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pve-qemu/debian/patches/pve/0029-backup-fix-race-in-bac...

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Wolfgang Bumiller <w.bumiller@proxmox.com>
Date: Tue, 5 Dec 2017 12:12:15 +0100
Subject: [PATCH] backup: fix race in backup-stop command
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
blockdev.c | 90 +++++++++++++++++++++++++++++++++-----------------------------
blockjob.c | 8 +++---
2 files changed, 52 insertions(+), 46 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index 19a82e8774..d3490936d8 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2934,31 +2934,6 @@ out:
aio_context_release(aio_context);
}
-void block_job_event_cancelled(BlockJob *job);
-void block_job_event_completed(BlockJob *job, const char *msg);
-static void block_job_cb(void *opaque, int ret)
-{
- /* Note that this function may be executed from another AioContext besides
- * the QEMU main loop. If you need to access anything that assumes the
- * QEMU global mutex, use a BH or introduce a mutex.
- */
-
- BlockDriverState *bs = opaque;
- const char *msg = NULL;
-
- assert(bs->job);
-
- if (ret < 0) {
- msg = strerror(-ret);
- }
-
- if (block_job_is_cancelled(bs->job)) {
- block_job_event_cancelled(bs->job);
- } else {
- block_job_event_completed(bs->job, msg);
- }
-}
-
/* PVE backup related function */
static struct PVEBackupState {
@@ -2975,6 +2950,8 @@ static struct PVEBackupState {
size_t total;
size_t transferred;
size_t zero_bytes;
+ QemuMutex backup_mutex;
+ bool backup_mutex_initialized;
} backup_state;
typedef struct PVEBackupDevInfo {
@@ -3055,6 +3032,13 @@ static int pvebackup_dump_cb(void *opaque, BlockBackend *target,
static void pvebackup_cleanup(void)
{
+ qemu_mutex_lock(&backup_state.backup_mutex);
+ // Avoid race between block jobs and backup-cancel command:
+ if (!backup_state.vmaw) {
+ qemu_mutex_unlock(&backup_state.backup_mutex);
+ return;
+ }
+
backup_state.end_time = time(NULL);
if (backup_state.vmaw) {
@@ -3064,16 +3048,9 @@ static void pvebackup_cleanup(void)
backup_state.vmaw = NULL;
}
- if (backup_state.di_list) {
- GList *l = backup_state.di_list;
- while (l) {
- PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data;
- l = g_list_next(l);
- g_free(di);
- }
- g_list_free(backup_state.di_list);
- backup_state.di_list = NULL;
- }
+ g_list_free(backup_state.di_list);
+ backup_state.di_list = NULL;
+ qemu_mutex_unlock(&backup_state.backup_mutex);
}
static void coroutine_fn backup_close_vma_stream(void *opaque)
@@ -3085,6 +3062,8 @@ static void coroutine_fn backup_close_vma_stream(void *opaque)
static void pvebackup_complete_cb(void *opaque, int ret)
{
+ // This always runs in the main loop
+
PVEBackupDevInfo *di = opaque;
di->completed = true;
@@ -3094,8 +3073,6 @@ static void pvebackup_complete_cb(void *opaque, int ret)
ret, strerror(-ret));
}
- BlockDriverState *bs = di->bs;
-
di->bs = NULL;
di->target = NULL;
@@ -3104,7 +3081,11 @@ static void pvebackup_complete_cb(void *opaque, int ret)
qemu_coroutine_enter(co);
}
- block_job_cb(bs, ret);
+ // remove self from job queue
+ qemu_mutex_lock(&backup_state.backup_mutex);
+ backup_state.di_list = g_list_remove(backup_state.di_list, di);
+ g_free(di);
+ qemu_mutex_unlock(&backup_state.backup_mutex);
if (!backup_state.cancel) {
pvebackup_run_next_job();
@@ -3114,6 +3095,12 @@ static void pvebackup_complete_cb(void *opaque, int ret)
static void pvebackup_cancel(void *opaque)
{
backup_state.cancel = true;
+ qemu_mutex_lock(&backup_state.backup_mutex);
