btrfs: backref: Add special time_seq == (u64)-1 case for
btrfs_find_all_roots().
Allow btrfs_find_all_roots() to skip all delayed_ref_head lock and tree
lock to do tree search.
This is important for later qgroup implement which will call
find_all_roots() after fs trees are committed.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 49bc5a4..802fabb 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -250,8 +250,12 @@
* the first item to check. But sometimes, we may enter it with
* slot==nritems. In that case, go to the next leaf before we continue.
*/
- if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
- ret = btrfs_next_old_leaf(root, path, time_seq);
+ if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
+ if (time_seq == (u64)-1)
+ ret = btrfs_next_leaf(root, path);
+ else
+ ret = btrfs_next_old_leaf(root, path, time_seq);
+ }
while (!ret && count < total_refs) {
eb = path->nodes[0];
@@ -291,7 +295,10 @@
eie = NULL;
}
next:
- ret = btrfs_next_old_item(root, path, time_seq);
+ if (time_seq == (u64)-1)
+ ret = btrfs_next_item(root, path);
+ else
+ ret = btrfs_next_old_item(root, path, time_seq);
}
if (ret > 0)
@@ -334,6 +341,8 @@
if (path->search_commit_root)
root_level = btrfs_header_level(root->commit_root);
+ else if (time_seq == (u64)-1)
+ root_level = btrfs_header_level(root->node);
else
root_level = btrfs_old_root_level(root, time_seq);
@@ -343,7 +352,12 @@
}
path->lowest_level = level;
- ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
+ if (time_seq == (u64)-1)
+ ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path,
+ 0, 0);
+ else
+ ret = btrfs_search_old_slot(root, &ref->key_for_search, path,
+ time_seq);
/* root node has been locked, we can release @subvol_srcu safely here */
srcu_read_unlock(&fs_info->subvol_srcu, index);
@@ -879,6 +893,11 @@
*
* NOTE: This can return values > 0
*
+ * If time_seq is set to (u64)-1, it will not search delayed_refs, and behave
+ * much like trans == NULL case, the difference only lies in it will not
+ * commit root.
+ * The special case is for qgroup to search roots in commit_transaction().
+ *
* FIXME some caching might speed things up
*/
static int find_parent_nodes(struct btrfs_trans_handle *trans,
@@ -917,6 +936,9 @@
path->skip_locking = 1;
}
+ if (time_seq == (u64)-1)
+ path->skip_locking = 1;
+
/*
* grab both a lock on the path and a lock on the delayed ref head.
* We need both to get a consistent picture of how the refs look
@@ -931,9 +953,10 @@
BUG_ON(ret == 0);
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
- if (trans && likely(trans->type != __TRANS_DUMMY)) {
+ if (trans && likely(trans->type != __TRANS_DUMMY) &&
+ time_seq != (u64)-1) {
#else
- if (trans) {
+ if (trans && time_seq != (u64)-1) {
#endif
/*
* look if there are updates for this ref queued and lock the