| /* |
| * 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 "qemu/cutils.h" |
| #include "qapi/error.h" |
| #include "qemu/error-report.h" |
| #include "qemu/main-loop.h" |
| #include "sysemu/replay.h" |
| |
| #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */ |
| |
| /* 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, int 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->role->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->role->drained_end) { |
| c->role->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, atomic_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->role->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->role->drained_poll) { |
| return c->role->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->role->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->role->drained_begin) { |
| c->role->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->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer); |
| dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_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); |
| } |
| |
| void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) |
| { |
| BlockDriver *drv = bs->drv; |
| Error *local_err = NULL; |
| |
| memset(&bs->bl, 0, sizeof(bs->bl)); |
| |
| if (!drv) { |
| return; |
| } |
| |
| /* 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 */ |
| if (bs->file) { |
| bdrv_refresh_limits(bs->file->bs, &local_err); |
| if (local_err) { |
| error_propagate(errp, local_err); |
| return; |
| } |
| bdrv_merge_limits(&bs->bl, &bs->file->bs->bl); |
| } else { |
| 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; |
| } |
| |
| if (bs->backing) { |
| bdrv_refresh_limits(bs->backing->bs, &local_err); |
| if (local_err) { |
| error_propagate(errp, local_err); |
| return; |
| } |
| bdrv_merge_limits(&bs->bl, &bs->backing->bs->bl); |
| } |
| |
| /* Then let the driver override it */ |
| if (drv->bdrv_refresh_limits) { |
| drv->bdrv_refresh_limits(bs, errp); |
| } |
| } |
| |
| /** |
| * The copy-on-read flag is actually a reference count so multiple users may |
| * use the feature without worrying about clobbering its previous state. |
| * Copy-on-read stays enabled until all users have called to disable it. |
| */ |
| void bdrv_enable_copy_on_read(BlockDriverState *bs) |
| { |
| atomic_inc(&bs->copy_on_read); |
| } |
| |
| void bdrv_disable_copy_on_read(BlockDriverState *bs) |
| { |
| int old = atomic_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() */ |
| atomic_mb_set(&data->done, true); |
| if (!data->begin) { |
| atomic_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) { |
| atomic_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 (atomic_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); |
| AioContext *co_ctx = qemu_coroutine_get_aio_context(co); |
| |
| /* |
| * When the coroutine yielded, the lock for its home context was |
| * released, so we need to re-acquire it here. If it explicitly |
| * acquired a different context, the lock is still held and we don't |
| * want to lock it a second time (or AIO_WAIT_WHILE() would hang). |
| */ |
| if (ctx == co_ctx) { |
| 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); |
| } |
| if (ctx == co_ctx) { |
| 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; |
| |
| /* 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 = qemu_coroutine_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); |
| } |
| replay_bh_schedule_oneshot_event(bdrv_get_aio_context(bs), |
| 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); |
| } |
| |
| 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 (atomic_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 = atomic_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, atomic_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, atomic_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, atomic_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(atomic_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(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, atomic_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) { |
