Btrfs: more inode indexed directory work
[linux-2.6-block.git] / fs / btrfs / extent-tree.c
index 9bc4ad38876dfa65a5114d04400658d04fb8294e..7c21f63f1b93321744679dec4436edc42c43dbf2 100644 (file)
@@ -1,7 +1,4 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include "kerncompat.h"
-#include "radix-tree.h"
+#include <linux/module.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "print-tree.h"
@@ -12,22 +9,13 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                            search_end, struct btrfs_key *ins);
 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
                                 btrfs_root *extent_root);
-static int run_pending(struct btrfs_trans_handle *trans, struct btrfs_root
-                      *extent_root);
-
-/*
- * pending extents are blocks that we're trying to allocate in the extent
- * map while trying to grow the map because of other allocations.  To avoid
- * recursing, they are tagged in the radix tree and cleaned up after
- * other allocations are done.  The pending tag is also used in the same
- * manner for deletes.
- */
-#define CTREE_EXTENT_PENDING_DEL 0
+static int del_pending_extents(struct btrfs_trans_handle *trans, struct
+                              btrfs_root *extent_root);
 
 static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
-                        *root, u64 blocknr)
+                        *root, u64 blocknr, u64 num_blocks)
 {
-       struct btrfs_path path;
+       struct btrfs_path *path;
        int ret;
        struct btrfs_key key;
        struct btrfs_leaf *l;
@@ -37,66 +25,91 @@ static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
 
        find_free_extent(trans, root->fs_info->extent_root, 0, 0, (u64)-1,
                         &ins);
-       btrfs_init_path(&path);
+       path = btrfs_alloc_path();
+       BUG_ON(!path);
+       btrfs_init_path(path);
        key.objectid = blocknr;
        key.flags = 0;
        btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-       key.offset = 1;
-       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
+       key.offset = num_blocks;
+       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
                                0, 1);
        if (ret != 0)
                BUG();
        BUG_ON(ret != 0);
-       l = &path.nodes[0]->leaf;
-       item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
+       l = btrfs_buffer_leaf(path->nodes[0]);
+       item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
        refs = btrfs_extent_refs(item);
        btrfs_set_extent_refs(item, refs + 1);
+       btrfs_mark_buffer_dirty(path->nodes[0]);
 
-       BUG_ON(list_empty(&path.nodes[0]->dirty));
-       btrfs_release_path(root->fs_info->extent_root, &path);
+       btrfs_release_path(root->fs_info->extent_root, path);
+       btrfs_free_path(path);
        finish_current_insert(trans, root->fs_info->extent_root);
-       run_pending(trans, root->fs_info->extent_root);
+       del_pending_extents(trans, root->fs_info->extent_root);
        return 0;
 }
 
 static int lookup_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
-                           *root, u64 blocknr, u32 *refs)
+                           *root, u64 blocknr, u64 num_blocks, u32 *refs)
 {
-       struct btrfs_path path;
+       struct btrfs_path *path;
        int ret;
        struct btrfs_key key;
        struct btrfs_leaf *l;
        struct btrfs_extent_item *item;
-       btrfs_init_path(&path);
+
+       path = btrfs_alloc_path();
+       btrfs_init_path(path);
        key.objectid = blocknr;
-       key.offset = 1;
+       key.offset = num_blocks;
        key.flags = 0;
        btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
+       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
                                0, 0);
        if (ret != 0)
                BUG();
-       l = &path.nodes[0]->leaf;
-       item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
+       l = btrfs_buffer_leaf(path->nodes[0]);
+       item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
        *refs = btrfs_extent_refs(item);
-       btrfs_release_path(root->fs_info->extent_root, &path);
+       btrfs_release_path(root->fs_info->extent_root, path);
+       btrfs_free_path(path);
        return 0;
 }
 
