Like in “rbd: Run co BH CB in the coroutine’s AioContext”, drop the
completion flag, yield exactly once, and run the BH in the coroutine’s
AioContext.

(Can be reproduced with multiqueue by adding a usleep(100000) before the
`while (!task.complete)` loops.)

Like in “iscsi: Run co BH CB in the coroutine’s AioContext”, this makes
nfs_co_generic_bh_cb() trivial, and we could just run aio_co_wake()
directly from nfs_co_generic_cb().  Like in iscsi, we don’t do that, so
as to keep the replay_bh_schedule_oneshot_event(), but we should at
least run the BH in the coroutine’s context to remove further BH
indirection.

Cc: qemu-stable@nongnu.org
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
---
 block/nfs.c | 23 ++++++-----------------
 1 file changed, 6 insertions(+), 17 deletions(-)

diff --git a/block/nfs.c b/block/nfs.c
index 0a7d38db09..4667d49416 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -69,7 +69,6 @@ typedef struct NFSClient {
 typedef struct NFSRPC {
     BlockDriverState *bs;
     int ret;
-    int complete;
     QEMUIOVector *iov;
     struct stat *st;
     Coroutine *co;
@@ -233,8 +232,6 @@ static void coroutine_fn nfs_co_init_task(BlockDriverState *bs, NFSRPC *task)
 static void nfs_co_generic_bh_cb(void *opaque)
 {
     NFSRPC *task = opaque;
-
-    task->complete = 1;
     aio_co_wake(task->co);
 }
 
@@ -256,7 +253,7 @@ nfs_co_generic_cb(int ret, struct nfs_context *nfs, void *data,
     if (task->ret < 0) {
         error_report("NFS Error: %s", nfs_get_error(nfs));
     }
-    replay_bh_schedule_oneshot_event(task->client->aio_context,
+    replay_bh_schedule_oneshot_event(qemu_coroutine_get_aio_context(task->co),
                                      nfs_co_generic_bh_cb, task);
 }
 
@@ -278,9 +275,7 @@ static int coroutine_fn nfs_co_preadv(BlockDriverState *bs, int64_t offset,
 
         nfs_set_events(client);
     }
-    while (!task.complete) {
-        qemu_coroutine_yield();
-    }
+    qemu_coroutine_yield();
 
     if (task.ret < 0) {
         return task.ret;
@@ -328,9 +323,7 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState *bs, int64_t offset,
 
         nfs_set_events(client);
     }
-    while (!task.complete) {
-        qemu_coroutine_yield();
-    }
+    qemu_coroutine_yield();
 
     if (my_buffer) {
         g_free(buf);
@@ -358,9 +351,7 @@ static int coroutine_fn nfs_co_flush(BlockDriverState *bs)
 
         nfs_set_events(client);
     }
-    while (!task.complete) {
-        qemu_coroutine_yield();
-    }
+    qemu_coroutine_yield();
 
     return task.ret;
 }
@@ -723,7 +714,7 @@ nfs_get_allocated_file_size_cb(int ret, struct nfs_context *nfs, void *data,
     if (task->ret < 0) {
         error_report("NFS Error: %s", nfs_get_error(nfs));
     }
-    replay_bh_schedule_oneshot_event(task->client->aio_context,
+    replay_bh_schedule_oneshot_event(qemu_coroutine_get_aio_context(task->co),
                                      nfs_co_generic_bh_cb, task);
 }
 
@@ -748,9 +739,7 @@ static int64_t coroutine_fn nfs_co_get_allocated_file_size(BlockDriverState *bs)
 
         nfs_set_events(client);
     }
-    while (!task.complete) {
-        qemu_coroutine_yield();
-    }
+    qemu_coroutine_yield();
 
     return (task.ret < 0 ? task.ret : st.st_blocks * 512);
 }
-- 
2.51.0