btrfs: introduce extra sanity checks for extent maps

Since extent_map structure has the all the needed members to represent a
file extent directly, we can apply all the file extent sanity checks to
an extent map.

The new sanity checks will cross check both the old members
(block_start/block_len/orig_start) and the new members
(disk_bytenr/disk_num_bytes/offset).

There is a special case for offset/orig_start/start cross check, we only
do such sanity check for compressed extent, as only compressed
read/encoded write really utilize orig_start.
This can be proved by the cleanup patch of orig_start.

The checks happens at the following times:

- add_extent_mapping()
  This is for newly added extent map

- replace_extent_mapping()
  This is for btrfs_drop_extent_map_range() and split_extent_map()

- try_merge_map()

For a lot of call sites we have to properly populate all the members to
pass the sanity check, meanwhile the following code needs extra
modification:

- setup_file_extents() from inode-tests
  The file extents layout of setup_file_extents() is already too invalid
  that tree-checker would reject most of them in real world.

  However there is just a special unaligned regular extent which has
  mismatched disk_num_bytes (4096) and ram_bytes (4096 - 1).
  So instead of dropping the whole test case, here we just unify
  disk_num_bytes and ram_bytes to 4096 - 1.

- test_case_7() from extent-map-tests
  An extent is inserted with 16K length, but on-disk extent size is
  only 4K.
  This means it must be a compressed extent, so set the compressed flag
  for it.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 5f1a909a1d91..151ed1ebd291 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2911,9 +2911,13 @@ static noinline_for_stack int setup_relocation_extent_mapping(struct inode *inod
 		return -ENOMEM;
 
 	em->start = start;
+	em->orig_start = start;
 	em->len = end + 1 - start;
 	em->block_len = em->len;
 	em->block_start = block_start;
+	em->disk_bytenr = block_start;
+	em->disk_num_bytes = em->len;
+	em->ram_bytes = em->len;
 	em->flags |= EXTENT_FLAG_PINNED;
 
 	lock_extent(&BTRFS_I(inode)->io_tree, start, end, &cached_state);