (p = bdrv_filter_or_cow_bs(bs); include_base || p != base; + p = bdrv_filter_or_cow_bs(p)) + { + ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map, + file); + ++*depth; + if (ret < 0) { + return ret; + } + if (*pnum == 0) { + /* + * The top layer deferred to this layer, and because this layer is + * short, any zeroes that we synthesize beyond EOF behave as if they + * were allocated at this layer. + * + * We don't include BDRV_BLOCK_EOF into ret, as upper layer may be + * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see + * below. + */ + assert(ret & BDRV_BLOCK_EOF); + *pnum = bytes; + if (file) { + *file = p; + } + ret = BDRV_BLOCK_ZERO | BDRV_BLOCK_ALLOCATED; + break; + } + if (ret & BDRV_BLOCK_ALLOCATED) { + /* + * We've found the node and the status, we must break. + * + * Drop BDRV_BLOCK_EOF, as it's not for upper layer, which may be + * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see + * below. + */ + ret &= ~BDRV_BLOCK_EOF; + break; + } + + if (p == base) { + assert(include_base); + break; + } + + /* + * OK, [offset, offset + *pnum) region is unallocated on this layer, + * let's continue the diving. + */ + assert(*pnum <= bytes); + bytes = *pnum; + } + + if (offset + *pnum == eof) { + ret |= BDRV_BLOCK_EOF; + } + + return ret; +} + +int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base, + int64_t offset, int64_t bytes, int64_t *pnum, + int64_t *map, BlockDriverState **file) +{ + return bdrv_common_block_status_above(bs, base, false, true, offset, bytes, + pnum, map, file, NULL); +} + +int bdrv_block_status(BlockDriverState *bs, int64_t offset, int64_t bytes, + int64_t *pnum, int64_t *map, BlockDriverState **file) +{ + return bdrv_block_status_above(bs, bdrv_filter_or_cow_bs(bs), + offset, bytes, pnum, map, file); +} + +/* + * Check @bs (and its backing chain) to see if the range defined + * by @offset and @bytes is known to read as zeroes. + * Return 1 if that is the case, 0 otherwise and -errno on error. + * This test is meant to be fast rather than accurate so returning 0 + * does not guarantee non-zero data. + */ +int coroutine_fn bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset, + int64_t bytes) +{ + int ret; + int64_t pnum = bytes; + + if (!bytes) { + return 1; + } + + ret = bdrv_common_block_status_above(bs, NULL, false, false, offset, + bytes, &pnum, NULL, NULL, NULL); + + if (ret < 0) { + return ret; + } + + return (pnum == bytes) && (ret & BDRV_BLOCK_ZERO); +} + +int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset, + int64_t bytes, int64_t *pnum) +{ + int ret; + int64_t dummy; + + ret = bdrv_common_block_status_above(bs, bs, true, false, offset, + bytes, pnum ? pnum : &dummy, NULL, + NULL, NULL); + if (ret < 0) { + return ret; + } + return !!(ret & BDRV_BLOCK_ALLOCATED); +} + +/* + * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP] + * + * Return a positive depth if (a prefix of) the given range is allocated + * in any image between BASE and TOP (BASE is only included if include_base + * is set). Depth 1 is TOP, 2 is the first backing layer, and so forth. + * BASE can be NULL to check if the given offset is allocated in any + * image of the chain. Return 0 otherwise, or negative errno on + * failure. + * + * 'pnum' is set to the number of bytes (including and immediately + * following the specified offset) that are known to be in the same + * allocated/unallocated state. Note that a subsequent call starting + * at 'offset + *pnum' may return the same allocation status (in other + * words, the result is not necessarily the maximum possible range); + * but 'pnum' will only be 0 when end of file is reached. + */ +int bdrv_is_allocated_above(BlockDriverState *top, + BlockDriverState *base, + bool include_base, int64_t offset, + int64_t bytes, int64_t *pnum) +{ + int depth; + int ret = bdrv_common_block_status_above(top, base, include_base, false, + offset, bytes, pnum, NULL, NULL, + &depth); + if (ret < 0) { + return ret; + } + + if (ret & BDRV_BLOCK_ALLOCATED) { + return depth; + } + return 0; +} + +int coroutine_fn +bdrv_co_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos) +{ + BlockDriver *drv = bs->drv; + BlockDriverState *child_bs = bdrv_primary_bs(bs); + int ret; + + ret = bdrv_check_qiov_request(pos, qiov->size, qiov, 0, NULL); + if (ret < 0) { + return ret; + } + + if (!drv) { + return -ENOMEDIUM; + } + + bdrv_inc_in_flight(bs); + + if (drv->bdrv_load_vmstate) { + ret = drv->bdrv_load_vmstate(bs, qiov, pos); + } else if (child_bs) { + ret = bdrv_co_readv_vmstate(child_bs, qiov, pos); + } else { + ret = -ENOTSUP; + } + + bdrv_dec_in_flight(bs); + + return ret; +} + +int coroutine_fn +bdrv_co_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos) +{ + BlockDriver *drv = bs->drv; + BlockDriverState *child_bs = bdrv_primary_bs(bs); + int ret; + + ret = bdrv_check_qiov_request(pos, qiov->size, qiov, 0, NULL); + if (ret < 0) { + return ret; + } + + if (!drv) { + return -ENOMEDIUM; + } + + bdrv_inc_in_flight(bs); + + if (drv->bdrv_save_vmstate) { + ret = drv->bdrv_save_vmstate(bs, qiov, pos); + } else if (child_bs) { + ret = bdrv_co_writev_vmstate(child_bs, qiov, pos); + } else { + ret = -ENOTSUP; + } + + bdrv_dec_in_flight(bs); + + return ret; +} + +int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf, + int64_t pos, int size) +{ + QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, size); + int ret = bdrv_writev_vmstate(bs, &qiov, pos); + + return ret < 0 ? ret : size; +} + +int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf, + int64_t pos, int size) +{ + QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, size); + int ret = bdrv_readv_vmstate(bs, &qiov, pos); + + return ret < 0 ? ret : size; +} + +/**************************************************************/ +/* async I/Os */ + +void bdrv_aio_cancel(BlockAIOCB *acb) +{ + qemu_aio_ref(acb); + bdrv_aio_cancel_async(acb); + while (acb->refcnt > 1) { + if (acb->aiocb_info->get_aio_context) { + aio_poll(acb->aiocb_info->get_aio_context(acb), true); + } else if (acb->bs) { + /* qemu_aio_ref and qemu_aio_unref are not thread-safe, so + * assert that we're not using an I/O thread. Thread-safe + * code should use bdrv_aio_cancel_async exclusively. + */ + assert(bdrv_get_aio_context(acb->bs) == qemu_get_aio_context()); + aio_poll(bdrv_get_aio_context(acb->bs), true); + } else { + abort(); + } + } + qemu_aio_unref(acb); +} + +/* Async version of aio cancel. The caller is not blocked if the acb implements + * cancel_async, otherwise we do nothing and let the request normally complete. + * In either case the completion callback must be called. */ +void bdrv_aio_cancel_async(BlockAIOCB *acb) +{ + if (acb->aiocb_info->cancel_async) { + acb->aiocb_info->cancel_async(acb); + } +} + +/**************************************************************/ +/* Coroutine block device emulation */ + +int coroutine_fn bdrv_co_flush(BlockDriverState *bs) +{ + BdrvChild *primary_child = bdrv_primary_child(bs); + BdrvChild *child; + int current_gen; + int ret = 0; + + bdrv_inc_in_flight(bs); + + if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs) || + bdrv_is_sg(bs)) { + goto early_exit; + } + + qemu_co_mutex_lock(&bs->reqs_lock); + current_gen = qatomic_read(&bs->write_gen); + + /* Wait until any previous flushes are completed */ + while (bs->active_flush_req) { + qemu_co_queue_wait(&bs->flush_queue, &bs->reqs_lock); + } + + /* Flushes reach this point in nondecreasing current_gen order. */ + bs->active_flush_req = true; + qemu_co_mutex_unlock(&bs->reqs_lock); + + /* Write back all layers by calling one driver function */ + if (bs->drv->bdrv_co_flush) { + ret = bs->drv->bdrv_co_flush(bs); + goto out; + } + + /* Write back cached data to the OS even with cache=unsafe */ + BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_OS); + if (bs->drv->bdrv_co_flush_to_os) { + ret = bs->drv->bdrv_co_flush_to_os(bs); + if (ret < 0) { + goto out; + } + } + + /* But don't actually force it to the disk with cache=unsafe */ + if (bs->open_flags & BDRV_O_NO_FLUSH) { + goto flush_children; + } + + /* Check if we really need to flush anything */ + if (bs->flushed_gen == current_gen) { + goto flush_children; + } + + BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_DISK); + if (!bs->drv) { + /* bs->drv->bdrv_co_flush() might have ejected the BDS + * (even in case of apparent success) */ + ret = -ENOMEDIUM; + goto out; + } + if (bs->drv->bdrv_co_flush_to_disk) { + ret = bs->drv->bdrv_co_flush_to_disk(bs); + } else if (bs->drv->bdrv_aio_flush) { + BlockAIOCB *acb; + CoroutineIOCompletion co = { + .coroutine = qemu_coroutine_self(), + }; + + acb = bs->drv->bdrv_aio_flush(bs, bdrv_co_io_em_complete, &co); + if (acb == NULL) { + ret = -EIO; + } else { + qemu_coroutine_yield(); + ret = co.ret; + } + } else { + /* + * Some block drivers always operate in either writethrough or unsafe + * mode and don't support bdrv_flush therefore. Usually qemu doesn't + * know how the server works (because the behaviour is hardcoded or + * depends on server-side configuration), so we can't ensure that + * everything is safe on disk. Returning an error doesn't work because + * that would break guests even if the server operates in writethrough + * mode. + * + * Let's hope the user knows what he's doing. + */ + ret = 0; + } + + if (ret < 0) { + goto out; + } + + /* Now flush the underlying protocol. It will also have BDRV_O_NO_FLUSH + * in the case of cache=unsafe, so there are no useless flushes. + */ +flush_children: + ret = 0; + QLIST_FOREACH(child, &bs->children, next) { + if (child->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) { + int this_child_ret = bdrv_co_flush(child->bs); + if (!ret) { + ret = this_child_ret; + } + } + } + +out: + /* Notify any pending flushes that we have completed */ + if (ret == 0) { + bs->flushed_gen = current_gen; + } + + qemu_co_mutex_lock(&bs->reqs_lock); + bs->active_flush_req = false; + /* Return value is ignored - it's ok if wait queue is empty */ + qemu_co_queue_next(&bs->flush_queue); + qemu_co_mutex_unlock(&bs->reqs_lock); + +early_exit: + bdrv_dec_in_flight(bs); + return ret; +} + +int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset, + int64_t bytes) +{ + BdrvTrackedRequest req; + int ret; + int64_t max_pdiscard; + int head, tail, align; + BlockDriverState *bs = child->bs; + + if (!bs || !bs->drv || !bdrv_is_inserted(bs)) { + return -ENOMEDIUM; + } + + if (bdrv_has_readonly_bitmaps(bs)) { + return -EPERM; + } + + ret = bdrv_check_request(offset, bytes, NULL); + if (ret < 0) { + return ret; + } + + /* Do nothing if disabled. */ + if (!(bs->open_flags & BDRV_O_UNMAP)) { + return 0; + } + + if (!bs->drv->bdrv_co_pdiscard && !bs->drv->bdrv_aio_pdiscard) { + return 0; + } + + /* Invalidate the cached block-status data range if this discard overlaps */ + bdrv_bsc_invalidate_range(bs, offset, bytes); + + /* Discard is advisory, but some devices track and coalesce + * unaligned requests, so we must pass everything down rather than + * round here. Still, most devices will just silently ignore + * unaligned requests (by returning -ENOTSUP), so we must fragment + * the request accordingly. */ + align = MAX(bs->bl.pdiscard_alignment, bs->bl.request_alignment); + assert(align % bs->bl.request_alignment == 0); + head = offset % align; + tail = (offset + bytes) % align; + + bdrv_inc_in_flight(bs); + tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_DISCARD); + + ret = bdrv_co_write_req_prepare(child, offset, bytes, &req, 0); + if (ret < 0) { + goto out; + } + + max_pdiscard = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_pdiscard, INT64_MAX), + align); + assert(max_pdiscard >= bs->bl.request_alignment); + + while (bytes > 0) { + int64_t