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![Michael Qiu](/assets/img/avatar_default.png)
Currently, if guest has workloads, IO thread will acquire aio_context
lock before do io_submit, it leads to segmentfault when do block commit
after snapshot. Just like below:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f7c7d91f700 (LWP 99907)]
0x00005576d0f65aab in bdrv_mirror_top_pwritev at ../block/mirror.c:1437
1437 ../block/mirror.c: No such file or directory.
(gdb) p s->job
$17 = (MirrorBlockJob *) 0x0
(gdb) p s->stop
$18 = false
Call trace of IO thread:
0 0x00005576d0f65aab in bdrv_mirror_top_pwritev at ../block/mirror.c:1437
1 0x00005576d0f7f3ab in bdrv_driver_pwritev at ../block/io.c:1174
2 0x00005576d0f8139d in bdrv_aligned_pwritev at ../block/io.c:1988
3 0x00005576d0f81b65 in bdrv_co_pwritev_part at ../block/io.c:2156
4 0x00005576d0f8e6b7 in blk_do_pwritev_part at ../block/block-backend.c:1260
5 0x00005576d0f8e84d in blk_aio_write_entry at ../block/block-backend.c:1476
...
Switch to qemu main thread:
0 0x00007f903be704ed in __lll_lock_wait at
/lib/../lib64/libpthread.so.0
1 0x00007f903be6bde6 in _L_lock_941 at /lib/../lib64/libpthread.so.0
2 0x00007f903be6bcdf in pthread_mutex_lock at
/lib/../lib64/libpthread.so.0
3 0x0000564b21456889 in qemu_mutex_lock_impl at
../util/qemu-thread-posix.c:79
4 0x0000564b213af8a5 in block_job_add_bdrv at ../blockjob.c:224
5 0x0000564b213b00ad in block_job_create at ../blockjob.c:440
6 0x0000564b21357c0a in mirror_start_job at ../block/mirror.c:1622
7 0x0000564b2135a9af in commit_active_start at ../block/mirror.c:1867
8 0x0000564b2133d132 in qmp_block_commit at ../blockdev.c:2768
9 0x0000564b2141fef3 in qmp_marshal_block_commit at
qapi/qapi-commands-block-core.c:346
10 0x0000564b214503c9 in do_qmp_dispatch_bh at
../qapi/qmp-dispatch.c:110
11 0x0000564b21451996 in aio_bh_poll at ../util/async.c:164
12 0x0000564b2146018e in aio_dispatch at ../util/aio-posix.c:381
13 0x0000564b2145187e in aio_ctx_dispatch at ../util/async.c:306
14 0x00007f9040239049 in g_main_context_dispatch at
/lib/../lib64/libglib-2.0.so.0
15 0x0000564b21447368 in main_loop_wait at ../util/main-loop.c:232
16 0x0000564b21447368 in main_loop_wait at ../util/main-loop.c:255
17 0x0000564b21447368 in main_loop_wait at ../util/main-loop.c:531
18 0x0000564b212304e1 in qemu_main_loop at ../softmmu/runstate.c:721
19 0x0000564b20f7975e in main at ../softmmu/main.c:50
In IO thread when do bdrv_mirror_top_pwritev, the job is NULL, and stop field
is false, this means the MirrorBDSOpaque "s" object has not been initialized
yet, and this object is initialized by block_job_create(), but the initialize
process is stuck in acquiring the lock.
In this situation, IO thread come to bdrv_mirror_top_pwritev(),which means that
mirror-top node is already inserted into block graph, but its bs->opaque->job
is not initialized.
The root cause is that qemu main thread do release/acquire when hold the lock,
at the same time, IO thread get the lock after release stage, and the crash
occured.
Actually, in this situation, job->job.aio_context will not equal to
qemu_get_aio_context(), and will be the same as bs->aio_context,
thus, no need to release the lock, becasue bdrv_root_attach_child()
will not change the context.
This patch fix this issue.
