xfs: add helpers to allocate and initialize fresh btree roots

Add a pair of helper functions to allocate and initialize fresh btree
roots.  The repair functions will use these as part of recreating
corrupted metadata.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>

diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index d86f873..be21a29 100644 (file)
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -288,3 +288,83 @@ xfs_repair_calc_ag_resblks(
 
        return max(max(bnobt_sz, inobt_sz), max(rmapbt_sz, refcbt_sz));
 }
+
+/* Allocate a block in an AG. */
+int
+xfs_repair_alloc_ag_block(
+       struct xfs_scrub_context        *sc,
+       struct xfs_owner_info           *oinfo,
+       xfs_fsblock_t                   *fsbno,
+       enum xfs_ag_resv_type           resv)
+{
+       struct xfs_alloc_arg            args = {0};
+       xfs_agblock_t                   bno;
+       int                             error;
+
+       switch (resv) {
+       case XFS_AG_RESV_AGFL:
+       case XFS_AG_RESV_RMAPBT:
+               error = xfs_alloc_get_freelist(sc->tp, sc->sa.agf_bp, &bno, 1);
+               if (error)
+                       return error;
+               if (bno == NULLAGBLOCK)
+                       return -ENOSPC;
+               xfs_extent_busy_reuse(sc->mp, sc->sa.agno, bno,
+                               1, false);
+               *fsbno = XFS_AGB_TO_FSB(sc->mp, sc->sa.agno, bno);
+               if (resv == XFS_AG_RESV_RMAPBT)
+                       xfs_ag_resv_rmapbt_alloc(sc->mp, sc->sa.agno);
+               return 0;
+       default:
+               break;
+       }
+
+       args.tp = sc->tp;
+       args.mp = sc->mp;
+       args.oinfo = *oinfo;
+       args.fsbno = XFS_AGB_TO_FSB(args.mp, sc->sa.agno, 0);
+       args.minlen = 1;
+       args.maxlen = 1;
+       args.prod = 1;
+       args.type = XFS_ALLOCTYPE_THIS_AG;
+       args.resv = resv;
+
+       error = xfs_alloc_vextent(&args);
+       if (error)
+               return error;
+       if (args.fsbno == NULLFSBLOCK)
+               return -ENOSPC;
+       ASSERT(args.len == 1);
+       *fsbno = args.fsbno;
+
+       return 0;
+}
+
+/* Initialize a new AG btree root block with zero entries. */
+int
+xfs_repair_init_btblock(
+       struct xfs_scrub_context        *sc,
+       xfs_fsblock_t                   fsb,
+       struct xfs_buf                  **bpp,
+       xfs_btnum_t                     btnum,
+       const struct xfs_buf_ops        *ops)
+{
+       struct xfs_trans                *tp = sc->tp;
+       struct xfs_mount                *mp = sc->mp;
+       struct xfs_buf                  *bp;
+
+       trace_xfs_repair_init_btblock(mp, XFS_FSB_TO_AGNO(mp, fsb),
+                       XFS_FSB_TO_AGBNO(mp, fsb), btnum);
+
+       ASSERT(XFS_FSB_TO_AGNO(mp, fsb) == sc->sa.agno);
+       bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, XFS_FSB_TO_DADDR(mp, fsb),
+                       XFS_FSB_TO_BB(mp, 1), 0);
+       xfs_buf_zero(bp, 0, BBTOB(bp->b_length));
+       xfs_btree_init_block(mp, bp, btnum, 0, 0, sc->sa.agno, 0);
+       xfs_trans_buf_set_type(tp, bp, XFS_BLFT_BTREE_BUF);
+       xfs_trans_log_buf(tp, bp, 0, bp->b_length);
+       bp->b_ops = ops;
+       *bpp = bp;
+
+       return 0;
+}

diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 8d181dc..40990fa 100644 (file)
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -36,6 +36,12 @@ int xfs_repair_roll_ag_trans(struct xfs_scrub_context *sc);
 bool xfs_repair_ag_has_space(struct xfs_perag *pag, xfs_extlen_t nr_blocks,
                enum xfs_ag_resv_type type);
 xfs_extlen_t xfs_repair_calc_ag_resblks(struct xfs_scrub_context *sc);
+int xfs_repair_alloc_ag_block(struct xfs_scrub_context *sc,
+               struct xfs_owner_info *oinfo, xfs_fsblock_t *fsbno,
+               enum xfs_ag_resv_type resv);
+int xfs_repair_init_btblock(struct xfs_scrub_context *sc, xfs_fsblock_t fsb,
+               struct xfs_buf **bpp, xfs_btnum_t btnum,
+               const struct xfs_buf_ops *ops);
 
 /* Metadata repairers */