[patch 12/16] fix race between writeback and unlink

Andrew Morton
2002-06-01T08:42:50Z

Fixes a race between unlink and writeback: on the sys_sync() and
pdflush paths the caller does not have a reference against the inode.

So run __iget prior to dropping inode_lock.

Oleg Drokin reported this and seems to believe that it fixes the
crashes he was observing. But I was never able to reproduce them..

=====================================

--- 2.5.19/fs/fs-writeback.c~sync-race Sat Jun 1 01:18:12 2002
+++ 2.5.19-akpm/fs/fs-writeback.c Sat Jun 1 01:18:12 2002
@@ -245,17 +245,19 @@ static void sync_sb_inodes(struct super_
if ((sync_mode == WB_SYNC_LAST) && (head->prev == head))
really_sync = 1;

+ BUG_ON(inode->i_state & I_FREEING);
+ __iget(inode);
__writeback_single_inode(inode, really_sync, nr_to_write);
-
if (sync_mode == WB_SYNC_HOLD) {
mapping->dirtied_when = jiffies;
list_del(&inode->i_list);
list_add(&inode->i_list, &inode->i_sb->s_dirty);
}
-
if (current_is_pdflush())
writeback_release(bdi);
-
+ spin_unlock(&inode_lock);
+ iput(inode);
+ spin_lock(&inode_lock);
if (nr_to_write && *nr_to_write <= 0)
break;
}

-