06e11b7589
Using fleecing backup like in [0] on a qcow2 image (with metadata
preallocation) can lead to the following assertion failure:
> bdrv_co_do_block_status: Assertion `!(ret & BDRV_BLOCK_ZERO)' failed.
In the reproducer [0], it happens because the BDRV_BLOCK_RECURSE flag
will be set by the qcow2 driver, so the caller will recursively check
the file child. Then the BDRV_BLOCK_ZERO set too. Later up the call
chain, in bdrv_co_do_block_status() for the snapshot-access driver,
the assertion failure will happen, because both flags are set.
To fix it, clear the recurse flag after the recursive check was done.
In detail:
> #0 qcow2_co_block_status
Returns 0x45 = BDRV_BLOCK_RECURSE | BDRV_BLOCK_DATA |
BDRV_BLOCK_OFFSET_VALID.
> #1 bdrv_co_do_block_status
Because of the data flag, bdrv_co_do_block_status() will now also set
BDRV_BLOCK_ALLOCATED. Because of the recurse flag,
bdrv_co_do_block_status() for the bdrv_file child will be called,
which returns 0x16 = BDRV_BLOCK_ALLOCATED | BDRV_BLOCK_OFFSET_VALID |
BDRV_BLOCK_ZERO. Now the return value inherits the zero flag.
Returns 0x57 = BDRV_BLOCK_RECURSE | BDRV_BLOCK_DATA |
BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_ALLOCATED | BDRV_BLOCK_ZERO.
> #2 bdrv_co_common_block_status_above
> #3 bdrv_co_block_status_above
> #4 bdrv_co_block_status
> #5 cbw_co_snapshot_block_status
> #6 bdrv_co_snapshot_block_status
> #7 snapshot_access_co_block_status
> #8 bdrv_co_do_block_status
Return value is propagated all the way up to here, where the assertion
failure happens, because BDRV_BLOCK_RECURSE and BDRV_BLOCK_ZERO are
both set.
> #9 bdrv_co_common_block_status_above
> #10 bdrv_co_block_status_above
> #11 block_copy_block_status
> #12 block_copy_dirty_clusters
> #13 block_copy_common
> #14 block_copy_async_co_entry
> #15 coroutine_trampoline
[0]:
> #!/bin/bash
> rm /tmp/disk.qcow2
> ./qemu-img create /tmp/disk.qcow2 -o preallocation=metadata -f qcow2 1G
> ./qemu-img create /tmp/fleecing.qcow2 -f qcow2 1G
> ./qemu-img create /tmp/backup.qcow2 -f qcow2 1G
> ./qemu-system-x86_64 --qmp stdio \
> --blockdev qcow2,node-name=node0,file.driver=file,file.filename=/tmp/disk.qcow2 \
> --blockdev qcow2,node-name=node1,file.driver=file,file.filename=/tmp/fleecing.qcow2 \
> --blockdev qcow2,node-name=node2,file.driver=file,file.filename=/tmp/backup.qcow2 \
> <<EOF
> {"execute": "qmp_capabilities"}
> {"execute": "blockdev-add", "arguments": { "driver": "copy-before-write", "file": "node0", "target": "node1", "node-name": "node3" } }
> {"execute": "blockdev-add", "arguments": { "driver": "snapshot-access", "file": "node3", "node-name": "snap0" } }
> {"execute": "blockdev-backup", "arguments": { "device": "snap0", "target": "node1", "sync": "full", "job-id": "backup0" } }
> EOF
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-id: 20240116154839.401030-1-f.ebner@proxmox.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 8a9be79924)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
3698 lines
112 KiB
C
3698 lines
112 KiB
C
/*
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* Block layer I/O functions
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "trace.h"
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#include "sysemu/block-backend.h"
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#include "block/aio-wait.h"
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#include "block/blockjob.h"
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#include "block/blockjob_int.h"
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#include "block/block_int.h"
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#include "block/coroutines.h"
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#include "block/write-threshold.h"
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#include "qemu/cutils.h"
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#include "qemu/memalign.h"
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#include "qapi/error.h"
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#include "qemu/error-report.h"
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#include "qemu/main-loop.h"
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#include "sysemu/replay.h"
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/* Maximum bounce buffer for copy-on-read and write zeroes, in bytes */
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#define MAX_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS)
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static void bdrv_parent_cb_resize(BlockDriverState *bs);
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static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
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int64_t offset, int64_t bytes, BdrvRequestFlags flags);
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static void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore,
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bool ignore_bds_parents)
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{
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BdrvChild *c, *next;
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QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
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if (c == ignore || (ignore_bds_parents && c->klass->parent_is_bds)) {
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continue;
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}
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bdrv_parent_drained_begin_single(c, false);
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}
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}
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static void bdrv_parent_drained_end_single_no_poll(BdrvChild *c,
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int *drained_end_counter)
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{
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assert(c->parent_quiesce_counter > 0);
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c->parent_quiesce_counter--;
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if (c->klass->drained_end) {
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c->klass->drained_end(c, drained_end_counter);
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}
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}
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void bdrv_parent_drained_end_single(BdrvChild *c)
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{
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int drained_end_counter = 0;
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AioContext *ctx = bdrv_child_get_parent_aio_context(c);
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IO_OR_GS_CODE();
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bdrv_parent_drained_end_single_no_poll(c, &drained_end_counter);
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AIO_WAIT_WHILE(ctx, qatomic_read(&drained_end_counter) > 0);
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}
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static void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore,
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bool ignore_bds_parents,
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int *drained_end_counter)
