LU-13763 osc: don't allow negative grants

Add check in the osc_init_grant() to prevent possible
underflow of cl_avail_grant and report error if it happens

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: Idcd25ed427c23735e1cdc70359bace43b5b9d886
Reviewed-on: https://review.whamcloud.com/39827
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>
Reviewed-by: Vladimir Saveliev <c17830@cray.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/osc/osc_request.c b/lustre/osc/osc_request.c
index 1acf2d1..290f26f 100644 (file)
--- a/lustre/osc/osc_request.c
+++ b/lustre/osc/osc_request.c
@@ -1023,12 +1023,19 @@ void osc_init_grant(struct client_obd *cli, struct obd_connect_data *ocd)
        spin_lock(&cli->cl_loi_list_lock);
        cli->cl_avail_grant = ocd->ocd_grant;
        if (cli->cl_import->imp_state != LUSTRE_IMP_EVICTED) {
-               cli->cl_avail_grant -= cli->cl_reserved_grant;
+               unsigned long consumed = cli->cl_reserved_grant;
+
                if (OCD_HAS_FLAG(ocd, GRANT_PARAM))
-                       cli->cl_avail_grant -= cli->cl_dirty_grant;
+                       consumed += cli->cl_dirty_grant;
                else
-                       cli->cl_avail_grant -=
-                                       cli->cl_dirty_pages << PAGE_SHIFT;
+                       consumed += cli->cl_dirty_pages << PAGE_SHIFT;
+               if (cli->cl_avail_grant < consumed) {
+                       CERROR("%s: granted %ld but already consumed %ld\n",
+                              cli_name(cli), cli->cl_avail_grant, consumed);
+                       cli->cl_avail_grant = 0;
+               } else {
+                       cli->cl_avail_grant -= consumed;
+               }
        }
 
        if (OCD_HAS_FLAG(ocd, GRANT_PARAM)) {