Btrfs: Fix cache_block_group to catch holes at the start of the group
[deliverable/linux.git] / fs / btrfs / extent-tree.c
index 5ace2c33f1aa7fb5bc7c59d360b08db2c1aa3eb4..9151850266b0bb7ae85cec3703d1bc4780f1bdb8 100644 (file)
 #include "print-tree.h"
 #include "transaction.h"
 
-static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-                           *orig_root, u64 num_blocks, u64 search_start,
-                           u64 search_end, u64 hint_block,
-                           struct btrfs_key *ins, u64 exclude_start,
-                           u64 exclude_nr, int data);
 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
                                 btrfs_root *extent_root);
 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
                               btrfs_root *extent_root);
 
-static void reada_extent_leaves(struct btrfs_root *root,
-                               struct btrfs_path *path, u64 limit)
-{
-       struct btrfs_node *node;
-       int i;
-       int nritems;
-       u64 item_objectid;
-       u64 blocknr;
-       int slot;
-       int ret;
-
-       if (!path->nodes[1])
-               return;
-       node = btrfs_buffer_node(path->nodes[1]);
-       slot = path->slots[1] + 1;
-       nritems = btrfs_header_nritems(&node->header);
-       for (i = slot; i < nritems && i < slot + 8; i++) {
-               item_objectid = btrfs_disk_key_objectid(&node->ptrs[i].key);
-               if (item_objectid > limit)
-                       break;
-               blocknr = btrfs_node_blockptr(node, i);
-               ret = readahead_tree_block(root, blocknr);
-               if (ret)
-                       break;
-       }
-}
-
 static int cache_block_group(struct btrfs_root *root,
                             struct btrfs_block_group_cache *block_group)
 {
@@ -71,7 +39,7 @@ static int cache_block_group(struct btrfs_root *root,
        u64 i;
        u64 last = 0;
        u64 hole_size;
-       u64 limit;
+       u64 first_free;
        int found = 0;
 
        root = root->fs_info->extent_root;
@@ -84,72 +52,74 @@ static int cache_block_group(struct btrfs_root *root,
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
+
+       path->reada = 2;
+       first_free = block_group->key.objectid;
        key.objectid = block_group->key.objectid;
        key.flags = 0;
        key.offset = 0;
+
        btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+
        if (ret < 0)
                return ret;
+
        if (ret && path->slots[0] > 0)
                path->slots[0]--;
-       limit = block_group->key.objectid + block_group->key.offset;
-       reada_extent_leaves(root, path, limit);
+
        while(1) {
                leaf = btrfs_buffer_leaf(path->nodes[0]);
                slot = path->slots[0];
                if (slot >= btrfs_header_nritems(&leaf->header)) {
-                       reada_extent_leaves(root, path, limit);
                        ret = btrfs_next_leaf(root, path);
                        if (ret < 0)
                                goto err;
                        if (ret == 0) {
                                continue;
                        } else {
-                               if (found) {
-                                       hole_size = block_group->key.objectid +
-                                               block_group->key.offset - last;
-                               } else {
-                                       last = block_group->key.objectid;
-                                       hole_size = block_group->key.offset;
-                               }
-                               for (i = 0; i < hole_size; i++) {
-                                       set_radix_bit(extent_radix,
-                                                     last + i);
-                               }
                                break;
                        }
                }
+
                btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
+               if (key.objectid < block_group->key.objectid) {
+                       if (key.objectid + key.offset > first_free)
+                               first_free = key.objectid + key.offset;
+                       goto next;
+               }
+
                if (key.objectid >= block_group->key.objectid +
                    block_group->key.offset) {
-                       if (found) {
-                               hole_size = block_group->key.objectid +
-                                       block_group->key.offset - last;
-                       } else {
-                               last = block_group->key.objectid;
-                               hole_size = block_group->key.offset;
-                       }
-                       for (i = 0; i < hole_size; i++) {
-                               set_radix_bit(extent_radix, last + i);
-                       }
                        break;
                }
+
                if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
                        if (!found) {
-                               last = key.objectid + key.offset;
+                               last = first_free;
                                found = 1;
-                       } else {
-                               hole_size = key.objectid - last;
-                               for (i = 0; i < hole_size; i++) {
-                                       set_radix_bit(extent_radix, last + i);
-                               }
-                               last = key.objectid + key.offset;
                        }
+                       hole_size = key.objectid - last;
+                       for (i = 0; i < hole_size; i++) {
+                               set_radix_bit(extent_radix, last + i);
+                       }
+                       last = key.objectid + key.offset;
                }
+next:
                path->slots[0]++;
        }
 