Fixes: 132ada80
"block: Adjust AioContexts when attaching nodes"
Signed-off-by: Michael Qiu <qiudayu@huayun.com>
Message-Id: <20210203024059.52683-1-08005325@163.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
528 lines
15 KiB
C
528 lines
15 KiB
C
/*
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* QEMU System Emulator block driver
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*
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* Copyright (c) 2011 IBM Corp.
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* Copyright (c) 2012 Red Hat, Inc.
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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 "block/block.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/trace.h"
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#include "sysemu/block-backend.h"
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#include "qapi/error.h"
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#include "qapi/qapi-events-block-core.h"
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#include "qapi/qmp/qerror.h"
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#include "qemu/coroutine.h"
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#include "qemu/main-loop.h"
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#include "qemu/timer.h"
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/*
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* The block job API is composed of two categories of functions.
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*
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* The first includes functions used by the monitor. The monitor is
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* peculiar in that it accesses the block job list with block_job_get, and
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* therefore needs consistency across block_job_get and the actual operation
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* (e.g. block_job_set_speed). The consistency is achieved with
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* aio_context_acquire/release. These functions are declared in blockjob.h.
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*
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* The second includes functions used by the block job drivers and sometimes
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* by the core block layer. These do not care about locking, because the
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* whole coroutine runs under the AioContext lock, and are declared in
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* blockjob_int.h.
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*/
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static bool is_block_job(Job *job)
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{
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return job_type(job) == JOB_TYPE_BACKUP ||
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job_type(job) == JOB_TYPE_COMMIT ||
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job_type(job) == JOB_TYPE_MIRROR ||
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job_type(job) == JOB_TYPE_STREAM;
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}
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BlockJob *block_job_next(BlockJob *bjob)
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{
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Job *job = bjob ? &bjob->job : NULL;
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do {
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job = job_next(job);
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} while (job && !is_block_job(job));
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return job ? container_of(job, BlockJob, job) : NULL;
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}
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BlockJob *block_job_get(const char *id)
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{
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Job *job = job_get(id);
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if (job && is_block_job(job)) {
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return container_of(job, BlockJob, job);
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} else {
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return NULL;
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}
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}
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void block_job_free(Job *job)
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{
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BlockJob *bjob = container_of(job, BlockJob, job);
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block_job_remove_all_bdrv(bjob);
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blk_unref(bjob->blk);
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error_free(bjob->blocker);
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}
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static char *child_job_get_parent_desc(BdrvChild *c)
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{
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BlockJob *job = c->opaque;
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return g_strdup_printf("%s job '%s'", job_type_str(&job->job), job->job.id);
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}
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static void child_job_drained_begin(BdrvChild *c)
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{
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BlockJob *job = c->opaque;
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job_pause(&job->job);
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}
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static bool child_job_drained_poll(BdrvChild *c)
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{
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BlockJob *bjob = c->opaque;
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Job *job = &bjob->job;
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const BlockJobDriver *drv = block_job_driver(bjob);
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/* An inactive or completed job doesn't have any pending requests. Jobs
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* with !job->busy are either already paused or have a pause point after
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* being reentered, so no job driver code will run before they pause. */
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if (!job->busy || job_is_completed(job)) {
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return false;
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}
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/* Otherwise, assume that it isn't fully stopped yet, but allow the job to
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* override this assumption. */
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if (drv->drained_poll) {
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return drv->drained_poll(bjob);
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} else {
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return true;
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}
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}
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static void child_job_drained_end(BdrvChild *c, int *drained_end_counter)
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{
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BlockJob *job = c->opaque;
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job_resume(&job->job);
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}
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static bool child_job_can_set_aio_ctx(BdrvChild *c, AioContext *ctx,
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GSList **ignore, Error **errp)
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{
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BlockJob *job = c->opaque;
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GSList *l;
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for (l = job->nodes; l; l = l->next) {
