3 files changed, 35 insertions, 0 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e6170e142cad..1220d04072c8 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -980,6 +980,38 @@ int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
         return ret;
 }
 
+int reada_tree_block_flagged(struct btrfs_root *root, u64 bytenr, u32 blocksize,
+                         int mirror_num, struct extent_buffer **eb)
+{
+        struct extent_buffer *buf = NULL;
+        struct inode *btree_inode = root->fs_info->btree_inode;
+        struct extent_io_tree *io_tree = &BTRFS_I(btree_inode)->io_tree;
+        int ret;
+
+        buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
+        if (!buf)
+                return 0;
+
+        set_bit(EXTENT_BUFFER_READAHEAD, &buf->bflags);
+
+        ret = read_extent_buffer_pages(io_tree, buf, 0, WAIT_PAGE_LOCK,
+                                       btree_get_extent, mirror_num);
+        if (ret) {
+                free_extent_buffer(buf);
+                return ret;
+        }
+
+        if (test_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags)) {
+                free_extent_buffer(buf);
+                return -EIO;
+        } else if (extent_buffer_uptodate(io_tree, buf, NULL)) {
+                *eb = buf;
+        } else {
+                free_extent_buffer(buf);
+        }
+        return 0;
+}
+
 struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
                                             u64 bytenr, u32 blocksize)
 {
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index bec3ea4bd67f..b3bdb5c1390f 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -40,6 +40,8 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
                                       u32 blocksize, u64 parent_transid);
 int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
                          u64 parent_transid);
+int reada_tree_block_flagged(struct btrfs_root *root, u64 bytenr, u32 blocksize,
+                         int mirror_num, struct extent_buffer **eb);
 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
                                                    u64 bytenr, u32 blocksize);
 int clean_tree_block(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 6d74c6b34691..fcaf49bcb880 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -32,6 +32,7 @@
 #define EXTENT_BUFFER_BLOCKING 1
 #define EXTENT_BUFFER_DIRTY 2
 #define EXTENT_BUFFER_CORRUPT 3
+#define EXTENT_BUFFER_READAHEAD 4       /* this got triggered by readahead */
 
 /* these are flags for extent_clear_unlock_delalloc */
 #define EXTENT_CLEAR_UNLOCK_PAGE 0x1