return 0;
}
+/*
+ * returns the logical address of the oldest predecessor of the given root.
+ * entries older than time_seq are ignored.
+ */
+static struct tree_mod_elem *
+__tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
+ struct btrfs_root *root, u64 time_seq)
+{
+ struct tree_mod_elem *tm;
+ struct tree_mod_elem *found = NULL;
+ u64 root_logical = root->node->start;
+ int looped = 0;
+
+ if (!time_seq)
+ return 0;
+
+ /*
+ * the very last operation that's logged for a root is the replacement
+ * operation (if it is replaced at all). this has the index of the *new*
+ * root, making it the very first operation that's logged for this root.
+ */
+ while (1) {
+ tm = tree_mod_log_search_oldest(fs_info, root_logical,
+ time_seq);
+ if (!looped && !tm)
+ return 0;
+ /*
+ * we must have key remove operations in the log before the
+ * replace operation.
+ */
+ BUG_ON(!tm);
+
+ if (tm->op != MOD_LOG_ROOT_REPLACE)
+ break;
+
+ found = tm;
+ root_logical = tm->old_root.logical;
+ BUG_ON(root_logical == root->node->start);
+ looped = 1;
+ }
+
+ return found;
+}
+
+/*
+ * tm is a pointer to the first operation to rewind within eb. then, all
+ * previous operations will be rewinded (until we reach something older than
+ * time_seq).
+ */
+static void
+__tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq,
+ struct tree_mod_elem *first_tm)
+{
+ u32 n;
+ struct rb_node *next;
+ struct tree_mod_elem *tm = first_tm;
+ unsigned long o_dst;
+ unsigned long o_src;
+ unsigned long p_size = sizeof(struct btrfs_key_ptr);
+
+ n = btrfs_header_nritems(eb);
+ while (tm && tm->elem.seq >= time_seq) {
+ /*
+ * all the operations are recorded with the operator used for
+ * the modification. as we're going backwards, we do the
+ * opposite of each operation here.
+ */
+ switch (tm->op) {
+ case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
+ BUG_ON(tm->slot < n);
+ case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
+ case MOD_LOG_KEY_REMOVE:
+ btrfs_set_node_key(eb, &tm->key, tm->slot);
+ btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
+ btrfs_set_node_ptr_generation(eb, tm->slot,
+ tm->generation);
+ n++;
+ break;
+ case MOD_LOG_KEY_REPLACE:
+ BUG_ON(tm->slot >= n);
+ btrfs_set_node_key(eb, &tm->key, tm->slot);
+ btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
+ btrfs_set_node_ptr_generation(eb, tm->slot,
+ tm->generation);
+ break;
+ case MOD_LOG_KEY_ADD:
+ if (tm->slot != n - 1) {
+ o_dst = btrfs_node_key_ptr_offset(tm->slot);
+ o_src = btrfs_node_key_ptr_offset(tm->slot + 1);
+ memmove_extent_buffer(eb, o_dst, o_src, p_size);
+ }
+ n--;
+ break;
+ case MOD_LOG_MOVE_KEYS:
+ memmove_extent_buffer(eb, tm->slot, tm->move.dst_slot,
+ tm->move.nr_items * p_size);
+ break;
+ case MOD_LOG_ROOT_REPLACE:
+ /*
+ * this operation is special. for roots, this must be
+ * handled explicitly before rewinding.
+ * for non-roots, this operation may exist if the node
+ * was a root: root A -> child B; then A gets empty and
+ * B is promoted to the new root. in the mod log, we'll
+ * have a root-replace operation for B, a tree block
+ * that is no root. we simply ignore that operation.
+ */
+ break;
+ }
+ next = rb_next(&tm->node);
+ if (!next)
+ break;
+ tm = container_of(next, struct tree_mod_elem, node);
+ if (tm->index != first_tm->index)
+ break;
+ }
+ btrfs_set_header_nritems(eb, n);
+}
+
+static struct extent_buffer *
+tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
+ u64 time_seq)
+{
+ struct extent_buffer *eb_rewin;
+ struct tree_mod_elem *tm;
+
+ if (!time_seq)
+ return eb;
+
+ if (btrfs_header_level(eb) == 0)
+ return eb;
+
+ tm = tree_mod_log_search(fs_info, eb->start, time_seq);
+ if (!tm)
+ return eb;
+
+ if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
+ BUG_ON(tm->slot != 0);
+ eb_rewin = alloc_dummy_extent_buffer(eb->start,
+ fs_info->tree_root->nodesize);
+ BUG_ON(!eb_rewin);
+ btrfs_set_header_bytenr(eb_rewin, eb->start);
+ btrfs_set_header_backref_rev(eb_rewin,
+ btrfs_header_backref_rev(eb));
+ btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
+ } else {
+ eb_rewin = btrfs_clone_extent_buffer(eb);
+ BUG_ON(!eb_rewin);
+ }
+
+ extent_buffer_get(eb_rewin);
+ free_extent_buffer(eb);
+
+ __tree_mod_log_rewind(eb_rewin, time_seq, tm);
+
+ return eb_rewin;
+}
+
+static inline struct extent_buffer *
+get_old_root(struct btrfs_root *root, u64 time_seq)
+{
+ struct tree_mod_elem *tm;
+ struct extent_buffer *eb;
+ struct tree_mod_root *old_root;
+ u64 old_generation;
+
+ tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
+ if (!tm)
+ return root->node;
+
+ old_root = &tm->old_root;
+ old_generation = tm->generation;
+
+ tm = tree_mod_log_search(root->fs_info, old_root->logical, time_seq);
+ /*
+ * there was an item in the log when __tree_mod_log_oldest_root
+ * returned. this one must not go away, because the time_seq passed to
+ * us must be blocking its removal.
