Btrfs: Fold some btree readahead routines into something more generic.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index aa824e2..7a08491 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -640,6 +640,73 @@
}
/*
+ * readahead one full node of leaves
+ */
+static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
+ int slot)
+{
+ struct btrfs_node *node;
+ int i;
+ u32 nritems;
+ u64 item_objectid;
+ u64 blocknr;
+ u64 search;
+ u64 cluster_start;
+ int ret;
+ int nread = 0;
+ int direction = path->reada;
+ struct radix_tree_root found;
+ unsigned long gang[8];
+ struct buffer_head *bh;
+
+ if (!path->nodes[1])
+ return;
+
+ node = btrfs_buffer_node(path->nodes[1]);
+ search = btrfs_node_blockptr(node, slot);
+ bh = btrfs_find_tree_block(root, search);
+ if (bh) {
+ brelse(bh);
+ return;
+ }
+
+ init_bit_radix(&found);
+ nritems = btrfs_header_nritems(&node->header);
+ for (i = slot; i < nritems; i++) {
+ item_objectid = btrfs_disk_key_objectid(&node->ptrs[i].key);
+ blocknr = btrfs_node_blockptr(node, i);
+ set_radix_bit(&found, blocknr);
+ }
+ if (direction > 0) {
+ cluster_start = search - 4;
+ if (cluster_start > search)
+ cluster_start = 0;
+ } else
+ cluster_start = search + 4;
+ while(1) {
+ ret = find_first_radix_bit(&found, gang, 0, ARRAY_SIZE(gang));
+ if (!ret)
+ break;
+ for (i = 0; i < ret; i++) {
+ blocknr = gang[i];
+ clear_radix_bit(&found, blocknr);
+ if (nread > 64)
+ continue;
+ if (direction > 0 && cluster_start <= blocknr &&
+ cluster_start + 8 > blocknr) {
+ cluster_start = blocknr;
+ readahead_tree_block(root, blocknr);
+ nread++;
+ } else if (direction < 0 && cluster_start >= blocknr &&
+ blocknr + 8 > cluster_start) {
+ cluster_start = blocknr;
+ readahead_tree_block(root, blocknr);
+ nread++;
+ }
+ }
+ }
+}
+/*
* look for key in the tree. path is filled in with nodes along the way
* if key is found, we return zero and you can find the item in the leaf
* level of the path (level 0)
@@ -660,9 +727,11 @@
struct buffer_head *cow_buf;
struct btrfs_node *c;
struct btrfs_root_item *root_item = &root->root_item;
+ u64 blocknr;
int slot;
int ret;
int level;
+ int should_reada = p->reada;
u8 lowest_level = 0;
if (btrfs_root_refs(root_item) == 0 && root->ref_cows) {
@@ -728,7 +797,11 @@
/* this is only true while dropping a snapshot */
if (level == lowest_level)
break;
+ blocknr = btrfs_node_blockptr(c, slot);
+ if (level == 1 && should_reada)
+ reada_for_search(root, p, slot);
b = read_tree_block(root, btrfs_node_blockptr(c, slot));
+
} else {
struct btrfs_leaf *l = (struct btrfs_leaf *)c;
p->slots[level] = slot;
@@ -1915,6 +1988,8 @@
blocknr = btrfs_node_blockptr(c_node, slot);
if (next)
btrfs_block_release(root, next);
+ if (level == 1 && path->reada)
+ reada_for_search(root, path, slot);
next = read_tree_block(root, blocknr);
break;
}
@@ -1927,6 +2002,8 @@
path->slots[level] = 0;
if (!level)
break;
+ if (level == 1 && path->reada)
+ reada_for_search(root, path, slot);
next = read_tree_block(root,
btrfs_node_blockptr(btrfs_buffer_node(next), 0));
}