| atomic_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, |
| uint64_t bytes, |
| enum BdrvTrackedRequestType type) |
| { |
| assert(bytes <= INT64_MAX && offset <= INT64_MAX - bytes); |
| |
| *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, uint64_t bytes) |
| { |
| /* aaaa bbbb */ |
| if (offset >= req->overlap_offset + req->overlap_bytes) { |
| return false; |
| } |
| /* bbbb aaaa */ |
| if (req->overlap_offset >= offset + bytes) { |
| return false; |
| } |
| return true; |
| } |
| |
| static bool coroutine_fn |
| bdrv_wait_serialising_requests_locked(BlockDriverState *bs, |
| BdrvTrackedRequest *self) |
| { |
| BdrvTrackedRequest *req; |
| bool retry; |
| bool waited = false; |
| |
| do { |
| retry = false; |
| QLIST_FOREACH(req, &bs->tracked_requests, list) { |
| if (req == self || (!req->serialising && !self->serialising)) { |
| continue; |
| } |
| if (tracked_request_overlaps(req, self->overlap_offset, |
| self->overlap_bytes)) |
| { |
| /* Hitting this means there was a reentrant request, for |
| * example, a block driver issuing nested requests. This must |
| * never happen since it means deadlock. |
| */ |
| assert(qemu_coroutine_self() != req->co); |
| |
| /* If the request is already (indirectly) waiting for us, or |
| * will wait for us as soon as it wakes up, then just go on |
| * (instead of producing a deadlock in the former case). */ |
| if (!req->waiting_for) { |
| self->waiting_for = req; |
| qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock); |
| self->waiting_for = NULL; |
| retry = true; |
| waited = true; |
| break; |
| } |
| } |
| } |
| } while (retry); |
| return waited; |
| } |
| |
| bool bdrv_mark_request_serialising(BdrvTrackedRequest *req, uint64_t align) |
| { |
| BlockDriverState *bs = req->bs; |
| int64_t overlap_offset = req->offset & ~(align - 1); |
| uint64_t overlap_bytes = ROUND_UP(req->offset + req->bytes, align) |
| - overlap_offset; |
| bool waited; |
| |
| qemu_co_mutex_lock(&bs->reqs_lock); |
| if (!req->serialising) { |
| atomic_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); |
| waited = bdrv_wait_serialising_requests_locked(bs, req); |
| qemu_co_mutex_unlock(&bs->reqs_lock); |
| return waited; |
| } |
| |
| /** |
| * 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) |
| { |
| atomic_inc(&bs->in_flight); |
| } |
| |
| void bdrv_wakeup(BlockDriverState *bs) |
| { |
| aio_wait_kick(); |
| } |
| |
| void bdrv_dec_in_flight(BlockDriverState *bs) |
| { |
| atomic_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 (!atomic_read(&bs->serialising_in_flight)) { |
| return false; |
| } |
| |
| qemu_co_mutex_lock(&bs->reqs_lock); |
| waited = bdrv_wait_serialising_requests_locked(bs, self); |
| qemu_co_mutex_unlock(&bs->reqs_lock); |
| |
| return waited; |
| } |
| |
| static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, |
| size_t size) |
| { |
| if (size > BDRV_REQUEST_MAX_BYTES) { |
| return -EIO; |
| } |
| |
| if (!bdrv_is_inserted(bs)) { |
| return -ENOMEDIUM; |
| } |
| |
| if (offset < 0) { |
| return -EIO; |
| } |
| |
| return 0; |
| } |
| |
| typedef struct RwCo { |
| BdrvChild *child; |
| int64_t offset; |
| QEMUIOVector *qiov; |
| bool is_write; |
| int ret; |
| BdrvRequestFlags flags; |
| } RwCo; |
| |
| static void coroutine_fn bdrv_rw_co_entry(void *opaque) |
| { |
| RwCo *rwco = opaque; |
| |
| if (!rwco->is_write) { |
| rwco->ret = bdrv_co_preadv(rwco->child, rwco->offset, |
| rwco->qiov->size, rwco->qiov, |
| rwco->flags); |
| } else { |
| rwco->ret = bdrv_co_pwritev(rwco->child, rwco->offset, |
| rwco->qiov->size, rwco->qiov, |
| rwco->flags); |
| } |
| aio_wait_kick(); |
| } |
| |
| /* |
| * Process a vectored synchronous request using coroutines |
| */ |
| static int bdrv_prwv_co(BdrvChild *child, int64_t offset, |
