Btrfs: create special free space cache inode
[linux-3.10.git] / fs / btrfs / free-space-cache.c
index f488fac..05efcc7 100644 (file)
 #include "ctree.h"
 #include "free-space-cache.h"
 #include "transaction.h"
+#include "disk-io.h"
 
 #define BITS_PER_BITMAP                (PAGE_CACHE_SIZE * 8)
 #define MAX_CACHE_BYTES_PER_GIG        (32 * 1024)
 
+struct inode *lookup_free_space_inode(struct btrfs_root *root,
+                                     struct btrfs_block_group_cache
+                                     *block_group, struct btrfs_path *path)
+{
+       struct btrfs_key key;
+       struct btrfs_key location;
+       struct btrfs_disk_key disk_key;
+       struct btrfs_free_space_header *header;
+       struct extent_buffer *leaf;
+       struct inode *inode = NULL;
+       int ret;
+
+       spin_lock(&block_group->lock);
+       if (block_group->inode)
+               inode = igrab(block_group->inode);
+       spin_unlock(&block_group->lock);
+       if (inode)
+               return inode;
+
+       key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+       key.offset = block_group->key.objectid;
+       key.type = 0;
+
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret < 0)
+               return ERR_PTR(ret);
+       if (ret > 0) {
+               btrfs_release_path(root, path);
+               return ERR_PTR(-ENOENT);
+       }
+
+       leaf = path->nodes[0];
+       header = btrfs_item_ptr(leaf, path->slots[0],
+                               struct btrfs_free_space_header);
+       btrfs_free_space_key(leaf, header, &disk_key);
+       btrfs_disk_key_to_cpu(&location, &disk_key);
+       btrfs_release_path(root, path);
+
+       inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
+       if (!inode)
+               return ERR_PTR(-ENOENT);
+       if (IS_ERR(inode))
+               return inode;
+       if (is_bad_inode(inode)) {
+               iput(inode);
+               return ERR_PTR(-ENOENT);
+       }
+
+       spin_lock(&block_group->lock);
+       if (!root->fs_info->closing) {
+               block_group->inode = igrab(inode);
+               block_group->iref = 1;
+       }
+       spin_unlock(&block_group->lock);
+
+       return inode;
+}
+
+int create_free_space_inode(struct btrfs_root *root,
+                           struct btrfs_trans_handle *trans,
+                           struct btrfs_block_group_cache *block_group,
+                           struct btrfs_path *path)
+{
+       struct btrfs_key key;
+       struct btrfs_disk_key disk_key;
+       struct btrfs_free_space_header *header;
+       struct btrfs_inode_item *inode_item;
+       struct extent_buffer *leaf;
+       u64 objectid;
+       int ret;
+
+       ret = btrfs_find_free_objectid(trans, root, 0, &objectid);
+       if (ret < 0)
+               return ret;
+
+       ret = btrfs_insert_empty_inode(trans, root, path, objectid);
+       if (ret)
+               return ret;
+
+       leaf = path->nodes[0];
+       inode_item = btrfs_item_ptr(leaf, path->slots[0],
+                                   struct btrfs_inode_item);
+       btrfs_item_key(leaf, &disk_key, path->slots[0]);
+       memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
+                            sizeof(*inode_item));
+       btrfs_set_inode_generation(leaf, inode_item, trans->transid);
+       btrfs_set_inode_size(leaf, inode_item, 0);
+       btrfs_set_inode_nbytes(leaf, inode_item, 0);
+       btrfs_set_inode_uid(leaf, inode_item, 0);
+       btrfs_set_inode_gid(leaf, inode_item, 0);
+       btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
+       btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
+                             BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
+       btrfs_set_inode_nlink(leaf, inode_item, 1);
+       btrfs_set_inode_transid(leaf, inode_item, trans->transid);
+       btrfs_set_inode_block_group(leaf, inode_item,
+                                   block_group->key.objectid);
+       btrfs_mark_buffer_dirty(leaf);
+       btrfs_release_path(root, path);
+
+       key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+       key.offset = block_group->key.objectid;
+       key.type = 0;
+
+       ret = btrfs_insert_empty_item(trans, root, path, &key,
+                                     sizeof(struct btrfs_free_space_header));
+       if (ret < 0) {
+               btrfs_release_path(root, path);
+               return ret;
+       }
+       leaf = path->nodes[0];
+       header = btrfs_item_ptr(leaf, path->slots[0],
+                               struct btrfs_free_space_header);
+       memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
+       btrfs_set_free_space_key(leaf, header, &disk_key);
+       btrfs_mark_buffer_dirty(leaf);
+       btrfs_release_path(root, path);
+
+       return 0;
+}
+
+int btrfs_truncate_free_space_cache(struct btrfs_root *root,
+                                   struct btrfs_trans_handle *trans,
+                                   struct btrfs_path *path,
+                                   struct inode *inode)
+{
+       loff_t oldsize;
+       int ret = 0;
+
+       trans->block_rsv = root->orphan_block_rsv;
+       ret = btrfs_block_rsv_check(trans, root,
+                                   root->orphan_block_rsv,
+                                   0, 5);
+       if (ret)
+               return ret;
+
+       oldsize = i_size_read(inode);
+       btrfs_i_size_write(inode, 0);
+       truncate_pagecache(inode, oldsize, 0);
+
+       /*
+        * We don't need an orphan item because truncating the free space cache
+        * will never be split across transactions.
+        */
+       ret = btrfs_truncate_inode_items(trans, root, inode,
+                                        0, BTRFS_EXTENT_DATA_KEY);
+       if (ret) {
+               WARN_ON(1);
+               return ret;
+       }
+
+       return btrfs_update_inode(trans, root, inode);
+}
+
 static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize,
                                          u64 offset)
 {