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{
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BdrvChild *c;
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QLIST_FOREACH(c, &bs->parents, next_parent) {
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if (c == ignore || (ignore_bds_parents && c->klass->parent_is_bds)) {
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continue;
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}
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bdrv_parent_drained_end_single_no_poll(c, drained_end_counter);
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}
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}
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static bool bdrv_parent_drained_poll_single(BdrvChild *c)
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{
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if (c->klass->drained_poll) {
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return c->klass->drained_poll(c);
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}
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return false;
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}
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static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore,
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bool ignore_bds_parents)
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{
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BdrvChild *c, *next;
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bool busy = false;
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QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
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if (c == ignore || (ignore_bds_parents && c->klass->parent_is_bds)) {
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continue;
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}
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busy |= bdrv_parent_drained_poll_single(c);
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}
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return busy;
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}
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void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll)
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{
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AioContext *ctx = bdrv_child_get_parent_aio_context(c);
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IO_OR_GS_CODE();
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c->parent_quiesce_counter++;
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if (c->klass->drained_begin) {
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c->klass->drained_begin(c);
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}
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if (poll) {
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AIO_WAIT_WHILE(ctx, bdrv_parent_drained_poll_single(c));
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}
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}
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static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src)
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{
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dst->pdiscard_alignment = MAX(dst->pdiscard_alignment,
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src->pdiscard_alignment);
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dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer);
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dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_transfer);
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dst->max_hw_transfer = MIN_NON_ZERO(dst->max_hw_transfer,
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src->max_hw_transfer);
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dst->opt_mem_alignment = MAX(dst->opt_mem_alignment,
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src->opt_mem_alignment);
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dst->min_mem_alignment = MAX(dst->min_mem_alignment,
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src->min_mem_alignment);
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dst->max_iov = MIN_NON_ZERO(dst->max_iov, src->max_iov);
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dst->max_hw_iov = MIN_NON_ZERO(dst->max_hw_iov, src->max_hw_iov);
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}
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typedef struct BdrvRefreshLimitsState {
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BlockDriverState *bs;
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BlockLimits old_bl;
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} BdrvRefreshLimitsState;
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static void bdrv_refresh_limits_abort(void *opaque)
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{
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BdrvRefreshLimitsState *s = opaque;
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s->bs->bl = s->old_bl;
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}
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static TransactionActionDrv bdrv_refresh_limits_drv = {
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.abort = bdrv_refresh_limits_abort,
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.clean = g_free,
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};
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/* @tran is allowed to be NULL, in this case no rollback is possible. */
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void bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error **errp)
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{
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ERRP_GUARD();
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BlockDriver *drv = bs->drv;
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BdrvChild *c;
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bool have_limits;
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GLOBAL_STATE_CODE();
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if (tran) {
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BdrvRefreshLimitsState *s = g_new(BdrvRefreshLimitsState, 1);
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*s = (BdrvRefreshLimitsState) {
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.bs = bs,
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.old_bl = bs->bl,
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};
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tran_add(tran, &bdrv_refresh_limits_drv, s);
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}
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memset(&bs->bl, 0, sizeof(bs->bl));
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if (!drv) {
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return;
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}
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/* Default alignment based on whether driver has byte interface */
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bs->bl.request_alignment = (drv->bdrv_co_preadv ||
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drv->bdrv_aio_preadv ||