num = bytes; + + if (head) { + /* Make small requests to get to alignment boundaries. */ + num = MIN(bytes, align - head); + if (!QEMU_IS_ALIGNED(num, bs->bl.request_alignment)) { + num %= bs->bl.request_alignment; + } + head = (head + num) % align; + assert(num < max_pdiscard); + } else if (tail) { + if (num > align) { + /* Shorten the request to the last aligned cluster. */ + num -= tail; + } else if (!QEMU_IS_ALIGNED(tail, bs->bl.request_alignment) && + tail > bs->bl.request_alignment) { + tail %= bs->bl.request_alignment; + num -= tail; + } + } + /* limit request size */ + if (num > max_pdiscard) { + num = max_pdiscard; + } + + if (!bs->drv) { + ret = -ENOMEDIUM; + goto out; + } + if (bs->drv->bdrv_co_pdiscard) { + ret = bs->drv->bdrv_co_pdiscard(bs, offset, num); + } else { + BlockAIOCB *acb; + CoroutineIOCompletion co = { + .coroutine = qemu_coroutine_self(), + }; + + acb = bs->drv->bdrv_aio_pdiscard(bs, offset, num, + bdrv_co_io_em_complete, &co); + if (acb == NULL) { + ret = -EIO; + goto out; + } else { + qemu_coroutine_yield(); + ret = co.ret; + } + } + if (ret && ret != -ENOTSUP) { + goto out; + } + + offset += num; + bytes -= num; + } + ret = 0; +out: + bdrv_co_write_req_finish(child, req.offset, req.bytes, &req, ret); + tracked_request_end(&req); + bdrv_dec_in_flight(bs); + return ret; +} + +int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf) +{ + BlockDriver *drv = bs->drv; + CoroutineIOCompletion co = { + .coroutine = qemu_coroutine_self(), + }; + BlockAIOCB *acb; + + bdrv_inc_in_flight(bs); + if (!drv || (!drv->bdrv_aio_ioctl && !drv->bdrv_co_ioctl)) { + co.ret = -ENOTSUP; + goto out; + } + + if (drv->bdrv_co_ioctl) { + co.ret = drv->bdrv_co_ioctl(bs, req, buf); + } else { + acb = drv->bdrv_aio_ioctl(bs, req, buf, bdrv_co_io_em_complete, &co); + if (!acb) { + co.ret = -ENOTSUP; + goto out; + } + qemu_coroutine_yield(); + } +out: + bdrv_dec_in_flight(bs); + return co.ret; +} + +void *qemu_blockalign(BlockDriverState *bs, size_t size) +{ + return qemu_memalign(bdrv_opt_mem_align(bs), size); +} + +void *qemu_blockalign0(BlockDriverState *bs, size_t size) +{ + return memset(qemu_blockalign(bs, size), 0, size); +} + +void *qemu_try_blockalign(BlockDriverState *bs, size_t size) +{ + size_t align = bdrv_opt_mem_align(bs); + + /* Ensure that NULL is never returned on success */ + assert(align > 0); + if (size == 0) { + size = align; + } + + return qemu_try_memalign(align, size); +} + +void *qemu_try_blockalign0(BlockDriverState *bs, size_t size) +{ + void *mem = qemu_try_blockalign(bs, size); + + if (mem) { + memset(mem, 0, size); + } + + return mem; +} + +/* + * Check if all memory in this vector is sector aligned. + */ +bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov) +{ + int i; + size_t alignment = bdrv_min_mem_align(bs); + + for (i = 0; i < qiov->niov; i++) { + if ((uintptr_t) qiov->iov[i].iov_base % alignment) { + return false; + } + if (qiov->iov[i].iov_len % alignment) { + return false; + } + } + + return true; +} + +void bdrv_io_plug(BlockDriverState *bs) +{ + BdrvChild *child; + + QLIST_FOREACH(child, &bs->children, next) { + bdrv_io_plug(child->bs); + } + + if (qatomic_fetch_inc(&bs->io_plugged) == 0) { + BlockDriver *drv = bs->drv; + if (drv && drv->bdrv_io_plug) { + drv->bdrv_io_plug(bs); + } + } +} + +void bdrv_io_unplug(BlockDriverState *bs) +{ + BdrvChild *child; + + assert(bs->io_plugged); + if (qatomic_fetch_dec(&bs->io_plugged) == 1) { + BlockDriver *drv = bs->drv; + if (drv && drv->bdrv_io_unplug) { + drv->bdrv_io_unplug(bs); + } + } + + QLIST_FOREACH(child, &bs->children, next) { + bdrv_io_unplug(child->bs); + } +} + +void bdrv_register_buf(BlockDriverState *bs, void *host, size_t size) +{ + BdrvChild *child; + + if (bs->drv && bs->drv->bdrv_register_buf) { + bs->drv->bdrv_register_buf(bs, host, size); + } + QLIST_FOREACH(child, &bs->children, next) { + bdrv_register_buf(child->bs, host, size); + } +} + +void