Btrfs: Add support for duplicate blocks on a single spindle

[linux-2.6-block.git] / fs / btrfs / volumes.c

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index bc3c0b97588ead16b257bb5ee88bfe7b873a1966..b9294e3c05f0b53447d5ac14f7028cfb6180d7d0 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -627,6 +627,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        struct extent_map *em;
        u64 physical;
        u64 calc_size = 1024 * 1024 * 1024;
+       u64 min_free = calc_size;
        u64 avail;
        u64 max_avail = 0;
        int num_stripes = 1;
@@ -641,6 +642,8 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 
        if (type & (BTRFS_BLOCK_GROUP_RAID0))
                num_stripes = btrfs_super_num_devices(&info->super_copy);
+       if (type & (BTRFS_BLOCK_GROUP_DUP))
+               num_stripes = 2;
        if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
                num_stripes = min_t(u64, 2,
                                  btrfs_super_num_devices(&info->super_copy));
@@ -649,16 +652,23 @@ again:
        INIT_LIST_HEAD(&private_devs);
        cur = dev_list->next;
        index = 0;
+
+       if (type & BTRFS_BLOCK_GROUP_DUP)
+               min_free = calc_size * 2;
+
        /* build a private list of devices we will allocate from */
        while(index < num_stripes) {
                device = list_entry(cur, struct btrfs_device, dev_list);
+
                avail = device->total_bytes - device->bytes_used;
                cur = cur->next;
                if (avail > max_avail)
                        max_avail = avail;
-               if (avail >= calc_size) {
+               if (avail >= min_free) {
                        list_move_tail(&device->dev_list, &private_devs);
                        index++;
+                       if (type & BTRFS_BLOCK_GROUP_DUP)
+                               index++;
                }
                if (cur == dev_list)
                        break;
@@ -689,17 +699,22 @@ again:
 
        stripes = &chunk->stripe;
 
-       if (type & BTRFS_BLOCK_GROUP_RAID1)
+       if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
                *num_bytes = calc_size;
        else
                *num_bytes = calc_size * num_stripes;
 
        index = 0;
+printk("new chunk type %Lu start %Lu size %Lu\n", type, key.objectid, *num_bytes);
        while(index < num_stripes) {
                BUG_ON(list_empty(&private_devs));
                cur = private_devs.next;
                device = list_entry(cur, struct btrfs_device, dev_list);
-               list_move_tail(&device->dev_list, dev_list);
+
+               /* loop over this device again if we're doing a dup group */
+               if (!(type & BTRFS_BLOCK_GROUP_DUP) ||
+                   (index == num_stripes - 1))
+                       list_move_tail(&device->dev_list, dev_list);
 
                ret = btrfs_alloc_dev_extent(trans, device,
                                             key.objectid,
@@ -839,6 +854,14 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                        }
                        *total_devs = 1;
                }
+       } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
+               if (rw == WRITE) {
+                       *total_devs = map->num_stripes;
+                       stripe_index = dev_nr;
+               } else {
+                       stripe_index = 0;
+                       *total_devs = 1;
+               }
        } else {
                /*
                 * after this do_div call, stripe_nr is the number of stripes
@@ -851,7 +874,8 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
        *phys = map->stripes[stripe_index].physical + stripe_offset +
                stripe_nr * map->stripe_len;
 
-       if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1)) {
+       if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
+                        BTRFS_BLOCK_GROUP_DUP)) {
                /* we limit the length of each bio to what fits in a stripe */
                *length = min_t(u64, em->len - offset,
                              map->stripe_len - stripe_offset);