return ret;
}
-int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,
- struct tree_mod_elem **tm_ret)
+static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
+ struct extent_buffer *eb) {
+ smp_mb();
+ if (list_empty(&(fs_info)->tree_mod_seq_list))
+ return 1;
+ if (!eb)
+ return 0;
+ if (btrfs_header_level(eb) == 0)
+ return 1;
+ return 0;
+}
+
+/*
+ * This allocates memory and gets a tree modification sequence number when
+ * needed.
+ *
+ * Returns 0 when no sequence number is needed, < 0 on error.
+ * Returns 1 when a sequence number was added. In this case,
+ * fs_info->tree_mod_seq_lock was acquired and must be released by the caller
+ * after inserting into the rb tree.
+ */
+static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,
+ struct tree_mod_elem **tm_ret)
{
struct tree_mod_elem *tm;
- u64 seq = 0;
+ int seq;
- smp_mb();
- if (list_empty(&fs_info->tree_mod_seq_list))
+ if (tree_mod_dont_log(fs_info, NULL))
return 0;
tm = *tm_ret = kzalloc(sizeof(*tm), flags);
if (!tm)
return -ENOMEM;
- __get_tree_mod_seq(fs_info, &tm->elem);
- seq = tm->elem.seq;
tm->elem.flags = 0;
+ spin_lock(&fs_info->tree_mod_seq_lock);
+ if (list_empty(&fs_info->tree_mod_seq_list)) {
+ /*
+ * someone emptied the list while we were waiting for the lock.
+ * we must not add to the list, because no blocker exists. items
+ * are removed from the list only when the existing blocker is
+ * removed from the list.
+ */
+ kfree(tm);
+ seq = 0;
+ spin_unlock(&fs_info->tree_mod_seq_lock);
+ } else {
+ __get_tree_mod_seq(fs_info, &tm->elem);
+ seq = tm->elem.seq;
+ }
return seq;
}
tm->slot = slot;
tm->generation = btrfs_node_ptr_generation(eb, slot);
- return __tree_mod_log_insert(fs_info, tm);
+ ret = __tree_mod_log_insert(fs_info, tm);
+ spin_unlock(&fs_info->tree_mod_seq_lock);
+ return ret;
}
static noinline int
int ret;
int i;
- ret = tree_mod_alloc(fs_info, flags, &tm);
- if (ret <= 0)
- return ret;
+ if (tree_mod_dont_log(fs_info, eb))
+ return 0;
for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
ret = tree_mod_log_insert_key(fs_info, eb, i + dst_slot,
BUG_ON(ret < 0);
}
+ ret = tree_mod_alloc(fs_info, flags, &tm);
+ if (ret <= 0)
+ return ret;
+
tm->index = eb->start >> PAGE_CACHE_SHIFT;
tm->slot = src_slot;
tm->move.dst_slot = dst_slot;
tm->move.nr_items = nr_items;
tm->op = MOD_LOG_MOVE_KEYS;
- return __tree_mod_log_insert(fs_info, tm);
+ ret = __tree_mod_log_insert(fs_info, tm);
+ spin_unlock(&fs_info->tree_mod_seq_lock);
+ return ret;
}
static noinline int
tm->generation = btrfs_header_generation(old_root);
tm->op = MOD_LOG_ROOT_REPLACE;
- return __tree_mod_log_insert(fs_info, tm);
+ ret = __tree_mod_log_insert(fs_info, tm);
+ spin_unlock(&fs_info->tree_mod_seq_lock);
+ return ret;
}
static struct tree_mod_elem *
int ret;
int i;
- smp_mb();
- if (list_empty(&fs_info->tree_mod_seq_list))
+ if (tree_mod_dont_log(fs_info, NULL))
return;
if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
int ret;
u32 nritems;
- smp_mb();
- if (list_empty(&fs_info->tree_mod_seq_list))
- return;
-
- if (btrfs_header_level(eb) == 0)
+ if (tree_mod_dont_log(fs_info, eb))
return;
nritems = btrfs_header_nritems(eb);
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;
+ /*
+ * if there are no tree operation for the oldest root, we simply
+ * return it. this should only happen if that (old) root is at
+ * level 0.
+ */
+ if (!tm)
+ break;
+
+ /*
+ * if there's an operation that's not a root replacement, we
+ * found the oldest version of our root. normally, we'll find a
+ * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
+ */
+ 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;
+ }
+
+ /* if there's no old root to return, return what we found instead */
+ if (!found)
+ found = tm;
+
+ 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 a move operation is needed it's in the log */
+ n--;
+ break;
+ case MOD_LOG_MOVE_KEYS:
+ o_dst = btrfs_node_key_ptr_offset(tm->slot);
+ o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
+ memmove_extent_buffer(eb, o_dst, o_src,
+ 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));
+ btrfs_set_header_level(eb_rewin, btrfs_header_level(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;
+}
+
+/*
+ * get_old_root() rewinds the state of @root's root node to the given @time_seq
+ * value. If there are no changes, the current root->root_node is returned. If
+ * anything changed in between, there's a fresh buffer allocated on which the
+ * rewind operations are done. In any case, the returned buffer is read locked.
+ * Returns NULL on error (with no locks held).
