From 4007ea87d900e20a7986cdcdcfdc866e8f8bd473 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 5 Mar 2020 14:06:29 +0800 Subject: [PATCH] btrfs: reloc: refactor direct tree backref processing into its own function For BTRFS_SHARED_BLOCK_REF_KEY, its processing is straightforward, as we now the parent node bytenr directly. If the parent is already cached, or a root, call it a day. If the parent is not cached, add it pending list. This patch will just refactor this part into its own function, handle_direct_tree_backref() and add some comment explaining the @ref_key parameter. Reviewed-by: Josef Bacik Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/relocation.c | 130 +++++++++++++++++++++++++----------------- 1 file changed, 78 insertions(+), 52 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index a46f82744b25..ff0b2f9b68eb 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -698,6 +698,81 @@ static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info, return btrfs_get_fs_root(fs_info, &key, false); } +/* + * Handle direct tree backref + * + * Direct tree backref means, the backref item shows its parent bytenr + * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined). + * + * @ref_key: The converted backref key. + * For keyed backref, it's the item key. + * For inlined backref, objectid is the bytenr, + * type is btrfs_inline_ref_type, offset is + * btrfs_inline_ref_offset. + */ +static int handle_direct_tree_backref(struct backref_cache *cache, + struct btrfs_key *ref_key, + struct backref_node *cur) +{ + struct backref_edge *edge; + struct backref_node *upper; + struct rb_node *rb_node; + + ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY); + + /* Only reloc root uses backref pointing to itself */ + if (ref_key->objectid == ref_key->offset) { + struct btrfs_root *root; + + cur->is_reloc_root = 1; + /* Only reloc backref cache cares about a specific root */ + if (cache->is_reloc) { + root = find_reloc_root(cache->fs_info, cur->bytenr); + if (WARN_ON(!root)) + return -ENOENT; + cur->root = root; + } else { + /* + * For generic purpose backref cache, reloc root node + * is useless. + */ + list_add(&cur->list, &cache->useless_node); + } + return 0; + } + + edge = alloc_backref_edge(cache); + if (!edge) + return -ENOMEM; + + rb_node = tree_search(&cache->rb_root, ref_key->offset); + if (!rb_node) { + /* Parent node not yet cached */ + upper = alloc_backref_node(cache); + if (!upper) { + free_backref_edge(cache, edge); + return -ENOMEM; + } + upper->bytenr = ref_key->offset; + upper->level = cur->level + 1; + + /* + * Backrefs for the upper level block isn't cached, add the + * block to pending list + */ + list_add_tail(&edge->list[UPPER], &cache->pending_edge); + } else { + /* Parent node already cached */ + upper = rb_entry(rb_node, struct backref_node, rb_node); + ASSERT(upper->checked); + INIT_LIST_HEAD(&edge->list[UPPER]); + } + list_add_tail(&edge->list[LOWER], &cur->upper); + edge->node[LOWER] = cur; + edge->node[UPPER] = upper; + return 0; +} + /* * build backref tree for a given tree block. root of the backref tree * corresponds the tree block, leaves of the backref tree correspond @@ -719,7 +794,6 @@ struct backref_node *build_backref_tree(struct reloc_control *rc, { struct btrfs_backref_iter *iter; struct backref_cache *cache = &rc->backref_cache; - struct btrfs_fs_info *fs_info = cache->fs_info; /* For searching parent of TREE_BLOCK_REF */ struct btrfs_path *path; struct btrfs_root *root; @@ -841,59 +915,11 @@ struct backref_node *build_backref_tree(struct reloc_control *rc, /* SHARED_BLOCK_REF means key.offset is the parent bytenr */ if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) { - if (key.objectid == key.offset) { - cur->is_reloc_root = 1; - /* Only reloc backref cache cares exact root */ - if (cache->is_reloc) { - root = find_reloc_root(fs_info, - cur->bytenr); - if (WARN_ON(!root)) { - err = -ENOENT; - goto out; - } - cur->root = root; - } else { - /* - * For generic purpose backref cache, - * reloc root node is useless. - */ - list_add(&cur->list, - &cache->useless_node); - } - break; - } - - edge = alloc_backref_edge(cache); - if (!edge) { - err = -ENOMEM; + ret = handle_direct_tree_backref(cache, &key, cur); + if (ret < 0) { + err = ret; goto out; } - rb_node = tree_search(&cache->rb_root, key.offset); - if (!rb_node) { - upper = alloc_backref_node(cache); - if (!upper) { - free_backref_edge(cache, edge); - err = -ENOMEM; - goto out; - } - upper->bytenr = key.offset; - upper->level = cur->level + 1; - /* - * backrefs for the upper level block isn't - * cached, add the block to pending list - */ - list_add_tail(&edge->list[UPPER], - &cache->pending_edge); - } else { - upper = rb_entry(rb_node, struct backref_node, - rb_node); - ASSERT(upper->checked); - INIT_LIST_HEAD(&edge->list[UPPER]); - } - list_add_tail(&edge->list[LOWER], &cur->upper); - edge->node[LOWER] = cur; - edge->node[UPPER] = upper; - continue; } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) { err = -EINVAL;