Reduce the number of metadata updates done by ddf.

1/ track if there are any actual updates pending, and only
   write metadata when we have changed something.

2/ when writing null virtual-configs, write full blocks,
   not just the first 4 bytes.  This will allow O_DIRECT
   writes in a subsequent patch.

diff --git a/super-ddf.c b/super-ddf.c
index e5f3fbdb65bd7a01af4e30958e89e575a0251e6f..a0a9cb0361a25945e667680346bdd814abfb7bf8 100644 (file)
--- a/super-ddf.c
+++ b/super-ddf.c
@@ -402,6 +402,7 @@ struct ddf_super {
        int pdsize, vdsize;
        int max_part, mppe, conf_rec_len;
        int currentdev;
+       int updates_pending;
        struct vcl {
                struct vcl      *next;
                __u64           *lba_offset; /* location in 'conf' of
@@ -1590,6 +1591,7 @@ static int init_super_ddf(struct supertype *st,
                memset(&vd->entries[i], 0xff, sizeof(struct virtual_entry));
 
        st->sb = ddf;
+       ddf->updates_pending = 1;
        return 1;
 }
 
@@ -1852,6 +1854,7 @@ static int init_super_ddf_bvd(struct supertype *st,
        vcl->next = ddf->conflist;
        ddf->conflist = vcl;
        ddf->currentconf = vcl;
+       ddf->updates_pending = 1;
        return 1;
 }
 
@@ -1943,6 +1946,7 @@ static void add_to_super_ddf_bvd(struct supertype *st,
 
        ddf->phys->entries[dl->pdnum].type &= ~__cpu_to_be16(DDF_Global_Spare);
        ddf->phys->entries[dl->pdnum].type |= __cpu_to_be16(DDF_Active_in_VD);
+       ddf->updates_pending = 1;
 }
 
 /* add a device to a container, either while creating it or while
@@ -2021,6 +2025,7 @@ static void add_to_super_ddf(struct supertype *st,
 
        dd->size = size >> 9;
        ddf->dlist = dd;
+       ddf->updates_pending = 1;
 }
 
 /*
@@ -2030,6 +2035,9 @@ static void add_to_super_ddf(struct supertype *st,
  */
 
 #ifndef MDASSEMBLE
+
+static unsigned char null_conf[4096];
+
 static int __write_init_super_ddf(struct supertype *st, int do_close)
 {
 
@@ -2100,9 +2108,14 @@ static int __write_init_super_ddf(struct supertype *st, int do_close)
                                c->conf.crc = calc_crc(&c->conf, conf_size);
                                write(fd, &c->conf, conf_size);
                        } else {
-                               __u32 sig = 0xffffffff;
-                               write(fd, &sig, 4);
-                               lseek64(fd, conf_size-4, SEEK_CUR);
+                               if (null_conf[0] != 0xff)
+                                       memset(null_conf, 0xff, sizeof(null_conf));
+                               int togo = conf_size;
+                               while (togo > sizeof(null_conf)) {
+                                       write(fd, null_conf, sizeof(null_conf));
+                                       togo -= sizeof(null_conf);
+                               }
+                               write(fd, null_conf, togo);
                        }
                }
                d->disk.crc = calc_crc(&d->disk, 512);
@@ -2632,10 +2645,15 @@ static void ddf_set_array_state(struct active_array *a, int consistent)
 {
        struct ddf_super *ddf = a->container->sb;
        int inst = a->info.container_member;
+       int old = ddf->virt->entries[inst].state;
        if (consistent)
                ddf->virt->entries[inst].state &= ~DDF_state_inconsistent;
        else
                ddf->virt->entries[inst].state |= DDF_state_inconsistent;
+       if (old != ddf->virt->entries[inst].state)
+               ddf->updates_pending = 1;
+
+       old = ddf->virt->entries[inst].init_state;
        ddf->virt->entries[inst].init_state &= ~DDF_initstate_mask;
        if (a->resync_start == ~0ULL)
                ddf->virt->entries[inst].init_state |= DDF_init_full;
@@ -2643,8 +2661,10 @@ static void ddf_set_array_state(struct active_array *a, int consistent)
                ddf->virt->entries[inst].init_state |= DDF_init_not;
        else
                ddf->virt->entries[inst].init_state |= DDF_init_quick;
+       if (old != ddf->virt->entries[inst].init_state)
+               ddf->updates_pending = 1;
 
-       printf("ddf mark %s %llu\n", consistent?"clean":"dirty",
+       printf("ddf mark %d %s %llu\n", inst, consistent?"clean":"dirty",
               a->resync_start);
 }
 
@@ -2685,12 +2705,15 @@ static void ddf_set_disk(struct active_array *a, int n, int state)
                        /* FIXME */
                }
        } else {
+               int old = ddf->phys->entries[pd].state;
                if (state & DS_FAULTY)
                        ddf->phys->entries[pd].state  |= __cpu_to_be16(DDF_Failed);
                if (state & DS_INSYNC) {
                        ddf->phys->entries[pd].state  |= __cpu_to_be16(DDF_Online);
                        ddf->phys->entries[pd].state  &= __cpu_to_be16(~DDF_Rebuilding);
                }
+               if (old != ddf->phys->entries[pd].state)
+                       ddf->updates_pending = 1;
        }
 
        fprintf(stderr, "ddf: set_disk %d to %x\n", n, state);
@@ -2736,9 +2759,15 @@ static void ddf_set_disk(struct active_array *a, int n, int state)
                break;
        }
 
-       ddf->virt->entries[inst].state =
-               (ddf->virt->entries[inst].state & ~DDF_state_mask)
-               | state;
+       if (ddf->virt->entries[inst].state !=
+           ((ddf->virt->entries[inst].state & ~DDF_state_mask)
+            | state)) {
+
+               ddf->virt->entries[inst].state =
+                       (ddf->virt->entries[inst].state & ~DDF_state_mask)
+                       | state;
+               ddf->updates_pending = 1;
+       }
 
 }
 
@@ -2752,6 +2781,10 @@ static void ddf_sync_metadata(struct supertype *st)
         * but ddf is sufficiently weird that it probably always
         * changes global data ....
         */
+       struct ddf_super *ddf = st->sb;
+       if (!ddf->updates_pending)
+               return;
+       ddf->updates_pending = 0;
        __write_init_super_ddf(st, 0);
        fprintf(stderr, "ddf: sync_metadata\n");
 }
@@ -2814,6 +2847,7 @@ static void ddf_process_update(struct supertype *st,
                ddf->phys->entries[ent] = pd->entries[0];
                ddf->phys->used_pdes = __cpu_to_be16(1 +
                                           __be16_to_cpu(ddf->phys->used_pdes));
+               ddf->updates_pending = 1;
                break;
 
        case DDF_VIRT_RECORDS_MAGIC:
@@ -2831,6 +2865,7 @@ static void ddf_process_update(struct supertype *st,
                ddf->virt->entries[ent] = vd->entries[0];
                ddf->virt->populated_vdes = __cpu_to_be16(1 +
                              __be16_to_cpu(ddf->virt->populated_vdes));
+               ddf->updates_pending = 1;
                break;
 
        case DDF_VD_CONF_MAGIC:
@@ -2895,6 +2930,7 @@ static void ddf_process_update(struct supertype *st,
                                                       DDF_Active_in_VD);
                        }
                }
+               ddf->updates_pending = 1;
                break;
        case DDF_SPARE_ASSIGN_MAGIC:
        default: break;