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                 struct btrfs_buffer *buf)
+                 struct buffer_head *buf)
 {
        u64 blocknr;
+       struct btrfs_node *buf_node;
+       struct btrfs_leaf *buf_leaf;
+       struct btrfs_disk_key *key;
+       struct btrfs_file_extent_item *fi;
        int i;
+       int leaf;
+       int ret;
 
        if (!root->ref_cows)
                return 0;
-       if (btrfs_is_leaf(&buf->node))
-               return 0;
-
-       for (i = 0; i < btrfs_header_nritems(&buf->node.header); i++) {
-               blocknr = btrfs_node_blockptr(&buf->node, i);
-               inc_block_ref(trans, root, blocknr);
+       buf_node = btrfs_buffer_node(buf);
+       leaf = btrfs_is_leaf(buf_node);
+       buf_leaf = btrfs_buffer_leaf(buf);
+       for (i = 0; i < btrfs_header_nritems(&buf_node->header); i++) {
+               if (leaf) {
+                       key = &buf_leaf->items[i].key;
+                       if (btrfs_disk_key_type(key) != BTRFS_EXTENT_DATA_KEY)
+                               continue;
+                       fi = btrfs_item_ptr(buf_leaf, i,
+                                           struct btrfs_file_extent_item);
+                       ret = inc_block_ref(trans, root,
+                                   btrfs_file_extent_disk_blocknr(fi),
+                                   btrfs_file_extent_disk_num_blocks(fi));
+                       BUG_ON(ret);
+               } else {
+                       blocknr = btrfs_node_blockptr(buf_node, i);
+                       ret = inc_block_ref(trans, root, blocknr, 1);
+                       BUG_ON(ret);
+               }
        }
        return 0;
 }
@@ -108,21 +121,21 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans, struct
        u64 first = 0;
        int ret;
        int i;
+       struct radix_tree_root *pinned_radix = &root->fs_info->pinned_radix;
 
        while(1) {
-               ret = radix_tree_gang_lookup(&root->fs_info->pinned_radix,
-                                            (void **)gang, 0,
-                                            ARRAY_SIZE(gang));
+               ret = find_first_radix_bit(pinned_radix, gang,
+                                          ARRAY_SIZE(gang));
                if (!ret)
                        break;
                if (!first)
                        first = gang[0];
                for (i = 0; i < ret; i++) {
-                       radix_tree_delete(&root->fs_info->pinned_radix,
-                                         gang[i]);
+                       clear_radix_bit(pinned_radix, gang[i]);
                }
        }
-       root->fs_info->last_insert.objectid = first;
+       if (root->fs_info->last_insert.objectid > first)
+               root->fs_info->last_insert.objectid = first;
        root->fs_info->last_insert.offset = 0;
        return 0;
 }
@@ -139,7 +152,7 @@ static int finish_current_insert(struct btrfs_trans_handle *trans, struct
 
        btrfs_set_extent_refs(&extent_item, 1);
        btrfs_set_extent_owner(&extent_item,
-               btrfs_header_parentid(&extent_root->node->node.header));
+               btrfs_header_parentid(btrfs_buffer_header(extent_root->node)));
        ins.offset = 1;
        ins.flags = 0;
        btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
@@ -158,13 +171,42 @@ static int finish_current_insert(struct btrfs_trans_handle *trans, struct
        return 0;
 }
 
+static int pin_down_block(struct btrfs_root *root, u64 blocknr, int pending)
+{
+       int err;
+       struct btrfs_header *header;
+       struct buffer_head *bh;
+
+       if (!pending) {
+               bh = btrfs_find_tree_block(root, blocknr);
+               if (bh) {
+                       if (buffer_uptodate(bh)) {
+                               u64 transid =
+                                   root->fs_info->running_transaction->transid;
+                               header = btrfs_buffer_header(bh);
+                               if (btrfs_header_generation(header) ==
+                                   transid) {
+                                       btrfs_block_release(root, bh);
+                                       return 0;
+                               }
+                       }
+                       btrfs_block_release(root, bh);
+               }
+               err = set_radix_bit(&root->fs_info->pinned_radix, blocknr);
+       } else {
+               err = set_radix_bit(&root->fs_info->pending_del_radix, blocknr);
+       }
+       BUG_ON(err);
+       return 0;
+}
+
 /*
  * remove an extent from the root, returns 0 on success
  */
 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                         *root, u64 blocknr, u64 num_blocks, int pin)
 {
-       struct btrfs_path path;
+       struct btrfs_path *path;
        struct btrfs_key key;
        struct btrfs_fs_info *info = root->fs_info;
        struct btrfs_root *extent_root = info->extent_root;
@@ -173,47 +215,46 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
        struct btrfs_key ins;
        u32 refs;
 