+       if (!found)
+               last = first_free;
+       if (block_group->key.objectid +
+           block_group->key.offset > last) {
+               hole_size = block_group->key.objectid +
+                       block_group->key.offset - last;
+               for (i = 0; i < hole_size; i++) {
+                       set_radix_bit(extent_radix,
+                                       last + i);
+               }
+       }
        block_group->cached = 1;
 err:
        btrfs_free_path(path);
@@ -201,9 +171,6 @@ static u64 find_search_start(struct btrfs_root *root,
 
        if (cache->data)
                goto out;
-       if (num > 1) {
-               last = max(last, cache->last_prealloc);
-       }
 again:
        ret = cache_block_group(root, cache);
        if (ret)
@@ -282,7 +249,7 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
        if (search_start) {
                struct btrfs_block_group_cache *shint;
                shint = btrfs_lookup_block_group(info, search_start);
-               if (shint->data == data) {
+               if (shint && shint->data == data) {
                        used = btrfs_block_group_used(&shint->item);
                        if (used + shint->pinned <
                            div_factor(shint->key.offset, factor)) {
@@ -401,18 +368,12 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
        struct btrfs_key key;
        struct btrfs_leaf *l;
        struct btrfs_extent_item *item;
-       struct btrfs_key ins;
        u32 refs;
 
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
-       ret = find_free_extent(trans, root->fs_info->extent_root, 0, 0,
-                              (u64)-1, 0, &ins, 0, 0, 0);
-       if (ret) {
-               btrfs_free_path(path);
-               return ret;
-       }
+
        key.objectid = blocknr;
        key.flags = 0;
        btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
@@ -438,6 +399,14 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
        return 0;
 }
 
+int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root)
+{
+       finish_current_insert(trans, root->fs_info->extent_root);
+       del_pending_extents(trans, root->fs_info->extent_root);
+       return 0;
+}
+
 static int lookup_extent_ref(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root, u64 blocknr,
                             u64 num_blocks, u32 *refs)
@@ -559,13 +528,7 @@ static int write_one_cache_group(struct btrfs_trans_handle *trans,
        int pending_ret;
        struct btrfs_root *extent_root = root->fs_info->extent_root;
        struct btrfs_block_group_item *bi;
-       struct btrfs_key ins;
 
-       ret = find_free_extent(trans, extent_root, 0, 0, (u64)-1, 0, &ins,
-                              0, 0, 0);
-       /* FIXME, set bit to recalc cache groups on next mount */
-       if (ret)
-               return ret;
        ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
        if (ret < 0)
                goto fail;
@@ -733,13 +696,6 @@ static int update_block_group(struct btrfs_trans_handle *trans,
        return 0;
 }
 
-static int try_remove_page(struct address_space *mapping, unsigned long index)
-{
-       int ret;
-       ret = invalidate_mapping_pages(mapping, index, index);
-       return ret;
-}
-
 int btrfs_copy_pinned(struct btrfs_root *root, struct radix_tree_root *copy)
 {
        unsigned long gang[8];
@@ -758,6 +714,9 @@ int btrfs_copy_pinned(struct btrfs_root *root, struct radix_tree_root *copy)
                        last = gang[i] + 1;
                }
        }
+       ret = find_first_radix_bit(&root->fs_info->extent_ins_radix, gang, 0,
+                                  ARRAY_SIZE(gang));
+       WARN_ON(ret);
        return 0;
 }
 