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drv->bdrv_co_preadv_part) ? 1 : 512;
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/* Take some limits from the children as a default */
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have_limits = false;
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QLIST_FOREACH(c, &bs->children, next) {
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if (c->role & (BDRV_CHILD_DATA | BDRV_CHILD_FILTERED | BDRV_CHILD_COW))
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{
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bdrv_merge_limits(&bs->bl, &c->bs->bl);
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have_limits = true;
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}
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}
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if (!have_limits) {
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bs->bl.min_mem_alignment = 512;
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bs->bl.opt_mem_alignment = qemu_real_host_page_size();
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/* Safe default since most protocols use readv()/writev()/etc */
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bs->bl.max_iov = IOV_MAX;
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}
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/* Then let the driver override it */
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if (drv->bdrv_refresh_limits) {
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drv->bdrv_refresh_limits(bs, errp);
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if (*errp) {
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return;
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}
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}
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if (bs->bl.request_alignment > BDRV_MAX_ALIGNMENT) {
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error_setg(errp, "Driver requires too large request alignment");
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}
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}
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/**
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* The copy-on-read flag is actually a reference count so multiple users may
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* use the feature without worrying about clobbering its previous state.
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* Copy-on-read stays enabled until all users have called to disable it.
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*/
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void bdrv_enable_copy_on_read(BlockDriverState *bs)
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{
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IO_CODE();
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qatomic_inc(&bs->copy_on_read);
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}
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void bdrv_disable_copy_on_read(BlockDriverState *bs)
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{
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int old = qatomic_fetch_dec(&bs->copy_on_read);
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IO_CODE();
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assert(old >= 1);
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}
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typedef struct {
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Coroutine *co;
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BlockDriverState *bs;
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bool done;
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bool begin;
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bool recursive;
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bool poll;
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BdrvChild *parent;
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bool ignore_bds_parents;
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int *drained_end_counter;
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} BdrvCoDrainData;
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static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)
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{
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BdrvCoDrainData *data = opaque;
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BlockDriverState *bs = data->bs;
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if (data->begin) {
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bs->drv->bdrv_co_drain_begin(bs);
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} else {
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bs->drv->bdrv_co_drain_end(bs);
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}
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/* Set data->done and decrement drained_end_counter before bdrv_wakeup() */
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qatomic_mb_set(&data->done, true);
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if (!data->begin) {
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qatomic_dec(data->drained_end_counter);
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}
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bdrv_dec_in_flight(bs);
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g_free(data);
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}
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/* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */
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static void bdrv_drain_invoke(BlockDriverState *bs, bool begin,
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int *drained_end_counter)
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{
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BdrvCoDrainData *data;
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if (!bs->drv || (begin && !bs->drv->bdrv_co_drain_begin) ||
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(!begin && !bs->drv->bdrv_co_drain_end)) {
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return;
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}
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data = g_new(BdrvCoDrainData, 1);
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*data = (BdrvCoDrainData) {
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.bs = bs,
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.done = false,
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.begin = begin,
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.drained_end_counter = drained_end_counter,
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};
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if (!begin) {
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qatomic_inc(drained_end_counter);
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}
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/* Make sure the driver callback completes during the polling phase for
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* drain_begin. */
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bdrv_inc_in_flight(bs);
