staging/lustre/ost: Ensure dirty flushed on fiemap ioctl

Data corruption is possible if cp(coreutils) uses FIEMAP to obtain
data holes in shared file, since there could be dirty cache on
other clients which hasn't been flushed back.

To ensure all the dirty on remote clients being flushed back on
fiemap ioctl, we'd acquire ldlm lock on server side for fiemap,
unless the local client (which invoke fiemap) has cached lock.

[picked osc part for upstream kernel submission]
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3219
Xyratex-bug-id: MRP-1001
Lustre-change: http://review.whamcloud.com/6127
Signed-off-by: Artem Blagodarenko <artem_blagodarenko@xyratex.com>
Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/osc/osc_request.c b/drivers/staging/lustre/lustre/osc/osc_request.c
index 7422215a2606c18f89b074cc585a7e7d2db16415..53d6a35c80b9b1e3bbe03d3235469918147c4fa5 100644 (file)
--- a/drivers/staging/lustre/lustre/osc/osc_request.c
+++ b/drivers/staging/lustre/lustre/osc/osc_request.c
@@ -3062,15 +3062,52 @@ static int osc_get_info(const struct lu_env *env, struct obd_export *exp,
                ptlrpc_req_finished(req);
                RETURN(rc);
        } else if (KEY_IS(KEY_FIEMAP)) {
-               struct ptlrpc_request *req;
-               struct ll_user_fiemap *reply;
-               char *tmp;
-               int rc;
+               struct ll_fiemap_info_key *fm_key =
+                               (struct ll_fiemap_info_key *)key;
+               struct ldlm_res_id       res_id;
+               ldlm_policy_data_t       policy;
+               struct lustre_handle     lockh;
+               ldlm_mode_t              mode = 0;
+               struct ptlrpc_request   *req;
+               struct ll_user_fiemap   *reply;
+               char                    *tmp;
+               int                      rc;
+
+               if (!(fm_key->fiemap.fm_flags & FIEMAP_FLAG_SYNC))
+                       goto skip_locking;
+
+               policy.l_extent.start = fm_key->fiemap.fm_start &
+                                               CFS_PAGE_MASK;
+
+               if (OBD_OBJECT_EOF - fm_key->fiemap.fm_length <=
+                   fm_key->fiemap.fm_start + PAGE_CACHE_SIZE - 1)
+                       policy.l_extent.end = OBD_OBJECT_EOF;
+               else
+                       policy.l_extent.end = (fm_key->fiemap.fm_start +
+                               fm_key->fiemap.fm_length +
+                               PAGE_CACHE_SIZE - 1) & CFS_PAGE_MASK;
+
+               ostid_build_res_name(&fm_key->oa.o_oi, &res_id);
+               mode = ldlm_lock_match(exp->exp_obd->obd_namespace,
+                                      LDLM_FL_BLOCK_GRANTED |
+                                      LDLM_FL_LVB_READY,
+                                      &res_id, LDLM_EXTENT, &policy,
+                                      LCK_PR | LCK_PW, &lockh, 0);
+               if (mode) { /* lock is cached on client */
+                       if (mode != LCK_PR) {
+                               ldlm_lock_addref(&lockh, LCK_PR);
+                               ldlm_lock_decref(&lockh, LCK_PW);
+                       }
+               } else { /* no cached lock, needs acquire lock on server side */
+                       fm_key->oa.o_valid |= OBD_MD_FLFLAGS;
+                       fm_key->oa.o_flags |= OBD_FL_SRVLOCK;
+               }
 
+skip_locking:
                req = ptlrpc_request_alloc(class_exp2cliimp(exp),
                                           &RQF_OST_GET_INFO_FIEMAP);
                if (req == NULL)
-                       RETURN(-ENOMEM);
+                       GOTO(drop_lock, rc = -ENOMEM);
 
                req_capsule_set_size(&req->rq_pill, &RMF_FIEMAP_KEY,
                                     RCL_CLIENT, keylen);
@@ -3082,7 +3119,7 @@ static int osc_get_info(const struct lu_env *env, struct obd_export *exp,
                rc = ptlrpc_request_pack(req, LUSTRE_OST_VERSION, OST_GET_INFO);
                if (rc) {
                        ptlrpc_request_free(req);
-                       RETURN(rc);
+                       GOTO(drop_lock, rc);
                }
 
                tmp = req_capsule_client_get(&req->rq_pill, &RMF_FIEMAP_KEY);
@@ -3093,16 +3130,18 @@ static int osc_get_info(const struct lu_env *env, struct obd_export *exp,
                ptlrpc_request_set_replen(req);
                rc = ptlrpc_queue_wait(req);
                if (rc)
-                       GOTO(out1, rc);
+                       GOTO(fini_req, rc);
 
                reply = req_capsule_server_get(&req->rq_pill, &RMF_FIEMAP_VAL);
                if (reply == NULL)
-                       GOTO(out1, rc = -EPROTO);
+                       GOTO(fini_req, rc = -EPROTO);
 
                memcpy(val, reply, *vallen);
-       out1:
+fini_req:
                ptlrpc_req_finished(req);
-
+drop_lock:
+               if (mode)
+                       ldlm_lock_decref(&lockh, LCK_PR);
                RETURN(rc);
        }