Btrfs: directory readahead

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

4 files changed, 63 insertions, 1 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e1b6e13a5ae8..354524adf984 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -5,6 +5,7 @@
 #include <linux/scatterlist.h>
 #include <linux/swap.h>
 #include <linux/radix-tree.h>
+#include <linux/file.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -253,6 +254,29 @@ static struct address_space_operations btree_aops = {
         .sync_page      = block_sync_page,
 };
 
+int readahead_tree_block(struct btrfs_root *root, u64 blocknr)
+{
+        struct buffer_head *bh = NULL;
+
+        bh = btrfs_find_create_tree_block(root, blocknr);
+        if (!bh)
+                return 0;
+        if (buffer_uptodate(bh))
+                goto done;
+        if (test_set_buffer_locked(bh))
+                goto done;
+        if (!buffer_uptodate(bh)) {
+                get_bh(bh);
+                bh->b_end_io = end_buffer_read_sync;
+                submit_bh(READ, bh);
+        } else {
+                unlock_buffer(bh);
+        }
+done:
+        brelse(bh);
+        return 0;
+}
+
 struct buffer_head *read_tree_block(struct btrfs_root *root, u64 blocknr)
 {
         struct buffer_head *bh = NULL;
@@ -270,11 +294,14 @@ struct buffer_head *read_tree_block(struct btrfs_root *root, u64 blocknr)
                 wait_on_buffer(bh);
                 if (!buffer_uptodate(bh))
                         goto fail;
-                csum_tree_block(root, bh, 1);
         } else {
                 unlock_buffer(bh);
         }
 uptodate:
+        if (!buffer_checked(bh)) {
+                csum_tree_block(root, bh, 1);
+                set_buffer_checked(bh);
+        }
         if (check_tree_block(root, bh))
                 BUG();
         return bh;
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 444ebb0141ae..1ee7d2a55b5b 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -5,6 +5,11 @@
 
 #define BTRFS_SUPER_INFO_OFFSET (16 * 1024)
 
+enum btrfs_bh_state_bits {
+        BH_Checked = BH_PrivateStart,
+};
+BUFFER_FNS(Checked, checked);
+
 static inline struct btrfs_node *btrfs_buffer_node(struct buffer_head *bh)
 {
         return (struct btrfs_node *)bh->b_data;
@@ -21,6 +26,7 @@ static inline struct btrfs_header *btrfs_buffer_header(struct buffer_head *bh)
 }
 
 struct buffer_head *read_tree_block(struct btrfs_root *root, u64 blocknr);
+int readahead_tree_block(struct btrfs_root *root, u64 blocknr);
 struct buffer_head *btrfs_find_create_tree_block(struct btrfs_root *root,
                                                  u64 blocknr);
 int write_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 8b8cbe25fffb..2837fddf7b1c 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -812,6 +812,7 @@ struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
         BUG_ON(ret);
         buf = btrfs_find_create_tree_block(root, ins.objectid);
         set_buffer_uptodate(buf);
+        set_buffer_checked(buf);
         set_radix_bit(&trans->transaction->dirty_pages, buf->b_page->index);
         return buf;
 }
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 7ecbe7c86186..a29a781b86c2 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -585,6 +585,31 @@ printk("adding new root for inode %lu root %p (found %p)\n", inode->i_ino, sub_r
         return d_splice_alias(inode, dentry);
 }
 
+static void reada_leaves(struct btrfs_root *root, struct btrfs_path *path)
+{
+        struct btrfs_node *node;
+        int i;
+        int nritems;
+        u64 objectid;
+        u64 item_objectid;
+        u64 blocknr;
+        int slot;
+
+        if (!path->nodes[1])
+                return;
+        node = btrfs_buffer_node(path->nodes[1]);
+        slot = path->slots[1];
+        objectid = btrfs_disk_key_objectid(&node->ptrs[slot].key);
+        nritems = btrfs_header_nritems(&node->header);
+        for (i = slot; i < nritems; i++) {
+                item_objectid = btrfs_disk_key_objectid(&node->ptrs[i].key);
+                if (item_objectid != objectid)
+                        break;
+                blocknr = btrfs_node_blockptr(node, i);
+                readahead_tree_block(root, blocknr);
+        }
+}
+
 static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 {
         struct inode *inode = filp->f_path.dentry->d_inode;
@@ -619,6 +644,7 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
         if (ret < 0)
                 goto err;
         advance = 0;
+        reada_leaves(root, path);
         while(1) {
                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                 nritems = btrfs_header_nritems(&leaf->header);
@@ -631,6 +657,8 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
                                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                                 nritems = btrfs_header_nritems(&leaf->header);
                                 slot = path->slots[0];
+                                if (path->slots[1] == 0)
+                                        reada_leaves(root, path);
                         } else {
                                 slot++;
                                 path->slots[0]++;