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data->co = qemu_coroutine_create(bdrv_drain_invoke_entry, data);
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aio_co_schedule(bdrv_get_aio_context(bs), data->co);
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}
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/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */
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bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,
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BdrvChild *ignore_parent, bool ignore_bds_parents)
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{
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BdrvChild *child, *next;
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IO_OR_GS_CODE();
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if (bdrv_parent_drained_poll(bs, ignore_parent, ignore_bds_parents)) {
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return true;
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}
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if (qatomic_read(&bs->in_flight)) {
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return true;
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}
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if (recursive) {
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assert(!ignore_bds_parents);
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QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
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if (bdrv_drain_poll(child->bs, recursive, child, false)) {
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return true;
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}
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}
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}
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return false;
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}
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static bool bdrv_drain_poll_top_level(BlockDriverState *bs, bool recursive,
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BdrvChild *ignore_parent)
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{
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return bdrv_drain_poll(bs, recursive, ignore_parent, false);
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}
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static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
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BdrvChild *parent, bool ignore_bds_parents,
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bool poll);
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static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
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BdrvChild *parent, bool ignore_bds_parents,
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int *drained_end_counter);
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static void bdrv_co_drain_bh_cb(void *opaque)
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{
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BdrvCoDrainData *data = opaque;
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Coroutine *co = data->co;
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BlockDriverState *bs = data->bs;
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if (bs) {
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AioContext *ctx = bdrv_get_aio_context(bs);
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aio_context_acquire(ctx);
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bdrv_dec_in_flight(bs);
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if (data->begin) {
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assert(!data->drained_end_counter);
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bdrv_do_drained_begin(bs, data->recursive, data->parent,
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data->ignore_bds_parents, data->poll);
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} else {
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assert(!data->poll);
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bdrv_do_drained_end(bs, data->recursive, data->parent,
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data->ignore_bds_parents,
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data->drained_end_counter);
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}
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aio_context_release(ctx);
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} else {
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assert(data->begin);
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bdrv_drain_all_begin();
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}
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data->done = true;
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aio_co_wake(co);
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}
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static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
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bool begin, bool recursive,
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BdrvChild *parent,
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bool ignore_bds_parents,
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bool poll,
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int *drained_end_counter)
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{
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BdrvCoDrainData data;
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Coroutine *self = qemu_coroutine_self();
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AioContext *ctx = bdrv_get_aio_context(bs);
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AioContext *co_ctx = qemu_coroutine_get_aio_context(self);
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/* Calling bdrv_drain() from a BH ensures the current coroutine yields and
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* other coroutines run if they were queued by aio_co_enter(). */
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assert(qemu_in_coroutine());
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data = (BdrvCoDrainData) {
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.co = self,
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.bs = bs,
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.done = false,
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.begin = begin,
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.recursive = recursive,
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.parent = parent,
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.ignore_bds_parents = ignore_bds_parents,
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.poll = poll,
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.drained_end_counter = drained_end_counter,
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};
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if (bs) {
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bdrv_inc_in_flight(bs);
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}
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/*
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* Temporarily drop the lock across yield or we would get deadlocks.