-       BUG_ON(pin && num_blocks != 1);
        key.objectid = blocknr;
        key.flags = 0;
        btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
        key.offset = num_blocks;
 
        find_free_extent(trans, root, 0, 0, (u64)-1, &ins);
-       btrfs_init_path(&path);
-       ret = btrfs_search_slot(trans, extent_root, &key, &path, -1, 1);
+       path = btrfs_alloc_path();
+       BUG_ON(!path);
+       btrfs_init_path(path);
+
+       ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
        if (ret) {
-               printf("failed to find %Lu\n", key.objectid);
+               printk("failed to find %Lu\n", key.objectid);
                btrfs_print_tree(extent_root, extent_root->node);
-               printf("failed to find %Lu\n", key.objectid);
+               printk("failed to find %Lu\n", key.objectid);
                BUG();
        }
-       ei = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0],
+       ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                            struct btrfs_extent_item);
        BUG_ON(ei->refs == 0);
        refs = btrfs_extent_refs(ei) - 1;
        btrfs_set_extent_refs(ei, refs);
+       btrfs_mark_buffer_dirty(path->nodes[0]);
        if (refs == 0) {
                u64 super_blocks_used;
+
                if (pin) {
-                       int err;
-                       radix_tree_preload(GFP_KERNEL);
-                       err = radix_tree_insert(&info->pinned_radix,
-                                               blocknr, (void *)blocknr);
-                       BUG_ON(err);
-                       radix_tree_preload_end();
+                       ret = pin_down_block(root, blocknr, 0);
+                       BUG_ON(ret);
                }
+
                super_blocks_used = btrfs_super_blocks_used(info->disk_super);
                btrfs_set_super_blocks_used(info->disk_super,
                                            super_blocks_used - num_blocks);
-               ret = btrfs_del_item(trans, extent_root, &path);
-               if (!pin && extent_root->fs_info->last_insert.objectid >
-                   blocknr)
-                       extent_root->fs_info->last_insert.objectid = blocknr;
+               ret = btrfs_del_item(trans, extent_root, path);
                if (ret)
                        BUG();
        }
-       btrfs_release_path(extent_root, &path);
+       btrfs_release_path(extent_root, path);
+       btrfs_free_path(path);
        finish_current_insert(trans, extent_root);
        return ret;
 }
@@ -226,39 +267,35 @@ static int del_pending_extents(struct btrfs_trans_handle *trans, struct
                               btrfs_root *extent_root)
 {
        int ret;
-       struct btrfs_buffer *gang[4];
+       int wret;
+       int err = 0;
+       unsigned long gang[4];
        int i;
+       struct radix_tree_root *pending_radix;
+       struct radix_tree_root *pinned_radix;
+
+       pending_radix = &extent_root->fs_info->pending_del_radix;
+       pinned_radix = &extent_root->fs_info->pinned_radix;
 
        while(1) {
-               ret = radix_tree_gang_lookup_tag(
-                                       &extent_root->fs_info->cache_radix,
-                                       (void **)gang, 0,
-                                       ARRAY_SIZE(gang),
-                                       CTREE_EXTENT_PENDING_DEL);
+               ret = find_first_radix_bit(pending_radix, gang,
+                                          ARRAY_SIZE(gang));
                if (!ret)
                        break;
                for (i = 0; i < ret; i++) {
-                       ret = __free_extent(trans, extent_root,
-                                           gang[i]->blocknr, 1, 1);
-                       radix_tree_tag_clear(&extent_root->fs_info->cache_radix,
-                                            gang[i]->blocknr,
-                                            CTREE_EXTENT_PENDING_DEL);
-                       btrfs_block_release(extent_root, gang[i]);
+                       wret = set_radix_bit(pinned_radix, gang[i]);
+                       BUG_ON(wret);
+                       wret = clear_radix_bit(pending_radix, gang[i]);
+                       BUG_ON(wret);
+                       wret = __free_extent(trans, extent_root,
+                                            gang[i], 1, 0);
+                       if (wret)
+                               err = wret;
                }
        }
-       return 0;
+       return err;
 }
 
