btrfs: tree-checker: add remap-tree checks to check_block_group_item()

Add some write-time checks for block group items relating to the remap
tree.

Here we're checking:

* That the REMAPPED or METADATA_REMAP flags aren't set unless the
  REMAP_TREE incompat flag is also set
* That `remap_bytes` isn't more than the size of the block group
* That `identity_remap_count` isn't more than the number of sectors in
  the block group

Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 9efa4116e0061b05ca32bd9447eb8a6165f7ba7d..1f15d0793a9c995c6f7cb2c27999a0269029fa58 100644 (file)
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -777,6 +777,47 @@ static int check_block_group_item(struct extent_buffer *leaf,
                        BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
                return -EUCLEAN;
        }
+
+       if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+                    type == BTRFS_BLOCK_GROUP_METADATA_REMAP)) {
+               block_group_err(leaf, slot,
+               "invalid type, METADATA_REMAP set but REMAP_TREE incompat flag not set");
+               return -EUCLEAN;
+       }
+
+       if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+                    flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
+               block_group_err(leaf, slot,
+               "invalid flags, REMAPPED set but REMAP_TREE incompat flag not set");
+               return -EUCLEAN;
+       }
+
+       if (item_size == sizeof(struct btrfs_block_group_item_v2)) {
+               struct btrfs_block_group_item_v2 *bgi2;
+               u64 remap_bytes;
+               u32 identity_remap_count;
+
+               bgi2 = btrfs_item_ptr(leaf, slot, struct btrfs_block_group_item_v2);
+               remap_bytes = btrfs_block_group_v2_remap_bytes(leaf, bgi2);
+
+               if (unlikely(remap_bytes > key->offset)) {
+                       block_group_err(leaf, slot,
+                               "invalid remap_bytes, have %llu expect [0, %llu]",
+                                       remap_bytes, key->offset);
+                       return -EUCLEAN;
+               }
+
+               identity_remap_count = btrfs_block_group_v2_identity_remap_count(leaf, bgi2);
+               if (unlikely((u64)identity_remap_count >
+                            key->offset >> fs_info->sectorsize_bits)) {
+                       block_group_err(leaf, slot,
+                               "invalid identity_remap_count, have %u expect [0, %llu]",
+                                       identity_remap_count,
+                                       key->offset >> fs_info->sectorsize_bits);
+                       return -EUCLEAN;
+               }
+       }
+
        return 0;
 }