| QEMUIOVector *qiov, bool is_write, |
| BdrvRequestFlags flags) |
| { |
| Coroutine *co; |
| RwCo rwco = { |
| .child = child, |
| .offset = offset, |
| .qiov = qiov, |
| .is_write = is_write, |
| .ret = NOT_DONE, |
| .flags = flags, |
| }; |
| |
| if (qemu_in_coroutine()) { |
| /* Fast-path if already in coroutine context */ |
| bdrv_rw_co_entry(&rwco); |
| } else { |
| co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco); |
| bdrv_coroutine_enter(child->bs, co); |
| BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE); |
| } |
| return rwco.ret; |
| } |
| |
| int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, |
| int bytes, BdrvRequestFlags flags) |
| { |
| QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, bytes); |
| |
| return bdrv_prwv_co(child, offset, &qiov, true, |
| 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_write(). |
| */ |
| 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; |
| } |
| } |
| |
| int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov) |
| { |
| int ret; |
| |
| ret = bdrv_prwv_co(child, offset, qiov, false, 0); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| return qiov->size; |
| } |
| |
| /* See bdrv_pwrite() for the return codes */ |
| int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes) |
| { |
| QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes); |
| |
| if (bytes < 0) { |
| return -EINVAL; |
| } |
| |
| return bdrv_preadv(child, offset, &qiov); |
| } |
| |
| int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov) |
| { |
| int ret; |
| |
| ret = bdrv_prwv_co(child, offset, qiov, true, 0); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| return qiov->size; |
| } |
| |
| /* 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, int bytes) |
| { |
| QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes); |
| |
| if (bytes < 0) { |
| return -EINVAL; |
| } |
| |
| return bdrv_pwritev(child, offset, &qiov); |
| } |
| |
| /* |
| * Writes to the file and ensures that no writes are reordered across this |
| * request (acts as a barrier) |
| * |
| * Returns 0 on success, -errno in error cases. |
| */ |
| int bdrv_pwrite_sync(BdrvChild *child, int64_t offset, |
| const void *buf, int 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, |
| uint64_t offset, uint64_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; |
| |
| 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, |
| uint64_t offset, uint64_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; |
| |
| 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, uint64_t offset, |
| uint64_t bytes, QEMUIOVector *qiov, |
| size_t qiov_offset) |
| { |
| BlockDriver *drv = bs->drv; |
| QEMUIOVector local_qiov; |
| int ret; |
| |
| 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, unsigned int 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; |
| size_t skip_bytes; |
| int ret; |
| int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, |
| BDRV_REQUEST_MAX_BYTES); |
| unsigned int progress = 0; |
| bool skip_write; |
| |
| 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, unsigned int 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; |
| uint64_t bytes_remaining = bytes; |
| int max_transfer; |
| |
| 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_mark_request_serialising(req, bdrv_get_cluster_size(bs)); |
| } else { |
| bdrv_wait_serialising_requests(req); |
| } |
| |
| if (flags & BDRV_REQ_COPY_ON_READ) { |
| int64_t pnum; |
| |
| 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; |
| } |
| |
| 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, 0); |
| goto out; |
| } |
| |
| while (bytes_remaining) { |
| int 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, bytes - bytes_remaining, 0); |
| max_bytes -= num; |
| } else { |
| num = bytes_remaining; |
| ret = qemu_iovec_memset(qiov, 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) |
| { |
| uint64_t align = bs->bl.request_alignment; |
| size_t sum; |
| |