+ */
+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 = NULL;
+ u64 old_generation = 0;
+ u64 logical;
+
+ eb = btrfs_read_lock_root_node(root);
+ tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
+ if (!tm)
+ return root->node;
+
+ if (tm->op == MOD_LOG_ROOT_REPLACE) {
+ old_root = &tm->old_root;
+ old_generation = tm->generation;
+ logical = old_root->logical;
+ } else {
+ logical = root->node->start;
+ }
+
+ tm = tree_mod_log_search(root->fs_info, logical, time_seq);
+ if (old_root)
+ eb = alloc_dummy_extent_buffer(logical, root->nodesize);
+ else
+ eb = btrfs_clone_extent_buffer(root->node);
+ btrfs_tree_read_unlock(root->node);
+ free_extent_buffer(root->node);
+ if (!eb)
+ return NULL;
+ btrfs_tree_read_lock(eb);
+ if (old_root) {
+ 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);
+ btrfs_set_header_level(eb, old_root->level);
+ btrfs_set_header_generation(eb, old_generation);
+ }
+ if (tm)
+ __tree_mod_log_rewind(eb, time_seq, tm);
+ else
+ WARN_ON(btrfs_header_level(eb) != 0);
+ extent_buffer_get(eb);
+
+ return eb;
+}
+
static inline int should_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf)
if (!cur)
return -EIO;
} else if (!uptodate) {
- btrfs_read_buffer(cur, gen);
+ err = btrfs_read_buffer(cur, gen);
+ if (err) {
+ free_extent_buffer(cur);
+ return err;
+ }
}
}
if (search_start == 0)
static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
int level, int *slot)
{
- if (level == 0) {
+ if (level == 0)
return generic_bin_search(eb,
offsetof(struct btrfs_leaf, items),
sizeof(struct btrfs_item),
key, btrfs_header_nritems(eb),
slot);
- } else {
+ else
return generic_bin_search(eb,
offsetof(struct btrfs_node, ptrs),
sizeof(struct btrfs_key_ptr),
key, btrfs_header_nritems(eb),
slot);
- }
- return -1;
}
int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
return 0;
- btrfs_header_nritems(mid);
-
left = read_node_slot(root, parent, pslot - 1);
if (left) {
btrfs_tree_lock(left);
wret = push_node_left(trans, root, left, mid, 1);
if (wret < 0)
ret = wret;
- btrfs_header_nritems(mid);
}
/*
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) {
return ret;
}
+/*
+ * 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:
+ b = get_old_root(root, time_seq);
+ level = btrfs_header_level(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'.
static void insert_ptr(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct btrfs_path *path,
struct btrfs_disk_key *key, u64 bytenr,
- int slot, int level, int tree_mod_log)
+ int slot, int level)
{
struct extent_buffer *lower;
int nritems;
BUG_ON(slot > nritems);
BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
if (slot != nritems) {
- if (tree_mod_log && level)
+ if (level)
tree_mod_log_eb_move(root->fs_info, lower, slot + 1,
slot, nritems - slot);
memmove_extent_buffer(lower,
btrfs_node_key_ptr_offset(slot),
(nritems - slot) * sizeof(struct btrfs_key_ptr));
}
- if (tree_mod_log && level) {
+ if (level) {
ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
MOD_LOG_KEY_ADD);
BUG_ON(ret < 0);
btrfs_mark_buffer_dirty(split);
insert_ptr(trans, root, path, &disk_key, split->start,
- path->slots[level + 1] + 1, level + 1, 1);
+ path->slots[level + 1] + 1, level + 1);
if (path->slots[level] >= mid) {
path->slots[level] -= mid;
btrfs_set_header_nritems(l, mid);
btrfs_item_key(right, &disk_key, 0);
insert_ptr(trans, root, path, &disk_key, right->start,
- path->slots[1] + 1, 1, 0);
+ path->slots[1] + 1, 1);
btrfs_mark_buffer_dirty(right);
btrfs_mark_buffer_dirty(l);
if (mid <= slot) {
btrfs_set_header_nritems(right, 0);
insert_ptr(trans, root, path, &disk_key, right->start,
- path->slots[1] + 1, 1, 0);
+ path->slots[1] + 1, 1);
btrfs_tree_unlock(path->nodes[0]);
free_extent_buffer(path->nodes[0]);
path->nodes[0] = right;
} else {
btrfs_set_header_nritems(right, 0);
insert_ptr(trans, root, path, &disk_key, right->start,
- path->slots[1], 1, 0);
+ path->slots[1], 1);
btrfs_tree_unlock(path->nodes[0]);
free_extent_buffer(path->nodes[0]);
path->nodes[0] = right;
btrfs_node_key_ptr_offset(slot + 1),
sizeof(struct btrfs_key_ptr) *
(nritems - slot - 1));
- }
-
- if (tree_mod_log && level) {
+ } else if (tree_mod_log && level) {
ret = tree_mod_log_insert_key(root->fs_info, parent, slot,
MOD_LOG_KEY_REMOVE);
BUG_ON(ret < 0);
* returns < 0 on io errors.
*/
int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
+{
+ return btrfs_next_old_leaf(root, path, 0);
+}
+
+int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
+ u64 time_seq)
{
int slot;
int level;
path->keep_locks = 1;
path->leave_spinning = 1;
- ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (time_seq)
+ ret = btrfs_search_old_slot(root, &key, path, time_seq);
+ else
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
path->keep_locks = 0;
if (ret < 0)
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;
if (!path->skip_locking) {
ret = btrfs_try_tree_read_lock(next);
+ if (!ret && time_seq) {
+ /*
+ * If we don't get the lock, we may be racing
+ * with push_leaf_left, holding that lock while
+ * itself waiting for the leaf we've currently
+ * locked. To solve this situation, we give up
+ * on our lock and cycle.
+ */
+ free_extent_buffer(next);
+ btrfs_release_path(path);
+ cond_resched();
+ goto again;
+ }
if (!ret) {
btrfs_set_path_blocking(path);
btrfs_tree_read_lock(next);
break;
ret = read_block_for_search(NULL, root, path, &next, level,
- 0, &key);
+ 0, &key, 0);
if (ret == -EAGAIN)
goto again;
projects / firefly-linux-kernel-4.4.55.git / blobdiff