@@ -766,7 +725,6 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
                               struct radix_tree_root *unpin_radix)
 {
        unsigned long gang[8];
-       struct inode *btree_inode = root->fs_info->btree_inode;
        struct btrfs_block_group_cache *block_group;
        u64 first = 0;
        int ret;
@@ -791,14 +749,9 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
                                block_group->pinned--;
                                if (gang[i] < block_group->last_alloc)
                                        block_group->last_alloc = gang[i];
-                               if (gang[i] < block_group->last_prealloc)
-                                       block_group->last_prealloc = gang[i];
                                if (!block_group->data)
                                        set_radix_bit(extent_radix, gang[i]);
                        }
-                       try_remove_page(btree_inode->i_mapping,
-                                       gang[i] << (PAGE_CACHE_SHIFT -
-                                                   btree_inode->i_blkbits));
                }
        }
        return 0;
@@ -811,7 +764,8 @@ static int finish_current_insert(struct btrfs_trans_handle *trans, struct
        struct btrfs_extent_item extent_item;
        int i;
        int ret;
-       u64 super_blocks_used;
+       int err;
+       unsigned long gang[8];
        struct btrfs_fs_info *info = extent_root->fs_info;
 
        btrfs_set_extent_refs(&extent_item, 1);
@@ -820,16 +774,21 @@ static int finish_current_insert(struct btrfs_trans_handle *trans, struct
        btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
        btrfs_set_extent_owner(&extent_item, extent_root->root_key.objectid);
 
-       for (i = 0; i < extent_root->fs_info->extent_tree_insert_nr; i++) {
-               ins.objectid = extent_root->fs_info->extent_tree_insert[i];
-               super_blocks_used = btrfs_super_blocks_used(&info->super_copy);
-               btrfs_set_super_blocks_used(&info->super_copy,
-                                           super_blocks_used + 1);
-               ret = btrfs_insert_item(trans, extent_root, &ins, &extent_item,
-                                       sizeof(extent_item));
-               BUG_ON(ret);
+       while(1) {
+               ret = find_first_radix_bit(&info->extent_ins_radix, gang, 0,
+                                          ARRAY_SIZE(gang));
+               if (!ret)
+                       break;
+
+               for (i = 0; i < ret; i++) {
+                       ins.objectid = gang[i];
+                       err = btrfs_insert_item(trans, extent_root, &ins,
+                                               &extent_item,
+                                               sizeof(extent_item));
+                       clear_radix_bit(&info->extent_ins_radix, gang[i]);
+                       WARN_ON(err);
+               }
        }
-       extent_root->fs_info->extent_tree_insert_nr = 0;
        return 0;
 }
 
@@ -882,7 +841,6 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
        struct btrfs_root *extent_root = info->extent_root;
        int ret;
        struct btrfs_extent_item *ei;
-       struct btrfs_key ins;
        u32 refs;
 
        key.objectid = blocknr;
@@ -894,12 +852,6 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
        if (!path)
                return -ENOMEM;
 
-       ret = find_free_extent(trans, root, 0, 0, (u64)-1, 0, &ins, 0, 0, 0);
-       if (ret) {
-               btrfs_free_path(path);
-               return ret;
-       }
-
        ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
        if (ret < 0)
                return ret;
@@ -911,16 +863,23 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
        btrfs_set_extent_refs(ei, refs);
        btrfs_mark_buffer_dirty(path->nodes[0]);
        if (refs == 0) {
-               u64 super_blocks_used;
+               u64 super_blocks_used, root_blocks_used;
 
                if (pin) {
                        ret = pin_down_block(root, blocknr, 0);
                        BUG_ON(ret);
                }
 
