xfs: validate fsmap offsets specified in the query keys

Improve the validation of the fsmap offset fields in the query keys and
move the validation to the top of the function now that we have pushed
the low key adjustment code downwards.

Also fix some indenting issues that aren't worth a separate patch.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/xfs_fsmap.c

@@ -802,6 +802,19 @@ xfs_getfsmap_check_keys(
 	struct xfs_fsmap		*low_key,
 	struct xfs_fsmap		*high_key)
 {
+	if (low_key->fmr_flags & (FMR_OF_SPECIAL_OWNER | FMR_OF_EXTENT_MAP)) {
+		if (low_key->fmr_offset)
+			return false;
+	}
+	if (high_key->fmr_flags != -1U &&
+	    (high_key->fmr_flags & (FMR_OF_SPECIAL_OWNER |
+				    FMR_OF_EXTENT_MAP))) {
+		if (high_key->fmr_offset && high_key->fmr_offset != -1ULL)
+			return false;
+	}
+	if (high_key->fmr_length && high_key->fmr_length != -1ULL)
+		return false;
+
 	if (low_key->fmr_device > high_key->fmr_device)
 		return false;
 	if (low_key->fmr_device < high_key->fmr_device)
@@ -845,15 +858,15 @@ xfs_getfsmap_check_keys(
  * ----------------
  * There are multiple levels of keys and counters at work here:
  * xfs_fsmap_head.fmh_keys	-- low and high fsmap keys passed in;
- * 				   these reflect fs-wide sector addrs.
+ *				   these reflect fs-wide sector addrs.
  * dkeys			-- fmh_keys used to query each device;
- * 				   these are fmh_keys but w/ the low key
- * 				   bumped up by fmr_length.
+ *				   these are fmh_keys but w/ the low key
+ *				   bumped up by fmr_length.
  * xfs_getfsmap_info.next_daddr	-- next disk addr we expect to see; this
  *				   is how we detect gaps in the fsmap
 				   records and report them.
  * xfs_getfsmap_info.low/high	-- per-AG low/high keys computed from
- * 				   dkeys; used to query the metadata.
+ *				   dkeys; used to query the metadata.
  */
 int
 xfs_getfsmap(
@@ -874,6 +887,8 @@ xfs_getfsmap(
 	if (!xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[0]) ||
 	    !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1]))
 		return -EINVAL;
+	if (!xfs_getfsmap_check_keys(&head->fmh_keys[0], &head->fmh_keys[1]))
+		return -EINVAL;
 
 	use_rmap = xfs_has_rmapbt(mp) &&
 		   has_capability_noaudit(current, CAP_SYS_ADMIN);
@@ -919,15 +934,8 @@ xfs_getfsmap(
 	 * other mapping for the same physical block range.
 	 */
 	dkeys[0] = head->fmh_keys[0];
-	if (dkeys[0].fmr_flags & (FMR_OF_SPECIAL_OWNER | FMR_OF_EXTENT_MAP)) {
-		if (dkeys[0].fmr_offset)
-			return -EINVAL;
-	}
 	memset(&dkeys[1], 0xFF, sizeof(struct xfs_fsmap));
 
-	if (!xfs_getfsmap_check_keys(dkeys, &head->fmh_keys[1]))
-		return -EINVAL;
-
 	info.next_daddr = head->fmh_keys[0].fmr_physical +
 			  head->fmh_keys[0].fmr_length;
 	info.fsmap_recs = fsmap_recs;