1 files changed, 92 insertions, 0 deletions

diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index c770e2d0b6aa..fdadc9e1dc49 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -9,6 +9,7 @@
 #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"
@@ -209,3 +210,94 @@ out:
 }
 #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);
+}