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Btrfs: superblock duplication

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This patch implements superblock duplication. Superblocks
are stored at offset 16K, 64M and 256G on every devices.
Spaces used by superblocks are preserved by the allocator,
which uses a reverse mapping function to find the logical
addresses that correspond to superblocks. Thank you,

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This commit is contained in:
Yan Zheng
2008-12-08 16:46:26 -05:00
committed by Chris Mason
parent d20f7043fa
commit a512bbf855
8 changed files with 279 additions and 119 deletions
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54
fs/btrfs/extent-tree.c
View File

@@ -189,6 +189,29 @@ static int add_new_free_space(struct btrfs_block_group_cache *block_group,
return 0;
}
static int remove_sb_from_cache(struct btrfs_root *root,
struct btrfs_block_group_cache *cache)
{
u64 bytenr;
u64 *logical;
int stripe_len;
int i, nr, ret;
for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
bytenr = btrfs_sb_offset(i);
ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
cache->key.objectid, bytenr, 0,
&logical, &nr, &stripe_len);
BUG_ON(ret);
while (nr--) {
btrfs_remove_free_space(cache, logical[nr],
stripe_len);
}
kfree(logical);
}
return 0;
}
static int cache_block_group(struct btrfs_root *root,
struct btrfs_block_group_cache *block_group)
{
@@ -197,9 +220,7 @@ static int cache_block_group(struct btrfs_root *root,
struct btrfs_key key;
struct extent_buffer *leaf;
int slot;
u64 last = 0;
u64 first_free;
int found = 0;
u64 last = block_group->key.objectid;
if (!block_group)
return 0;
@@ -220,23 +241,13 @@ static int cache_block_group(struct btrfs_root *root,
* skip the locking here
*/
path->skip_locking = 1;
first_free = max_t(u64, block_group->key.objectid,
BTRFS_SUPER_INFO_OFFSET + BTRFS_SUPER_INFO_SIZE);
key.objectid = block_group->key.objectid;
key.objectid = last;
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)
goto err;
ret = btrfs_previous_item(root, path, 0, BTRFS_EXTENT_ITEM_KEY);
if (ret < 0)
goto err;
if (ret == 0) {
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid + key.offset > first_free)
first_free = key.objectid + key.offset;
}
while(1) {
leaf = path->nodes[0];
slot = path->slots[0];
@@ -258,11 +269,6 @@ static int cache_block_group(struct btrfs_root *root,
break;
if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
if (!found) {
last = first_free;
found = 1;
}
add_new_free_space(block_group, root->fs_info, last,
key.objectid);
@@ -272,13 +278,11 @@ next:
path->slots[0]++;
}
if (!found)
last = first_free;
add_new_free_space(block_group, root->fs_info, last,
block_group->key.objectid +
block_group->key.offset);
remove_sb_from_cache(root, block_group);
block_group->cached = 1;
ret = 0;
err:
@@ -1974,10 +1978,8 @@ static int update_block_group(struct btrfs_trans_handle *trans,
if (alloc) {
old_val += num_bytes;
cache->space_info->bytes_used += num_bytes;
if (cache->ro) {
if (cache->ro)
cache->space_info->bytes_readonly -= num_bytes;
WARN_ON(1);
}
btrfs_set_block_group_used(&cache->item, old_val);
spin_unlock(&cache->lock);
spin_unlock(&cache->space_info->lock);