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 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1020,7 +1020,7 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
 
        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 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
        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;
        }