Commit 1a9476a7 authored Aug 08, 2010 by Artem Bityutskiy

UBIFS: fix assertion warnings in comparison function



When running the integrity test ('integck' from mtd-utils) on current
UBIFS on 2.6.35, I see that assertions in UBIFS 'list_sort()' comparison
functions trigger sometimes, e.g.:

UBIFS assert failed in data_nodes_cmp at 132 (pid 28311)

My investigation showed that this happens when 'list_sort()' calls the 'cmp()'
function with equivalent arguments. In this case, the 'struct list_head'
parameter, passed to 'cmp()' is bogus, and it does not belong to any element in
the original list.

And this issue seems to be introduced by commit:

commit 835cc0c8
Author: Don Mullis <don.mullis@gmail.com>
Date:   Fri Mar 5 13:43:15 2010 -0800

It is easy to work around the issue by doing:

if (a == b)
	return 0;

in UBIFS. It works, but 'lib_sort()' should nevertheless be fixed. Although it
is harmless to have this piece of code in UBIFS.

This patch adds that code to both UBIFS 'cmp()' functions:
'data_nodes_cmp()' and 'nondata_nodes_cmp()'.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

parent ba2f48f7

fs/ubifs/gc.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -125,6 +125,9 @@ int data_nodes_cmp(void priv, struct list_head a, struct list_head *b)
		struct ubifs_scan_node sa, sb;

		cond_resched();
		if (a == b)
		return 0;

		sa = list_entry(a, struct ubifs_scan_node, list);
		sb = list_entry(b, struct ubifs_scan_node, list);

		@@ -165,6 +168,9 @@ int nondata_nodes_cmp(void priv, struct list_head a, struct list_head *b)
		struct ubifs_scan_node sa, sb;

		cond_resched();
		if (a == b)
		return 0;

		sa = list_entry(a, struct ubifs_scan_node, list);
		sb = list_entry(b, struct ubifs_scan_node, list);

Admin message