return type;
}
-static int find_next_key(struct btrfs_path *path, struct btrfs_key *key)
+static int find_next_key(struct btrfs_path *path, int level,
+ struct btrfs_key *key)
{
- int level;
- BUG_ON(!path->keep_locks);
- for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
+ for (; level < BTRFS_MAX_LEVEL; level++) {
if (!path->nodes[level])
break;
- btrfs_assert_tree_locked(path->nodes[level]);
if (path->slots[level] + 1 >=
btrfs_header_nritems(path->nodes[level]))
continue;
* For simplicity, we just do not add new inline back
* ref if there is any kind of item for this block
*/
- if (find_next_key(path, &key) == 0 && key.objectid == bytenr &&
+ if (find_next_key(path, 0, &key) == 0 &&
+ key.objectid == bytenr &&
key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
err = -EAGAIN;
goto out;
return buf;
}
+#if 0
int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *leaf)
{
return 0;
}
-#if 0
-
static noinline int cache_drop_leaf_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_leaf_ref *ref)
}
#endif
+struct walk_control {
+ u64 refs[BTRFS_MAX_LEVEL];
+ u64 flags[BTRFS_MAX_LEVEL];
+ struct btrfs_key update_progress;
+ int stage;
+ int level;
+ int shared_level;
+ int update_ref;
+ int keep_locks;
+};
+
+#define DROP_REFERENCE 1
+#define UPDATE_BACKREF 2
+
/*
- * helper function for drop_subtree, this function is similar to
- * walk_down_tree. The main difference is that it checks reference
- * counts while tree blocks are locked.
+ * hepler to process tree block while walking down the tree.
+ *
+ * when wc->stage == DROP_REFERENCE, this function checks
+ * reference count of the block. if the block is shared and
+ * we need update back refs for the subtree rooted at the
+ * block, this function changes wc->stage to UPDATE_BACKREF
+ *
+ * when wc->stage == UPDATE_BACKREF, this function updates
+ * back refs for pointers in the block.
+ *
+ * NOTE: return value 1 means we should stop walking down.
*/
-static noinline int walk_down_tree(struct btrfs_trans_handle *trans,
+static noinline int walk_down_proc(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
- struct btrfs_path *path, int *level)
+ struct btrfs_path *path,
+ struct walk_control *wc)
{
- struct extent_buffer *next;
- struct extent_buffer *cur;
- struct extent_buffer *parent;
- u64 bytenr;
- u64 ptr_gen;
- u64 refs;
- u64 flags;
- u32 blocksize;
+ int level = wc->level;
+ struct extent_buffer *eb = path->nodes[level];
+ struct btrfs_key key;
+ u64 flag = BTRFS_BLOCK_FLAG_FULL_BACKREF;
int ret;
- cur = path->nodes[*level];
- ret = btrfs_lookup_extent_info(trans, root, cur->start, cur->len,
- &refs, &flags);
- BUG_ON(ret);
- if (refs > 1)
- goto out;
+ if (wc->stage == UPDATE_BACKREF &&
+ btrfs_header_owner(eb) != root->root_key.objectid)
+ return 1;
- BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
+ /*
+ * when reference count of tree block is 1, it won't increase
+ * again. once full backref flag is set, we never clear it.