| 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) { |
| uint64_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); |
| } |
| } |
| |
| /* |
| * 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. |
| * |
| * All parameters except @bs are in-out: they represent original request at |
| * function call and padded (if padding needed) at function finish. |
| * |
| * Function always succeeds. |
| */ |
| static bool bdrv_pad_request(BlockDriverState *bs, |
| QEMUIOVector **qiov, size_t *qiov_offset, |
| int64_t *offset, unsigned int *bytes, |
| BdrvRequestPadding *pad) |
| { |
| if (!bdrv_init_padding(bs, *offset, *bytes, pad)) { |
| return false; |
| } |
| |
| qemu_iovec_init_extended(&pad->local_qiov, pad->buf, pad->head, |
| *qiov, *qiov_offset, *bytes, |
| pad->buf + pad->buf_len - pad->tail, pad->tail); |
| *bytes += pad->head + pad->tail; |
| *offset -= pad->head; |
| *qiov = &pad->local_qiov; |
| *qiov_offset = 0; |
| |
| return true; |
| } |
| |
| int coroutine_fn bdrv_co_preadv(BdrvChild *child, |
| int64_t offset, unsigned int 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, unsigned int bytes, |
| QEMUIOVector *qiov, size_t qiov_offset, |
| BdrvRequestFlags flags) |
| { |
| BlockDriverState *bs = child->bs; |
| BdrvTrackedRequest req; |
| BdrvRequestPadding pad; |
| int ret; |
| |
| trace_bdrv_co_preadv(bs, offset, bytes, flags); |
| |
| ret = bdrv_check_byte_request(bs, offset, bytes); |
| 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 (atomic_read(&bs->copy_on_read)) { |
| flags |= BDRV_REQ_COPY_ON_READ; |
| } |
| |
| bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad); |
| |
| 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_dec_in_flight(bs); |
| |
| bdrv_padding_destroy(&pad); |
| |
| return ret; |
| } |
| |
| static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, |
| int64_t offset, int 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; |
| |
| int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_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); |
| |
| if (!drv) { |
| return -ENOMEDIUM; |
| } |
| |
| if ((flags & ~bs->supported_zero_flags) & BDRV_REQ_NO_FALLBACK) { |
| return -ENOTSUP; |
| } |
| |
| 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) { |
| int 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, uint64_t bytes, |
| BdrvTrackedRequest *req, int flags) |
| { |
| BlockDriverState *bs = child->bs; |
| bool waited; |
| int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE); |
| |
| if (bs->read_only) { |
| return -EPERM; |
| } |
| |
| assert(!(bs->open_flags & BDRV_O_INACTIVE)); |
| assert((bs->open_flags & BDRV_O_NO_IO) == 0); |
| assert(!(flags & ~BDRV_REQ_MASK)); |
| |
| if (flags & BDRV_REQ_SERIALISING) { |
| waited = bdrv_mark_request_serialising(req, bdrv_get_cluster_size(bs)); |
| /* |
| * For a misaligned request we should have already waited earlier, |
| * because we come after bdrv_padding_rmw_read which must be called |
| * with the request already marked as serialising. |
| */ |
| assert(!waited || |
| (req->offset == req->overlap_offset && |
| req->bytes == req->overlap_bytes)); |
| } else { |
| bdrv_wait_serialising_requests(req); |
| } |
| |
| assert(req->overlap_offset <= offset); |
| assert(offset + bytes <= req->overlap_offset + req->overlap_bytes); |
| assert(end_sector <= bs->total_sectors || 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); |
| } |
| return notifier_with_return_list_notify(&bs->before_write_notifiers, |
| req); |
| 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, uint64_t bytes, |
| BdrvTrackedRequest *req, int ret) |
| { |
| int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE); |
| BlockDriverState *bs = child->bs; |
| |
| atomic_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, unsigned int bytes, |
| int64_t align, QEMUIOVector *qiov, size_t qiov_offset, int flags) |
| { |
| BlockDriverState *bs = child->bs; |
| BlockDriver *drv = bs->drv; |
