qcow2: Avoid direct AIO callback
bdrv_aio_* must not call the callback before returning to its caller. In qcow2,
this could happen in some error cases. This starts the real requests processing
in a BH to avoid this situation.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/qcow2.c b/block/qcow2.c
index 8451ded..2c51e7c 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -378,6 +378,7 @@
uint64_t bytes_done;
uint64_t cluster_offset;
uint8_t *cluster_data;
+ bool is_write;
BlockDriverAIOCB *hd_aiocb;
QEMUIOVector hd_qiov;
QEMUBH *bh;
@@ -399,12 +400,19 @@
};
static void qcow2_aio_read_cb(void *opaque, int ret);
-static void qcow2_aio_read_bh(void *opaque)
+static void qcow2_aio_write_cb(void *opaque, int ret);
+
+static void qcow2_aio_rw_bh(void *opaque)
{
QCowAIOCB *acb = opaque;
qemu_bh_delete(acb->bh);
acb->bh = NULL;
- qcow2_aio_read_cb(opaque, 0);
+
+ if (acb->is_write) {
+ qcow2_aio_write_cb(opaque, 0);
+ } else {
+ qcow2_aio_read_cb(opaque, 0);
+ }
}
static int qcow2_schedule_bh(QEMUBHFunc *cb, QCowAIOCB *acb)
@@ -493,14 +501,14 @@
goto done;
}
} else {
- ret = qcow2_schedule_bh(qcow2_aio_read_bh, acb);
+ ret = qcow2_schedule_bh(qcow2_aio_rw_bh, acb);
if (ret < 0)
goto done;
}
} else {
/* Note: in this case, no need to wait */
qemu_iovec_memset(&acb->hd_qiov, 0, 512 * acb->cur_nr_sectors);
- ret = qcow2_schedule_bh(qcow2_aio_read_bh, acb);
+ ret = qcow2_schedule_bh(qcow2_aio_rw_bh, acb);
if (ret < 0)
goto done;
}
@@ -515,7 +523,7 @@
s->cluster_cache + index_in_cluster * 512,
512 * acb->cur_nr_sectors);
- ret = qcow2_schedule_bh(qcow2_aio_read_bh, acb);
+ ret = qcow2_schedule_bh(qcow2_aio_rw_bh, acb);
if (ret < 0)
goto done;
} else {
@@ -572,6 +580,7 @@
acb->hd_aiocb = NULL;
acb->sector_num = sector_num;
acb->qiov = qiov;
+ acb->is_write = is_write;
qemu_iovec_init(&acb->hd_qiov, qiov->niov);
@@ -591,17 +600,22 @@
void *opaque)
{
QCowAIOCB *acb;
+ int ret;
acb = qcow2_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
if (!acb)
return NULL;
- qcow2_aio_read_cb(acb, 0);
+ ret = qcow2_schedule_bh(qcow2_aio_rw_bh, acb);
+ if (ret < 0) {
+ qemu_iovec_destroy(&acb->hd_qiov);
+ qemu_aio_release(acb);
+ return NULL;
+ }
+
return &acb->common;
}
-static void qcow2_aio_write_cb(void *opaque, int ret);
-
static void run_dependent_requests(QCowL2Meta *m)
{
QCowAIOCB *req;
@@ -724,6 +738,7 @@
{
BDRVQcowState *s = bs->opaque;
QCowAIOCB *acb;
+ int ret;
s->cluster_cache_offset = -1; /* disable compressed cache */
@@ -731,7 +746,13 @@
if (!acb)
return NULL;
- qcow2_aio_write_cb(acb, 0);
+ ret = qcow2_schedule_bh(qcow2_aio_rw_bh, acb);
+ if (ret < 0) {
+ qemu_iovec_destroy(&acb->hd_qiov);
+ qemu_aio_release(acb);
+ return NULL;
+ }
+
return &acb->common;
}