Btrfs: keep track of the extents original block length

If we've written to a prealloc extent we need to know the original block len
for the extent.  We can't figure this out currently since ->block_len is
just set to the extent length.  So introduce ->orig_block_len so that we
know how many bytes were in the original extent for proper extent logging
that future patches will need.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 7f4654a15207..6810145f4e97 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -588,6 +588,8 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
                                 split->block_len = em->block_len;
                         else
                                 split->block_len = split->len;
+                        split->orig_block_len = max(split->block_len,
+                                                    em->orig_block_len);
                         split->generation = gen;
                         split->bdev = em->bdev;
                         split->flags = flags;
@@ -609,6 +611,8 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
                         split->flags = flags;
                         split->compress_type = em->compress_type;
                         split->generation = gen;
+                        split->orig_block_len = max(em->block_len,
+                                                    em->orig_block_len);
 
                         if (compressed) {
                                 split->block_len = em->block_len;
@@ -1838,6 +1842,7 @@ out:
 
                 hole_em->block_start = EXTENT_MAP_HOLE;
                 hole_em->block_len = 0;
+                hole_em->orig_block_len = 0;
                 hole_em->bdev = root->fs_info->fs_devices->latest_bdev;
                 hole_em->compress_type = BTRFS_COMPRESS_NONE;
                 hole_em->generation = trans->transid;