xfs: reap large AG metadata extents when possible

When we're freeing extents that have been set in a bitmap, break the
bitmap extent into multiple sub-extents organized by fate, and reap the
extents.  This enables us to dispose of old resources more efficiently
than doing them block by block.

While we're at it, rename the reaping functions to make it clear that
they're reaping per-AG extents.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/scrub/agheader_repair.c

@@ -775,7 +775,7 @@ xrep_agfl(
 		goto err;
 
 	/* Dump any AGFL overflow. */
-	error = xrep_reap_extents(sc, &agfl_extents, &XFS_RMAP_OINFO_AG,
+	error = xrep_reap_ag_metadata(sc, &agfl_extents, &XFS_RMAP_OINFO_AG,
 			XFS_AG_RESV_AGFL);
 err:
 	xbitmap_destroy(&agfl_extents);

fs/xfs/scrub/bitmap.c

@@ -385,43 +385,6 @@ xbitmap_walk(
 	return error;
 }
 
-struct xbitmap_walk_bits {
-	xbitmap_walk_bits_fn	fn;
-	void			*priv;
-};
-
-/* Walk all the bits in a run. */
-static int
-xbitmap_walk_bits_in_run(
-	uint64_t			start,
-	uint64_t			len,
-	void				*priv)
-{
-	struct xbitmap_walk_bits	*wb = priv;
-	uint64_t			i;
-	int				error = 0;
-
-	for (i = start; i < start + len; i++) {
-		error = wb->fn(i, wb->priv);
-		if (error)
-			break;
-	}
-
-	return error;
-}
-
-/* Call a function for every set bit in this bitmap. */
-int
-xbitmap_walk_bits(
-	struct xbitmap			*bitmap,
-	xbitmap_walk_bits_fn		fn,
-	void				*priv)
-{
-	struct xbitmap_walk_bits	wb = {.fn = fn, .priv = priv};
-
-	return xbitmap_walk(bitmap, xbitmap_walk_bits_in_run, &wb);
-}
-
 /* Does this bitmap have no bits set at all? */
 bool
 xbitmap_empty(

fs/xfs/scrub/bitmap.h

@@ -33,10 +33,6 @@ typedef int (*xbitmap_walk_fn)(uint64_t start, uint64_t len, void *priv);
 int xbitmap_walk(struct xbitmap *bitmap, xbitmap_walk_fn fn,
 		void *priv);
 
-typedef int (*xbitmap_walk_bits_fn)(uint64_t bit, void *priv);
-int xbitmap_walk_bits(struct xbitmap *bitmap, xbitmap_walk_bits_fn fn,
-		void *priv);
-
 bool xbitmap_empty(struct xbitmap *bitmap);
 bool xbitmap_test(struct xbitmap *bitmap, uint64_t start, uint64_t *len);