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[PATCH V2] Always reset btree cursor after an insert

To: xfs-dev <xfs-dev@xxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
Subject: [PATCH V2] Always reset btree cursor after an insert
From: Lachlan McIlroy <lachlan@xxxxxxx>
Date: Thu, 19 Jun 2008 16:17:15 +1000
Reply-to: lachlan@xxxxxxx
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Thunderbird 2.0.0.14 (X11/20080421)
After a btree insert operation a cursor can be invalid due to block
splits and a maybe a new root block.  We reset the cursor in
xfs_bmbt_insert() in the cases where we think we need to but it
isn't enough as we still see assertions.  Just do what we do elsewhere
and reset the cursor unconditionally.  Version 2 adds
XFS_WANT_CORRUPTED_GOTO checks throughout xfs_bmap.c and removes the
fix to revalidate the original cursor in xfs_bmbt_insert().

Lachlan

--- fs/xfs/xfs_bmap.c_1.392     2008-06-16 17:25:09.000000000 +1000
+++ fs/xfs/xfs_bmap.c   2008-06-19 16:07:47.000000000 +1000
@@ -428,7 +428,8 @@ xfs_bmap_add_attrfork_btree(
                cur->bc_private.b.firstblock = *firstblock;
                if ((error = xfs_bmbt_lookup_ge(cur, 0, 0, 0, &stat)))
                        goto error0;
-               ASSERT(stat == 1);      /* must be at least one entry */
+               /* must be at least one entry */
+               XFS_WANT_CORRUPTED_GOTO(stat == 1, error0);
                if ((error = xfs_bmbt_newroot(cur, flags, &stat)))
                        goto error0;
                if (stat == 0) {
@@ -816,13 +817,13 @@ xfs_bmap_add_extent_delay_real(
                                        RIGHT.br_startblock,
                                        RIGHT.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_delete(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_decrement(cur, 0, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, LEFT.br_startoff,
                                        LEFT.br_startblock,
                                        LEFT.br_blockcount +
@@ -860,7 +861,7 @@ xfs_bmap_add_extent_delay_real(
                                        LEFT.br_startblock, LEFT.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, LEFT.br_startoff,
                                        LEFT.br_startblock,
                                        LEFT.br_blockcount +
@@ -895,7 +896,7 @@ xfs_bmap_add_extent_delay_real(
                                        RIGHT.br_startblock,
                                        RIGHT.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, PREV.br_startoff,
                                        new->br_startblock,
                                        PREV.br_blockcount +
@@ -928,11 +929,11 @@ xfs_bmap_add_extent_delay_real(
                                        new->br_startblock, new->br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 0);
+                       XFS_WANT_CORRUPTED_GOTO(i == 0, done);
                        cur->bc_rec.b.br_state = XFS_EXT_NORM;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                *dnew = 0;
                /* DELTA: The in-core extent described by new changed type. */
@@ -963,7 +964,7 @@ xfs_bmap_add_extent_delay_real(
                                        LEFT.br_startblock, LEFT.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, LEFT.br_startoff,
                                        LEFT.br_startblock,
                                        LEFT.br_blockcount +
@@ -1004,11 +1005,11 @@ xfs_bmap_add_extent_delay_real(
                                        new->br_startblock, new->br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 0);
+                       XFS_WANT_CORRUPTED_GOTO(i == 0, done);
                        cur->bc_rec.b.br_state = XFS_EXT_NORM;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
                    ip->i_d.di_nextents > ip->i_df.if_ext_max) {
@@ -1054,7 +1055,7 @@ xfs_bmap_add_extent_delay_real(
                                        RIGHT.br_startblock,
                                        RIGHT.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, new->br_startoff,
                                        new->br_startblock,
                                        new->br_blockcount +
@@ -1094,11 +1095,11 @@ xfs_bmap_add_extent_delay_real(
                                        new->br_startblock, new->br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 0);
+                       XFS_WANT_CORRUPTED_GOTO(i == 0, done);
                        cur->bc_rec.b.br_state = XFS_EXT_NORM;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
                    ip->i_d.di_nextents > ip->i_df.if_ext_max) {
@@ -1149,11 +1150,11 @@ xfs_bmap_add_extent_delay_real(
                                        new->br_startblock, new->br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 0);
+                       XFS_WANT_CORRUPTED_GOTO(i == 0, done);
                        cur->bc_rec.b.br_state = XFS_EXT_NORM;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
                    ip->i_d.di_nextents > ip->i_df.if_ext_max) {
@@ -1377,19 +1378,19 @@ xfs_bmap_add_extent_unwritten_real(
                                        RIGHT.br_startblock,
                                        RIGHT.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_delete(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_decrement(cur, 0, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_delete(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_decrement(cur, 0, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, LEFT.br_startoff,
                                LEFT.br_startblock,
                                LEFT.br_blockcount + PREV.br_blockcount +
@@ -1426,13 +1427,13 @@ xfs_bmap_add_extent_unwritten_real(
                                        PREV.br_startblock, PREV.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_delete(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_decrement(cur, 0, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, LEFT.br_startoff,
                                LEFT.br_startblock,
                                LEFT.br_blockcount + PREV.br_blockcount,
@@ -1469,13 +1470,13 @@ xfs_bmap_add_extent_unwritten_real(
                                        RIGHT.br_startblock,
                                        RIGHT.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_delete(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_decrement(cur, 0, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, new->br_startoff,