+               /* block accounting for super block */
                super_blocks_used = btrfs_super_blocks_used(&info->super_copy);
                btrfs_set_super_blocks_used(&info->super_copy,
                                            super_blocks_used - num_blocks);
+
+               /* block accounting for root item */
+               root_blocks_used = btrfs_root_blocks_used(&root->root_item);
+               btrfs_set_root_blocks_used(&root->root_item,
+                                          root_blocks_used - num_blocks);
+
                ret = btrfs_del_item(trans, extent_root, path);
                if (ret) {
                        return ret;
@@ -1011,8 +970,8 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
  * Any available blocks before search_start are skipped.
  */
 static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-                           *orig_root, u64 num_blocks, u64 search_start, u64
-                           search_end, u64 hint_block,
+                           *orig_root, u64 num_blocks, u64 empty_size,
+                           u64 search_start, u64 search_end, u64 hint_block,
                            struct btrfs_key *ins, u64 exclude_start,
                            u64 exclude_nr, int data)
 {
@@ -1029,35 +988,16 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
        struct btrfs_root * root = orig_root->fs_info->extent_root;
        struct btrfs_fs_info *info = root->fs_info;
        int total_needed = num_blocks;
-       int total_found = 0;
-       int fill_prealloc = 0;
        int level;
        struct btrfs_block_group_cache *block_group;
        int full_scan = 0;
        int wrapped = 0;
-       u64 limit;
 
+       WARN_ON(num_blocks < 1);
        ins->flags = 0;
        btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
 
        level = btrfs_header_level(btrfs_buffer_header(root->node));
-       if (num_blocks == 0) {
-               fill_prealloc = 1;
-               num_blocks = 1;
-               total_needed = (min(level + 1, BTRFS_MAX_LEVEL) + 2) * 3;
-       }
-       if (fill_prealloc) {
-               u64 first;
-               int nr = info->extent_tree_prealloc_nr;
-               first = info->extent_tree_prealloc[nr - 1];
-               if (info->extent_tree_prealloc_nr >= total_needed &&
-                   first >= search_start) {
-                       ins->objectid = info->extent_tree_prealloc[0];
-                       ins->offset = 1;
-                       return 0;
-               }
-               info->extent_tree_prealloc_nr = 0;
-       }
        if (search_end == (u64)-1)
                search_end = btrfs_super_total_blocks(&info->super_copy);
        if (hint_block) {
@@ -1070,6 +1010,7 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                                                     data, 1);
        }
 
+       total_needed += empty_size;
        path = btrfs_alloc_path();
 
 check_failed:
@@ -1083,6 +1024,7 @@ check_failed:
        ins->objectid = search_start;
        ins->offset = 0;
        start_found = 0;
+       path->reada = 2;
 
        ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
        if (ret < 0)
@@ -1116,16 +1058,6 @@ check_failed:
                l = btrfs_buffer_leaf(path->nodes[0]);
                slot = path->slots[0];
                if (slot >= btrfs_header_nritems(&l->header)) {
-                       if (fill_prealloc) {
-                               info->extent_tree_prealloc_nr = 0;
-                               total_found = 0;
-                       }
-                       if (start_found)
-                               limit = last_block +
-                                       (block_group->key.offset >> 1);
-                       else
-                               limit = search_start +
-                                       (block_group->key.offset >> 1);
                        ret = btrfs_next_leaf(root, path);
                        if (ret == 0)
                                continue;
@@ -1185,75 +1117,31 @@ check_pending:
                        goto error;
                }
                search_start = orig_search_start;
-               if (wrapped)
+               if (wrapped) {
+                       if (!full_scan)
+                               total_needed -= empty_size;
                        full_scan = 1;
-               else
+               else
                        wrapped = 1;
                goto new_group;
        }
        for (test_block = ins->objectid;
             test_block < ins->objectid + num_blocks; test_block++) {
-               if (test_radix_bit(&info->pinned_radix, test_block)) {
+               if (test_radix_bit(&info->pinned_radix, test_block) ||
+                   test_radix_bit(&info->extent_ins_radix, test_block)) {
                        search_start = test_block + 1;
                        goto new_group;
                }
        }
-       if (!fill_prealloc && info->extent_tree_insert_nr) {
-               u64 last =
-                 info->extent_tree_insert[info->extent_tree_insert_nr - 1];
-               if (ins->objectid + num_blocks >
-                   info->extent_tree_insert[0] &&
-                   ins->objectid <= last) {
-                       search_start = last + 1;
-                       WARN_ON(!full_scan);
-                       goto new_group;
-               }
-       }
-       if (!fill_prealloc && info->extent_tree_prealloc_nr) {
-               u64 first =
-                 info->extent_tree_prealloc[info->extent_tree_prealloc_nr - 1];
-               if (ins->objectid + num_blocks > first &&
-                   ins->objectid <= info->extent_tree_prealloc[0]) {
-                       search_start = info->extent_tree_prealloc[0] + 1;
-                       goto new_group;
-               }
-       }
        if (exclude_nr > 0 && (ins->objectid + num_blocks > exclude_start &&
            ins->objectid < exclude_start + exclude_nr)) {
                search_start = exclude_start + exclude_nr;
                goto new_group;
        }
-       if (fill_prealloc) {
-               int nr;
-               test_block = ins->objectid;
-               if (test_block - info->extent_tree_prealloc[total_needed - 1] >=
-                   leaf_range(root)) {
-                       total_found = 0;
-                       info->extent_tree_prealloc_nr = total_found;
-               }
-               while(test_block < ins->objectid + ins->offset &&
-                     total_found < total_needed) {
-                       nr = total_needed - total_found - 1;
-                       BUG_ON(nr < 0);
-                       info->extent_tree_prealloc[nr] = test_block;
-                       total_found++;
-                       test_block++;
-               }
-               if (total_found < total_needed) {
-                       search_start = test_block;
-                       goto new_group;
-               }
-               info->extent_tree_prealloc_nr = total_found;
-       }
        if (!data) {
                block_group = btrfs_lookup_block_group(info, ins->objectid);
-               if (block_group) {
-                       if (fill_prealloc)
-                               block_group->last_prealloc =
-                                    info->extent_tree_prealloc[total_needed-1];
-                       else
-                               trans->block_group = block_group;
-               }
+               if (block_group)
+                       trans->block_group = block_group;
        }
        ins->offset = num_blocks;
        btrfs_free_path(path);
@@ -1266,9 +1154,11 @@ new_group:
                        ret = -ENOSPC;
                        goto error;
                }
-               if (wrapped)
+               if (wrapped) {
+                       if (!full_scan)
+                               total_needed -= empty_size;
                        full_scan = 1;
-               else
+               else
                        wrapped = 1;
        }
        block_group = btrfs_lookup_block_group(info, search_start);
@@ -1292,90 +1182,54 @@ error:
  */
 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
                       struct btrfs_root *root, u64 owner,
-                      u64 num_blocks, u64 hint_block,
+                      u64 num_blocks, u64 empty_size, u64 hint_block,
                       u64 search_end, struct btrfs_key *ins, int data)
 {
        int ret;
        int pending_ret;
-       u64 super_blocks_used;
+       u64 super_blocks_used, root_blocks_used;
        u64 search_start = 0;
-       u64 exclude_start = 0;
-       u64 exclude_nr = 0;
        struct btrfs_fs_info *info = root->fs_info;
        struct btrfs_root *extent_root = info->extent_root;
        struct btrfs_extent_item extent_item;
-       struct btrfs_key prealloc_key;
 
        btrfs_set_extent_refs(&extent_item, 1);
        btrfs_set_extent_owner(&extent_item, owner);
 
-       if (root == extent_root) {
-               int nr;
-               BUG_ON(info->extent_tree_prealloc_nr == 0);
-               BUG_ON(num_blocks != 1);
-               ins->offset = 1;
-               info->extent_tree_prealloc_nr--;
-               nr = info->extent_tree_prealloc_nr;
-               ins->objectid = info->extent_tree_prealloc[nr];
-               info->extent_tree_insert[info->extent_tree_insert_nr++] =
-                       ins->objectid;
-               ret = update_block_group(trans, root,
-                                        ins->objectid, ins->offset, 1, 0, 0);
-               BUG_ON(ret);
-               return 0;
-       }
-
-       /*
-        * if we're doing a data allocation, preallocate room in the
-        * extent tree first.  This way the extent tree blocks end up
-        * in the correct block group.
-        */
-       if (data) {
-               ret = find_free_extent(trans, root, 0, 0,
-                                      search_end, 0, &prealloc_key, 0, 0, 0);
-               BUG_ON(ret);
-               if (ret)
-                       return ret;
-               exclude_nr = info->extent_tree_prealloc_nr;
-               exclude_start = info->extent_tree_prealloc[exclude_nr - 1];
-       }
-
-       /* do the real allocation */
-       ret = find_free_extent(trans, root, num_blocks, search_start,
-                              search_end, hint_block, ins,
-                              exclude_start, exclude_nr, data);
+       WARN_ON(num_blocks < 1);
+       ret = find_free_extent(trans, root, num_blocks, empty_size,
+                              search_start, search_end, hint_block, ins,
+                              trans->alloc_exclude_start,
+                              trans->alloc_exclude_nr, data);
        BUG_ON(ret);
        if (ret)
                return ret;
 
