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Btrfs: fix panic when trying to destroy a newly allocated

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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>
This commit is contained in:
Josef Bacik 2009-11-11 15:53:34 -05:00 committed by Chris Mason
parent 33b2580864
commit a6dbd429d8
1 changed files with 10 additions and 0 deletions
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10
fs/btrfs/inode.c
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@ -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));
}