+ */
+ if ((wc->stage == DROP_REFERENCE && wc->refs[level] != 1) ||
+ (wc->stage == UPDATE_BACKREF && !(wc->flags[level] & flag))) {
+ BUG_ON(!path->locks[level]);
+ ret = btrfs_lookup_extent_info(trans, root,
+ eb->start, eb->len,
+ &wc->refs[level],
+ &wc->flags[level]);
+ BUG_ON(ret);
+ BUG_ON(wc->refs[level] == 0);
+ }
- while (*level >= 0) {
- cur = path->nodes[*level];
- if (*level == 0) {
- ret = btrfs_drop_leaf_ref(trans, root, cur);
- BUG_ON(ret);
- clean_tree_block(trans, root, cur);
- break;
- }
- if (path->slots[*level] >= btrfs_header_nritems(cur)) {
- clean_tree_block(trans, root, cur);
- break;
+ if (wc->stage == DROP_REFERENCE &&
+ wc->update_ref && wc->refs[level] > 1) {
+ BUG_ON(eb == root->node);
+ BUG_ON(path->slots[level] > 0);
+ if (level == 0)
+ btrfs_item_key_to_cpu(eb, &key, path->slots[level]);
+ else
+ btrfs_node_key_to_cpu(eb, &key, path->slots[level]);
+ if (btrfs_header_owner(eb) == root->root_key.objectid &&
+ btrfs_comp_cpu_keys(&key, &wc->update_progress) >= 0) {
+ wc->stage = UPDATE_BACKREF;
+ wc->shared_level = level;
}
+ }
- bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
- blocksize = btrfs_level_size(root, *level - 1);
- ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
+ if (wc->stage == DROP_REFERENCE) {
+ if (wc->refs[level] > 1)
+ return 1;
- next = read_tree_block(root, bytenr, blocksize, ptr_gen);
- btrfs_tree_lock(next);
- btrfs_set_lock_blocking(next);
+ if (path->locks[level] && !wc->keep_locks) {
+ btrfs_tree_unlock(eb);
+ path->locks[level] = 0;
+ }
+ return 0;
+ }
- ret = btrfs_lookup_extent_info(trans, root, bytenr, blocksize,
- &refs, &flags);
+ /* wc->stage == UPDATE_BACKREF */
+ if (!(wc->flags[level] & flag)) {
+ BUG_ON(!path->locks[level]);
+ ret = btrfs_inc_ref(trans, root, eb, 1);
BUG_ON(ret);
- if (refs > 1) {
- parent = path->nodes[*level];
- ret = btrfs_free_extent(trans, root, bytenr,
- blocksize, parent->start,
- btrfs_header_owner(parent),
- *level - 1, 0);
+ ret = btrfs_dec_ref(trans, root, eb, 0);
+ BUG_ON(ret);
+ ret = btrfs_set_disk_extent_flags(trans, root, eb->start,
+ eb->len, flag, 0);
+ BUG_ON(ret);
+ wc->flags[level] |= flag;
+ }
+
+ /*
+ * the block is shared by multiple trees, so it's not good to
+ * keep the tree lock
+ */
+ if (path->locks[level] && level > 0) {
+ btrfs_tree_unlock(eb);
+ path->locks[level] = 0;
+ }
+ return 0;
+}
+
+/*
+ * hepler to process tree block while walking up the tree.
+ *
+ * when wc->stage == DROP_REFERENCE, this function drops
+ * reference count on the block.
+ *
+ * when wc->stage == UPDATE_BACKREF, this function changes
+ * wc->stage back to DROP_REFERENCE if we changed wc->stage
+ * to UPDATE_BACKREF previously while processing the block.
+ *
+ * NOTE: return value 1 means we should stop walking up.
+ */
+static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ struct walk_control *wc)
+{
+ int ret = 0;
+ int level = wc->level;
+ struct extent_buffer *eb = path->nodes[level];
+ u64 parent = 0;
+
+ if (wc->stage == UPDATE_BACKREF) {
+ BUG_ON(wc->shared_level < level);
+ if (level < wc->shared_level)
+ goto out;
+
+ BUG_ON(wc->refs[level] <= 1);
+ ret = find_next_key(path, level + 1, &wc->update_progress);
+ if (ret > 0)
+ wc->update_ref = 0;
+
+ wc->stage = DROP_REFERENCE;
+ wc->shared_level = -1;
+ path->slots[level] = 0;
+
+ /*
+ * check reference count again if the block isn't locked.
+ * we should start walking down the tree again if reference
+ * count is one.