bdrv_unregister_buf(BlockDriverState *bs, void *host) +{ + BdrvChild *child; + + if (bs->drv && bs->drv->bdrv_unregister_buf) { + bs->drv->bdrv_unregister_buf(bs, host); + } + QLIST_FOREACH(child, &bs->children, next) { + bdrv_unregister_buf(child->bs, host); + } +} + +static int coroutine_fn bdrv_co_copy_range_internal( + BdrvChild *src, int64_t src_offset, BdrvChild *dst, + int64_t dst_offset, int64_t bytes, + BdrvRequestFlags read_flags, BdrvRequestFlags write_flags, + bool recurse_src) +{ + BdrvTrackedRequest req; + int ret; + + /* TODO We can support BDRV_REQ_NO_FALLBACK here */ + assert(!(read_flags & BDRV_REQ_NO_FALLBACK)); + assert(!(write_flags & BDRV_REQ_NO_FALLBACK)); + + if (!dst || !dst->bs || !bdrv_is_inserted(dst->bs)) { + return -ENOMEDIUM; + } + ret = bdrv_check_request32(dst_offset, bytes, NULL, 0); + if (ret) { + return ret; + } + if (write_flags & BDRV_REQ_ZERO_WRITE) { + return bdrv_co_pwrite_zeroes(dst, dst_offset, bytes, write_flags); + } + + if (!src || !src->bs || !bdrv_is_inserted(src->bs)) { + return -ENOMEDIUM; + } + ret = bdrv_check_request32(src_offset, bytes, NULL, 0); + if (ret) { + return ret; + } + + if (!src->bs->drv->bdrv_co_copy_range_from + || !dst->bs->drv->bdrv_co_copy_range_to + || src->bs->encrypted || dst->bs->encrypted) { + return -ENOTSUP; + } + + if (recurse_src) { + bdrv_inc_in_flight(src->bs); + tracked_request_begin(&req, src->bs, src_offset, bytes, + BDRV_TRACKED_READ); + + /* BDRV_REQ_SERIALISING is only for write operation */ + assert(!(read_flags & BDRV_REQ_SERIALISING)); + bdrv_wait_serialising_requests(&req); + + ret = src->bs->drv->bdrv_co_copy_range_from(src->bs, + src, src_offset, + dst, dst_offset, + bytes, + read_flags, write_flags); + + tracked_request_end(&req); + bdrv_dec_in_flight(src->bs); + } else { + bdrv_inc_in_flight(dst->bs); + tracked_request_begin(&req, dst->bs, dst_offset, bytes, + BDRV_TRACKED_WRITE); + ret = bdrv_co_write_req_prepare(dst, dst_offset, bytes, &req, + write_flags); + if (!ret) { + ret = dst->bs->drv->bdrv_co_copy_range_to(dst->bs, + src, src_offset, + dst, dst_offset, + bytes, + read_flags, write_flags); + } + bdrv_co_write_req_finish(dst, dst_offset, bytes, &req, ret); + tracked_request_end(&req); + bdrv_dec_in_flight(dst->bs); + } + + return ret; +} + +/* Copy range from @src to @dst. + * + * See the comment of bdrv_co_copy_range for the parameter and return value + * semantics. */ +int coroutine_fn bdrv_co_copy_range_from(BdrvChild *src, int64_t src_offset, + BdrvChild *dst, int64_t dst_offset, + int64_t bytes, + BdrvRequestFlags read_flags, + BdrvRequestFlags write_flags) +{ + trace_bdrv_co_copy_range_from(src, src_offset, dst, dst_offset, bytes, + read_flags, write_flags); + return bdrv_co_copy_range_internal(src, src_offset, dst, dst_offset, + bytes, read_flags, write_flags, true); +} + +/* Copy range from @src to @dst. + * + * See the comment of bdrv_co_copy_range for the parameter and return value + * semantics. */ +int coroutine_fn bdrv_co_copy_range_to(BdrvChild *src, int64_t src_offset, + BdrvChild *dst, int64_t dst_offset, + int64_t bytes, + BdrvRequestFlags read_flags, + BdrvRequestFlags write_flags) +{ + trace_bdrv_co_copy_range_to(src, src_offset, dst, dst_offset, bytes, + read_flags, write_flags); + return bdrv_co_copy_range_internal(src, src_offset, dst, dst_offset, + bytes, read_flags, write_flags, false); +} + +int coroutine_fn bdrv_co_copy_range(BdrvChild *src, int64_t src_offset, + BdrvChild *dst, int64_t dst_offset, + int64_t bytes, BdrvRequestFlags read_flags, + BdrvRequestFlags write_flags) +{ + return bdrv_co_copy_range_from(src, src_offset, + dst, dst_offset, + bytes, read_flags, write_flags); +} + +static void bdrv_parent_cb_resize(BlockDriverState *bs) +{ + BdrvChild *c; + QLIST_FOREACH(c, &bs->parents, next_parent) { + if (c->klass->resize) { + c->klass->resize(c); + } + } +} + +/** + * Truncate