Btrfs: Fold some btree readahead routines into something more generic.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

4 files changed, 81 insertions, 96 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index aa824e2c521f..7a08491e208e 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -640,6 +640,73 @@ static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 }
 
 /*
+ * 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 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
         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 @@ again:
                         /* 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 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
                 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 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
                 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));
         }
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 73c2e75a136d..c5a18d5d7f7c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -177,6 +177,7 @@ struct btrfs_node {
 struct btrfs_path {
         struct buffer_head *nodes[BTRFS_MAX_LEVEL];
         int slots[BTRFS_MAX_LEVEL];
+        int reada;
 };
 
 /*
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 9455974dabea..5d4d5d8db8ef 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -32,33 +32,6 @@ static int finish_current_insert(struct btrfs_trans_handle *trans, struct
 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
                                btrfs_root *extent_root);
 
-static void reada_extent_leaves(struct btrfs_root *root,
-                                struct btrfs_path *path, u64 limit)
-{
-        struct btrfs_node *node;
-        int i;
-        int nritems;
-        u64 item_objectid;
-        u64 blocknr;
-        int slot;
-        int ret;
-
-        if (!path->nodes[1])
-                return;
-        node = btrfs_buffer_node(path->nodes[1]);
-        slot = path->slots[1] + 1;
-        nritems = btrfs_header_nritems(&node->header);
-        for (i = slot; i < nritems && i < slot + 8; i++) {
-                item_objectid = btrfs_disk_key_objectid(&node->ptrs[i].key);
-                if (item_objectid > limit)
-                        break;
-                blocknr = btrfs_node_blockptr(node, i);
-                ret = readahead_tree_block(root, blocknr);
-                if (ret)
-                        break;
-        }
-}
-
 static int cache_block_group(struct btrfs_root *root,
                              struct btrfs_block_group_cache *block_group)
 {
@@ -84,6 +57,7 @@ static int cache_block_group(struct btrfs_root *root,
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
+        path->reada = 1;
         key.objectid = block_group->key.objectid;
         key.flags = 0;
         key.offset = 0;
@@ -94,12 +68,10 @@ static int cache_block_group(struct btrfs_root *root,
         if (ret && path->slots[0] > 0)
                 path->slots[0]--;
         limit = block_group->key.objectid + block_group->key.offset;
-        reada_extent_leaves(root, path, limit);
         while(1) {
                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                 slot = path->slots[0];
                 if (slot >= btrfs_header_nritems(&leaf->header)) {
-                        reada_extent_leaves(root, path, limit);
                         ret = btrfs_next_leaf(root, path);
                         if (ret < 0)
                                 goto err;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index fa9c531c86b7..3889032fc449 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -375,40 +375,6 @@ static int btrfs_free_inode(struct btrfs_trans_handle *trans,
 }
 
 /*
- * truncates go from a high offset to a low offset.  So, walk
- * from hi to lo in the node and issue readas.  Stop when you find
- * keys from a different objectid
- */
-static void reada_truncate(struct btrfs_root *root, struct btrfs_path *path,
-                           u64 objectid)
-{
-        struct btrfs_node *node;
-        int i;
-        int nritems;
-        u64 item_objectid;
-        u64 blocknr;
-        int slot;
-        int ret;
-
-        if (!path->nodes[1])
-                return;
-        node = btrfs_buffer_node(path->nodes[1]);
-        slot = path->slots[1];
-        if (slot == 0)
-                return;
-        nritems = btrfs_header_nritems(&node->header);
-        for (i = slot - 1; i >= 0; i--) {
-                item_objectid = btrfs_disk_key_objectid(&node->ptrs[i].key);
-                if (item_objectid != objectid)
-                        break;
-                blocknr = btrfs_node_blockptr(node, i);
-                ret = readahead_tree_block(root, blocknr);
-                if (ret)
-                        break;
-        }
-}
-
-/*
  * this can truncate away extent items, csum items and directory items.
  * It starts at a high offset and removes keys until it can't find
  * any higher than i_size.
@@ -434,6 +400,7 @@ static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
         int del_item;
 
         path = btrfs_alloc_path();
+        path->reada = -1;
         BUG_ON(!path);
         /* FIXME, add redo link to tree so we don't leak on crash */
         key.objectid = inode->i_ino;
@@ -450,7 +417,6 @@ static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
                         BUG_ON(path->slots[0] == 0);
                         path->slots[0]--;
                 }
-                reada_truncate(root, path, inode->i_ino);
                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                 found_key = &leaf->items[path->slots[0]].key;
                 found_type = btrfs_disk_key_type(found_key);
@@ -827,36 +793,6 @@ static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
         return d_splice_alias(inode, dentry);
 }
 
-/*
- * readahead one full node of leaves as long as their keys include
- * the objectid supplied
- */
-static void reada_leaves(struct btrfs_root *root, struct btrfs_path *path,
-                         u64 objectid)
-{
-        struct btrfs_node *node;
-        int i;
-        u32 nritems;
-        u64 item_objectid;
-        u64 blocknr;
-        int slot;
-        int ret;
-
-        if (!path->nodes[1])
-                return;
-        node = btrfs_buffer_node(path->nodes[1]);
-        slot = path->slots[1];
-        nritems = btrfs_header_nritems(&node->header);
-        for (i = slot + 1; i < nritems; i++) {
-                item_objectid = btrfs_disk_key_objectid(&node->ptrs[i].key);
-                if (item_objectid != objectid)
-                        break;
-                blocknr = btrfs_node_blockptr(node, i);
-                ret = readahead_tree_block(root, blocknr);
-                if (ret)
-                        break;
-        }
-}
 static unsigned char btrfs_filetype_table[] = {
         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
 };
@@ -890,18 +826,17 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
         btrfs_set_key_type(&key, key_type);
         key.offset = filp->f_pos;
         path = btrfs_alloc_path();
+        path->reada = 1;
         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
         if (ret < 0)
                 goto err;
         advance = 0;
-        reada_leaves(root, path, inode->i_ino);
         while(1) {
                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                 nritems = btrfs_header_nritems(&leaf->header);
                 slot = path->slots[0];
                 if (advance || slot >= nritems) {
                         if (slot >= nritems -1) {
-                                reada_leaves(root, path, inode->i_ino);
                                 ret = btrfs_next_leaf(root, path);
                                 if (ret)
                                         break;