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BdrvChild *sibling = l->data;
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if (!bdrv_child_can_set_aio_context(sibling, ctx, ignore, errp)) {
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return false;
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}
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}
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return true;
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}
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static void child_job_set_aio_ctx(BdrvChild *c, AioContext *ctx,
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GSList **ignore)
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{
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BlockJob *job = c->opaque;
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GSList *l;
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for (l = job->nodes; l; l = l->next) {
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BdrvChild *sibling = l->data;
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if (g_slist_find(*ignore, sibling)) {
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continue;
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}
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*ignore = g_slist_prepend(*ignore, sibling);
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bdrv_set_aio_context_ignore(sibling->bs, ctx, ignore);
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}
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job->job.aio_context = ctx;
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}
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static const BdrvChildClass child_job = {
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.get_parent_desc = child_job_get_parent_desc,
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.drained_begin = child_job_drained_begin,
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.drained_poll = child_job_drained_poll,
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.drained_end = child_job_drained_end,
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.can_set_aio_ctx = child_job_can_set_aio_ctx,
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.set_aio_ctx = child_job_set_aio_ctx,
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.stay_at_node = true,
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};
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void block_job_remove_all_bdrv(BlockJob *job)
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{
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/*
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* bdrv_root_unref_child() may reach child_job_[can_]set_aio_ctx(),
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* which will also traverse job->nodes, so consume the list one by
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* one to make sure that such a concurrent access does not attempt
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* to process an already freed BdrvChild.
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*/
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while (job->nodes) {
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GSList *l = job->nodes;
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BdrvChild *c = l->data;
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job->nodes = l->next;
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bdrv_op_unblock_all(c->bs, job->blocker);
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bdrv_root_unref_child(c);
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g_slist_free_1(l);
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}
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}
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bool block_job_has_bdrv(BlockJob *job, BlockDriverState *bs)
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{
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GSList *el;
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for (el = job->nodes; el; el = el->next) {
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BdrvChild *c = el->data;
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if (c->bs == bs) {
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return true;
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}
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}
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return false;
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}
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int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs,
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uint64_t perm, uint64_t shared_perm, Error **errp)
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{
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BdrvChild *c;
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bool need_context_ops;
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bdrv_ref(bs);
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need_context_ops = bdrv_get_aio_context(bs) != job->job.aio_context;
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if (need_context_ops && job->job.aio_context != qemu_get_aio_context()) {
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aio_context_release(job->job.aio_context);
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}
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c = bdrv_root_attach_child(bs, name, &child_job, 0,
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job->job.aio_context, perm, shared_perm, job,
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errp);
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if (need_context_ops && job->job.aio_context != qemu_get_aio_context()) {
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aio_context_acquire(job->job.aio_context);
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}
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if (c == NULL) {
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return -EPERM;
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}
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job->nodes = g_slist_prepend(job->nodes, c);
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bdrv_op_block_all(bs, job->blocker);
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return 0;
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}
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static void block_job_on_idle(Notifier *n, void *opaque)
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{
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aio_wait_kick();
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}
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bool block_job_is_internal(BlockJob *job)
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{
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return (job->job.id == NULL);
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}
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const BlockJobDriver *block_job_driver(BlockJob *job)
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{
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return container_of(job->job.driver, BlockJobDriver, job_driver);
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}
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/* Assumes the job_mutex is held */
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static bool job_timer_pending(Job *job)
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{
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return timer_pending(&job->sleep_timer);
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}
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void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
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{
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const BlockJobDriver *drv = block_job_driver(job);
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int64_t old_speed = job->speed;
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if (job_apply_verb(&job->job, JOB_VERB_SET_SPEED, errp)) {
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return;
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}
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if (speed < 0) {
