Btrfs: directory readahead

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

1 files changed, 28 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;