1 files changed, 303 insertions, 0 deletions
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
new file mode 100644
index 000000000..fdadc9e1d
--- /dev/null
+++ b/fs/xfs/scrub/bitmap.c
@@ -0,0 +1,303 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_btree.h"
+#include "scrub/xfs_scrub.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/bitmap.h"
+
+/*
+ * Set a range of this bitmap.  Caller must ensure the range is not set.
+ *
+ * This is the logical equivalent of bitmap |= mask(start, len).
+ */
+int
+xfs_bitmap_set(
+	struct xfs_bitmap	*bitmap,
+	uint64_t		start,
+	uint64_t		len)
+{
+	struct xfs_bitmap_range	*bmr;
+
+	bmr = kmem_alloc(sizeof(struct xfs_bitmap_range), KM_MAYFAIL);
+	if (!bmr)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&bmr->list);
+	bmr->start = start;
+	bmr->len = len;
+	list_add_tail(&bmr->list, &bitmap->list);
+
+	return 0;
+}
+
+/* Free everything related to this bitmap. */
+void
+xfs_bitmap_destroy(
+	struct xfs_bitmap	*bitmap)
+{
+	struct xfs_bitmap_range	*bmr;
+	struct xfs_bitmap_range	*n;
+
+	for_each_xfs_bitmap_extent(bmr, n, bitmap) {
+		list_del(&bmr->list);
+		kmem_free(bmr);
+	}
+}
+
+/* Set up a per-AG block bitmap. */
+void
+xfs_bitmap_init(
+	struct xfs_bitmap	*bitmap)
+{
+	INIT_LIST_HEAD(&bitmap->list);
+}
+
+/* Compare two btree extents. */
+static int
+xfs_bitmap_range_cmp(
+	void			*priv,
+	struct list_head	*a,
+	struct list_head	*b)
+{
+	struct xfs_bitmap_range	*ap;
+	struct xfs_bitmap_range	*bp;
+
+	ap = container_of(a, struct xfs_bitmap_range, list);
+	bp = container_of(b, struct xfs_bitmap_range, list);
+
+	if (ap->start > bp->start)
+		return 1;
+	if (ap->start < bp->start)
+		return -1;
+	return 0;
+}
+
+/*
+ * Remove all the blocks mentioned in @sub from the extents in @bitmap.
+ *
+ * The intent is that callers will iterate the rmapbt for all of its records
+ * for a given owner to generate @bitmap; and iterate all the blocks of the
+ * metadata structures that are not being rebuilt and have the same rmapbt
+ * owner to generate @sub.  This routine subtracts all the extents
+ * mentioned in sub from all the extents linked in @bitmap, which leaves
+ * @bitmap as the list of blocks that are not accounted for, which we assume
+ * are the dead blocks of the old metadata structure.  The blocks mentioned in
+ * @bitmap can be reaped.
+ *
+ * This is the logical equivalent of bitmap &= ~sub.
+ */
+#define LEFT_ALIGNED	(1 << 0)
+#define RIGHT_ALIGNED	(1 << 1)
+int
+xfs_bitmap_disunion(
+	struct xfs_bitmap	*bitmap,
+	struct xfs_bitmap	*sub)
+{
+	struct list_head	*lp;
+	struct xfs_bitmap_range	*br;
+	struct xfs_bitmap_range	*new_br;
+	struct xfs_bitmap_range	*sub_br;
+	uint64_t		sub_start;
+	uint64_t		sub_len;
+	int			state;
+	int			error = 0;
+
+	if (list_empty(&bitmap->list) || list_empty(&sub->list))
+		return 0;
+	ASSERT(!list_empty(&sub->list));
+
+	list_sort(NULL, &bitmap->list, xfs_bitmap_range_cmp);
+	list_sort(NULL, &sub->list, xfs_bitmap_range_cmp);
+
+	/*
+	 * Now that we've sorted both lists, we iterate bitmap once, rolling
+	 * forward through sub and/or bitmap as necessary until we find an
+	 * overlap or reach the end of either list.  We do not reset lp to the
+	 * head of bitmap nor do we reset sub_br to the head of sub.  The
+	 * list traversal is similar to merge sort, but we're deleting
+	 * instead.  In this manner we avoid O(n^2) operations.
+	 */
+	sub_br = list_first_entry(&sub->list, struct xfs_bitmap_range,
+			list);
+	lp = bitmap->list.next;
+	while (lp != &bitmap->list) {
+		br = list_entry(lp, struct xfs_bitmap_range, list);
+
+		/*
+		 * Advance sub_br and/or br until we find a pair that
+		 * intersect or we run out of extents.