+ // Avoid race between block jobs and backup-cancel command:
+ if (!backup_state.vmaw) {
+ qemu_mutex_unlock(&backup_state.backup_mutex);
+ return;
+ }
if (!backup_state.error) {
error_setg(&backup_state.error, "backup cancelled");
@@ -3131,13 +3118,17 @@ static void pvebackup_cancel(void *opaque)
if (!di->completed && di->bs) {
BlockJob *job = di->bs->job;
if (job) {
+ AioContext *aio_context = blk_get_aio_context(job->blk);
+ aio_context_acquire(aio_context);
if (!di->completed) {
- block_job_cancel_sync(job);
+ block_job_cancel(job);
}
+ aio_context_release(aio_context);
}
}
}
+ qemu_mutex_unlock(&backup_state.backup_mutex);
pvebackup_cleanup();
}
@@ -3193,24 +3184,31 @@ static int config_to_vma(const char *file, BackupFormat format,
bool block_job_should_pause(BlockJob *job);
static void pvebackup_run_next_job(void)
{
+ qemu_mutex_lock(&backup_state.backup_mutex);
+
GList *l = backup_state.di_list;
while (l) {
PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data;
l = g_list_next(l);
if (!di->completed && di->bs && di->bs->job) {
BlockJob *job = di->bs->job;
+ AioContext *aio_context = blk_get_aio_context(job->blk);
+ aio_context_acquire(aio_context);
+ qemu_mutex_unlock(&backup_state.backup_mutex);
if (block_job_should_pause(job)) {
- bool cancel = backup_state.error || backup_state.cancel;
- if (cancel) {
- block_job_cancel(job);
+ if (backup_state.error || backup_state.cancel) {
+ block_job_cancel_sync(job);
} else {
block_job_resume(job);
}
}
+ aio_context_release(aio_context);
return;
}
}
+ qemu_mutex_unlock(&backup_state.backup_mutex);
+ // no more jobs, run the cleanup
pvebackup_cleanup();
}
@@ -3233,6 +3231,11 @@ UuidInfo *qmp_backup(const char *backup_file, bool has_format,
UuidInfo *uuid_info;
BlockJob *job;
+ if (!backup_state.backup_mutex_initialized) {
+ qemu_mutex_init(&backup_state.backup_mutex);
+ backup_state.backup_mutex_initialized = true;
+ }
+
if (backup_state.di_list) {
error_set(errp, ERROR_CLASS_GENERIC_ERROR,
"previous backup not finished");
@@ -3405,6 +3408,7 @@ UuidInfo *qmp_backup(const char *backup_file, bool has_format,
uuid_copy(backup_state.uuid, uuid);
uuid_unparse_lower(uuid, backup_state.uuid_str);
+ qemu_mutex_lock(&backup_state.backup_mutex);
backup_state.di_list = di_list;
backup_state.total = total;
@@ -3428,6 +3432,8 @@ UuidInfo *qmp_backup(const char *backup_file, bool has_format,
block_job_start(job);
}
+ qemu_mutex_unlock(&backup_state.backup_mutex);
+
if (!backup_state.error) {
pvebackup_run_next_job(); // run one job
}
diff --git a/blockjob.c b/blockjob.c
index cb3741f6dd..199d5852db 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -37,8 +37,8 @@
#include "qemu/timer.h"
#include "qapi-event.h"
-void block_job_event_cancelled(BlockJob *job);
-void block_job_event_completed(BlockJob *job, const char *msg);
+static void block_job_event_cancelled(BlockJob *job);
+static void block_job_event_completed(BlockJob *job, const char *msg);
/* Transactional group of block jobs */
struct BlockJobTxn {
@@ -688,7 +688,7 @@ static void block_job_iostatus_set_err(BlockJob *job, int error)
}
}
-void block_job_event_cancelled(BlockJob *job)
+static void block_job_event_cancelled(BlockJob *job)
{
if (block_job_is_internal(job)) {
return;
@@ -702,7 +702,7 @@ void block_job_event_cancelled(BlockJob *job)
&error_abort);
}
-void block_job_event_completed(BlockJob *job, const char *msg)
+static void block_job_event_completed(BlockJob *job, const char *msg)
{
if (block_job_is_internal(job)) {
return;
--
2.11.0
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