| int ret; |
| |
| uint64_t bytes_remaining = bytes; |
| int max_transfer; |
| |
| 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); |
| assert(!qiov || qiov_offset + bytes <= qiov->size); |
| 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, 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, |
| unsigned int 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_mark_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. */ |
| uint64_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, unsigned int 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, unsigned int 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; |
| |
| trace_bdrv_co_pwritev(child->bs, offset, bytes, flags); |
| |
| if (!bs->drv) { |
| return -ENOMEDIUM; |
| } |
| |
| ret = bdrv_check_byte_request(bs, offset, bytes); |
| 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; |
| } |
| |
| bdrv_inc_in_flight(bs); |
| /* |
| * Align write if necessary by performing a read-modify-write cycle. |
| * Pad qiov with the read parts and be sure to have a tracked request not |
| * only for bdrv_aligned_pwritev, but also for the reads of the RMW cycle. |
| */ |
| tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE); |
| |
| if (flags & BDRV_REQ_ZERO_WRITE) { |
| ret = bdrv_co_do_zero_pwritev(child, offset, bytes, flags, &req); |
| goto out; |
| } |
| |
| if (bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad)) { |
| bdrv_mark_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, |
| int 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; |
| } |
| |
| |
| typedef struct BdrvCoBlockStatusData { |
| BlockDriverState *bs; |
| BlockDriverState *base; |
| bool want_zero; |
| int64_t offset; |
| int64_t bytes; |
| int64_t *pnum; |
| int64_t *map; |
| BlockDriverState **file; |
| int ret; |
| bool done; |
| } BdrvCoBlockStatusData; |
| |
| int coroutine_fn bdrv_co_block_status_from_file(BlockDriverState *bs, |
| bool want_zero, |
| int64_t offset, |
| int64_t bytes, |
| int64_t *pnum, |
| int64_t *map, |
| BlockDriverState **file) |
| { |
| assert(bs->file && bs->file->bs); |
| *pnum = bytes; |
| *map = offset; |
| *file = bs->file->bs; |
| return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID; |
| } |
| |
| int coroutine_fn bdrv_co_block_status_from_backing(BlockDriverState *bs, |
| bool want_zero, |
| int64_t offset, |
| int64_t bytes, |
| int64_t *pnum, |
| int64_t *map, |
| BlockDriverState **file) |
| { |
| assert(bs->backing && bs->backing->bs); |
| *pnum = bytes; |
| *map = offset; |
| *file = bs->backing->bs; |
| return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID; |
| } |
| |
| /* |
| * 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; |
| |
| 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); |
| if (!bs->drv->bdrv_co_block_status) { |
| *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; |
| |
| ret = bs->drv->bdrv_co_block_status(bs, want_zero, aligned_offset, |
| aligned_bytes, pnum, &local_map, |
| &local_file); |
| 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 (want_zero) { |
| if (bdrv_unallocated_blocks_are_zero(bs)) { |
| ret |= BDRV_BLOCK_ZERO; |
| } else if (bs->backing) { |
| BlockDriverState *bs2 = bs->backing->bs; |
| int64_t size2 = bdrv_getlength(bs2); |
| |
| 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; |
| } |
| |
| static int coroutine_fn bdrv_co_block_status_above(BlockDriverState *bs, |
| BlockDriverState *base, |
| bool want_zero, |
| int64_t offset, |
| int64_t bytes, |
| int64_t *pnum, |
| int64_t *map, |
| BlockDriverState **file) |
| { |
| BlockDriverState *p; |
| int ret = 0; |
| bool first = true; |
| |
| assert(bs != base); |
| for (p = bs; p != base; p = backing_bs(p)) { |
| ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map, |
| file); |
| if (ret < 0) { |
| break; |
| } |
| if (ret & BDRV_BLOCK_ZERO && ret & BDRV_BLOCK_EOF && !first) { |
| /* |
| * Reading beyond the end of the file continues to read |
