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Btrfs: reference counts on data extents 

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2007-03-27 06:33:00 -04:00 committed by David Woodhouse
parent dee26a9f7a
commit 6407bf6d7c
5 changed files with 82 additions and 24 deletions
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3
fs/btrfs/TODO
View File

@ -8,7 +8,10 @@
* Add block mapping tree (simple dm layer)
* Add simple tree locking (semaphore per tree)
* Make allocator smarter
* make level a field in header
* add a block group to struct inode
* Make directory hashing work on 32 bit
* Make sure nobh stuff is working properly for cows
* Do actual block accounting
* Check compat and incompat flags on the inode
* Add virtual filesystems, mountable snapshots

9
fs/btrfs/ctree.h
View File

@ -9,10 +9,11 @@ struct btrfs_transaction;
#define BTRFS_MAGIC "_BtRfS_M"
#define BTRFS_ROOT_TREE_OBJECTID 1
#define BTRFS_EXTENT_TREE_OBJECTID 2
#define BTRFS_INODE_MAP_OBJECTID 3
#define BTRFS_FS_TREE_OBJECTID 4
#define BTRFS_ROOT_TREE_OBJECTID 1ULL
#define BTRFS_EXTENT_TREE_OBJECTID 2ULL
#define BTRFS_INODE_MAP_OBJECTID 3ULL
#define BTRFS_FS_TREE_OBJECTID 4ULL
#define BTRFS_FIRST_FREE_OBJECTID 5ULL
/*
* we can actually store much bigger names, but lets not confuse the rest

87
fs/btrfs/extent-tree.c
View File

@ -13,7 +13,7 @@ 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;
int ret;
@ -29,7 +29,7 @@ static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
key.objectid = blocknr;
key.flags = 0;
btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
key.offset = 1;
key.offset = num_blocks;
ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
0, 1);
if (ret != 0)
@ -48,7 +48,7 @@ static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
}
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;
int ret;
@ -57,7 +57,7 @@ static int lookup_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
struct btrfs_extent_item *item;
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,
@ -76,17 +76,34 @@ int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
{
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;
buf_node = btrfs_buffer_node(buf);
if (btrfs_is_leaf(buf_node))
return 0;
leaf = btrfs_is_leaf(buf_node);
buf_leaf = btrfs_buffer_leaf(buf);
for (i = 0; i < btrfs_header_nritems(&buf_node->header); i++) {
blocknr = btrfs_node_blockptr(buf_node, i);
inc_block_ref(trans, root, blocknr);
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;
}
@ -469,6 +486,37 @@ struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
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.
@ -483,28 +531,33 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
u32 refs;
ret = lookup_block_ref(trans, root, path->nodes[*level]->b_blocknr,
&refs);
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) {
cur = path->nodes[*level];
if (path->slots[*level] >=
btrfs_header_nritems(btrfs_buffer_header(cur)))
break;
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, &refs);
if (refs != 1 || *level == 1) {
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);
if (path->nodes[*level-1])
btrfs_block_release(root, path->nodes[*level-1]);
@ -513,8 +566,8 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
path->slots[*level] = 0;
}
out:
ret = btrfs_free_extent(trans, root, path->nodes[*level]->b_blocknr,
1, 1);
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;
@ -544,10 +597,10 @@ static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
ret = btrfs_free_extent(trans, root,
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;

1
fs/btrfs/inode-map.c
View File

@ -25,6 +25,7 @@ int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
if (fs_root->fs_info->last_inode_alloc_dirid == dirid)
search_start = fs_root->fs_info->last_inode_alloc;
search_start = max(search_start, BTRFS_FIRST_FREE_OBJECTID);
search_key.objectid = search_start;
search_key.flags = 0;
btrfs_set_key_type(&search_key, BTRFS_INODE_MAP_ITEM_KEY);

6
fs/btrfs/super.c
View File

@ -700,7 +700,7 @@ out:
static int btrfs_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
return block_prepare_write(page, from, to, btrfs_get_block);
return nobh_prepare_write(page, from, to, btrfs_get_block);
}
static void btrfs_write_super(struct super_block *sb)
@ -721,7 +721,7 @@ static int btrfs_readpages(struct file *file, struct address_space *mapping,
static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, btrfs_get_block, wbc);
return nobh_writepage(page, btrfs_get_block, wbc);
}
static int btrfs_get_sb(struct file_system_type *fs_type,
@ -768,7 +768,7 @@ static struct address_space_operations btrfs_aops = {
.writepage = btrfs_writepage,
.sync_page = block_sync_page,
.prepare_write = btrfs_prepare_write,
.commit_write = generic_commit_write,
.commit_write = nobh_commit_write,
};
static struct inode_operations btrfs_file_inode_operations = {