xfs: repair the AGF

Regenerate the AGF from the rmap data.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

4 files changed, 400 insertions, 10 deletions

diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index 1e96621ece3a..aa180492a4a5 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -17,12 +17,19 @@
 #include "xfs_sb.h"
 #include "xfs_inode.h"
 #include "xfs_alloc.h"
+#include "xfs_alloc_btree.h"
 #include "xfs_ialloc.h"
+#include "xfs_ialloc_btree.h"
 #include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_refcount_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"
 
 /* Superblock */
 
@@ -54,3 +61,375 @@ xrep_superblock(
         xfs_trans_log_buf(sc->tp, bp, 0, BBTOB(bp->b_length) - 1);
         return error;
 }
+
+/* AGF */
+
+struct xrep_agf_allocbt {
+        struct xfs_scrub        *sc;
+        xfs_agblock_t           freeblks;
+        xfs_agblock_t           longest;
+};
+
+/* Record free space shape information. */
+STATIC int
+xrep_agf_walk_allocbt(
+        struct xfs_btree_cur            *cur,
+        struct xfs_alloc_rec_incore     *rec,
+        void                            *priv)
+{
+        struct xrep_agf_allocbt         *raa = priv;
+        int                             error = 0;
+
+        if (xchk_should_terminate(raa->sc, &error))
+                return error;
+
+        raa->freeblks += rec->ar_blockcount;
+        if (rec->ar_blockcount > raa->longest)
+                raa->longest = rec->ar_blockcount;
+        return error;
+}
+
+/* Does this AGFL block look sane? */
+STATIC int
+xrep_agf_check_agfl_block(
+        struct xfs_mount        *mp,
+        xfs_agblock_t           agbno,
+        void                    *priv)
+{
+        struct xfs_scrub        *sc = priv;
+
+        if (!xfs_verify_agbno(mp, sc->sa.agno, agbno))
+                return -EFSCORRUPTED;
+        return 0;
+}
+
+/*
+ * Offset within the xrep_find_ag_btree array for each btree type.  Avoid the
+ * XFS_BTNUM_ names here to avoid creating a sparse array.
+ */
+enum {
+        XREP_AGF_BNOBT = 0,
+        XREP_AGF_CNTBT,
+        XREP_AGF_RMAPBT,
+        XREP_AGF_REFCOUNTBT,
+        XREP_AGF_END,
+        XREP_AGF_MAX
+};
+
+/* Check a btree root candidate. */
+static inline bool
+xrep_check_btree_root(
+        struct xfs_scrub                *sc,
+        struct xrep_find_ag_btree       *fab)
+{
+        struct xfs_mount                *mp = sc->mp;
+        xfs_agnumber_t                  agno = sc->sm->sm_agno;
+
+        return xfs_verify_agbno(mp, agno, fab->root) &&
+               fab->height <= XFS_BTREE_MAXLEVELS;
+}
+
+/*
+ * Given the btree roots described by *fab, find the roots, check them for
+ * sanity, and pass the root data back out via *fab.
+ *
+ * This is /also/ a chicken and egg problem because we have to use the rmapbt
+ * (rooted in the AGF) to find the btrees rooted in the AGF.  We also have no
+ * idea if the btrees make any sense.  If we hit obvious corruptions in those
+ * btrees we'll bail out.
+ */
+STATIC int
+xrep_agf_find_btrees(
+        struct xfs_scrub                *sc,
+        struct xfs_buf                  *agf_bp,
+        struct xrep_find_ag_btree       *fab,
+        struct xfs_buf                  *agfl_bp)
+{
+        struct xfs_agf                  *old_agf = XFS_BUF_TO_AGF(agf_bp);
+        int                             error;
+
+        /* Go find the root data. */
+        error = xrep_find_ag_btree_roots(sc, agf_bp, fab, agfl_bp);
+        if (error)
+                return error;
+
+        /* We must find the bnobt, cntbt, and rmapbt roots. */
+        if (!xrep_check_btree_root(sc, &fab[XREP_AGF_BNOBT]) ||
+            !xrep_check_btree_root(sc, &fab[XREP_AGF_CNTBT]) ||
+            !xrep_check_btree_root(sc, &fab[XREP_AGF_RMAPBT]))
+                return -EFSCORRUPTED;
+
+        /*
+         * We relied on the rmapbt to reconstruct the AGF.  If we get a
+         * different root then something's seriously wrong.
+         */
+        if (fab[XREP_AGF_RMAPBT].root !=
+            be32_to_cpu(old_agf->agf_roots[XFS_BTNUM_RMAPi]))
+                return -EFSCORRUPTED;
+
+        /* We must find the refcountbt root if that feature is enabled. */
+        if (xfs_sb_version_hasreflink(&sc->mp->m_sb) &&
+            !xrep_check_btree_root(sc, &fab[XREP_AGF_REFCOUNTBT]))
+                return -EFSCORRUPTED;
+
+        return 0;
+}
+
+/*
+ * Reinitialize the AGF header, making an in-core copy of the old contents so
+ * that we know which in-core state needs to be reinitialized.
+ */
+STATIC void
+xrep_agf_init_header(
+        struct xfs_scrub        *sc,
+        struct xfs_buf          *agf_bp,
+        struct xfs_agf          *old_agf)
+{
+        struct xfs_mount        *mp = sc->mp;
+        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agf_bp);
+
+        memcpy(old_agf, agf, sizeof(*old_agf));
+        memset(agf, 0, BBTOB(agf_bp->b_length));
+        agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