                                new->br_startblock,
                                new->br_blockcount + RIGHT.br_blockcount,
@@ -1508,7 +1509,7 @@ xfs_bmap_add_extent_unwritten_real(
                                        new->br_startblock, new->br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, new->br_startoff,
                                new->br_startblock, new->br_blockcount,
                                newext)))
@@ -1549,7 +1550,7 @@ xfs_bmap_add_extent_unwritten_real(
                                        PREV.br_startblock, PREV.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur,
                                PREV.br_startoff + new->br_blockcount,
                                PREV.br_startblock + new->br_blockcount,
@@ -1596,7 +1597,7 @@ xfs_bmap_add_extent_unwritten_real(
                                        PREV.br_startblock, PREV.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur,
                                PREV.br_startoff + new->br_blockcount,
                                PREV.br_startblock + new->br_blockcount,
@@ -1606,7 +1607,7 @@ xfs_bmap_add_extent_unwritten_real(
                        cur->bc_rec.b = *new;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                /* DELTA: One in-core extent is split in two. */
                temp = PREV.br_startoff;
@@ -1640,7 +1641,7 @@ xfs_bmap_add_extent_unwritten_real(
                                        PREV.br_startblock,
                                        PREV.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, PREV.br_startoff,
                                PREV.br_startblock,
                                PREV.br_blockcount - new->br_blockcount,
@@ -1682,7 +1683,7 @@ xfs_bmap_add_extent_unwritten_real(
                                        PREV.br_startblock, PREV.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, PREV.br_startoff,
                                PREV.br_startblock,
                                PREV.br_blockcount - new->br_blockcount,
@@ -1692,11 +1693,11 @@ xfs_bmap_add_extent_unwritten_real(
                                        new->br_startblock, new->br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 0);
+                       XFS_WANT_CORRUPTED_GOTO(i == 0, done);
                        cur->bc_rec.b.br_state = XFS_EXT_NORM;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                /* DELTA: One in-core extent is split in two. */
                temp = PREV.br_startoff;
@@ -1732,7 +1733,7 @@ xfs_bmap_add_extent_unwritten_real(
                                        PREV.br_startblock, PREV.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        /* new right extent - oldext */
                        if ((error = xfs_bmbt_update(cur, r[1].br_startoff,
                                r[1].br_startblock, r[1].br_blockcount,
@@ -1744,15 +1745,22 @@ xfs_bmap_add_extent_unwritten_real(
                        cur->bc_rec.b = PREV;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
-                       if ((error = xfs_bmbt_increment(cur, 0, &i)))
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
+                       /*
+                        * Reset the cursor to the position of the new extent
+                        * we are about to insert as we can't trust it after
+                        * the previous insert.
+                        */
+                       if ((error = xfs_bmbt_lookup_eq(cur, new->br_startoff,
+                                       new->br_startblock, new->br_blockcount,
+                                       &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 0, done);
                        /* new middle extent - newext */
-                       cur->bc_rec.b = *new;
+                       cur->bc_rec.b.br_state = new->br_state;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                /* DELTA: One in-core extent is split in three. */
                temp = PREV.br_startoff;
@@ -2097,13 +2105,13 @@ xfs_bmap_add_extent_hole_real(
                                        right.br_startblock,
                                        right.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_delete(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_decrement(cur, 0, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, left.br_startoff,
                                        left.br_startblock,
                                        left.br_blockcount +
@@ -2139,7 +2147,7 @@ xfs_bmap_add_extent_hole_real(
                                        left.br_startblock,
                                        left.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, left.br_startoff,
                                        left.br_startblock,
                                        left.br_blockcount +
@@ -2174,7 +2182,7 @@ xfs_bmap_add_extent_hole_real(
                                        right.br_startblock,
                                        right.br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        if ((error = xfs_bmbt_update(cur, new->br_startoff,
                                        new->br_startblock,
                                        new->br_blockcount +
@@ -2208,11 +2216,11 @@ xfs_bmap_add_extent_hole_real(
                                        new->br_startblock,
                                        new->br_blockcount, &i)))
                                goto done;
-                       ASSERT(i == 0);
+                       XFS_WANT_CORRUPTED_GOTO(i == 0, done);
                        cur->bc_rec.b.br_state = new->br_state;
                        if ((error = xfs_bmbt_insert(cur, &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                /* DELTA: A new extent was added in a hole. */
                temp = new->br_startoff;
@@ -3131,7 +3139,7 @@ xfs_bmap_del_extent(
                                        got.br_startblock, got.br_blockcount,
                                        &i)))
                                goto done;
-                       ASSERT(i == 1);
+                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                }
                da_old = da_new = 0;
        } else {
@@ -3164,7 +3172,7 @@ xfs_bmap_del_extent(
                }
                if ((error = xfs_bmbt_delete(cur, &i)))
                        goto done;
-               ASSERT(i == 1);
+               XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                break;

