From: Oleg Drokin <green@whamcloud.com>
Date: Wed, 28 Jul 2021 18:02:19 +0000 (-0400)
Subject: LU-14711 osc: Do not attempt sending empty pages
X-Git-Tag: 2.14.56~192
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=1a409a3e6a74685970ee779ebe32917bf51eaf3a

LU-14711 osc: Do not attempt sending empty pages

Do not crash if trying to send a lock-prolonging emtpy read
to an old server, if the server does not support short reads.
Otherwise the client crashes when access the NULL page.

Test-Parameters: trivial
Fixes: 564070343ac4 ("LU-14711 osc: Notify server if cache discard takes a long time")
Change-Id: Icae7bf3ef16c45d33894b3c5fbac15b1a98c39d9
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/44654
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
---

diff --git a/lustre/osc/osc_request.c b/lustre/osc/osc_request.c
index b80f8f4..4ca9be0 100644
--- a/lustre/osc/osc_request.c
+++ b/lustre/osc/osc_request.c
@@ -1557,6 +1557,12 @@ retry_encrypt:
 	    !imp_connect_shortio(cli->cl_import))
 		short_io_size = 0;
 
+	/* If this is an empty RPC to old server, just ignore it */
+	if (!short_io_size && !pga[0]->pg) {
+		ptlrpc_request_free(req);
+		RETURN(-ENODATA);
+	}
+
 	req_capsule_set_size(pill, &RMF_SHORT_IO, RCL_CLIENT,
 			     opc == OST_READ ? 0 : short_io_size);
 	if (opc == OST_READ)