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error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "speed",
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"a non-negative value");
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return;
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}
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ratelimit_set_speed(&job->limit, speed, BLOCK_JOB_SLICE_TIME);
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job->speed = speed;
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if (drv->set_speed) {
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drv->set_speed(job, speed);
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}
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if (speed && speed <= old_speed) {
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return;
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}
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/* kick only if a timer is pending */
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job_enter_cond(&job->job, job_timer_pending);
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}
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int64_t block_job_ratelimit_get_delay(BlockJob *job, uint64_t n)
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{
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if (!job->speed) {
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return 0;
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}
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return ratelimit_calculate_delay(&job->limit, n);
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}
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BlockJobInfo *block_job_query(BlockJob *job, Error **errp)
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{
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BlockJobInfo *info;
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if (block_job_is_internal(job)) {
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error_setg(errp, "Cannot query QEMU internal jobs");
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return NULL;
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}
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info = g_new0(BlockJobInfo, 1);
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info->type = g_strdup(job_type_str(&job->job));
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info->device = g_strdup(job->job.id);
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info->busy = qatomic_read(&job->job.busy);
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info->paused = job->job.pause_count > 0;
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info->offset = job->job.progress.current;
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info->len = job->job.progress.total;
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info->speed = job->speed;
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info->io_status = job->iostatus;
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info->ready = job_is_ready(&job->job),
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info->status = job->job.status;
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info->auto_finalize = job->job.auto_finalize;
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info->auto_dismiss = job->job.auto_dismiss;
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info->has_error = job->job.ret != 0;
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info->error = job->job.ret ? g_strdup(strerror(-job->job.ret)) : NULL;
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return info;
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}
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static void block_job_iostatus_set_err(BlockJob *job, int error)
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{
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if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
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job->iostatus = error == ENOSPC ? BLOCK_DEVICE_IO_STATUS_NOSPACE :
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BLOCK_DEVICE_IO_STATUS_FAILED;
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}
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}
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static void block_job_event_cancelled(Notifier *n, void *opaque)
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{
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BlockJob *job = opaque;
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if (block_job_is_internal(job)) {
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return;
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}
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qapi_event_send_block_job_cancelled(job_type(&job->job),
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job->job.id,
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job->job.progress.total,
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job->job.progress.current,
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job->speed);
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}
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static void block_job_event_completed(Notifier *n, void *opaque)
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{
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BlockJob *job = opaque;
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const char *msg = NULL;
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if (block_job_is_internal(job)) {
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return;
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}
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if (job->job.ret < 0) {
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msg = strerror(-job->job.ret);
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}
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qapi_event_send_block_job_completed(job_type(&job->job),
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job->job.id,
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job->job.progress.total,
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job->job.progress.current,
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job->speed,
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!!msg,
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msg);
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}
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static void block_job_event_pending(Notifier *n, void *opaque)
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{
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BlockJob *job = opaque;
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if (block_job_is_internal(job)) {
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return;
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}
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qapi_event_send_block_job_pending(job_type(&job->job),
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job->job.id);
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}
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static void block_job_event_ready(Notifier *n, void *opaque)
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{
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BlockJob *job = opaque;
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if (block_job_is_internal(job)) {
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return;
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}
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qapi_event_send_block_job_ready(job_type(&job->job),
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job->job.id,
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job->job.progress.total,
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job->job.progress.current,
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job->speed);
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}
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/*
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* API for block job drivers and the block layer. These functions are
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* declared in blockjob_int.h.
