cluster/dht: use readdir for fix-layout in rebalance

Problem:
On a cluster with 15 million files, when fix-layout was started, it was
not progressing at all. So we tried to do a os.walk() + os.stat() on the
backend filesystem directly. It took 2.5 days. We removed os.stat() and
re-ran it on another brick with similar data-set. It took 15 minutes. We
realized that readdirp is extremely costly compared to readdir if the
stat is not useful. fix-layout operation only needs to know that the
entry is a directory so that fix-layout operation can be triggered on
it. Most of the modern filesystems provide this information in readdir
operation. We don't need readdirp i.e. readdir+stat.

Fix:
Use readdir operation in fix-layout. Do readdir+stat/lookup for
filesystems that don't provide d_type in readdir operation.

fixes: #2241
Change-Id: I5fe2ecea25a399ad58e31a2e322caf69fc7f49eb
Signed-off-by: Pranith Kumar K <[email protected]>

cli/src/cli-rpc-ops.c

@@ -906,9 +906,9 @@ gf_cli_get_volume_cbk(struct rpc_req *req, struct iovec *iov, int count,
                                       replica_count, disperse_count,
                                       redundancy_count, arbiter_count);
 
-        cli_out("Transport-type: %s",
-                ((transport == 0) ? "tcp"
-                                  : (transport == 1) ? "rdma" : "tcp,rdma"));
+        cli_out("Transport-type: %s", ((transport == 0)   ? "tcp"
+                                       : (transport == 1) ? "rdma"
+                                                          : "tcp,rdma"));
         j = 1;
 
         GF_FREE(local->get_vol.volname);
@@ -1576,7 +1576,7 @@ gf_cli_print_rebalance_status(dict_t *dict, enum gf_task_types task_type)
         sec = ((uint64_t)elapsed % 3600) % 60;
 
         if (fix_layout) {
-            cli_out("%35s %50s %8d:%d:%d", node_name, status_str, hrs, min,
+            cli_out("%35s %50s %8d:%02d:%02d", node_name, status_str, hrs, min,
                     sec);
         } else {
             if (size_str) {

libglusterfs/src/common-utils.c

@@ -3325,7 +3325,7 @@ gf_process_reserved_ports(unsigned char *ports, uint32_t ceiling)
 out:
     GF_FREE(ports_info);
 
-#else  /* FIXME: Non Linux Host */
+#else /* FIXME: Non Linux Host */
     ret = 0;
 #endif /* GF_LINUX_HOST_OS */
 
@@ -5197,7 +5197,7 @@ close_fds_except_custom(int *fdv, size_t count, void *prm,
             closer(i, prm);
     }
     sys_closedir(d);
-#else  /* !GF_LINUX_HOST_OS */
+#else /* !GF_LINUX_HOST_OS */
     struct rlimit rl;
     int ret = -1;
 
@@ -5433,6 +5433,30 @@ gf_d_type_from_ia_type(ia_type_t type)
     }
 }
 
+int
+gf_d_type_from_st_mode(mode_t st_mode)
+{
+    switch (st_mode & S_IFMT) {
+        case S_IFREG:
+            return DT_REG;
+        case S_IFDIR:
+            return DT_DIR;
+        case S_IFLNK:
+            return DT_LNK;
+        case S_IFBLK:
+            return DT_BLK;
+        case S_IFCHR:
+            return DT_CHR;
+        case S_IFIFO:
+            return DT_FIFO;
+        case S_IFSOCK:
+            return DT_SOCK;
+        default:
+            return DT_UNKNOWN;
+    }
+    return DT_UNKNOWN;
+}
+
 int
 gf_nanosleep(uint64_t nsec)
 {

libglusterfs/src/glusterfs/common-utils.h

@@ -1257,4 +1257,6 @@ gf_tsdiff(struct timespec *start, struct timespec *end)
            (int64_t)(end->tv_nsec - start->tv_nsec);
 }
 