| * zeroes, but we can only widen the result to the |
| * unallocated length we learned from an earlier |
| * iteration. |
| */ |
| *pnum = bytes; |
| } |
| if (ret & (BDRV_BLOCK_ZERO | BDRV_BLOCK_DATA)) { |
| break; |
| } |
| /* [offset, pnum] unallocated on this layer, which could be only |
| * the first part of [offset, bytes]. */ |
| bytes = MIN(bytes, *pnum); |
| first = false; |
| } |
| return ret; |
| } |
| |
| /* Coroutine wrapper for bdrv_block_status_above() */ |
| static void coroutine_fn bdrv_block_status_above_co_entry(void *opaque) |
| { |
| BdrvCoBlockStatusData *data = opaque; |
| |
| data->ret = bdrv_co_block_status_above(data->bs, data->base, |
| data->want_zero, |
| data->offset, data->bytes, |
| data->pnum, data->map, data->file); |
| data->done = true; |
| aio_wait_kick(); |
| } |
| |
| /* |
| * Synchronous wrapper around bdrv_co_block_status_above(). |
| * |
| * See bdrv_co_block_status_above() for details. |
| */ |
| static int bdrv_common_block_status_above(BlockDriverState *bs, |
| BlockDriverState *base, |
| bool want_zero, int64_t offset, |
| int64_t bytes, int64_t *pnum, |
| int64_t *map, |
| BlockDriverState **file) |
| { |
| Coroutine *co; |
| BdrvCoBlockStatusData data = { |
| .bs = bs, |
| .base = base, |
| .want_zero = want_zero, |
| .offset = offset, |
| .bytes = bytes, |
| .pnum = pnum, |
| .map = map, |
| .file = file, |
| .done = false, |
| }; |
| |
| if (qemu_in_coroutine()) { |
| /* Fast-path if already in coroutine context */ |
| bdrv_block_status_above_co_entry(&data); |
| } else { |
| co = qemu_coroutine_create(bdrv_block_status_above_co_entry, &data); |
| bdrv_coroutine_enter(bs, co); |
| BDRV_POLL_WHILE(bs, !data.done); |
| } |
| return data.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, true, offset, bytes, |
| pnum, map, file); |
| } |
| |
| 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, backing_bs(bs), |
| offset, bytes, pnum, map, file); |
| } |
| |
| 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, backing_bs(bs), false, offset, |
| bytes, pnum ? pnum : &dummy, NULL, |
| NULL); |
| if (ret < 0) { |
| return ret; |
| } |
| return !!(ret & BDRV_BLOCK_ALLOCATED); |
| } |
| |
| /* |
| * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP] |
| * |
| * Return 1 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). |
| * 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) |
| { |
| BlockDriverState *intermediate; |
| int ret; |
| int64_t n = bytes; |
| |
| assert(base || !include_base); |
| |
| intermediate = top; |
| while (include_base || intermediate != base) { |
| int64_t pnum_inter; |
| int64_t size_inter; |
| |
| assert(intermediate); |
| ret = bdrv_is_allocated(intermediate, offset, bytes, &pnum_inter); |
| if (ret < 0) { |
| return ret; |
| } |
| if (ret) { |
| *pnum = pnum_inter; |
| return 1; |
| } |
| |
| size_inter = bdrv_getlength(intermediate); |
| if (size_inter < 0) { |
| return size_inter; |
| } |
| if (n > pnum_inter && |
| (intermediate == top || offset + pnum_inter < size_inter)) { |
| n = pnum_inter; |
| } |
| |
| if (intermediate == base) { |
| break; |
| } |
| |
| intermediate = backing_bs(intermediate); |
| } |
| |
| *pnum = n; |
| return 0; |
| } |
| |
| typedef struct BdrvVmstateCo { |
| BlockDriverState *bs; |
| QEMUIOVector *qiov; |
| int64_t pos; |
| bool is_read; |
| int ret; |
| } BdrvVmstateCo; |
| |
| static int coroutine_fn |
| bdrv_co_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos, |
| bool is_read) |
| { |
| BlockDriver *drv = bs->drv; |
| int ret = -ENOTSUP; |
| |
| bdrv_inc_in_flight(bs); |
| |
| if (!drv) { |
| ret = -ENOMEDIUM; |
| } else if (drv->bdrv_load_vmstate) { |
| if (is_read) { |
| ret = drv->bdrv_load_vmstate(bs, qiov, pos); |
| } else { |
| ret = drv->bdrv_save_vmstate(bs, qiov, pos); |
| } |
| } else if (bs->file) { |
| ret = bdrv_co_rw_vmstate(bs->file->bs, qiov, pos, is_read); |
| } |
| |
| bdrv_dec_in_flight(bs); |
| return ret; |
| } |
| |