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*/
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void *block_job_create(const char *job_id, const BlockJobDriver *driver,
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JobTxn *txn, BlockDriverState *bs, uint64_t perm,
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uint64_t shared_perm, int64_t speed, int flags,
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BlockCompletionFunc *cb, void *opaque, Error **errp)
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{
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BlockBackend *blk;
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BlockJob *job;
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if (job_id == NULL && !(flags & JOB_INTERNAL)) {
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job_id = bdrv_get_device_name(bs);
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}
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blk = blk_new_with_bs(bs, perm, shared_perm, errp);
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if (!blk) {
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return NULL;
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}
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job = job_create(job_id, &driver->job_driver, txn, blk_get_aio_context(blk),
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flags, cb, opaque, errp);
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if (job == NULL) {
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blk_unref(blk);
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return NULL;
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}
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assert(is_block_job(&job->job));
|
|
assert(job->job.driver->free == &block_job_free);
|
|
assert(job->job.driver->user_resume == &block_job_user_resume);
|
|
|
|
job->blk = blk;
|
|
|
|
job->finalize_cancelled_notifier.notify = block_job_event_cancelled;
|
|
job->finalize_completed_notifier.notify = block_job_event_completed;
|
|
job->pending_notifier.notify = block_job_event_pending;
|
|
job->ready_notifier.notify = block_job_event_ready;
|
|
job->idle_notifier.notify = block_job_on_idle;
|
|
|
|
notifier_list_add(&job->job.on_finalize_cancelled,
|
|
&job->finalize_cancelled_notifier);
|
|
notifier_list_add(&job->job.on_finalize_completed,
|
|
&job->finalize_completed_notifier);
|
|
notifier_list_add(&job->job.on_pending, &job->pending_notifier);
|
|
notifier_list_add(&job->job.on_ready, &job->ready_notifier);
|
|
notifier_list_add(&job->job.on_idle, &job->idle_notifier);
|
|
|
|
error_setg(&job->blocker, "block device is in use by block job: %s",
|
|
job_type_str(&job->job));
|
|
block_job_add_bdrv(job, "main node", bs, 0, BLK_PERM_ALL, &error_abort);
|
|
|
|
bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
|
|
|
|
/* Disable request queuing in the BlockBackend to avoid deadlocks on drain:
|
|
* The job reports that it's busy until it reaches a pause point. */
|
|
blk_set_disable_request_queuing(blk, true);
|
|
blk_set_allow_aio_context_change(blk, true);
|
|
|
|
/* Only set speed when necessary to avoid NotSupported error */
|
|
if (speed != 0) {
|
|
Error *local_err = NULL;
|
|
|
|
block_job_set_speed(job, speed, &local_err);
|
|
if (local_err) {
|
|
job_early_fail(&job->job);
|
|
error_propagate(errp, local_err);
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
return job;
|
|
}
|
|
|
|
void block_job_iostatus_reset(BlockJob *job)
|
|
{
|
|
if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
|
|
return;
|
|
}
|
|
assert(job->job.user_paused && job->job.pause_count > 0);
|
|
job->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
|
|
}
|
|
|
|
void block_job_user_resume(Job *job)
|
|
{
|
|
BlockJob *bjob = container_of(job, BlockJob, job);
|
|
block_job_iostatus_reset(bjob);
|
|
}
|
|
|
|
BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
|
|
int is_read, int error)
|
|
{
|
|
BlockErrorAction action;
|
|
|
|
switch (on_err) {
|
|
case BLOCKDEV_ON_ERROR_ENOSPC:
|
|
case BLOCKDEV_ON_ERROR_AUTO:
|
|
action = (error == ENOSPC) ?
|
|
BLOCK_ERROR_ACTION_STOP : BLOCK_ERROR_ACTION_REPORT;
|
|
break;
|
|
case BLOCKDEV_ON_ERROR_STOP:
|
|
action = BLOCK_ERROR_ACTION_STOP;
|
|
break;
|
|
case BLOCKDEV_ON_ERROR_REPORT:
|
|
action = BLOCK_ERROR_ACTION_REPORT;
|
|
break;
|
|
case BLOCKDEV_ON_ERROR_IGNORE:
|
|
action = BLOCK_ERROR_ACTION_IGNORE;
|
|
break;
|
|
default:
|
|
abort();
|
|
}
|
|
if (!block_job_is_internal(job)) {
|
|
qapi_event_send_block_job_error(job->job.id,
|
|
is_read ? IO_OPERATION_TYPE_READ :
|
|
IO_OPERATION_TYPE_WRITE,
|
|
action);
|
|
}
|
|
if (action == BLOCK_ERROR_ACTION_STOP) {
|
|
if (!job->job.user_paused) {
|
|
job_pause(&job->job);
|
|
/* make the pause user visible, which will be resumed from QMP. */
|
|
job->job.user_paused = true;
|
|
}
|
|
block_job_iostatus_set_err(job, error);
|
|
}
|
|
return action;
|
|
}
|