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block: remove AioContext locking

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This is the big patch that removes
aio_context_acquire()/aio_context_release() from the block layer and
affected block layer users.

There isn't a clean way to split this patch and the reviewers are likely
the same group of people, so I decided to do it in one patch.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-ID: <20231205182011.1976568-7-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2023-12-05 13:20:03 -05:00 • committed by Kevin Wolf
parent 6bc30f1949
commit b49f4755c7
41 changed files with 104 additions and 1169 deletions
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22
migration/savevm.c
View file

@ -3049,7 +3049,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
int saved_vm_running;
uint64_t vm_state_size;
g_autoptr(GDateTime) now = g_date_time_new_now_local();
AioContext *aio_context;
GLOBAL_STATE_CODE();
@ -3092,7 +3091,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
if (bs == NULL) {
return false;
}
aio_context = bdrv_get_aio_context(bs);
saved_vm_running = runstate_is_running();
@ -3101,8 +3099,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
bdrv_drain_all_begin();
aio_context_acquire(aio_context);
memset(sn, 0, sizeof(*sn));
/* fill auxiliary fields */
@ -3139,14 +3135,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
goto the_end;
}
/* The bdrv_all_create_snapshot() call that follows acquires the AioContext
* for itself. BDRV_POLL_WHILE() does not support nested locking because
* it only releases the lock once. Therefore synchronous I/O will deadlock
* unless we release the AioContext before bdrv_all_create_snapshot().
*/
aio_context_release(aio_context);
aio_context = NULL;
ret = bdrv_all_create_snapshot(sn, bs, vm_state_size,
has_devices, devices, errp);
if (ret < 0) {
@ -3157,10 +3145,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
ret = 0;
the_end:
if (aio_context) {
aio_context_release(aio_context);
}
bdrv_drain_all_end();
if (saved_vm_running) {
@ -3258,7 +3242,6 @@ bool load_snapshot(const char *name, const char *vmstate,
QEMUSnapshotInfo sn;
QEMUFile *f;
int ret;
AioContext *aio_context;
MigrationIncomingState *mis = migration_incoming_get_current();
if (!bdrv_all_can_snapshot(has_devices, devices, errp)) {
@ -3278,12 +3261,9 @@ bool load_snapshot(const char *name, const char *vmstate,
if (!bs_vm_state) {
return false;
}
aio_context = bdrv_get_aio_context(bs_vm_state);
/* Don't even try to load empty VM states */
aio_context_acquire(aio_context);
ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
aio_context_release(aio_context);
if (ret < 0) {
return false;
} else if (sn.vm_state_size == 0) {
@ -3320,10 +3300,8 @@ bool load_snapshot(const char *name, const char *vmstate,
ret = -EINVAL;
goto err_drain;
}
aio_context_acquire(aio_context);
ret = qemu_loadvm_state(f);
migration_incoming_state_destroy();
aio_context_release(aio_context);
bdrv_drain_all_end();