Btrfs: cow file extents before writing
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 3e8bfb0..91aa1b4 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1020,7 +1020,7 @@
ret = btrfs_lookup_file_extent(trans, root, path,
inode->i_ino,
- iblock << inode->i_blkbits, 0);
+ iblock << inode->i_blkbits, 1);
if (ret < 0) {
err = ret;
goto out;
@@ -1040,9 +1040,25 @@
blocknr = btrfs_file_extent_disk_blocknr(item);
blocknr += btrfs_file_extent_offset(item);
- /* exact match found, use it */
+ /* exact match found, use it, FIXME, deal with extents
+ * other than the page size
+ */
if (ret == 0) {
err = 0;
+ BUG_ON(btrfs_file_extent_disk_num_blocks(item) != 1);
+ if (btrfs_file_extent_generation(item) != trans->transid) {
+ struct btrfs_key ins;
+ ret = btrfs_alloc_extent(trans, root, 1,
+ blocknr, (u64)-1, &ins);
+ BUG_ON(ret);
+ btrfs_set_file_extent_disk_blocknr(item, ins.objectid);
+ mark_buffer_dirty(path->nodes[0]);
+ ret = btrfs_free_extent(trans, root,
+ blocknr, 1, 0);
+ BUG_ON(ret);
+ blocknr = ins.objectid;
+
+ }
map_bh(result, inode->i_sb, blocknr);
goto out;
}