btrfs: Add checker for EXTENT_CSUM

commit 4b865cab96fe2a30ed512cf667b354bd291b3b0a upstream.

EXTENT_CSUM checker is a relatively easy one, only needs to check:

1) Objectid
   Fixed to BTRFS_EXTENT_CSUM_OBJECTID

2) Key offset alignment
   Must be aligned to sectorsize

3) Item size alignedment
   Must be aligned to csum size

Signed-off-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[bwh: Backported to 4.4: Use root->sectorsize instead of
 root->fs_info->sectorsize]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 80ebcfd..e1ac4b8 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -605,6 +605,27 @@ static int check_extent_data_item(struct btrfs_root *root,
        return 0;
 }
 
+static int check_csum_item(struct btrfs_root *root, struct extent_buffer *leaf,
+                          struct btrfs_key *key, int slot)
+{
+       u32 sectorsize = root->sectorsize;
+       u32 csumsize = btrfs_super_csum_size(root->fs_info->super_copy);
+
+       if (key->objectid != BTRFS_EXTENT_CSUM_OBJECTID) {
+               CORRUPT("invalid objectid for csum item", leaf, root, slot);
+               return -EUCLEAN;
+       }
+       if (!IS_ALIGNED(key->offset, sectorsize)) {
+               CORRUPT("unaligned key offset for csum item", leaf, root, slot);
+               return -EUCLEAN;
+       }
+       if (!IS_ALIGNED(btrfs_item_size_nr(leaf, slot), csumsize)) {
+               CORRUPT("unaligned csum item size", leaf, root, slot);
+               return -EUCLEAN;
+       }
+       return 0;
+}
+
 /*
  * Common point to switch the item-specific validation.
  */
@@ -618,6 +639,9 @@ static int check_leaf_item(struct btrfs_root *root,
        case BTRFS_EXTENT_DATA_KEY:
                ret = check_extent_data_item(root, leaf, key, slot);
                break;
+       case BTRFS_EXTENT_CSUM_KEY:
+               ret = check_csum_item(root, leaf, key, slot);
+               break;
        }
        return ret;
 }