+ */
+ BUG_ON(!tm);
+
+ if (old_root->logical == root->node->start) {
+ /* there are logged operations for the current root */
+ eb = btrfs_clone_extent_buffer(root->node);
+ } else {
+ /* there's a root replace operation for the current root */
+ eb = alloc_dummy_extent_buffer(tm->index << PAGE_CACHE_SHIFT,
+ root->nodesize);
+ btrfs_set_header_bytenr(eb, eb->start);
+ btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
+ btrfs_set_header_owner(eb, root->root_key.objectid);
+ }
+ if (!eb)
+ return NULL;
+ btrfs_set_header_level(eb, old_root->level);
+ btrfs_set_header_generation(eb, old_generation);
+ __tree_mod_log_rewind(eb, time_seq, tm);
+
+ return eb;
+}
+
static inline int should_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf)
read_block_for_search(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct btrfs_path *p,
struct extent_buffer **eb_ret, int level, int slot,
- struct btrfs_key *key)
+ struct btrfs_key *key, u64 time_seq)
{
u64 blocknr;
u64 gen;
}
err = read_block_for_search(trans, root, p,
- &b, level, slot, key);
+ &b, level, slot, key, 0);
if (err == -EAGAIN)
goto again;
if (err) {
}
/*
+ * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
+ * current state of the tree together with the operations recorded in the tree
+ * modification log to search for the key in a previous version of this tree, as
+ * denoted by the time_seq parameter.
+ *
+ * Naturally, there is no support for insert, delete or cow operations.
+ *
+ * The resulting path and return value will be set up as if we called
+ * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
+ */
+int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key,
+ struct btrfs_path *p, u64 time_seq)
+{
+ struct extent_buffer *b;
+ int slot;
+ int ret;
+ int err;
+ int level;
+ int lowest_unlock = 1;
+ u8 lowest_level = 0;
+
+ lowest_level = p->lowest_level;
+ WARN_ON(p->nodes[0] != NULL);
+
+ if (p->search_commit_root) {
+ BUG_ON(time_seq);
+ return btrfs_search_slot(NULL, root, key, p, 0, 0);
+ }
+
+again:
+ level = 0;
+ b = get_old_root(root, time_seq);
+ extent_buffer_get(b);
+ level = btrfs_header_level(b);
+ btrfs_tree_read_lock(b);
+ p->locks[level] = BTRFS_READ_LOCK;
+
+ while (b) {
+ level = btrfs_header_level(b);
+ p->nodes[level] = b;
+ btrfs_clear_path_blocking(p, NULL, 0);
+
+ /*
+ * we have a lock on b and as long as we aren't changing
+ * the tree, there is no way to for the items in b to change.
+ * It is safe to drop the lock on our parent before we
+ * go through the expensive btree search on b.
+ */
+ btrfs_unlock_up_safe(p, level + 1);
+
+ ret = bin_search(b, key, level, &slot);
+
+ if (level != 0) {
+ int dec = 0;
+ if (ret && slot > 0) {
+ dec = 1;
+ slot -= 1;
+ }
+ p->slots[level] = slot;
+ unlock_up(p, level, lowest_unlock, 0, NULL);
+
+ if (level == lowest_level) {
+ if (dec)
+ p->slots[level]++;
+ goto done;
+ }
+
+ err = read_block_for_search(NULL, root, p, &b, level,
+ slot, key, time_seq);
+ if (err == -EAGAIN)
+ goto again;
+ if (err) {
+ ret = err;
+ goto done;
+ }
+
+ level = btrfs_header_level(b);
+ err = btrfs_try_tree_read_lock(b);
+ if (!err) {
+ btrfs_set_path_blocking(p);
+ btrfs_tree_read_lock(b);
+ btrfs_clear_path_blocking(p, b,
+ BTRFS_READ_LOCK);
+ }
+ p->locks[level] = BTRFS_READ_LOCK;
+ p->nodes[level] = b;
+ b = tree_mod_log_rewind(root->fs_info, b, time_seq);
+ if (b != p->nodes[level]) {
+ btrfs_tree_unlock_rw(p->nodes[level],
+ p->locks[level]);
+ p->locks[level] = 0;
+ p->nodes[level] = b;
+ }
+ } else {
+ p->slots[level] = slot;
+ unlock_up(p, level, lowest_unlock, 0, NULL);
+ goto done;
+ }
+ }
+ ret = 1;
+done:
+ if (!p->leave_spinning)
+ btrfs_set_path_blocking(p);
+ if (ret < 0)
+ btrfs_release_path(p);
+
+ return ret;
+}
+
+/*
* adjust the pointers going up the tree, starting at level
* making sure the right key of each node is points to 'key'.
* This is used after shifting pointers to the left, so it stops
next = c;
next_rw_lock = path->locks[level];
ret = read_block_for_search(NULL, root, path, &next, level,
- slot, &key);
+ slot, &key, 0);
if (ret == -EAGAIN)
goto again;
break;
ret = read_block_for_search(NULL, root, path, &next, level,
- 0, &key);
+ 0, &key, 0);
if (ret == -EAGAIN)
goto again;
projects / platform / kernel / linux-stable.git / commitdiff