+int
+gf_d_type_from_st_mode(mode_t st_mode);
 #endif /* _COMMON_UTILS_H */

libglusterfs/src/libglusterfs.sym

@@ -1179,6 +1179,7 @@ gf_changelog_register_generic
 gf_gfid_generate_from_xxh64
 find_xlator_option_in_cmd_args_t
 gf_d_type_from_ia_type
+gf_d_type_from_st_mode
 glusterfs_graph_fini
 glusterfs_process_svc_attach_volfp
 glusterfs_mux_volfile_reconfigure

tests/bugs/glusterd/rebalance-operations-in-single-node.t

@@ -108,10 +108,16 @@ done
 TEST $CLI volume add-brick $V0 $H0:$B0/${V0}{5,6};
 
 #perform rebalance fix-layout
+TEST $CLI volume profile $V0 start
 TEST $CLI volume rebalance $V0 fix-layout start
 
 EXPECT_WITHIN $REBALANCE_TIMEOUT "fix-layout completed" fix-layout_status_field $V0;
 
+readdir_count=$($CLI volume profile $V0 info | grep -w READDIR | wc -l)
+readdirp_count=$($CLI volume profile $V0 info | grep -w READDIRP | wc -l)
+EXPECT_NOT "^0$" echo $readdir_count
+EXPECT "^0$" echo $readdirp_count
+
 #bug-1075087 - rebalance post add brick
 TEST mkdir $M0/dir{21..30};
 TEST touch $M0/dir{21..30}/files{1..10};

xlators/cluster/dht/src/dht-common.c

@@ -7037,6 +7037,8 @@ dht_readdir_cbk(call_frame_t *frame, void *cookie, xlator_t *this, int op_ret,
     dht_conf_t *conf = NULL;
     dht_methods_t *methods = NULL;
     gf_boolean_t skip_hashed_check = _gf_false;
+    gf_boolean_t readdir_optimize = _gf_false;
+    gf_boolean_t add = _gf_false;
 
     INIT_LIST_HEAD(&entries.list);
 
@@ -7046,6 +7048,7 @@ dht_readdir_cbk(call_frame_t *frame, void *cookie, xlator_t *this, int op_ret,
     conf = this->private;
     GF_VALIDATE_OR_GOTO(this->name, conf, done);
 
+    readdir_optimize = conf->readdir_optimize;
     methods = &(conf->methods);
 
     if (op_ret <= 0)
@@ -7069,12 +7072,25 @@ dht_readdir_cbk(call_frame_t *frame, void *cookie, xlator_t *this, int op_ret,
     {
         next_offset = orig_entry->d_off;
 
-        gf_msg_debug(this->name, 0, "%s: entry = %s, type = %d", prev->name,
-                     orig_entry->d_name, orig_entry->d_type);
-
         subvol = methods->layout_search(this, layout, orig_entry->d_name);
+        gf_msg_debug(this->name, 0, "%s: entry = %s, type = %d %p, %p",
+                     prev->name, orig_entry->d_name, orig_entry->d_type, subvol,
+                     prev);
+
+        /* a) If rebalance is running, pick from first_up_subvol
+         */
+        if (DT_ISDIR(orig_entry->d_type) && readdir_optimize) {
+            if (prev == local->first_up_subvol) {
+                add = _gf_true;
+            } else {
+                continue;
+            }
+        } else if (!subvol || (subvol == prev)) {
+            add = _gf_true;
+        }
 
-        if (!subvol || (subvol == prev)) {
+        if (add) {
+            add = _gf_false;
             entry = gf_dirent_for_name(orig_entry->d_name);
             if (!entry) {
                 gf_msg(this->name, GF_LOG_ERROR, ENOMEM, DHT_MSG_NO_MEMORY,

xlators/cluster/dht/src/dht-rebalance.c

@@ -3608,6 +3608,9 @@ gf_defrag_fix_layout(xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc,
     struct iatt iatt = {
         0,
     };
+    struct iatt entry_iatt = {
+        0,
+    };
     inode_t *linked_inode = NULL, *inode = NULL;
     dht_conf_t *conf = NULL;
     int perrno = 0;
@@ -3643,6 +3646,12 @@ gf_defrag_fix_layout(xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc,
         goto out;
     }
 
