Re: corruption

Stephen C. Tweedie
2000-12-01T14:49:19Z

Hi,

On Fri, Dec 01, 2000 at 08:35:41AM +1100, Andrew Morton wrote:
>
> I bet this'll catch it:
>
> static __inline__ void list_del(struct list_head *entry)
> {
> __list_del(entry->prev, entry->next);
> + entry->next = entry->prev = 0;
> }

No, because the buffer hash list is never referenced unless
buffer->b_inode is non-null, so we can't ever do a double-list_del on
the buffer.

The patch below should fix it. It has been sent to Linus. The
important part is the first hunk of the inode.c diff.

Cheers,
Stephen

fsync-fix2.diff:
--- fs/buffer.c.~1~ Wed Nov 29 15:16:43 2000
+++ fs/buffer.c Fri Dec 1 00:41:28 2000
@@ -871,10 +871,11 @@
else {
bh->b_inode = &tmp;
list_add(&bh->b_inode_buffers, &tmp.i_dirty_buffers);
- atomic_inc(&bh->b_count);
if (buffer_dirty(bh)) {
+ atomic_inc(&bh->b_count);
spin_unlock(&lru_list_lock);
ll_rw_block(WRITE, 1, &bh);
+ brelse(bh);
spin_lock(&lru_list_lock);
}
}
@@ -883,6 +884,7 @@
while (!list_empty(&tmp.i_dirty_buffers)) {
bh = BH_ENTRY(tmp.i_dirty_buffers.prev);
remove_inode_queue(bh);
+ atomic_inc(&bh->b_count);
spin_unlock(&lru_list_lock);
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
@@ -929,9 +931,9 @@
atomic_inc(&bh->b_count);
spin_unlock(&lru_list_lock);
wait_on_buffer(bh);
- brelse(bh);
if (!buffer_uptodate(bh))
err = -EIO;
+ brelse(bh);
spin_lock(&lru_list_lock);
goto repeat;
}
--- fs/inode.c.~1~ Wed Nov 29 15:16:43 2000
+++ fs/inode.c Fri Dec 1 00:40:26 2000
@@ -77,7 +77,13 @@

#define alloc_inode() \
((struct inode *) kmem_cache_alloc(inode_cachep, SLAB_KERNEL))
-#define destroy_inode(inode) kmem_cache_free(inode_cachep, (inode))
+static void destroy_inode(struct inode *inode)
+{
+ if (!list_empty(&inode->i_dirty_buffers))
+ BUG();
+ kmem_cache_free(inode_cachep, (inode));
+}
+

/*
* These are initializations that only need to be done
@@ -348,6 +354,12 @@

void clear_inode(struct inode *inode)
{
+ if (!list_empty(&inode->i_dirty_buffers)) {
+ if (inode->i_nlink)
+ BUG();
+ invalidate_inode_buffers(inode);
+ }
+
if (inode->i_data.nrpages)
BUG();
if (!(inode->i_state & I_FREEING))
@@ -407,6 +419,7 @@
inode = list_entry(tmp, struct inode, i_list);
if (inode->i_sb != sb)
continue;
+ invalidate_inode_buffers(inode);
if (!atomic_read(&inode->i_count)) {
list_del(&inode->i_hash);
INIT_LIST_HEAD(&inode->i_hash);