[PATCH 19/24] xfs: cross-reference reverse-mapping btree

["Darrick J. Wong" <darrick.wong@xxxxxxxxxx>]

When scrubbing various btrees, we should cross-reference the records
with the reverse mapping btree.

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 libxfs/xfs_rmap.c |   58 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 libxfs/xfs_rmap.h |    5 +++++
 2 files changed, 63 insertions(+)


diff --git a/libxfs/xfs_rmap.c b/libxfs/xfs_rmap.c
index 4ce2025..62096cd 100644
--- a/libxfs/xfs_rmap.c
+++ b/libxfs/xfs_rmap.c
@@ -2290,3 +2290,61 @@ xfs_rmap_free_extent(
        return __xfs_rmap_add(mp, dfops, XFS_RMAP_FREE, owner,
                        XFS_DATA_FORK, &bmap);
 }
+
+/* Is there a record covering a given extent? */
+int
+xfs_rmap_has_record(
+       struct xfs_btree_cur    *cur,
+       xfs_fsblock_t           bno,
+       xfs_filblks_t           len,
+       bool                    *exists)
+{
+       union xfs_btree_irec    low;
+       union xfs_btree_irec    high;
+
+       memset(&low, 0, sizeof(low));
+       low.r.rm_startblock = bno;
+       memset(&high, 0xFF, sizeof(high));
+       high.r.rm_startblock = bno + len - 1;
+
+       return xfs_btree_has_record(cur, &low, &high, exists);
+}
+
+/* Is there a record covering a given extent? */
+int
+xfs_rmap_record_exists(
+       struct xfs_btree_cur    *cur,
+       xfs_fsblock_t           bno,
+       xfs_filblks_t           len,
+       struct xfs_owner_info   *oinfo,
+       bool                    *has_rmap)
+{
+       uint64_t                owner;
+       uint64_t                offset;
+       unsigned int            flags;
+       int                     stat;
+       struct xfs_rmap_irec    irec;
+       int                     error;
+
+       xfs_owner_info_unpack(oinfo, &owner, &offset, &flags);
+
+       error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, flags, &stat);
+       if (error)
+               return error;
+       if (!stat) {
+               *has_rmap = false;
+               return 0;
+       }
+
+       error = xfs_rmap_get_rec(cur, &irec, &stat);
+       if (error)
+               return error;
+       if (!stat) {
+               *has_rmap = false;
+               return 0;
+       }
+
+       *has_rmap = (irec.rm_startblock <= bno &&
+                    irec.rm_startblock + irec.rm_blockcount >= bno + len);
+       return 0;
+}
diff --git a/libxfs/xfs_rmap.h b/libxfs/xfs_rmap.h
index 188db38..c5c5817 100644
--- a/libxfs/xfs_rmap.h
+++ b/libxfs/xfs_rmap.h
@@ -215,5 +215,10 @@ int xfs_rmap_lookup_le_range(struct xfs_btree_cur *cur, 
xfs_agblock_t bno,
 union xfs_btree_rec;
 int xfs_rmap_btrec_to_irec(union xfs_btree_rec *rec,
                struct xfs_rmap_irec *irec);
+int xfs_rmap_has_record(struct xfs_btree_cur *cur, xfs_fsblock_t bno,
+               xfs_filblks_t len, bool *exists);
+int xfs_rmap_record_exists(struct xfs_btree_cur *cur, xfs_fsblock_t bno,
+               xfs_filblks_t len, struct xfs_owner_info *oinfo,
+               bool *has_rmap);
 
 #endif /* __XFS_RMAP_H__ */