Btrfs: Add balance ioctl to restripe the chunks

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 106 insertions, 9 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b93c15aa17db..6476ecbf132e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -869,6 +869,107 @@ out:
         return 0;
 }
 
+static u64 div_factor(u64 num, int factor)
+{
+        if (factor == 10)
+                return num;
+        num *= factor;
+        do_div(num, 10);
+        return num;
+}
+
+
+int btrfs_balance(struct btrfs_root *dev_root)
+{
+        int ret;
+        struct list_head *cur;
+        struct list_head *devices = &dev_root->fs_info->fs_devices->devices;
+        struct btrfs_device *device;
+        u64 old_size;
+        u64 size_to_free;
+        struct btrfs_path *path;
+        struct btrfs_key key;
+        struct btrfs_chunk *chunk;
+        struct btrfs_root *chunk_root = dev_root->fs_info->chunk_root;
+        struct btrfs_trans_handle *trans;
+        struct btrfs_key found_key;
+
+
+        dev_root = dev_root->fs_info->dev_root;
+
+        mutex_lock(&dev_root->fs_info->fs_mutex);
+        /* step one make some room on all the devices */
+        list_for_each(cur, devices) {
+                device = list_entry(cur, struct btrfs_device, dev_list);
+                old_size = device->total_bytes;
+                size_to_free = div_factor(old_size, 1);
+                size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
+                if (device->total_bytes - device->bytes_used > size_to_free)
+                        continue;
+
+                ret = btrfs_shrink_device(device, old_size - size_to_free);
+                BUG_ON(ret);
+
+                trans = btrfs_start_transaction(dev_root, 1);
+                BUG_ON(!trans);
+
+                ret = btrfs_grow_device(trans, device, old_size);
+                BUG_ON(ret);
+
+                btrfs_end_transaction(trans, dev_root);
+        }
+
+        /* step two, relocate all the chunks */
+        path = btrfs_alloc_path();
+        BUG_ON(!path);
+
+        key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+        key.offset = (u64)-1;
+        key.type = BTRFS_CHUNK_ITEM_KEY;
+
+        while(1) {
+                ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
+                if (ret < 0)
+                        goto error;
+
+                /*
+                 * this shouldn't happen, it means the last relocate
+                 * failed
+                 */
+                if (ret == 0)
+                        break;
+
+                ret = btrfs_previous_item(chunk_root, path, 0,
+                                          BTRFS_CHUNK_ITEM_KEY);
+                if (ret) {
+                        break;
+                }
+                btrfs_item_key_to_cpu(path->nodes[0], &found_key,
+                                      path->slots[0]);
+                if (found_key.objectid != key.objectid)
+                        break;
+                chunk = btrfs_item_ptr(path->nodes[0],
+                                       path->slots[0],
+                                       struct btrfs_chunk);
+                key.offset = found_key.offset;
+                /* chunk zero is special */
+                if (key.offset == 0)
+                        break;
+
+                ret = btrfs_relocate_chunk(chunk_root,
+                                           chunk_root->root_key.objectid,
+                                           found_key.objectid,
+                                           found_key.offset);
+                BUG_ON(ret);
+                btrfs_release_path(chunk_root, path);
+        }
+        ret = 0;
+error:
+        btrfs_free_path(path);
+        mutex_unlock(&dev_root->fs_info->fs_mutex);
+        return ret;
+}
+
 /*
  * shrinking a device means finding all of the device extents past
  * the new size, and then following the back refs to the chunks.
@@ -985,15 +1086,6 @@ int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
         return 0;
 }
 
-static u64 div_factor(u64 num, int factor)
-{
-        if (factor == 10)
-                return num;
-        num *= factor;
-        do_div(num, 10);
-        return num;
-}
-
 static u64 chunk_bytes_by_type(u64 type, u64 calc_size, int num_stripes,
                                int sub_stripes)
 {
@@ -1040,6 +1132,11 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         int stripe_len = 64 * 1024;
         struct btrfs_key key;
 
+        if ((type & BTRFS_BLOCK_GROUP_RAID1) &&
+            (type & BTRFS_BLOCK_GROUP_DUP)) {
+                WARN_ON(1);
+                type &= ~BTRFS_BLOCK_GROUP_DUP;
+        }
         dev_list = &extent_root->fs_info->fs_devices->alloc_list;
         if (list_empty(dev_list))
                 return -ENOSPC;