Sometimes there is no need to rehandle AIOs although I/O hang is enabled. For
example, when deleting a block backend, we have to wait AIO completed by calling
blk_drain(), but not care about the results. So a pause interface of I/O hang
is helpful to bypass the rehandle mechanism.
Signed-off-by: Jiahui Cen <cenjia...@huawei.com>
Signed-off-by: Ying Fang <fangyi...@huawei.com>
---
block/block-backend.c | 60 +++++++++++++++++++++++++++++++---
include/sysemu/block-backend.h | 2 ++
2 files changed, 58 insertions(+), 4 deletions(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index 90fcc678b5..c16d95a2c9 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -37,6 +37,9 @@ static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb);
/* block backend rehandle timer interval 5s */
#define BLOCK_BACKEND_REHANDLE_TIMER_INTERVAL 5000
+#define BLOCK_BACKEND_REHANDLE_NORMAL 1
+#define BLOCK_BACKEND_REHANDLE_DRAIN_REQUESTED 2
+#define BLOCK_BACKEND_REHANDLE_DRAINED 3
enum BlockIOHangStatus {
BLOCK_IO_HANG_STATUS_NORMAL = 0,
@@ -50,6 +53,8 @@ typedef struct BlockBackendRehandleInfo {
unsigned int in_flight;
QTAILQ_HEAD(, BlkAioEmAIOCB) re_aios;
+
+ int status;
} BlockBackendRehandleInfo;
typedef struct BlockBackendAioNotifier {
@@ -2461,6 +2466,51 @@ static void blk_rehandle_remove_aiocb(BlockBackend *blk,
BlkAioEmAIOCB *acb)
qatomic_dec(&blk->reinfo.in_flight);
}
+static void blk_rehandle_drain(BlockBackend *blk)
+{
+ if (blk_bs(blk)) {
+ bdrv_drained_begin(blk_bs(blk));
+ BDRV_POLL_WHILE(blk_bs(blk), qatomic_read(&blk->reinfo.in_flight) > 0);
+ bdrv_drained_end(blk_bs(blk));
+ }
+}
+
+static bool blk_rehandle_is_paused(BlockBackend *blk)
+{
+ return blk->reinfo.status == BLOCK_BACKEND_REHANDLE_DRAIN_REQUESTED ||
+ blk->reinfo.status == BLOCK_BACKEND_REHANDLE_DRAINED;
+}
+
+void blk_rehandle_pause(BlockBackend *blk)
+{
+ BlockBackendRehandleInfo *reinfo = &blk->reinfo;
+
+ aio_context_acquire(blk_get_aio_context(blk));
+ if (!reinfo->enable || reinfo->status == BLOCK_BACKEND_REHANDLE_DRAINED) {
+ aio_context_release(blk_get_aio_context(blk));
+ return;
+ }
+
+ reinfo->status = BLOCK_BACKEND_REHANDLE_DRAIN_REQUESTED;
+ blk_rehandle_drain(blk);
+ reinfo->status = BLOCK_BACKEND_REHANDLE_DRAINED;
+ aio_context_release(blk_get_aio_context(blk));
+}
+
+void blk_rehandle_unpause(BlockBackend *blk)
+{
+ BlockBackendRehandleInfo *reinfo = &blk->reinfo;
+
+ aio_context_acquire(blk_get_aio_context(blk));
+ if (!reinfo->enable || reinfo->status == BLOCK_BACKEND_REHANDLE_NORMAL) {
+ aio_context_release(blk_get_aio_context(blk));
+ return;
+ }
+
+ reinfo->status = BLOCK_BACKEND_REHANDLE_NORMAL;
+ aio_context_release(blk_get_aio_context(blk));
+}
+
static void blk_rehandle_timer_cb(void *opaque)
{
BlockBackend *blk = opaque;
@@ -2560,10 +2610,12 @@ static void blk_rehandle_aio_complete(BlkAioEmAIOCB
*acb)
if (acb->has_returned) {
blk_dec_in_flight(acb->rwco.blk);
- need_rehandle = blk_rehandle_aio(acb, &has_timeout);
- if (need_rehandle) {
- blk_rehandle_insert_aiocb(acb->rwco.blk, acb);
- return;
+ if (!blk_rehandle_is_paused(acb->rwco.blk)) {
+ need_rehandle = blk_rehandle_aio(acb, &has_timeout);
+ if (need_rehandle) {
+ blk_rehandle_insert_aiocb(acb->rwco.blk, acb);
+ return;
+ }
}
acb->common.cb(acb->common.opaque, acb->rwco.ret);
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index bfebe3a960..391a047444 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -268,6 +268,8 @@ const BdrvChild *blk_root(BlockBackend *blk);
int blk_make_empty(BlockBackend *blk, Error **errp);
+void blk_rehandle_pause(BlockBackend *blk);
+void blk_rehandle_unpause(BlockBackend *blk);
void blk_iohang_init(BlockBackend *blk, int64_t iohang_timeout);
#endif
--
2.28.0