+ */
+ if (!path->locks[level]) {
+ BUG_ON(level == 0);
+ btrfs_tree_lock(eb);
+ btrfs_set_lock_blocking(eb);
+ path->locks[level] = 1;
+
+ ret = btrfs_lookup_extent_info(trans, root,
+ eb->start, eb->len,
+ &wc->refs[level],
+ &wc->flags[level]);
BUG_ON(ret);
- path->slots[*level]++;
- btrfs_tree_unlock(next);
- free_extent_buffer(next);
- continue;
+ BUG_ON(wc->refs[level] == 0);
+ if (wc->refs[level] == 1) {
+ btrfs_tree_unlock(eb);
+ path->locks[level] = 0;
+ return 1;
+ }
+ } else {
+ BUG_ON(level != 0);
}
+ }
- BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
+ /* wc->stage == DROP_REFERENCE */
+ BUG_ON(wc->refs[level] > 1 && !path->locks[level]);
- *level = btrfs_header_level(next);
- path->nodes[*level] = next;
- path->slots[*level] = 0;
- path->locks[*level] = 1;
- cond_resched();
+ if (wc->refs[level] == 1) {
+ if (level == 0) {
+ if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
+ ret = btrfs_dec_ref(trans, root, eb, 1);
+ else
+ ret = btrfs_dec_ref(trans, root, eb, 0);
+ BUG_ON(ret);
+ }
+ /* make block locked assertion in clean_tree_block happy */
+ if (!path->locks[level] &&
+ btrfs_header_generation(eb) == trans->transid) {
+ btrfs_tree_lock(eb);
+ btrfs_set_lock_blocking(eb);
+ path->locks[level] = 1;
+ }
+ clean_tree_block(trans, root, eb);
+ }
+
+ if (eb == root->node) {
+ if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
+ parent = eb->start;
+ else
+ BUG_ON(root->root_key.objectid !=
+ btrfs_header_owner(eb));
+ } else {
+ if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
+ parent = path->nodes[level + 1]->start;
+ else
+ BUG_ON(root->root_key.objectid !=
+ btrfs_header_owner(path->nodes[level + 1]));
}
-out:
- if (path->nodes[*level] == root->node)
- parent = path->nodes[*level];
- else
- parent = path->nodes[*level + 1];
- bytenr = path->nodes[*level]->start;
- blocksize = path->nodes[*level]->len;
- ret = btrfs_free_extent(trans, root, bytenr, blocksize, parent->start,
- btrfs_header_owner(parent), *level, 0);
+ ret = btrfs_free_extent(trans, root, eb->start, eb->len, parent,
+ root->root_key.objectid, level, 0);
BUG_ON(ret);
+out:
+ wc->refs[level] = 0;
+ wc->flags[level] = 0;
+ return ret;
+}
+
+static noinline int walk_down_tree(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ struct walk_control *wc)
+{
+ struct extent_buffer *next;
+ struct extent_buffer *cur;
+ u64 bytenr;
+ u64 ptr_gen;
+ u32 blocksize;
+ int level = wc->level;
+ int ret;
+
+ while (level >= 0) {
+ cur = path->nodes[level];
+ BUG_ON(path->slots[level] >= btrfs_header_nritems(cur));
- if (path->locks[*level]) {
- btrfs_tree_unlock(path->nodes[*level]);
- path->locks[*level] = 0;
+ ret = walk_down_proc(trans, root, path, wc);
+ if (ret > 0)
+ break;
+
+ if (level == 0)
+ break;
+
+ bytenr = btrfs_node_blockptr(cur, path->slots[level]);
+ blocksize = btrfs_level_size(root, level - 1);
+ ptr_gen = btrfs_node_ptr_generation(cur, path->slots[level]);
+
+ next = read_tree_block(root, bytenr, blocksize, ptr_gen);
+ btrfs_tree_lock(next);
+ btrfs_set_lock_blocking(next);
+
+ level--;
+ BUG_ON(level != btrfs_header_level(next));
+ path->nodes[level] = next;
+ path->slots[level] = 0;
+ path->locks[level] = 1;
+ wc->level = level;
}
- free_extent_buffer(path->nodes[*level]);
- path->nodes[*level] = NULL;
- *level += 1;
- cond_resched();
return 0;
}
-/*
- * helper for dropping snapshots. This walks back up the tree in the path
- * to find the first node higher up where we haven't yet gone through
- * all the slots
- */
static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
- int *level, int max_level)
+ struct walk_control *wc, int max_level)
{
- struct btrfs_root_item *root_item = &root->root_item;
- int i;
- int slot;
+ int level = wc->level;
int ret;
- for (i = *level; i < max_level && path->nodes[i]; i++) {
- slot = path->slots[i];
- if (slot + 1 < btrfs_header_nritems(path->nodes[i])) {
- /*
- * there is more work to do in this level.
