[PATCH] btrfs: tree-checker: add qgroup status item check

[Qu Wenruo <wqu@suse.com>]

This adds the following checks:

- Key check

- Item size check
  Include the old size (before simple mode) and the new size (with
  simple mode's enable_gen).

  This means we will reject any newer status item size expansion.

- Version check

- Flags check
  Mostly to catch any unexpected RUNTIME flags.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/tree-checker.c | 59 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 0ce91396b517..a99fa7729c0b 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -2313,6 +2313,62 @@ static int check_free_space_bitmap(struct extent_buffer *leaf,
 	return 0;
 }
 
+static int check_qgroup_status_item(const struct extent_buffer *leaf,
+				    const struct btrfs_key *key, int slot)
+{
+	struct btrfs_qgroup_status_item *qsi;
+	const u32 item_size = btrfs_item_size(leaf, slot);
+	/*
+	 * Since the introduction of simple mode, the size of qsi is enlarged.
+	 * We need to handle both the old and new size.
+	 */
+	const unsigned int old_qsi_size =
+		offsetof(struct btrfs_qgroup_status_item, enable_gen);
+	u64 flags;
+
+	if (unlikely(key->objectid != 0 || key->offset != 0)) {
+		const struct btrfs_key expected = { .type = BTRFS_QGROUP_STATUS_KEY };
+
+		generic_err(leaf, slot,
+	"invalid qgroup status item key, has " BTRFS_KEY_FMT " expect " BTRFS_KEY_FMT,
+			    BTRFS_KEY_FMT_VALUE(key),
+			    BTRFS_KEY_FMT_VALUE(&expected));
+		return -EUCLEAN;
+	}
+
+	if (unlikely(item_size != sizeof(*qsi) && item_size != old_qsi_size)) {
+		generic_err(leaf, slot,
+			    "invalid qgroup status item size, has %u expect %zu or %u",
+			    item_size, sizeof(*qsi), old_qsi_size);
+		return -EUCLEAN;
+	}
+
+	qsi = btrfs_item_ptr(leaf, slot, struct btrfs_qgroup_status_item);
+	if (unlikely(btrfs_qgroup_status_version(leaf, qsi) !=
+		     BTRFS_QGROUP_STATUS_VERSION)) {
+		generic_err(leaf, slot,
+			    "invalid qgroup status version, has %llu expect %u",
+			    btrfs_qgroup_status_version(leaf, qsi),
+			    BTRFS_QGROUP_STATUS_VERSION);
+		return -EUCLEAN;
+	}
+	flags = btrfs_qgroup_status_flags(leaf, qsi);
+	if (unlikely(flags & ~BTRFS_QGROUP_STATUS_FLAGS_MASK)) {
+		generic_err(leaf, slot,
+			    "unknown qgroup status flags, has 0x%llx unknown flags 0x%llx",
+			    flags, flags & ~BTRFS_QGROUP_STATUS_FLAGS_MASK);
+		return -EUCLEAN;
+	}
+	if (unlikely(flags & BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE &&
+		     item_size != sizeof(*qsi))) {
+		generic_err(leaf, slot,
+			    "invalid qgroup status item size, has %u expect %zu",
+			    item_size, sizeof(*qsi));
+		return -EUCLEAN;
+	}
+	return 0;
+}
+
 /*
  * Common point to switch the item-specific validation.
  */
@@ -2394,6 +2450,9 @@ static enum btrfs_tree_block_status check_leaf_item(struct extent_buffer *leaf,
 	case BTRFS_REMAP_BACKREF_KEY:
 		ret = check_remap_key(leaf, key, slot);
 		break;
+	case BTRFS_QGROUP_STATUS_KEY:
+		ret = check_qgroup_status_item(leaf, key, slot);
+		break;
 	}
 
 	if (unlikely(ret))
-- 
2.55.0