file to 'offset' bytes (needed only for file protocols) + * + * If 'exact' is true, the file must be resized to exactly the given + * 'offset'. Otherwise, it is sufficient for the node to be at least + * 'offset' bytes in length. + */ +int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact, + PreallocMode prealloc, BdrvRequestFlags flags, + Error **errp) +{ + BlockDriverState *bs = child->bs; + BdrvChild *filtered, *backing; + BlockDriver *drv = bs->drv; + BdrvTrackedRequest req; + int64_t old_size, new_bytes; + int ret; + + + /* if bs->drv == NULL, bs is closed, so there's nothing to do here */ + if (!drv) { + error_setg(errp, "No medium inserted"); + return -ENOMEDIUM; + } + if (offset < 0) { + error_setg(errp, "Image size cannot be negative"); + return -EINVAL; + } + + ret = bdrv_check_request(offset, 0, errp); + if (ret < 0) { + return ret; + } + + old_size = bdrv_getlength(bs); + if (old_size < 0) { + error_setg_errno(errp, -old_size, "Failed to get old image size"); + return old_size; + } + + if (bdrv_is_read_only(bs)) { + error_setg(errp, "Image is read-only"); + return -EACCES; + } + + if (offset > old_size) { + new_bytes = offset - old_size; + } else { + new_bytes = 0; + } + + bdrv_inc_in_flight(bs); + tracked_request_begin(&req, bs, offset - new_bytes, new_bytes, + BDRV_TRACKED_TRUNCATE); + + /* If we are growing the image and potentially using preallocation for the + * new area, we need to make sure that no write requests are made to it + * concurrently or they might be overwritten by preallocation. */ + if (new_bytes) { + bdrv_make_request_serialising(&req, 1); + } + ret = bdrv_co_write_req_prepare(child, offset - new_bytes, new_bytes, &req, + 0); + if (ret < 0) { + error_setg_errno(errp, -ret, + "Failed to prepare request for truncation"); + goto out; + } + + filtered = bdrv_filter_child(bs); + backing = bdrv_cow_child(bs); + + /* + * If the image has a backing file that is large enough that it would + * provide data for the new area, we cannot leave it unallocated because + * then the backing file content would become visible. Instead, zero-fill + * the new area. + * + * Note that if the image has a backing file, but was opened without the + * backing file, taking care of keeping things consistent with that backing + * file is the user's responsibility. + */ + if (new_bytes && backing) { + int64_t backing_len; + + backing_len = bdrv_getlength(backing->bs); + if (backing_len < 0) { + ret = backing_len; + error_setg_errno(errp, -ret, "Could not get backing file size"); + goto out; + } + + if (backing_len > old_size) { + flags |= BDRV_REQ_ZERO_WRITE; + } + } + + if (drv->bdrv_co_truncate) { + if (flags & ~bs->supported_truncate_flags) { + error_setg(errp, "Block driver does not support requested flags"); + ret = -ENOTSUP; + goto out; + } + ret = drv->bdrv_co_truncate(bs, offset, exact, prealloc, flags, errp); + } else if (filtered) { + ret = bdrv_co_truncate(filtered, offset, exact, prealloc, flags, errp); + } else { + error_setg(errp, "Image format driver does not support resize"); + ret = -ENOTSUP; + goto out; + } + if (ret < 0) { + goto out; + } + + ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS); + if (ret < 0) { + error_setg_errno(errp, -ret, "Could not refresh total sector count"); + } else { + offset = bs->total_sectors * BDRV_SECTOR_SIZE; + } + /* It's possible that truncation succeeded but refresh_total_sectors + * failed, but the latter doesn't affect how we should finish the request. + * Pass 0 as the last parameter so that dirty bitmaps etc. are handled. */ + bdrv_co_write_req_finish(child, offset - new_bytes, new_bytes, &req, 0); + +out: + tracked_request_end(&req); + bdrv_dec_in_flight(bs); + + return ret; +} + +void bdrv_cancel_in_flight(BlockDriverState *bs) +{ + if (!bs || !bs->drv) { + return; + } + + if (bs->drv->bdrv_cancel_in_flight) { + bs->drv->bdrv_cancel_in_flight(bs); + } +} |