- * Update the drop_progress marker to reflect
- * the work we've done so far, and then bump
- * the slot number
- */
- path->slots[i]++;
- WARN_ON(*level == 0);
- if (max_level == BTRFS_MAX_LEVEL) {
- btrfs_node_key(path->nodes[i],
- &root_item->drop_progress,
- path->slots[i]);
- root_item->drop_level = i;
- }
- *level = i;
+ path->slots[level] = btrfs_header_nritems(path->nodes[level]);
+ while (level < max_level && path->nodes[level]) {
+ wc->level = level;
+ if (path->slots[level] + 1 <
+ btrfs_header_nritems(path->nodes[level])) {
+ path->slots[level]++;
return 0;
} else {
- struct extent_buffer *parent;
-
- /*
- * this whole node is done, free our reference
- * on it and go up one level
- */
- if (path->nodes[*level] == root->node)
- parent = path->nodes[*level];
- else
- parent = path->nodes[*level + 1];
+ ret = walk_up_proc(trans, root, path, wc);
+ if (ret > 0)
+ return 0;
- clean_tree_block(trans, root, path->nodes[i]);
- ret = btrfs_free_extent(trans, root,
- path->nodes[i]->start,
- path->nodes[i]->len,
- parent->start,
- btrfs_header_owner(parent),
- *level, 0);
- BUG_ON(ret);
- if (path->locks[*level]) {
- btrfs_tree_unlock(path->nodes[i]);
- path->locks[i] = 0;
+ if (path->locks[level]) {
+ btrfs_tree_unlock(path->nodes[level]);
+ path->locks[level] = 0;
}
- free_extent_buffer(path->nodes[i]);
- path->nodes[i] = NULL;
- *level = i + 1;
+ free_extent_buffer(path->nodes[level]);
+ path->nodes[level] = NULL;
+ level++;
}
}
return 1;
}
/*
- * drop the reference count on the tree rooted at 'snap'. This traverses
- * the tree freeing any blocks that have a ref count of zero after being
- * decremented.
+ * drop a subvolume tree.
+ *
+ * this function traverses the tree freeing any blocks that only
+ * referenced by the tree.
+ *
+ * when a shared tree block is found. this function decreases its
+ * reference count by one. if update_ref is true, this function
+ * also make sure backrefs for the shared block and all lower level
+ * blocks are properly updated.
*/
-int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
- *root)
+int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref)
{
- int ret = 0;
- int wret;
- int level;
struct btrfs_path *path;
- int update_count;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *tree_root = root->fs_info->tree_root;
struct btrfs_root_item *root_item = &root->root_item;
+ struct walk_control *wc;
+ struct btrfs_key key;
+ int err = 0;
+ int ret;
+ int level;
path = btrfs_alloc_path();
BUG_ON(!path);
- level = btrfs_header_level(root->node);
+ wc = kzalloc(sizeof(*wc), GFP_NOFS);
+ BUG_ON(!wc);
+
+ trans = btrfs_start_transaction(tree_root, 1);
+
if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
+ level = btrfs_header_level(root->node);
path->nodes[level] = btrfs_lock_root_node(root);
btrfs_set_lock_blocking(path->nodes[level]);
path->slots[level] = 0;
path->locks[level] = 1;
+ memset(&wc->update_progress, 0,
+ sizeof(wc->update_progress));
} else {
- struct btrfs_key key;
- struct btrfs_disk_key found_key;
- struct extent_buffer *node;
-
btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
+ memcpy(&wc->update_progress, &key,
+ sizeof(wc->update_progress));
+
level = root_item->drop_level;
+ BUG_ON(level == 0);
path->lowest_level = level;
- wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
- if (wret < 0) {
- ret = wret;
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ path->lowest_level = 0;
+ if (ret < 0) {
+ err = ret;
goto out;
}
- node = path->nodes[level];
- btrfs_node_key(node, &found_key, path->slots[level]);
- WARN_ON(memcmp(&found_key, &root_item->drop_progress,
- sizeof(found_key)));
+ btrfs_node_key_to_cpu(path->nodes[level], &key,
+ path->slots[level]);
+ WARN_ON(memcmp(&key, &wc->update_progress, sizeof(key)));
+
/*
* unlock our path, this is safe because only this