        case 2:
@@ -3268,7 +3276,7 @@ xfs_bmap_del_extent(
                                                        got.br_startblock,
                                                        temp, &i)))
                                                goto done;
-                                       ASSERT(i == 1);
+                                       XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                                        /*
                                         * Update the btree record back
                                         * to the original value.
@@ -3289,7 +3297,7 @@ xfs_bmap_del_extent(
                                        error = XFS_ERROR(ENOSPC);
                                        goto done;
                                }
-                               ASSERT(i == 1);
+                               XFS_WANT_CORRUPTED_GOTO(i == 1, done);
                        } else
                                flags |= XFS_ILOG_FEXT(whichfork);
                        XFS_IFORK_NEXT_SET(ip, whichfork,
--- fs/xfs/xfs_bmap_btree.c_1.169       2008-06-16 17:25:10.000000000 +1000
+++ fs/xfs/xfs_bmap_btree.c     2008-06-19 16:12:43.000000000 +1000
@@ -2029,22 +2029,8 @@ xfs_bmbt_increment(
 * Insert the current record at the point referenced by cur.
 *
 * A multi-level split of the tree on insert will invalidate the original
- * cursor. It appears, however, that some callers assume that the cursor is
- * always valid. Hence if we do a multi-level split we need to revalidate the
- * cursor.
- *
- * When a split occurs, we will see a new cursor returned. Use that as a
- * trigger to determine if we need to revalidate the original cursor. If we get
- * a split, then use the original irec to lookup up the path of the record we
- * just inserted.
- *
- * Note that the fact that the btree root is in the inode means that we can
- * have the level of the tree change without a "split" occurring at the root
- * level. What happens is that the root is migrated to an allocated block and
- * the inode root is pointed to it. This means a single split can change the
- * level of the tree (level 2 -> level 3) and invalidate the old cursor. Hence
- * the level change should be accounted as a split so as to correctly trigger a
- * revalidation of the old cursor.
+ * cursor.  All callers of this function should assume that the cursor is
+ * no longer valid and revalidate it.
 */
int                                     /* error */
xfs_bmbt_insert(
@@ -2057,14 +2043,11 @@ xfs_bmbt_insert(
        xfs_fsblock_t   nbno;
        xfs_btree_cur_t *ncur;
        xfs_bmbt_rec_t  nrec;
-       xfs_bmbt_irec_t oirec;          /* original irec */
        xfs_btree_cur_t *pcur;
-       int             splits = 0;

        XFS_BMBT_TRACE_CURSOR(cur, ENTRY);
        level = 0;
        nbno = NULLFSBLOCK;
-       oirec = cur->bc_rec.b;
        xfs_bmbt_disk_set_all(&nrec, &cur->bc_rec.b);
        ncur = NULL;
        pcur = cur;
@@ -2073,13 +2056,11 @@ xfs_bmbt_insert(
                                &i))) {
                        if (pcur != cur)
                                xfs_btree_del_cursor(pcur, XFS_BTREE_ERROR);
-                       goto error0;
+                       XFS_BMBT_TRACE_CURSOR(cur, ERROR);
+                       return error;
                }
                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
                if (pcur != cur && (ncur || nbno == NULLFSBLOCK)) {
-                       /* allocating a new root is effectively a split */
-                       if (cur->bc_nlevels != pcur->bc_nlevels)
-                               splits++;
                        cur->bc_nlevels = pcur->bc_nlevels;
                        cur->bc_private.b.allocated +=
                                pcur->bc_private.b.allocated;
@@ -2093,21 +2074,10 @@ xfs_bmbt_insert(
                        xfs_btree_del_cursor(pcur, XFS_BTREE_NOERROR);
                }
                if (ncur) {
-                       splits++;
                        pcur = ncur;
                        ncur = NULL;
                }
        } while (nbno != NULLFSBLOCK);
-
-       if (splits > 1) {
-               /* revalidate the old cursor as we had a multi-level split */
-               error = xfs_bmbt_lookup_eq(cur, oirec.br_startoff,
-                               oirec.br_startblock, oirec.br_blockcount, &i);
-               if (error)
-                       goto error0;
-               ASSERT(i == 1);
-       }
-
        XFS_BMBT_TRACE_CURSOR(cur, EXIT);
        *stat = i;
        return 0;


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