+		 */
+		while (sub_br->start + sub_br->len <= br->start) {
+			if (list_is_last(&sub_br->list, &sub->list))
+				goto out;
+			sub_br = list_next_entry(sub_br, list);
+		}
+		if (sub_br->start >= br->start + br->len) {
+			lp = lp->next;
+			continue;
+		}
+
+		/* trim sub_br to fit the extent we have */
+		sub_start = sub_br->start;
+		sub_len = sub_br->len;
+		if (sub_br->start < br->start) {
+			sub_len -= br->start - sub_br->start;
+			sub_start = br->start;
+		}
+		if (sub_len > br->len)
+			sub_len = br->len;
+
+		state = 0;
+		if (sub_start == br->start)
+			state |= LEFT_ALIGNED;
+		if (sub_start + sub_len == br->start + br->len)
+			state |= RIGHT_ALIGNED;
+		switch (state) {
+		case LEFT_ALIGNED:
+			/* Coincides with only the left. */
+			br->start += sub_len;
+			br->len -= sub_len;
+			break;
+		case RIGHT_ALIGNED:
+			/* Coincides with only the right. */
+			br->len -= sub_len;
+			lp = lp->next;
+			break;
+		case LEFT_ALIGNED | RIGHT_ALIGNED:
+			/* Total overlap, just delete ex. */
+			lp = lp->next;
+			list_del(&br->list);
+			kmem_free(br);
+			break;
+		case 0:
+			/*
+			 * Deleting from the middle: add the new right extent
+			 * and then shrink the left extent.
+			 */
+			new_br = kmem_alloc(sizeof(struct xfs_bitmap_range),
+					KM_MAYFAIL);
+			if (!new_br) {
+				error = -ENOMEM;
+				goto out;
+			}
+			INIT_LIST_HEAD(&new_br->list);
+			new_br->start = sub_start + sub_len;
+			new_br->len = br->start + br->len - new_br->start;
+			list_add(&new_br->list, &br->list);
+			br->len = sub_start - br->start;
+			lp = lp->next;
+			break;
+		default:
+			ASSERT(0);
+			break;
+		}
+	}
+
+out:
+	return error;
+}
+#undef LEFT_ALIGNED
+#undef RIGHT_ALIGNED
+
+/*
+ * Record all btree blocks seen while iterating all records of a btree.
+ *
+ * We know that the btree query_all function starts at the left edge and walks
+ * towards the right edge of the tree.  Therefore, we know that we can walk up
+ * the btree cursor towards the root; if the pointer for a given level points
+ * to the first record/key in that block, we haven't seen this block before;
+ * and therefore we need to remember that we saw this block in the btree.
+ *
+ * So if our btree is:
+ *
+ *    4
+ *  / | \
+ * 1  2  3
+ *
+ * Pretend for this example that each leaf block has 100 btree records.  For
+ * the first btree record, we'll observe that bc_ptrs[0] == 1, so we record
+ * that we saw block 1.  Then we observe that bc_ptrs[1] == 1, so we record
+ * block 4.  The list is [1, 4].
+ *
+ * For the second btree record, we see that bc_ptrs[0] == 2, so we exit the
+ * loop.  The list remains [1, 4].
+ *
+ * For the 101st btree record, we've moved onto leaf block 2.  Now
+ * bc_ptrs[0] == 1 again, so we record that we saw block 2.  We see that
+ * bc_ptrs[1] == 2, so we exit the loop.  The list is now [1, 4, 2].
+ *
+ * For the 102nd record, bc_ptrs[0] == 2, so we continue.
+ *
+ * For the 201st record, we've moved on to leaf block 3.  bc_ptrs[0] == 1, so
+ * we add 3 to the list.  Now it is [1, 4, 2, 3].
+ *
+ * For the 300th record we just exit, with the list being [1, 4, 2, 3].
+ */
+
+/*
+ * Record all the buffers pointed to by the btree cursor.  Callers already
+ * engaged in a btree walk should call this function to capture the list of
+ * blocks going from the leaf towards the root.
+ */
+int
+xfs_bitmap_set_btcur_path(
+	struct xfs_bitmap	*bitmap,
+	struct xfs_btree_cur	*cur)
+{
+	struct xfs_buf		*bp;
+	xfs_fsblock_t		fsb;
+	int			i;
+	int			error;
+
+	for (i = 0; i < cur->bc_nlevels && cur->bc_ptrs[i] == 1; i++) {
+		xfs_btree_get_block(cur, i, &bp);
+		if (!bp)
+			continue;
+		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
+		error = xfs_bitmap_set(bitmap, fsb, 1);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/* Collect a btree's block in the bitmap. */
+STATIC int
+xfs_bitmap_collect_btblock(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	void			*priv)
+{
+	struct xfs_bitmap	*bitmap = priv;
+	struct xfs_buf		*bp;
+	xfs_fsblock_t		fsbno;
+
+	xfs_btree_get_block(cur, level, &bp);
+	if (!bp)
+		return 0;
+
+	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
+	return xfs_bitmap_set(bitmap, fsbno, 1);
+}
+
+/* Walk the btree and mark the bitmap wherever a btree block is found. */
+int
+xfs_bitmap_set_btblocks(
+	struct xfs_bitmap	*bitmap,
+	struct xfs_btree_cur	*cur)
+{
+	return xfs_btree_visit_blocks(cur, xfs_bitmap_collect_btblock, bitmap);
+}