* function is allowed to delete this snapshot
*/
btrfs_unlock_up_safe(path, 0);
+
+ level = btrfs_header_level(root->node);
+ while (1) {
+ btrfs_tree_lock(path->nodes[level]);
+ btrfs_set_lock_blocking(path->nodes[level]);
+
+ ret = btrfs_lookup_extent_info(trans, root,
+ path->nodes[level]->start,
+ path->nodes[level]->len,
+ &wc->refs[level],
+ &wc->flags[level]);
+ BUG_ON(ret);
+ BUG_ON(wc->refs[level] == 0);
+
+ if (level == root_item->drop_level)
+ break;
+
+ btrfs_tree_unlock(path->nodes[level]);
+ WARN_ON(wc->refs[level] != 1);
+ level--;
+ }
}
+
+ wc->level = level;
+ wc->shared_level = -1;
+ wc->stage = DROP_REFERENCE;
+ wc->update_ref = update_ref;
+ wc->keep_locks = 0;
+
while (1) {
- unsigned long update;
- wret = walk_down_tree(trans, root, path, &level);
- if (wret > 0)
+ ret = walk_down_tree(trans, root, path, wc);
+ if (ret < 0) {
+ err = ret;
break;
- if (wret < 0)
- ret = wret;
+ }
- wret = walk_up_tree(trans, root, path, &level,
- BTRFS_MAX_LEVEL);
- if (wret > 0)
+ ret = walk_up_tree(trans, root, path, wc, BTRFS_MAX_LEVEL);
+ if (ret < 0) {
+ err = ret;
break;
- if (wret < 0)
- ret = wret;
- if (trans->transaction->in_commit ||
- trans->transaction->delayed_refs.flushing) {
- ret = -EAGAIN;
+ }
+
+ if (ret > 0) {
+ BUG_ON(wc->stage != DROP_REFERENCE);
break;
}
- for (update_count = 0; update_count < 16; update_count++) {
+
+ if (wc->stage == DROP_REFERENCE) {
+ level = wc->level;
+ btrfs_node_key(path->nodes[level],
+ &root_item->drop_progress,
+ path->slots[level]);
+ root_item->drop_level = level;
+ }
+
+ BUG_ON(wc->level == 0);
+ if (trans->transaction->in_commit ||
+ trans->transaction->delayed_refs.flushing) {
+ ret = btrfs_update_root(trans, tree_root,
+ &root->root_key,
+ root_item);
+ BUG_ON(ret);
+
+ btrfs_end_transaction(trans, tree_root);
+ trans = btrfs_start_transaction(tree_root, 1);
+ } else {
+ unsigned long update;
update = trans->delayed_ref_updates;
trans->delayed_ref_updates = 0;
if (update)
- btrfs_run_delayed_refs(trans, root, update);
- else
- break;
+ btrfs_run_delayed_refs(trans, tree_root,
+ update);
}
}
+ btrfs_release_path(root, path);
+ BUG_ON(err);
+
+ ret = btrfs_del_root(trans, tree_root, &root->root_key);
+ BUG_ON(ret);
+
+ free_extent_buffer(root->node);
+ free_extent_buffer(root->commit_root);
+ kfree(root);
out:
+ btrfs_end_transaction(trans, tree_root);
+ kfree(wc);
btrfs_free_path(path);
- return ret;
+ return err;
}
+/*
+ * drop subtree rooted at tree block 'node'.
+ *
+ * NOTE: this function will unlock and release tree block 'node'
+ */
int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *node,
struct extent_buffer *parent)
{
struct btrfs_path *path;
+ struct walk_control *wc;
int level;
int parent_level;
int ret = 0;
int wret;
+ BUG_ON(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
+
path = btrfs_alloc_path();
BUG_ON(!path);
+ wc = kzalloc(sizeof(*wc), GFP_NOFS);
+ BUG_ON(!wc);
+
btrfs_assert_tree_locked(parent);
parent_level = btrfs_header_level(parent);
extent_buffer_get(parent);
btrfs_assert_tree_locked(node);
level = btrfs_header_level(node);
- extent_buffer_get(node);
path->nodes[level] = node;
path->slots[level] = 0;
+ path->locks[level] = 1;
+
+ wc->refs[parent_level] = 1;
+ wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;
+ wc->level = level;
+ wc->shared_level = -1;
+ wc->stage = DROP_REFERENCE;
+ wc->update_ref = 0;
+ wc->keep_locks = 1;
while (1) {
- wret = walk_down_tree(trans, root, path, &level);
- if (wret < 0)
+ wret = walk_down_tree(trans, root, path, wc);
+ if (wret < 0) {
ret = wret;
- if (wret != 0)
break;
+ }
- wret = walk_up_tree(trans, root, path, &level, parent_level);
+ wret = walk_up_tree(trans, root, path, wc, parent_level);
if (wret < 0)
ret = wret;
if (wret != 0)
break;
}
+ kfree(wc);
btrfs_free_path(path);
return ret;
}
projects / openwrt / staging / blogic.git / commitdiff