It helps catch bugs like this:
[ 738.645689] fs/fs-writeback.c:535: s_dirty got screwed up
[ 738.646114] ffff8100028532b0:4295082249
[ 738.646255] ffff810002856858:4295082259
[ 738.646388] ffff810002831b58:4295082667
[ 738.646520] ffff81000281b1b0:4295082671
[ 738.646651] ffff81000281d798:4295083507
========================================== s_dirty/s_io
[ 738.646783] ffff81000287e998:4295081393
[ 738.646916] ffff81000287e430:4295081403
[ 738.647068] ffff8100028789d8:4295081409
[ 738.647212] ffff810002878470:4295081415
[ 738.647358] ffff810002884a18:4295081421
[ 738.647503] ffff8100028844b0:4295081427
[ 738.647648] ffff810002890a58:4295081433
[ 738.647782] ffff8100028904f0:4295081441
[ 738.647894] ffff81000288da98:4295081449
[ 738.648011] ffff81000288d530:4295081455
[ 738.648123] ffff810002897ad8:4295081461
[ 738.648235] ffff810002897570:4295081469
[ 738.648347] ffff810002894b18:4295081477
[ 738.648459] ffff8100028945b0:4295081483
The buggy line 534 is
list_splice_init(&sb->s_io, sb->s_dirty.prev);
This is not the only time-ordering bug in linux-2.6.23-rc1-mm2.
Let's fix them all.
Cc: Ken Chen <kenchen@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 37 +++++++++++++++++++++++++++++++------
1 file changed, 31 insertions(+), 6 deletions(-)
--- linux-2.6.23-rc1-mm2.orig/fs/fs-writeback.c
+++ linux-2.6.23-rc1-mm2/fs/fs-writeback.c
@@ -26,12 +26,12 @@
int sysctl_inode_debug __read_mostly;
-static int __check(struct super_block *sb, int print_stuff)
+static int __check(struct list_head *head, int print_stuff)
{
- struct list_head *cursor = &sb->s_dirty;
+ struct list_head *cursor = head;
unsigned long dirtied_when = 0;
- while ((cursor = cursor->prev) != &sb->s_dirty) {
+ while ((cursor = cursor->prev) != head) {
struct inode *inode = list_entry(cursor, struct inode, i_list);
if (print_stuff) {
printk("%p:%lu\n", inode, inode->dirtied_when);
@@ -51,14 +51,32 @@ static void __check_dirty_inode_list(str
if (!sysctl_inode_debug)
return;
- if (__check(sb, 0)) {
+ if (__check(&sb->s_dirty, 0)) {
sysctl_inode_debug = 0;
if (inode)
printk("%s:%d: s_dirty got screwed up. inode=%p:%lu\n",
file, line, inode, inode->dirtied_when);
else
printk("%s:%d: s_dirty got screwed up\n", file, line);
- __check(sb, 1);
+ __check(&sb->s_dirty, 1);
+ }
+ if (__check(&sb->s_io, 0)) {
+ sysctl_inode_debug = 0;
+ if (inode)
+ printk("%s:%d: s_io got screwed up. inode=%p:%lu\n",
+ file, line, inode, inode->dirtied_when);
+ else
+ printk("%s:%d: s_io got screwed up\n", file, line);
+ __check(&sb->s_io, 1);
+ }
+ if (__check(&sb->s_more_io, 0)) {
+ sysctl_inode_debug = 0;
+ if (inode)
+ printk("%s:%d: s_more_io got screwed up. inode=%p:%lu\n",
+ file, line, inode, inode->dirtied_when);
+ else
+ printk("%s:%d: s_more_io got screwed up\n", file, line);
+ __check(&sb->s_more_io, 1);
}
}
@@ -223,7 +241,9 @@ static void redirty_tail(struct inode *i
*/
static void requeue_io(struct inode *inode)
{
+ check_dirty_inode(inode);
list_move(&inode->i_list, &inode->i_sb->s_more_io);
+ check_dirty_inode(inode);
}
static void inode_sync_complete(struct inode *inode)
@@ -483,7 +503,9 @@ int generic_sync_sb_inodes(struct super_
/* Was this inode dirtied too recently? */
if (wbc->older_than_this && time_after(inode->dirtied_when,
*wbc->older_than_this)) {
+ check_dirty_inode_list(sb);
list_splice_init(&sb->s_io, sb->s_dirty.prev);
+ check_dirty_inode_list(sb);
break;
}
@@ -520,8 +542,11 @@ int generic_sync_sb_inodes(struct super_
break;
}
- if (list_empty(&sb->s_io))
+ if (list_empty(&sb->s_io)) {
+ check_dirty_inode_list(sb);
list_splice_init(&sb->s_more_io, &sb->s_io);
+ check_dirty_inode_list(sb);
+ }
spin_unlock(&inode_lock);
return ret; /* Leave any unwritten inodes on s_io */
}
--
-
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