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* bdrv_co_drain_bh_cb() reaquires the lock as needed.
|
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*
|
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* When we yield below, the lock for the current context will be
|
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* released, so if this is actually the lock that protects bs, don't drop
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* it a second time.
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*/
|
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if (ctx != co_ctx) {
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aio_context_release(ctx);
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}
|
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replay_bh_schedule_oneshot_event(ctx, bdrv_co_drain_bh_cb, &data);
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|
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qemu_coroutine_yield();
|
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/* 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)
|
|
{
|
|
IO_OR_GS_CODE();
|
|
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)
|
|
{
|
|
IO_OR_GS_CODE();
|
|
bdrv_do_drained_begin(bs, false, NULL, false, true);
|
|
}
|
|
|
|
void bdrv_subtree_drained_begin(BlockDriverState *bs)
|
|
{
|
|
IO_OR_GS_CODE();
|
|
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;
|
|
IO_OR_GS_CODE();
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
bdrv_do_drained_end(bs, false, NULL, false, drained_end_counter);
|
|
}
|
|
|
|
void bdrv_subtree_drained_end(BlockDriverState *bs)
|
|
{
|
|
int drained_end_counter = 0;
|
|
IO_OR_GS_CODE();
|
|
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;
|
|
IO_OR_GS_CODE();
|
|
|
|
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;
|
|
IO_OR_GS_CODE();
|
|
|
|
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);
|
|
}
|
|
|
|
void bdrv_drain(BlockDriverState *bs)
|
|
{
|
|
IO_OR_GS_CODE();
|
|
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;
|
|
GLOBAL_STATE_CODE();
|
|
|
|
/* 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;
|
|
GLOBAL_STATE_CODE();
|
|
|
|
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;
|
|
GLOBAL_STATE_CODE();
|
|
|
|
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;
|
|
GLOBAL_STATE_CODE();
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
GLOBAL_STATE_CODE();
|
|
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 coroutine_fn 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 coroutine_fn 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 coroutine_fn 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 void coroutine_fn
|
|
bdrv_wait_serialising_requests_locked(BdrvTrackedRequest *self)
|
|
{
|
|
BdrvTrackedRequest *req;
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
/* 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();
|
|
IO_CODE();
|
|
|
|
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;
|
|
IO_CODE();
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
qatomic_inc(&bs->in_flight);
|
|
}
|
|
|
|
void bdrv_wakeup(BlockDriverState *bs)
|
|
{
|
|
IO_CODE();
|
|
aio_wait_kick();
|
|
}
|
|
|
|
void bdrv_dec_in_flight(BlockDriverState *bs)
|
|
{
|
|
IO_CODE();
|
|
qatomic_dec(&bs->in_flight);
|
|
bdrv_wakeup(bs);
|
|
}
|
|
|
|
static void coroutine_fn
|
|
bdrv_wait_serialising_requests(BdrvTrackedRequest *self)
|
|
{
|
|
BlockDriverState *bs = self->bs;
|
|
|
|
if (!qatomic_read(&bs->serialising_in_flight)) {
|
|
return;
|
|
}
|
|
|
|
qemu_co_mutex_lock(&bs->reqs_lock);
|
|
bdrv_wait_serialising_requests_locked(self);
|
|
qemu_co_mutex_unlock(&bs->reqs_lock);
|
|
}
|
|
|
|
void coroutine_fn bdrv_make_request_serialising(BdrvTrackedRequest *req,
|
|
uint64_t align)
|
|
{
|
|
IO_CODE();
|
|
|
|
qemu_co_mutex_lock(&req->bs->reqs_lock);
|
|
|
|
tracked_request_set_serialising(req, align);
|
|
bdrv_wait_serialising_requests_locked(req);
|
|
|
|
qemu_co_mutex_unlock(&req->bs->reqs_lock);
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
IO_CODE();
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 coroutine_fn bdrv_co_pwrite_sync(BdrvChild *child, int64_t offset,
|
|
int64_t bytes, const void *buf,
|
|
BdrvRequestFlags flags)
|
|
{
|
|
int ret;
|
|
IO_CODE();
|
|
|
|
ret = bdrv_co_pwrite(child, offset, bytes, buf, flags);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
ret = bdrv_co_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 & ~bs->supported_read_flags));
|
|
|
|
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;
|
|
bool emulate_fua = false;
|
|
int64_t sector_num;
|
|
unsigned int nb_sectors;
|
|
QEMUIOVector local_qiov;
|
|
int ret;
|
|
|
|
bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort);
|
|
|
|
if (!drv) {
|
|
return -ENOMEDIUM;
|
|
}
|
|
|
|
if ((flags & BDRV_REQ_FUA) &&
|
|
(~bs->supported_write_flags & BDRV_REQ_FUA)) {
|
|
flags &= ~BDRV_REQ_FUA;
|
|
emulate_fua = true;
|
|
}
|
|
|
|
flags &= bs->supported_write_flags;
|
|
|
|
if (drv->bdrv_co_pwritev_part) {
|
|
ret = drv->bdrv_co_pwritev_part(bs, offset, bytes, qiov, qiov_offset,
|
|
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);
|
|
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,
|
|
bdrv_co_io_em_complete, &co);
|
|
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);
|
|
|
|
emulate_flags:
|
|
if (ret == 0 && emulate_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 except the BDRV_REQ_REGISTERED_BUF optimization hint.
|
|
*/
|
|
assert(!(flags & ~(BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH |
|
|
BDRV_REQ_REGISTERED_BUF)));
|
|
|
|
/* 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 | BDRV_REQ_REGISTERED_BUF)));
|
|
|
|
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 coroutine_fn 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,
|
|
BdrvRequestFlags *flags)
|
|
{
|
|
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;
|
|
}
|
|
if (flags) {
|
|
/* Can't use optimization hint with bounce buffer */
|
|
*flags &= ~BDRV_REQ_REGISTERED_BUF;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int coroutine_fn bdrv_co_preadv(BdrvChild *child,
|
|
int64_t offset, int64_t bytes, QEMUIOVector *qiov,
|
|
BdrvRequestFlags flags)
|
|
{
|
|
IO_CODE();
|
|
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;
|
|
IO_CODE();
|
|
|
|
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, &flags);
|
|
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;
|
|
}
|
|
|
|
/* By definition there is no user buffer so this flag doesn't make sense */
|
|
if (flags & BDRV_REQ_REGISTERED_BUF) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* 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;
|
|
}
|
|
|
|
/* Can't use optimization hint with bufferless zero write */
|
|
flags &= ~BDRV_REQ_REGISTERED_BUF;
|
|
}
|
|
|
|
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;
|
|
|
|
/* This flag doesn't make sense for padding or zero writes */
|
|
flags &= ~BDRV_REQ_REGISTERED_BUF;
|
|
|
|
padding = bdrv_init_padding(bs, offset, bytes, &pad);
|
|
if (padding) {
|
|
assert(!(flags & BDRV_REQ_NO_WAIT));
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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;
|
|
IO_CODE();
|
|
|
|
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, &flags);
|
|
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.
