smbd: Issue fsync for SMB2 FLUSH asynchronously

SMB2 FLUSH mainly calls fsync and there is already code in place to
handle fsync asynchronously, so use the asynchronous code path for SMB2
FLUSH. This avoids a SMB2 FLUSH stalling other requests processing.

Signed-off-by: Christof Schmitt <cs@samba.org>
Signed-off-by: Jeremy Allison <jra@samba.org>

1 files changed, 67 insertions, 7 deletions

diff --git a/source3/smbd/smb2_flush.c b/source3/smbd/smb2_flush.c
index 04a8710fe90..d26707acc0c 100644
--- a/source3/smbd/smb2_flush.c
+++ b/source3/smbd/smb2_flush.c
@@ -110,15 +110,18 @@ struct smbd_smb2_flush_state {
 	struct smbd_smb2_request *smb2req;
 };
 
+static void smbd_smb2_flush_done(struct tevent_req *subreq);
+
 static struct tevent_req *smbd_smb2_flush_send(TALLOC_CTX *mem_ctx,
 					       struct tevent_context *ev,
 					       struct smbd_smb2_request *smb2req,
 					       struct files_struct *fsp)
 {
 	struct tevent_req *req;
+	struct tevent_req *subreq;
 	struct smbd_smb2_flush_state *state;
-	NTSTATUS status;
 	struct smb_request *smbreq;
+	int ret;
 
 	req = tevent_req_create(mem_ctx, &state,
 				struct smbd_smb2_flush_state);
@@ -145,16 +148,73 @@ static struct tevent_req *smbd_smb2_flush_send(TALLOC_CTX *mem_ctx,
 		return tevent_req_post(req, ev);
 	}
 
-	status = sync_file(smbreq->conn, fsp, true);
-	if (!NT_STATUS_IS_OK(status)) {
-		DEBUG(5,("smbd_smb2_flush: sync_file for %s returned %s\n",
-			 fsp_str_dbg(fsp), nt_errstr(status)));
-		tevent_req_nterror(req, status);
+	if (fsp->fh->fd == -1) {
+		tevent_req_nterror(req, NT_STATUS_INVALID_HANDLE);
+		return tevent_req_post(req, ev);
+	}
+
+	if (!lp_strict_sync(SNUM(smbreq->conn))) {
+		/*
+		 * No strict sync. Don't really do
+		 * anything here.
+		 */
+		tevent_req_done(req);
+		return tevent_req_post(req, ev);
+	}
+
+	if (get_outstanding_aio_calls() >= get_aio_pending_size()) {
+		/* No more allowed aio. Synchronous flush. */
+		NTSTATUS status = sync_file(smbreq->conn, fsp, true);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(5,("sync_file for %s returned %s\n",
+				fsp_str_dbg(fsp),
+				nt_errstr(status)));
+			tevent_req_nterror(req, status);
+			return tevent_req_post(req, ev);
+		}
+		tevent_req_done(req);
+		return tevent_req_post(req, ev);
+	}
+
+	ret = flush_write_cache(fsp, SAMBA_SYNC_FLUSH);
+	if (ret == -1) {
+		tevent_req_nterror(req,  map_nt_error_from_unix(errno));
+		return tevent_req_post(req, ev);
+	}
+
+	subreq = SMB_VFS_FSYNC_SEND(state, ev, fsp);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+
+	tevent_req_set_callback(subreq, smbd_smb2_flush_done, req);
+
+	/* Ensure any close request knows about this outstanding IO. */
+	if (!aio_add_req_to_fsp(fsp, req)) {
+		tevent_req_nterror(req, NT_STATUS_NO_MEMORY);
 		return tevent_req_post(req, ev);
 	}
 
+	increment_outstanding_aio_calls();
+	return req;
+
+}
+
+static void smbd_smb2_flush_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	int ret, err;
+
+	decrement_outstanding_aio_calls();
+
+	ret = SMB_VFS_FSYNC_RECV(subreq, &err);
+	TALLOC_FREE(subreq);
+	if (ret == -1) {
+		tevent_req_error(req, err);
+		return;
+	}
 	tevent_req_done(req);
-	return tevent_req_post(req, ev);
 }
 
 static NTSTATUS smbd_smb2_flush_recv(struct tevent_req *req)