-static int run_pending(struct btrfs_trans_handle *trans, struct btrfs_root
-                      *extent_root)
-{
-       while(radix_tree_tagged(&extent_root->fs_info->cache_radix,
-                               CTREE_EXTENT_PENDING_DEL))
-               del_pending_extents(trans, extent_root);
-       return 0;
-}
-
-
 /*
  * remove an extent from the root, returns 0 on success
  */
@@ -266,18 +303,15 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                      *root, u64 blocknr, u64 num_blocks, int pin)
 {
        struct btrfs_root *extent_root = root->fs_info->extent_root;
-       struct btrfs_buffer *t;
        int pending_ret;
        int ret;
 
        if (root == extent_root) {
-               t = find_tree_block(root, blocknr);
-               radix_tree_tag_set(&root->fs_info->cache_radix, blocknr,
-                                  CTREE_EXTENT_PENDING_DEL);
+               pin_down_block(root, blocknr, 1);
                return 0;
        }
        ret = __free_extent(trans, root, blocknr, num_blocks, pin);
-       pending_ret = run_pending(trans, root->fs_info->extent_root);
+       pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
        return ret ? ret : pending_ret;
 }
 
@@ -293,42 +327,60 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                            *orig_root, u64 num_blocks, u64 search_start, u64
                            search_end, struct btrfs_key *ins)
 {
-       struct btrfs_path path;
+       struct btrfs_path *path;
        struct btrfs_key key;
        int ret;
        u64 hole_size = 0;
        int slot = 0;
-       u64 last_block;
+       u64 last_block = 0;
        u64 test_block;
        int start_found;
        struct btrfs_leaf *l;
        struct btrfs_root * root = orig_root->fs_info->extent_root;
        int total_needed = num_blocks;
+       int level;
 
-       total_needed += (btrfs_header_level(&root->node->node.header) + 1) * 3;
-       if (root->fs_info->last_insert.objectid > search_start)
-               search_start = root->fs_info->last_insert.objectid;
-
+       path = btrfs_alloc_path();
        ins->flags = 0;
        btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
 
+       level = btrfs_header_level(btrfs_buffer_header(root->node));
+       total_needed += (level + 1) * 3;
+       if (root->fs_info->last_insert.objectid == 0 && search_end == (u64)-1) {
+               struct btrfs_disk_key *last_key;
+               btrfs_init_path(path);
+               ins->objectid = (u64)-1;
+               ins->offset = (u64)-1;
+               ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
+               if (ret < 0)
+                       goto error;
+               BUG_ON(ret == 0);
+               if (path->slots[0] > 0)
+                       path->slots[0]--;
+               l = btrfs_buffer_leaf(path->nodes[0]);
+               last_key = &l->items[path->slots[0]].key;
+               search_start = btrfs_disk_key_objectid(last_key);
+       }
+       if (root->fs_info->last_insert.objectid > search_start)
+               search_start = root->fs_info->last_insert.objectid;
+
 check_failed:
-       btrfs_init_path(&path);
+       btrfs_init_path(path);
        ins->objectid = search_start;
        ins->offset = 0;
        start_found = 0;
-       ret = btrfs_search_slot(trans, root, ins, &path, 0, 0);
+       ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
        if (ret < 0)
                goto error;
 
-       if (path.slots[0] > 0)
-               path.slots[0]--;
+       if (path->slots[0] > 0)
+               path->slots[0]--;
 
        while (1) {
-               l = &path.nodes[0]->leaf;
-               slot = path.slots[0];
+               l = btrfs_buffer_leaf(path->nodes[0]);
+               slot = path->slots[0];
                if (slot >= btrfs_header_nritems(&l->header)) {
-                       ret = btrfs_next_leaf(root, &path);
+                       ret = btrfs_next_leaf(root, path);
                        if (ret == 0)
                                continue;
                        if (ret < 0)
@@ -359,18 +411,18 @@ check_failed:
                }
                start_found = 1;
                last_block = key.objectid + key.offset;
-               path.slots[0]++;
+               path->slots[0]++;
        }
        // FIXME -ENOSPC
 check_pending:
        /* we have to make sure we didn't find an extent that has already
         * been allocated by the map tree or the original allocation
         */
-       btrfs_release_path(root, &path);
+       btrfs_release_path(root, path);
        BUG_ON(ins->objectid < search_start);
        for (test_block = ins->objectid;
             test_block < ins->objectid + total_needed; test_block++) {
-               if (radix_tree_lookup(&root->fs_info->pinned_radix,
+               if (test_radix_bit(&root->fs_info->pinned_radix,
                                      test_block)) {
                        search_start = test_block + 1;
                        goto check_failed;
@@ -382,9 +434,11 @@ check_pending:
        root->fs_info->current_insert.flags = 0;
        root->fs_info->last_insert.objectid = ins->objectid;
        ins->offset = num_blocks;
+       btrfs_free_path(path);
        return 0;
 error:
-       btrfs_release_path(root, &path);
+       btrfs_release_path(root, path);
+       btrfs_free_path(path);
        return ret;
 }
 
