Commit 997def25 authored Sep 23, 2013 by Mark Tinguely Committed by Ben Myers Sep 26, 2013

xfs: fix node forward in xfs_node_toosmall



Commit f5ea1100 cleans up the disk to host conversions for
node directory entries, but because a variable is reused in
xfs_node_toosmall() the next node is not correctly found.
If the original node is small enough (<= 3/8 of the node size),
this change may incorrectly cause a node collapse when it should
not. That will cause an assert in xfstest generic/319:

   Assertion failed: first <= last && last < BBTOB(bp->b_length),
   file: /root/newest/xfs/fs/xfs/xfs_trans_buf.c, line: 569

Keep the original node header to get the correct forward node.

(When a node is considered for a merge with a sibling, it overwrites the
 sibling pointers of the original incore nodehdr with the sibling's
 pointers.  This leads to loop considering the original node as a merge
 candidate with itself in the second pass, and so it incorrectly
 determines a merge should occur.)

Signed-off-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

[v3: added Dave Chinner's (slightly modified) suggestion to the commit header,
	cleaned up whitespace.  -bpm]

parent 566055d3

fs/xfs/xfs_da_btree.c

+3 −2

Original line number	Original line	Diff line number	Diff line
	@@ -1224,6 +1224,7 @@ xfs_da3_node_toosmall(
	/* start with smaller blk num */		/* start with smaller blk num */
	forward = nodehdr.forw < nodehdr.back;		forward = nodehdr.forw < nodehdr.back;
	for (i = 0; i < 2; forward = !forward, i++) {		for (i = 0; i < 2; forward = !forward, i++) {
			struct xfs_da3_icnode_hdr thdr;
	if (forward)		if (forward)
	blkno = nodehdr.forw;		blkno = nodehdr.forw;
	else		else
	@@ -1236,10 +1237,10 @@ xfs_da3_node_toosmall(
	return(error);		return(error);

	node = bp->b_addr;		node = bp->b_addr;
	xfs_da3_node_hdr_from_disk(&nodehdr, node);		xfs_da3_node_hdr_from_disk(&thdr, node);
	xfs_trans_brelse(state->args->trans, bp);		xfs_trans_brelse(state->args->trans, bp);

	if (count - nodehdr.count >= 0)		if (count - thdr.count >= 0)
	break; /* fits with at least 25% to spare */		break; /* fits with at least 25% to spare */
	}		}
	if (i >= 2) {		if (i >= 2) {