+    linked_inode = inode_link(loc->inode, loc->parent, loc->name, &iatt);
+
+    inode = loc->inode;
+    loc->inode = linked_inode;
+    inode_unref(inode);
+
     fd = fd_create(loc->inode, defrag->pid);
     if (!fd) {
         gf_log(this->name, GF_LOG_ERROR, "Failed to create fd");
@@ -3675,8 +3684,8 @@ gf_defrag_fix_layout(xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc,
     fd_bind(fd);
     INIT_LIST_HEAD(&entries.list);
 
-    while ((ret = syncop_readdirp(this, fd, 131072, offset, &entries, NULL,
-                                  NULL)) != 0) {
+    while ((ret = syncop_readdir(this, fd, 131072, offset, &entries, NULL,
+                                 NULL)) != 0) {
         if (ret < 0) {
             if (-ret == ENOENT || -ret == ESTALE) {
                 if (conf->decommission_subvols_cnt) {
@@ -3711,9 +3720,11 @@ gf_defrag_fix_layout(xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc,
 
             if (!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, ".."))
                 continue;
-            if (!IA_ISDIR(entry->d_stat.ia_type)) {
+
+            if ((DT_DIR != entry->d_type) && (DT_UNKNOWN != entry->d_type)) {
                 continue;
             }
+
             loc_wipe(&entry_loc);
 
             ret = dht_build_child_loc(this, &entry_loc, loc, entry->d_name);
@@ -3734,40 +3745,18 @@ gf_defrag_fix_layout(xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc,
                 }
             }
 
-            if (gf_uuid_is_null(entry->d_stat.ia_gfid)) {
-                gf_log(this->name, GF_LOG_ERROR,
-                       "%s/%s"
-                       " gfid not present",
-                       loc->path, entry->d_name);
-                continue;
-            }
-
-            gf_uuid_copy(entry_loc.gfid, entry->d_stat.ia_gfid);
-
-            /*In case the gfid stored in the inode by inode_link
-             * and the gfid obtained in the lookup differs, then
-             * client3_3_lookup_cbk will return ESTALE and proper
-             * error will be captured
-             */
-
-            linked_inode = inode_link(entry_loc.inode, loc->inode,
-                                      entry->d_name, &entry->d_stat);
-
-            inode = entry_loc.inode;
-            entry_loc.inode = linked_inode;
-            inode_unref(inode);
-
-            if (gf_uuid_is_null(loc->gfid)) {
-                gf_log(this->name, GF_LOG_ERROR,
-                       "%s/%s"
-                       " gfid not present",
-                       loc->path, entry->d_name);
-                defrag->total_failures++;
-                continue;
+            if (DT_UNKNOWN == entry->d_type) {
+                ret = syncop_lookup(this, &entry_loc, &entry_iatt, NULL, NULL,
+                                    NULL);
+                if ((ret == 0) && (entry_iatt.ia_type != IA_IFDIR)) {
+                    continue;
+                }
+                /*If it is directory, gf_defrag_fix_layout() call will again do
+                 * one more lookup. Not optimizing this part as all modern
+                 * filesystems populate entry->d_type. We can optimize it when
+                 * such a filesystem is found.*/
             }
 
-            gf_uuid_copy(entry_loc.pargfid, loc->gfid);
-
             /* A return value of 2 means, either process_dir or
              * lookup of a dir failed. Hence, don't commit hash
              * for the current directory*/

xlators/mgmt/glusterd/src/glusterd-rebalance.c

@@ -289,7 +289,7 @@ glusterd_handle_defrag_start(glusterd_volinfo_t *volinfo, char *op_errstr,
 
     runner_add_args(
         &runner, SBIN_DIR "/glusterfs", "-s", volfileserver, "--volfile-id",
-        volname, "--xlator-option", "*dht.use-readdirp=yes", "--xlator-option",
+        volname, "--xlator-option", "*dht.use-readdirp=no", "--xlator-option",
         "*dht.lookup-unhashed=yes", "--xlator-option",
         "*dht.assert-no-child-down=yes", "--xlator-option",
         "*dht.readdir-optimize=on", "--process-name", "rebalance", NULL);