+        agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
+        agf->agf_seqno = cpu_to_be32(sc->sa.agno);
+        agf->agf_length = cpu_to_be32(xfs_ag_block_count(mp, sc->sa.agno));
+        agf->agf_flfirst = old_agf->agf_flfirst;
+        agf->agf_fllast = old_agf->agf_fllast;
+        agf->agf_flcount = old_agf->agf_flcount;
+        if (xfs_sb_version_hascrc(&mp->m_sb))
+                uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
+
+        /* Mark the incore AGF data stale until we're done fixing things. */
+        ASSERT(sc->sa.pag->pagf_init);
+        sc->sa.pag->pagf_init = 0;
+}
+
+/* Set btree root information in an AGF. */
+STATIC void
+xrep_agf_set_roots(
+        struct xfs_scrub                *sc,
+        struct xfs_agf                  *agf,
+        struct xrep_find_ag_btree       *fab)
+{
+        agf->agf_roots[XFS_BTNUM_BNOi] =
+                        cpu_to_be32(fab[XREP_AGF_BNOBT].root);
+        agf->agf_levels[XFS_BTNUM_BNOi] =
+                        cpu_to_be32(fab[XREP_AGF_BNOBT].height);
+
+        agf->agf_roots[XFS_BTNUM_CNTi] =
+                        cpu_to_be32(fab[XREP_AGF_CNTBT].root);
+        agf->agf_levels[XFS_BTNUM_CNTi] =
+                        cpu_to_be32(fab[XREP_AGF_CNTBT].height);
+
+        agf->agf_roots[XFS_BTNUM_RMAPi] =
+                        cpu_to_be32(fab[XREP_AGF_RMAPBT].root);
+        agf->agf_levels[XFS_BTNUM_RMAPi] =
+                        cpu_to_be32(fab[XREP_AGF_RMAPBT].height);
+
+        if (xfs_sb_version_hasreflink(&sc->mp->m_sb)) {
+                agf->agf_refcount_root =
+                                cpu_to_be32(fab[XREP_AGF_REFCOUNTBT].root);
+                agf->agf_refcount_level =
+                                cpu_to_be32(fab[XREP_AGF_REFCOUNTBT].height);
+        }
+}
+
+/* Update all AGF fields which derive from btree contents. */
+STATIC int
+xrep_agf_calc_from_btrees(
+        struct xfs_scrub        *sc,
+        struct xfs_buf          *agf_bp)
+{
+        struct xrep_agf_allocbt raa = { .sc = sc };
+        struct xfs_btree_cur    *cur = NULL;
+        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agf_bp);
+        struct xfs_mount        *mp = sc->mp;
+        xfs_agblock_t           btreeblks;
+        xfs_agblock_t           blocks;
+        int                     error;
+
+        /* Update the AGF counters from the bnobt. */
+        cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
+                        XFS_BTNUM_BNO);
+        error = xfs_alloc_query_all(cur, xrep_agf_walk_allocbt, &raa);
+        if (error)
+                goto err;
+        error = xfs_btree_count_blocks(cur, &blocks);
+        if (error)
+                goto err;
+        xfs_btree_del_cursor(cur, error);
+        btreeblks = blocks - 1;
+        agf->agf_freeblks = cpu_to_be32(raa.freeblks);
+        agf->agf_longest = cpu_to_be32(raa.longest);
+
+        /* Update the AGF counters from the cntbt. */
+        cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
+                        XFS_BTNUM_CNT);
+        error = xfs_btree_count_blocks(cur, &blocks);
+        if (error)
+                goto err;
+        xfs_btree_del_cursor(cur, error);
+        btreeblks += blocks - 1;
+
+        /* Update the AGF counters from the rmapbt. */
+        cur = xfs_rmapbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno);
+        error = xfs_btree_count_blocks(cur, &blocks);
+        if (error)
+                goto err;
+        xfs_btree_del_cursor(cur, error);
+        agf->agf_rmap_blocks = cpu_to_be32(blocks);
+        btreeblks += blocks - 1;
+
+        agf->agf_btreeblks = cpu_to_be32(btreeblks);
+
+        /* Update the AGF counters from the refcountbt. */
+        if (xfs_sb_version_hasreflink(&mp->m_sb)) {
+                cur = xfs_refcountbt_init_cursor(mp, sc->tp, agf_bp,
+                                sc->sa.agno);
+                error = xfs_btree_count_blocks(cur, &blocks);
+                if (error)
+                        goto err;
+                xfs_btree_del_cursor(cur, error);
+                agf->agf_refcount_blocks = cpu_to_be32(blocks);
+        }
+
+        return 0;
+err:
+        xfs_btree_del_cursor(cur, error);
+        return error;
+}
+
+/* Commit the new AGF and reinitialize the incore state. */
+STATIC int
+xrep_agf_commit_new(
+        struct xfs_scrub        *sc,
+        struct xfs_buf          *agf_bp)
+{
+        struct xfs_perag        *pag;
+        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agf_bp);
+
+        /* Trigger fdblocks recalculation */
+        xfs_force_summary_recalc(sc->mp);
+
+        /* Write this to disk. */
+        xfs_trans_buf_set_type(sc->tp, agf_bp, XFS_BLFT_AGF_BUF);
+        xfs_trans_log_buf(sc->tp, agf_bp, 0, BBTOB(agf_bp->b_length) - 1);
+
+        /* Now reinitialize the in-core counters we changed. */
+        pag = sc->sa.pag;
