fsdev/aio: Handle io_submit failures appropriately

There are several cases to handle here. One is an outright failure
return code. Some of these only apply to the first iocb submitted, so in
this case we make sure to queue up the remaining iocbs to try again. The
other is fewer being submitted than we intended, forcing is to queue
back up the excess.

Change-Id: I0e0d5c5e32d3d6dd4fa8fafbb06b75b6dbae658e
Signed-off-by: Ben Walker <[email protected]>

Author: benlwalker

module/fsdev/aio/fsdev_aio.c

@@ -3951,7 +3951,7 @@ aio_io_poll(void *arg)
 {
 	struct aio_fsdev_io *vfsdev_io, *tmp;
 	struct aio_io_channel *ch = arg;
-	TAILQ_HEAD(, aio_fsdev_io) ios = TAILQ_HEAD_INITIALIZER(ios);
+	TAILQ_HEAD(aio_tmp_list, aio_fsdev_io) ios = TAILQ_HEAD_INITIALIZER(ios);
 	struct io_event events[32];
 	struct iocb *iocbs[32];
 	long to_submit = 0;
@@ -3978,29 +3978,30 @@ aio_io_poll(void *arg)
 		struct spdk_fsdev_io *fsdev_io = aio_to_fsdev_io(vfsdev_io);
 		enum spdk_fsdev_io_type type = spdk_fsdev_io_get_type(fsdev_io);
 
-		TAILQ_REMOVE(&ios, vfsdev_io, link);
-
 		rc = -EOPNOTSUPP;
 		res = SPDK_POLLER_BUSY;
 
 		switch (type) {
 		case SPDK_FSDEV_IO_READ:
 		case SPDK_FSDEV_IO_WRITE:
-			TAILQ_INSERT_TAIL(&ch->ios_in_progress, vfsdev_io, link);
 			iocbs[to_submit++] = &vfsdev_io->io;
 			rc = IO_STATUS_ASYNC;
 			break;
 		case SPDK_FSDEV_IO_POLL:
+			TAILQ_REMOVE(&ios, vfsdev_io, link);
 			rc = fsdev_aio_do_poll(ch, fsdev_io);
 			break;
 		case SPDK_FSDEV_IO_SETLK:
+			TAILQ_REMOVE(&ios, vfsdev_io, link);
 			rc = fsdev_aio_do_setlk(ch, fsdev_io);
 			break;
 		default:
+			TAILQ_REMOVE(&ios, vfsdev_io, link);
 			break;
 		}
 
 		if (rc != IO_STATUS_ASYNC) {
+			vfsdev_io->status = rc;
 			TAILQ_INSERT_TAIL(&ch->ios_to_complete, vfsdev_io, link);
 		}
 
@@ -4011,9 +4012,42 @@ aio_io_poll(void *arg)
 
 	if (to_submit > 0) {
 		rc = io_submit(ch->io_ctx, to_submit, iocbs);
-		if (rc < to_submit) {
-			/* TODO: Need to handle this error. Just blow up for now. */
-			assert(false);
+		if (rc < 0) {
+			res = rc;
+			rc = 0; /* 0 were submitted. This will get them all queued back up. */
+
+			if (res != -EAGAIN) {
+				/* The failures typically apply to the first iocb. Fail that one, but let the others
+				 * queue back up to be resubmitted. */
+				SPDK_ERRLOG("Failed io_submit: %s (%d)\n", spdk_strerror(-res), res);
+				vfsdev_io = TAILQ_FIRST(&ios);
+				TAILQ_REMOVE(&ios, vfsdev_io, link);
+				vfsdev_io->status = res;
+				TAILQ_INSERT_TAIL(&ch->ios_to_complete, vfsdev_io, link);
+			}
+		}
+
+		/* For each request actually submitted, shift it into the in progress list. */
+		i = 0;
+		TAILQ_FOREACH_SAFE(vfsdev_io, &ios, link, tmp) {
+			if (i == rc) {
+				break;
+			}
+
+			assert(&vfsdev_io->io == iocbs[i]);
+
+			TAILQ_REMOVE(&ios, vfsdev_io, link);
+			TAILQ_INSERT_TAIL(&ch->ios_in_progress, vfsdev_io, link);
+
+			i++;
+		}
+
+		/* For all remaining requests, put them back into the ios_for_submit list */
+		vfsdev_io = TAILQ_LAST(&ios, aio_tmp_list);
+		while (vfsdev_io != NULL) {
+			TAILQ_REMOVE(&ios, vfsdev_io, link);
+			TAILQ_INSERT_HEAD(&ch->ios_for_submit, vfsdev_io, link);
+			vfsdev_io = TAILQ_LAST(&ios, aio_tmp_list);
 		}
 	}