|
|
*/
|
|
assert(!(flags & BDRV_REQ_NO_WAIT));
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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;
|
|
|
|
GLOBAL_STATE_CODE();
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* Check want_zero, because we only want to update the cache when we
|
|
* have accurate information about what is zero and what is data.
|
|
*/
|
|
if (want_zero &&
|
|
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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Now that the recursive search was done, clear the flag. Otherwise,
|
|
* with more complicated block graphs like snapshot-access ->
|
|
* copy-before-write -> qcow2, where the return value will be propagated
|
|
* further up to a parent bdrv_co_do_block_status() call, both the
|
|
* BDRV_BLOCK_RECURSE and BDRV_BLOCK_ZERO flags would be set, which is
|
|
* not allowed.
|
|
*/
|
|
ret &= ~BDRV_BLOCK_RECURSE;
|
|
}
|
|
|
|
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;
|
|
IO_CODE();
|
|
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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;
|
|
IO_CODE();
|
|
|
|
if (!bytes) {
|
|
return 1;
|
|
}
|
|
|
|
ret = bdrv_co_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 bdrv_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
|
|
int64_t *pnum)
|
|
{
|
|
int ret;
|
|
int64_t dummy;
|
|
IO_CODE();
|
|
|
|
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);
|
|
IO_CODE();
|
|
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;
|
|
IO_CODE();
|
|
|
|
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;
|
|
IO_CODE();
|
|
|
|
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);
|
|
IO_CODE();
|
|
|
|
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);
|
|
IO_CODE();
|
|
|
|
return ret < 0 ? ret : size;
|
|
}
|
|
|
|
/**************************************************************/
|
|
/* async I/Os */
|
|
|
|
void bdrv_aio_cancel(BlockAIOCB *acb)
|
|
{
|
|
IO_CODE();
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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;
|
|
IO_CODE();
|
|
|
|
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;
|
|
IO_CODE();
|
|
|
|
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 coroutine_fn bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf)
|
|
{
|
|
BlockDriver *drv = bs->drv;
|
|
CoroutineIOCompletion co = {
|
|
.coroutine = qemu_coroutine_self(),
|
|
};
|
|
BlockAIOCB *acb;
|
|
IO_CODE();
|
|
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
return qemu_memalign(bdrv_opt_mem_align(bs), size);
|
|
}
|
|
|
|
void *qemu_blockalign0(BlockDriverState *bs, size_t size)
|
|
{
|
|
IO_CODE();
|
|
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);
|
|
IO_CODE();
|
|
|
|
/* 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);
|
|
IO_CODE();
|
|
|
|
if (mem) {
|
|
memset(mem, 0, size);
|
|
}
|
|
|
|
return mem;
|
|
}
|
|
|
|
void bdrv_io_plug(BlockDriverState *bs)
|
|
{
|
|
BdrvChild *child;
|
|
IO_CODE();
|
|
|
|
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;
|
|
IO_CODE();
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
/* Helper that undoes bdrv_register_buf() when it fails partway through */
|
|
static void bdrv_register_buf_rollback(BlockDriverState *bs,
|
|
void *host,
|
|
size_t size,
|
|
BdrvChild *final_child)
|
|
{
|
