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btrfs: backref: rename and move finish_upper_links() 

This the the 2nd major part of generic backref cache. Move it to
backref.c so we can reuse it.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2020-03-23 16:14:08 +08:00 committed by David Sterba
parent 1b60d2ec98
commit fc997ed05a
3 changed files with 110 additions and 115 deletions
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106
fs/btrfs/backref.c
View File

@ -2830,6 +2830,7 @@ out:
*
* NOTE: Even if the function returned 0, @cur is not yet cached as its upper
* links aren't yet bi-directional. Needs to finish such links.
* Use btrfs_backref_finish_upper_links() to finish such linkage.
*
* @path: Released path for indirect tree backref lookup
* @iter: Released backref iter for extent tree search
@ -2957,3 +2958,108 @@ out:
btrfs_backref_iter_release(iter);
return ret;
}
/*
* Finish the upwards linkage created by btrfs_backref_add_tree_node()
*/
int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *start)
{
struct list_head *useless_node = &cache->useless_node;
struct btrfs_backref_edge *edge;
struct rb_node *rb_node;
LIST_HEAD(pending_edge);
ASSERT(start->checked);
/* Insert this node to cache if it's not COW-only */
if (!start->cowonly) {
rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
&start->rb_node);
if (rb_node)
btrfs_backref_panic(cache->fs_info, start->bytenr,
-EEXIST);
list_add_tail(&start->lower, &cache->leaves);
}
/*
* Use breadth first search to iterate all related edges.
*
* The starting points are all the edges of this node
*/
list_for_each_entry(edge, &start->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &pending_edge);
while (!list_empty(&pending_edge)) {
struct btrfs_backref_node *upper;
struct btrfs_backref_node *lower;
struct rb_node *rb_node;
edge = list_first_entry(&pending_edge,
struct btrfs_backref_edge, list[UPPER]);
list_del_init(&edge->list[UPPER]);
upper = edge->node[UPPER];
lower = edge->node[LOWER];
/* Parent is detached, no need to keep any edges */
if (upper->detached) {
list_del(&edge->list[LOWER]);
btrfs_backref_free_edge(cache, edge);
/* Lower node is orphan, queue for cleanup */
if (list_empty(&lower->upper))
list_add(&lower->list, useless_node);
continue;
}
/*
* All new nodes added in current build_backref_tree() haven't
* been linked to the cache rb tree.
* So if we have upper->rb_node populated, this means a cache
* hit. We only need to link the edge, as @upper and all its
* parents have already been linked.
*/
if (!RB_EMPTY_NODE(&upper->rb_node)) {
if (upper->lowest) {
list_del_init(&upper->lower);
upper->lowest = 0;
}
list_add_tail(&edge->list[UPPER], &upper->lower);
continue;
}
/* Sanity check, we shouldn't have any unchecked nodes */
if (!upper->checked) {
ASSERT(0);
return -EUCLEAN;
}
/* Sanity check, COW-only node has non-COW-only parent */
if (start->cowonly != upper->cowonly) {
ASSERT(0);
return -EUCLEAN;
}
/* Only cache non-COW-only (subvolume trees) tree blocks */
if (!upper->cowonly) {
rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
&upper->rb_node);
if (rb_node) {
btrfs_backref_panic(cache->fs_info,
upper->bytenr, -EEXIST);
return -EUCLEAN;
}
}
list_add_tail(&edge->list[UPPER], &upper->lower);
/*
* Also queue all the parent edges of this uncached node
* to finish the upper linkage
*/
list_for_each_entry(edge, &upper->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &pending_edge);
}
return 0;
}

3
fs/btrfs/backref.h
View File

@ -369,4 +369,7 @@ int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
struct btrfs_key *node_key,
struct btrfs_backref_node *cur);
int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *start);
#endif

116
fs/btrfs/relocation.c
View File

@ -377,120 +377,6 @@ static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
return btrfs_get_fs_root(fs_info, &key, false);
}
/*
* In handle_one_tree_backref(), we have only linked the lower node to the edge,
* but the upper node hasn't been linked to the edge.
* This means we can only iterate through btrfs_backref_node::upper to reach
* parent edges, but not through btrfs_backref_node::lower to reach children
* edges.
*
* This function will finish the btrfs_backref_node::lower to related edges,
* so that backref cache can be bi-directionally iterated.
*
* Also, this will add the nodes to backref cache for the next run.
*/
static int finish_upper_links(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *start)
{
struct list_head *useless_node = &cache->useless_node;
struct btrfs_backref_edge *edge;
struct rb_node *rb_node;
LIST_HEAD(pending_edge);
ASSERT(start->checked);
/* Insert this node to cache if it's not COW-only */
if (!start->cowonly) {
rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
&start->rb_node);
if (rb_node)
btrfs_backref_panic(cache->fs_info, start->bytenr,
-EEXIST);
list_add_tail(&start->lower, &cache->leaves);
}
/*
* Use breadth first search to iterate all related edges.
*
* The starting points are all the edges of this node
*/
list_for_each_entry(edge, &start->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &pending_edge);
while (!list_empty(&pending_edge)) {
struct btrfs_backref_node *upper;
struct btrfs_backref_node *lower;
struct rb_node *rb_node;
edge = list_first_entry(&pending_edge,
struct btrfs_backref_edge, list[UPPER]);
list_del_init(&edge->list[UPPER]);
upper = edge->node[UPPER];
lower = edge->node[LOWER];
/* Parent is detached, no need to keep any edges */
if (upper->detached) {
list_del(&edge->list[LOWER]);
btrfs_backref_free_edge(cache, edge);
/* Lower node is orphan, queue for cleanup */
if (list_empty(&lower->upper))
list_add(&lower->list, useless_node);
continue;
}
/*
* All new nodes added in current build_backref_tree() haven't
* been linked to the cache rb tree.
* So if we have upper->rb_node populated, this means a cache
* hit. We only need to link the edge, as @upper and all its
* parent have already been linked.
*/
if (!RB_EMPTY_NODE(&upper->rb_node)) {
if (upper->lowest) {
list_del_init(&upper->lower);
upper->lowest = 0;
}
list_add_tail(&edge->list[UPPER], &upper->lower);
continue;
}
/* Sanity check, we shouldn't have any unchecked nodes */
if (!upper->checked) {
ASSERT(0);
return -EUCLEAN;
}
/* Sanity check, COW-only node has non-COW-only parent */
if (start->cowonly != upper->cowonly) {
ASSERT(0);
return -EUCLEAN;
}
/* Only cache non-COW-only (subvolume trees) tree blocks */
if (!upper->cowonly) {
rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
&upper->rb_node);
if (rb_node) {
btrfs_backref_panic(cache->fs_info,
upper->bytenr, -EEXIST);
return -EUCLEAN;
}
}
list_add_tail(&edge->list[UPPER], &upper->lower);
/*
* Also queue all the parent edges of this uncached node to
* finish the upper linkage
*/
list_for_each_entry(edge, &upper->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &pending_edge);
}
return 0;
}
/*
* For useless nodes, do two major clean ups:
*
@ -634,7 +520,7 @@ static noinline_for_stack struct btrfs_backref_node *build_backref_tree(
} while (edge);
/* Finish the upper linkage of newly added edges/nodes */
ret = finish_upper_links(cache, node);
ret = btrfs_backref_finish_upper_links(cache, node);
if (ret < 0) {
err = ret;
goto out;