@@ -395,7 +449,7 @@ error:
  *
  * returns 0 if everything worked, non-zero otherwise.
  */
-static int alloc_extent(struct btrfs_trans_handle *trans, struct btrfs_root
+int btrfs_alloc_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                        *root, u64 num_blocks, u64 search_start, u64
                        search_end, u64 owner, struct btrfs_key *ins)
 {
@@ -431,7 +485,7 @@ static int alloc_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                                sizeof(extent_item));
 
        finish_current_insert(trans, extent_root);
-       pending_ret = run_pending(trans, extent_root);
+       pending_ret = del_pending_extents(trans, extent_root);
        if (ret)
                return ret;
        if (pending_ret)
@@ -443,25 +497,55 @@ static int alloc_extent(struct btrfs_trans_handle *trans, struct btrfs_root
  * helper function to allocate a block for a given tree
  * returns the tree buffer or NULL.
  */
-struct btrfs_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
+struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                            struct btrfs_root *root)
 {
        struct btrfs_key ins;
        int ret;
-       struct btrfs_buffer *buf;
+       struct buffer_head *buf;
 
-       ret = alloc_extent(trans, root, 1, 0, (unsigned long)-1,
-                          btrfs_header_parentid(&root->node->node.header),
-                          &ins);
+       ret = btrfs_alloc_extent(trans, root, 1, 0, (unsigned long)-1,
+               btrfs_header_parentid(btrfs_buffer_header(root->node)), &ins);
        if (ret) {
                BUG();
                return NULL;
        }
-       buf = find_tree_block(root, ins.objectid);
-       dirty_tree_block(trans, root, buf);
+       buf = btrfs_find_create_tree_block(root, ins.objectid);
+       set_buffer_uptodate(buf);
        return buf;
 }
 
+static int drop_leaf_ref(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root, struct buffer_head *cur)
+{
+       struct btrfs_disk_key *key;
+       struct btrfs_leaf *leaf;
+       struct btrfs_file_extent_item *fi;
+       int i;
+       int nritems;
+       int ret;
+
+       BUG_ON(!btrfs_is_leaf(btrfs_buffer_node(cur)));
+       leaf = btrfs_buffer_leaf(cur);
+       nritems = btrfs_header_nritems(&leaf->header);
+       for (i = 0; i < nritems; i++) {
+               key = &leaf->items[i].key;
+               if (btrfs_disk_key_type(key) != BTRFS_EXTENT_DATA_KEY)
+                       continue;
+               fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
+               /*
+                * FIXME make sure to insert a trans record that
+                * repeats the snapshot del on crash
+                */
+               ret = btrfs_free_extent(trans, root,
+                                       btrfs_file_extent_disk_blocknr(fi),
+                                       btrfs_file_extent_disk_num_blocks(fi),
+                                       0);
+               BUG_ON(ret);
+       }
+       return 0;
+}
+
 /*
  * helper function for drop_snapshot, this walks down the tree dropping ref
  * counts as it goes.
@@ -469,44 +553,59 @@ struct btrfs_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
 static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
                          *root, struct btrfs_path *path, int *level)
 {
-       struct btrfs_buffer *next;
-       struct btrfs_buffer *cur;
+       struct buffer_head *next;
+       struct buffer_head *cur;
        u64 blocknr;
        int ret;
        u32 refs;
 