|
BdrvChild *child;
|
|
|
|
QLIST_FOREACH(child, &bs->children, next) {
|
|
if (child == final_child) {
|
|
break;
|
|
}
|
|
|
|
bdrv_unregister_buf(child->bs, host, size);
|
|
}
|
|
|
|
if (bs->drv && bs->drv->bdrv_unregister_buf) {
|
|
bs->drv->bdrv_unregister_buf(bs, host, size);
|
|
}
|
|
}
|
|
|
|
bool bdrv_register_buf(BlockDriverState *bs, void *host, size_t size,
|
|
Error **errp)
|
|
{
|
|
BdrvChild *child;
|
|
|
|
GLOBAL_STATE_CODE();
|
|
if (bs->drv && bs->drv->bdrv_register_buf) {
|
|
if (!bs->drv->bdrv_register_buf(bs, host, size, errp)) {
|
|
return false;
|
|
}
|
|
}
|
|
QLIST_FOREACH(child, &bs->children, next) {
|
|
if (!bdrv_register_buf(child->bs, host, size, errp)) {
|
|
bdrv_register_buf_rollback(bs, host, size, child);
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void bdrv_unregister_buf(BlockDriverState *bs, void *host, size_t size)
|
|
{
|
|
BdrvChild *child;
|
|
|
|
GLOBAL_STATE_CODE();
|
|
if (bs->drv && bs->drv->bdrv_unregister_buf) {
|
|
bs->drv->bdrv_unregister_buf(bs, host, size);
|
|
}
|
|
QLIST_FOREACH(child, &bs->children, next) {
|
|
bdrv_unregister_buf(child->bs, host, size);
|
|
}
|
|
}
|
|
|
|
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));
|
|
assert(!(read_flags & BDRV_REQ_NO_WAIT));
|
|
assert(!(write_flags & BDRV_REQ_NO_WAIT));
|
|
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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)
|
|
{
|
|
IO_CODE();
|
|
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;
|
|
IO_CODE();
|
|
|
|
/* 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)
|
|
{
|
|
GLOBAL_STATE_CODE();
|
|
if (!bs || !bs->drv) {
|
|
return;
|
|
}
|
|
|
|
if (bs->drv->bdrv_cancel_in_flight) {
|
|
bs->drv->bdrv_cancel_in_flight(bs);
|
|
}
|
|
}
|
|
|
|
int coroutine_fn
|
|
bdrv_co_preadv_snapshot(BdrvChild *child, int64_t offset, int64_t bytes,
|
|
QEMUIOVector *qiov, size_t qiov_offset)
|
|
{
|
|
BlockDriverState *bs = child->bs;
|
|
BlockDriver *drv = bs->drv;
|
|
int ret;
|
|
IO_CODE();
|
|
|
|
if (!drv) {
|
|
return -ENOMEDIUM;
|
|
}
|
|
|
|
if (!drv->bdrv_co_preadv_snapshot) {
|
|
return -ENOTSUP;
|
|
}
|
|
|
|
bdrv_inc_in_flight(bs);
|
|
ret = drv->bdrv_co_preadv_snapshot(bs, offset, bytes, qiov, qiov_offset);
|
|
bdrv_dec_in_flight(bs);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int coroutine_fn
|
|
bdrv_co_snapshot_block_status(BlockDriverState *bs,
|
|
bool want_zero, int64_t offset, int64_t bytes,
|
|
int64_t *pnum, int64_t *map,
|
|
BlockDriverState **file)
|
|
{
|
|
BlockDriver *drv = bs->drv;
|
|
int ret;
|
|
IO_CODE();
|
|
|
|
if (!drv) {
|
|
return -ENOMEDIUM;
|
|
}
|
|
|
|
if (!drv->bdrv_co_snapshot_block_status) {
|
|
return -ENOTSUP;
|
|
}
|
|
|
|
bdrv_inc_in_flight(bs);
|
|
ret = drv->bdrv_co_snapshot_block_status(bs, want_zero, offset, bytes,
|
|
pnum, map, file);
|
|
bdrv_dec_in_flight(bs);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int coroutine_fn
|
|
bdrv_co_pdiscard_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes)
|
|
{
|
|
BlockDriver *drv = bs->drv;
|
|
int ret;
|
|
IO_CODE();
|
|
|
|
if (!drv) {
|
|
return -ENOMEDIUM;
|
|
}
|
|
|
|
if (!drv->bdrv_co_pdiscard_snapshot) {
|
|
return -ENOTSUP;
|
|
}
|
|
|
|
bdrv_inc_in_flight(bs);
|
|
ret = drv->bdrv_co_pdiscard_snapshot(bs, offset, bytes);
|
|
bdrv_dec_in_flight(bs);
|
|
|
|
return ret;
|
|
}
|