-       /*
-        * if we're doing a metadata allocation, preallocate space in the
-        * extent tree second.  This way, we don't create a tiny hole
-        * in the allocation map between any unused preallocation blocks
-        * and the metadata block we're actually allocating.  On disk,
-        * it'll go:
-        * [block we've allocated], [used prealloc 1], [ unused prealloc ]
-        * The unused prealloc will get reused the next time around.
-        */
-       if (!data) {
-               exclude_start = ins->objectid;
-               exclude_nr = ins->offset;
-               hint_block = exclude_start + exclude_nr;
-               ret = find_free_extent(trans, root, 0, search_start,
-                                      search_end, hint_block,
-                                      &prealloc_key, exclude_start,
-                                      exclude_nr, 0);
-               BUG_ON(ret);
-               if (ret)
-                       return ret;
-       }
-
+       /* block accounting for super block */
        super_blocks_used = btrfs_super_blocks_used(&info->super_copy);
        btrfs_set_super_blocks_used(&info->super_copy, super_blocks_used +
                                    num_blocks);
+
+       /* block accounting for root item */
+       root_blocks_used = btrfs_root_blocks_used(&root->root_item);
+       btrfs_set_root_blocks_used(&root->root_item, root_blocks_used +
+                                  num_blocks);
+
+       if (root == extent_root) {
+               BUG_ON(num_blocks != 1);
+               set_radix_bit(&root->fs_info->extent_ins_radix, ins->objectid);
+               goto update_block;
+       }
+
+       WARN_ON(trans->alloc_exclude_nr);
+       trans->alloc_exclude_start = ins->objectid;
+       trans->alloc_exclude_nr = ins->offset;
        ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
                                sizeof(extent_item));
 
+       trans->alloc_exclude_start = 0;
+       trans->alloc_exclude_nr = 0;
+
        BUG_ON(ret);
        finish_current_insert(trans, extent_root);
        pending_ret = del_pending_extents(trans, extent_root);
@@ -1385,6 +1239,8 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
        if (pending_ret) {
                return pending_ret;
        }
+
+update_block:
        ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0,
                                 data);
        BUG_ON(ret);
@@ -1396,14 +1252,15 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
  * returns the tree buffer or NULL.
  */
 struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-                                          struct btrfs_root *root, u64 hint)
+                                          struct btrfs_root *root, u64 hint,
+                                          u64 empty_size)
 {
        struct btrfs_key ins;
        int ret;
        struct buffer_head *buf;
 