+        pag->pagf_btreeblks = be32_to_cpu(agf->agf_btreeblks);
+        pag->pagf_freeblks = be32_to_cpu(agf->agf_freeblks);
+        pag->pagf_longest = be32_to_cpu(agf->agf_longest);
+        pag->pagf_levels[XFS_BTNUM_BNOi] =
+                        be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNOi]);
+        pag->pagf_levels[XFS_BTNUM_CNTi] =
+                        be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]);
+        pag->pagf_levels[XFS_BTNUM_RMAPi] =
+                        be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAPi]);
+        pag->pagf_refcount_level = be32_to_cpu(agf->agf_refcount_level);
+        pag->pagf_init = 1;
+
+        return 0;
+}
+
+/* Repair the AGF. v5 filesystems only. */
+int
+xrep_agf(
+        struct xfs_scrub                *sc)
+{
+        struct xrep_find_ag_btree       fab[XREP_AGF_MAX] = {
+                [XREP_AGF_BNOBT] = {
+                        .rmap_owner = XFS_RMAP_OWN_AG,
+                        .buf_ops = &xfs_allocbt_buf_ops,
+                        .magic = XFS_ABTB_CRC_MAGIC,
+                },
+                [XREP_AGF_CNTBT] = {
+                        .rmap_owner = XFS_RMAP_OWN_AG,
+                        .buf_ops = &xfs_allocbt_buf_ops,
+                        .magic = XFS_ABTC_CRC_MAGIC,
+                },
+                [XREP_AGF_RMAPBT] = {
+                        .rmap_owner = XFS_RMAP_OWN_AG,
+                        .buf_ops = &xfs_rmapbt_buf_ops,
+                        .magic = XFS_RMAP_CRC_MAGIC,
+                },
+                [XREP_AGF_REFCOUNTBT] = {
+                        .rmap_owner = XFS_RMAP_OWN_REFC,
+                        .buf_ops = &xfs_refcountbt_buf_ops,
+                        .magic = XFS_REFC_CRC_MAGIC,
+                },
+                [XREP_AGF_END] = {
+                        .buf_ops = NULL,
+                },
+        };
+        struct xfs_agf                  old_agf;
+        struct xfs_mount                *mp = sc->mp;
+        struct xfs_buf                  *agf_bp;
+        struct xfs_buf                  *agfl_bp;
+        struct xfs_agf                  *agf;
+        int                             error;
+
+        /* We require the rmapbt to rebuild anything. */
+        if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+                return -EOPNOTSUPP;
+
+        xchk_perag_get(sc->mp, &sc->sa);
+        /*
+         * Make sure we have the AGF buffer, as scrub might have decided it
+         * was corrupt after xfs_alloc_read_agf failed with -EFSCORRUPTED.
+         */
+        error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
+                        XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGF_DADDR(mp)),
+                        XFS_FSS_TO_BB(mp, 1), 0, &agf_bp, NULL);
+        if (error)
+                return error;
+        agf_bp->b_ops = &xfs_agf_buf_ops;
+        agf = XFS_BUF_TO_AGF(agf_bp);
+
+        /*
+         * Load the AGFL so that we can screen out OWN_AG blocks that are on
+         * the AGFL now; these blocks might have once been part of the
+         * bno/cnt/rmap btrees but are not now.  This is a chicken and egg
+         * problem: the AGF is corrupt, so we have to trust the AGFL contents
+         * because we can't do any serious cross-referencing with any of the
+         * btrees rooted in the AGF.  If the AGFL contents are obviously bad
+         * then we'll bail out.
+         */
+        error = xfs_alloc_read_agfl(mp, sc->tp, sc->sa.agno, &agfl_bp);
+        if (error)
+                return error;
+
+        /*
+         * Spot-check the AGFL blocks; if they're obviously corrupt then
+         * there's nothing we can do but bail out.
+         */
+        error = xfs_agfl_walk(sc->mp, XFS_BUF_TO_AGF(agf_bp), agfl_bp,
+                        xrep_agf_check_agfl_block, sc);
+        if (error)
+                return error;
+
+        /*
+         * Find the AGF btree roots.  This is also a chicken-and-egg situation;
+         * see the function for more details.
+         */
+        error = xrep_agf_find_btrees(sc, agf_bp, fab, agfl_bp);
+        if (error)
+                return error;
+
+        /* Start rewriting the header and implant the btrees we found. */
+        xrep_agf_init_header(sc, agf_bp, &old_agf);
+        xrep_agf_set_roots(sc, agf, fab);
+        error = xrep_agf_calc_from_btrees(sc, agf_bp);
+        if (error)
+                goto out_revert;
+
+        /* Commit the changes and reinitialize incore state. */
+        return xrep_agf_commit_new(sc, agf_bp);
+
+out_revert:
+        /* Mark the incore AGF state stale and revert the AGF. */
+        sc->sa.pag->pagf_init = 0;
+        memcpy(agf, &old_agf, sizeof(old_agf));
+        return error;
+}
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 85b048b341a0..17cf48564390 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -128,9 +128,12 @@ xrep_roll_ag_trans(
         int                     error;
 
