Always reset btree cursor after an insert

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

@@ -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,

@@ -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;

Can you commit the XFS_WANT_CORRUPTED_GOTO checks as a separate patch before the cursor reset? ACK from me for those hunks.

Yeah, no problem, thanks.

The rest of it looks ok as well, Lachlan.

Cheers,

Dave.

Dave Chinner
[email protected]

Ta.