| static void coroutine_fn bdrv_co_rw_vmstate_entry(void *opaque) |
| { |
| BdrvVmstateCo *co = opaque; |
| co->ret = bdrv_co_rw_vmstate(co->bs, co->qiov, co->pos, co->is_read); |
| aio_wait_kick(); |
| } |
| |
| static inline int |
| bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos, |
| bool is_read) |
| { |
| if (qemu_in_coroutine()) { |
| return bdrv_co_rw_vmstate(bs, qiov, pos, is_read); |
| } else { |
| BdrvVmstateCo data = { |
| .bs = bs, |
| .qiov = qiov, |
| .pos = pos, |
| .is_read = is_read, |
| .ret = -EINPROGRESS, |
| }; |
| Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data); |
| |
| bdrv_coroutine_enter(bs, co); |
| BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS); |
| return data.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; |
| |
| ret = bdrv_writev_vmstate(bs, &qiov, pos); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| return size; |
| } |
| |
| int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos) |
| { |
| return bdrv_rw_vmstate(bs, qiov, pos, false); |
| } |
| |
| 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; |
| |
| ret = bdrv_readv_vmstate(bs, &qiov, pos); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| return size; |
| } |
| |
| int bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos) |
| { |
| return bdrv_rw_vmstate(bs, qiov, pos, true); |
| } |
| |
| /**************************************************************/ |
| /* 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 */ |
| |
| typedef struct FlushCo { |
| BlockDriverState *bs; |
| int ret; |
| } FlushCo; |
| |
| |
| static void coroutine_fn bdrv_flush_co_entry(void *opaque) |
| { |
| FlushCo *rwco = opaque; |
| |
| rwco->ret = bdrv_co_flush(rwco->bs); |
| aio_wait_kick(); |
| } |
| |
| int coroutine_fn bdrv_co_flush(BlockDriverState *bs) |
| { |
| 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 = atomic_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(bs->file, BLKDBG_FLUSH_TO_OS); |
| if (bs->drv->bdrv_co_flush_to_os) { |
| ret = bs->drv->bdrv_co_flush_to_os(bs); |
| if (ret < 0) { |
| goto out; |
| } |
| } |
| |
| /* But don't actually force it to the disk with cache=unsafe */ |
| if (bs->open_flags & BDRV_O_NO_FLUSH) { |
| goto flush_parent; |
| } |
| |
| /* Check if we really need to flush anything */ |
| if (bs->flushed_gen == current_gen) { |
| goto flush_parent; |
| } |
| |
| BLKDBG_EVENT(bs->file, 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_parent: |
| ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0; |
| 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 bdrv_flush(BlockDriverState *bs) |
| { |
| Coroutine *co; |
| FlushCo flush_co = { |
| .bs = bs, |
| .ret = NOT_DONE, |
| }; |
| |
| if (qemu_in_coroutine()) { |
| /* Fast-path if already in coroutine context */ |
| bdrv_flush_co_entry(&flush_co); |
| } else { |
| co = qemu_coroutine_create(bdrv_flush_co_entry, &flush_co); |
| bdrv_coroutine_enter(bs, co); |
| BDRV_POLL_WHILE(bs, flush_co.ret == NOT_DONE); |
| } |
| |
| return flush_co.ret; |
| } |
| |
| typedef struct DiscardCo { |
| BdrvChild *child; |
| int64_t offset; |
| int64_t bytes; |
| int ret; |
| } DiscardCo; |
| static void coroutine_fn bdrv_pdiscard_co_entry(void *opaque) |
| { |
| DiscardCo *rwco = opaque; |
| |
| rwco->ret = bdrv_co_pdiscard(rwco->child, rwco->offset, rwco->bytes); |
| aio_wait_kick(); |
| } |
| |
| int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset, |
| int64_t bytes) |
| { |
| BdrvTrackedRequest req; |
| int max_pdiscard, ret; |
| 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; |
| } |
| |
| if (offset < 0 || bytes < 0 || bytes > INT64_MAX - offset) { |
| return -EIO; |
| } |
| |
| /* 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; |
| } |
| |
| /* 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, INT_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_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes) |
| { |
| Coroutine *co; |
| DiscardCo rwco = { |