         /* Keep the AG header buffers locked so we can keep going. */
-        xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
-        xfs_trans_bhold(sc->tp, sc->sa.agf_bp);
-        xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
+        if (sc->sa.agi_bp)
+                xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
+        if (sc->sa.agf_bp)
+                xfs_trans_bhold(sc->tp, sc->sa.agf_bp);
+        if (sc->sa.agfl_bp)
+                xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
 
         /* Roll the transaction. */
         error = xfs_trans_roll(&sc->tp);
@@ -138,9 +141,12 @@ xrep_roll_ag_trans(
                 goto out_release;
 
         /* Join AG headers to the new transaction. */
-        xfs_trans_bjoin(sc->tp, sc->sa.agi_bp);
-        xfs_trans_bjoin(sc->tp, sc->sa.agf_bp);
-        xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
+        if (sc->sa.agi_bp)
+                xfs_trans_bjoin(sc->tp, sc->sa.agi_bp);
+        if (sc->sa.agf_bp)
+                xfs_trans_bjoin(sc->tp, sc->sa.agf_bp);
+        if (sc->sa.agfl_bp)
+                xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
 
         return 0;
 
@@ -150,9 +156,12 @@ out_release:
          * buffers will be released during teardown on our way out
          * of the kernel.
          */
-        xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
-        xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
-        xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
+        if (sc->sa.agi_bp)
+                xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
+        if (sc->sa.agf_bp)
+                xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
+        if (sc->sa.agfl_bp)
+                xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
 
         return error;
 }
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 5a4e92221916..6f0903c51a47 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -58,6 +58,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
 
 int xrep_probe(struct xfs_scrub *sc);
 int xrep_superblock(struct xfs_scrub *sc);
+int xrep_agf(struct xfs_scrub *sc);
 
 #else
 
@@ -81,6 +82,7 @@ xrep_calc_ag_resblks(
 
 #define xrep_probe                      xrep_notsupported
 #define xrep_superblock                 xrep_notsupported
+#define xrep_agf                        xrep_notsupported
 
 #endif /* CONFIG_XFS_ONLINE_REPAIR */
 
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 6efb926f3cf8..1e8a17c8e2b9 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -214,7 +214,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
                 .type   = ST_PERAG,
                 .setup  = xchk_setup_fs,
                 .scrub  = xchk_agf,
-                .repair = xrep_notsupported,
+                .repair = xrep_agf,
         },
         [XFS_SCRUB_TYPE_AGFL]= {        /* agfl */
                 .type   = ST_PERAG,