-       ret = lookup_block_ref(trans, root, path->nodes[*level]->blocknr,
-                              &refs);
+       WARN_ON(*level < 0);
+       WARN_ON(*level >= BTRFS_MAX_LEVEL);
+       ret = lookup_block_ref(trans, root, path->nodes[*level]->b_blocknr,
+                              1, &refs);
        BUG_ON(ret);
        if (refs > 1)
                goto out;
        /*
         * walk down to the last node level and free all the leaves
         */
-       while(*level > 0) {
+       while(*level >= 0) {
+               WARN_ON(*level < 0);
+               WARN_ON(*level >= BTRFS_MAX_LEVEL);
                cur = path->nodes[*level];
+               if (btrfs_header_level(btrfs_buffer_header(cur)) != *level)
+                       WARN_ON(1);
                if (path->slots[*level] >=
-                   btrfs_header_nritems(&cur->node.header))
+                   btrfs_header_nritems(btrfs_buffer_header(cur)))
                        break;
-               blocknr = btrfs_node_blockptr(&cur->node, path->slots[*level]);
-               ret = lookup_block_ref(trans, root, blocknr, &refs);
-               if (refs != 1 || *level == 1) {
+               if (*level == 0) {
+                       ret = drop_leaf_ref(trans, root, cur);
+                       BUG_ON(ret);
+                       break;
+               }
+               blocknr = btrfs_node_blockptr(btrfs_buffer_node(cur),
+                                             path->slots[*level]);
+               ret = lookup_block_ref(trans, root, blocknr, 1, &refs);
+               BUG_ON(ret);
+               if (refs != 1) {
                        path->slots[*level]++;
                        ret = btrfs_free_extent(trans, root, blocknr, 1, 1);
                        BUG_ON(ret);
                        continue;
                }
-               BUG_ON(ret);
                next = read_tree_block(root, blocknr);
+               WARN_ON(*level <= 0);
                if (path->nodes[*level-1])
                        btrfs_block_release(root, path->nodes[*level-1]);
                path->nodes[*level-1] = next;
-               *level = btrfs_header_level(&next->node.header);
+               *level = btrfs_header_level(btrfs_buffer_header(next));
                path->slots[*level] = 0;
        }
 out:
-       ret = btrfs_free_extent(trans, root, path->nodes[*level]->blocknr, 1,
-                               1);
+       WARN_ON(*level < 0);
+       WARN_ON(*level >= BTRFS_MAX_LEVEL);
+       ret = btrfs_free_extent(trans, root,
+                               path->nodes[*level]->b_blocknr, 1, 1);
        btrfs_block_release(root, path->nodes[*level]);
        path->nodes[*level] = NULL;
        *level += 1;
@@ -527,19 +626,19 @@ static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
        int ret;
        for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
                slot = path->slots[i];
-               if (slot <
-                   btrfs_header_nritems(&path->nodes[i]->node.header)- 1) {
+               if (slot < btrfs_header_nritems(
+                   btrfs_buffer_header(path->nodes[i])) - 1) {
                        path->slots[i]++;
                        *level = i;
                        return 0;
                } else {
                        ret = btrfs_free_extent(trans, root,
-                                               path->nodes[*level]->blocknr,
+                                               path->nodes[*level]->b_blocknr,
                                                1, 1);
+                       BUG_ON(ret);
                        btrfs_block_release(root, path->nodes[*level]);
                        path->nodes[*level] = NULL;
                        *level = i + 1;
-                       BUG_ON(ret);
                }
        }
        return 1;
@@ -551,38 +650,41 @@ 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 btrfs_buffer *snap)
+                       *root, struct buffer_head *snap)
 {
        int ret = 0;
        int wret;
        int level;
-       struct btrfs_path path;
+       struct btrfs_path *path;
        int i;
        int orig_level;
 
-       btrfs_init_path(&path);
+       path = btrfs_alloc_path();
+       BUG_ON(!path);
+       btrfs_init_path(path);
 
-       level = btrfs_header_level(&snap->node.header);
+       level = btrfs_header_level(btrfs_buffer_header(snap));
        orig_level = level;
-       path.nodes[level] = snap;
-       path.slots[level] = 0;
+       path->nodes[level] = snap;
+       path->slots[level] = 0;
        while(1) {
-               wret = walk_down_tree(trans, root, &path, &level);
+               wret = walk_down_tree(trans, root, path, &level);
                if (wret > 0)
                        break;
                if (wret < 0)
                        ret = wret;
 
-               wret = walk_up_tree(trans, root, &path, &level);
+               wret = walk_up_tree(trans, root, path, &level);
                if (wret > 0)
                        break;
                if (wret < 0)
                        ret = wret;
        }
        for (i = 0; i <= orig_level; i++) {
-               if (path.nodes[i]) {
-                       btrfs_block_release(root, path.nodes[i]);
+               if (path->nodes[i]) {
+                       btrfs_block_release(root, path->nodes[i]);
                }
        }
+       btrfs_free_path(path);
        return ret;
 }