        ret = btrfs_alloc_extent(trans, root, root->root_key.objectid,
-                                1, hint, (unsigned long)-1, &ins, 0);
+                                1, empty_size, hint, (u64)-1, &ins, 0);
        if (ret) {
                BUG_ON(ret > 0);
                return ERR_PTR(ret);
@@ -1413,8 +1270,10 @@ struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                btrfs_free_extent(trans, root, ins.objectid, 1, 0);
                return ERR_PTR(-ENOMEM);
        }
+       WARN_ON(buffer_dirty(buf));
        set_buffer_uptodate(buf);
        set_buffer_checked(buf);
+       set_buffer_defrag(buf);
        set_radix_bit(&trans->transaction->dirty_pages, buf->b_page->index);
        return buf;
 }
@@ -1471,7 +1330,10 @@ static void reada_walk_down(struct btrfs_root *root,
                BUG_ON(ret);
                if (refs != 1)
                        continue;
+               mutex_unlock(&root->fs_info->fs_mutex);
                ret = readahead_tree_block(root, blocknr);
+               cond_resched();
+               mutex_lock(&root->fs_info->fs_mutex);
                if (ret)
                        break;
        }
@@ -1530,7 +1392,25 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
                        BUG_ON(ret);
                        continue;
                }
-               next = read_tree_block(root, blocknr);
+               next = btrfs_find_tree_block(root, blocknr);
+               if (!next || !buffer_uptodate(next)) {
+                       brelse(next);
+                       mutex_unlock(&root->fs_info->fs_mutex);
+                       next = read_tree_block(root, blocknr);
+                       mutex_lock(&root->fs_info->fs_mutex);
+
+                       /* we dropped the lock, check one more time */
+                       ret = lookup_extent_ref(trans, root, blocknr, 1, &refs);
+                       BUG_ON(ret);
+                       if (refs != 1) {
+                               path->slots[*level]++;
+                               brelse(next);
+                               ret = btrfs_free_extent(trans, root,
+                                                       blocknr, 1, 1);
+                               BUG_ON(ret);
+                               continue;
+                       }
+               }
                WARN_ON(*level <= 0);
                if (path->nodes[*level-1])
                        btrfs_block_release(root, path->nodes[*level-1]);
@@ -1561,12 +1441,21 @@ static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
        int i;
        int slot;
        int ret;
+       struct btrfs_root_item *root_item = &root->root_item;
+
        for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
                slot = path->slots[i];
                if (slot < btrfs_header_nritems(
                    btrfs_buffer_header(path->nodes[i])) - 1) {
+                       struct btrfs_node *node;
+                       node = btrfs_buffer_node(path->nodes[i]);
                        path->slots[i]++;
                        *level = i;
+                       WARN_ON(*level == 0);
+                       memcpy(&root_item->drop_progress,
+                              &node->ptrs[path->slots[i]].key,
+                              sizeof(root_item->drop_progress));
+                       root_item->drop_level = i;
                        return 0;
                } else {
                        ret = btrfs_free_extent(trans, root,
@@ -1587,7 +1476,7 @@ static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
  * decremented.
  */
 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
-                       *root, struct buffer_head *snap)
+                       *root)
 {
        int ret = 0;
        int wret;
@@ -1595,14 +1484,34 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
        struct btrfs_path *path;
        int i;
        int orig_level;
+       struct btrfs_root_item *root_item = &root->root_item;
 
        path = btrfs_alloc_path();
        BUG_ON(!path);
 
-       level = btrfs_header_level(btrfs_buffer_header(snap));
+       level = btrfs_header_level(btrfs_buffer_header(root->node));
        orig_level = level;
-       path->nodes[level] = snap;
-       path->slots[level] = 0;
+       if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
+               path->nodes[level] = root->node;
+               path->slots[level] = 0;
+       } else {
+               struct btrfs_key key;
+               struct btrfs_disk_key *found_key;
+               struct btrfs_node *node;
+
+               btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
+               level = root_item->drop_level;
+               path->lowest_level = level;
+               wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+               if (wret < 0) {
+                       ret = wret;
+                       goto out;
+               }
+               node = btrfs_buffer_node(path->nodes[level]);
+               found_key = &node->ptrs[path->slots[level]].key;
+               WARN_ON(memcmp(found_key, &root_item->drop_progress,
+                              sizeof(*found_key)));
+       }
        while(1) {
                wret = walk_down_tree(trans, root, path, &level);
                if (wret > 0)
@@ -1615,12 +1524,17 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
                        break;
                if (wret < 0)
                        ret = wret;
+               ret = -EAGAIN;
+               get_bh(root->node);
+               break;
        }
        for (i = 0; i <= orig_level; i++) {
                if (path->nodes[i]) {
                        btrfs_block_release(root, path->nodes[i]);
+                       path->nodes[i] = 0;
                }
        }
+out:
        btrfs_free_path(path);
        return ret;
 }
@@ -1728,7 +1642,6 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                memcpy(&cache->key, &found_key, sizeof(found_key));
                cache->last_alloc = cache->key.objectid;
                cache->first_free = cache->key.objectid;
-               cache->last_prealloc = cache->key.objectid;
                cache->pinned = 0;
                cache->cached = 0;
 
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