Commit a6dbd429 authored Nov 11, 2009 by Josef Bacik Committed by Chris Mason Nov 11, 2009

Btrfs: fix panic when trying to destroy a newly allocated

There is a problem where iget5_locked will look for an inode, not find it, and
then subsequently try to allocate it. Another CPU will have raced in and
allocated the inode instead, so when iget5_locked gets the inode spin lock again
and does a search, it finds the new inode. So it goes ahead and calls
destroy_inode on the inode it just allocated. The problem is we don't set
BTRFS_I(inode)->root until the new inode is completely initialized. This patch
makes us set root to NULL when alloc'ing a new inode, so when we get to
btrfs_destroy_inode and we see that root is NULL we can just free up the memory
and continue on. This fixes the panic

http://www.kerneloops.org/submitresult.php?number=812690

Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

parent 33b25808

fs/btrfs/inode.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -5180,6 +5180,7 @@ struct inode btrfs_alloc_inode(struct super_block sb)
		ei->logged_trans = 0;
		ei->outstanding_extents = 0;
		ei->reserved_extents = 0;
		ei->root = NULL;
		spin_lock_init(&ei->accounting_lock);
		btrfs_ordered_inode_tree_init(&ei->ordered_tree);
		INIT_LIST_HEAD(&ei->i_orphan);
		@@ -5195,6 +5196,14 @@ void btrfs_destroy_inode(struct inode *inode)
		WARN_ON(!list_empty(&inode->i_dentry));
		WARN_ON(inode->i_data.nrpages);

		/*
		* This can happen where we create an inode, but somebody else also
		* created the same inode and we need to destroy the one we already
		* created.
		*/
		if (!root)
		goto free;

		/*
		* Make sure we're properly removed from the ordered operation
		* lists.
		@@ -5230,6 +5239,7 @@ void btrfs_destroy_inode(struct inode *inode)
		}
		inode_tree_del(inode);
		btrfs_drop_extent_cache(inode, 0, (u64)-1, 0);
		free:
		kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
		}