linux-kernel - Re: [PATCH v2 (v4.18 regression fix)] vfs: don't evict uninitialized inode

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Date:   Wed, 18 Jul 2018 13:40:08 +0200
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Miklos Szeredi <mszeredi@...hat.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 (v4.18 regression fix)] vfs: don't evict uninitialized inode

Ping?

This (or some variant) needs to go into 4.18.

Thanks,
Miklos

On Fri, Jul 6, 2018 at 10:45 PM, Miklos Szeredi <mszeredi@...hat.com> wrote:
> iput() ends up calling ->evict() on new inode, which is not yet initialized
> by owning fs.  So use destroy_inode() instead.
>
> Add to sb->s_inodes list only if inode is not in I_CREATING state (meaning
> that it wasn't allocated with new_inode(), which already does the
> insertion).
>
> Reported-by: Al Viro <viro@...iv.linux.org.uk>
> Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
> Fixes: 80ea09a002bf ("vfs: factor out inode_insert5()")
> ---
>  fs/inode.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index 04dd7e0d5142..e7de38c1d9d8 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1050,6 +1050,7 @@ struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
>  {
>         struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
>         struct inode *old;
> +       bool creating = inode->i_state & I_CREATING;
>
>  again:
>         spin_lock(&inode_hash_lock);
> @@ -1083,6 +1084,8 @@ struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
>         inode->i_state |= I_NEW;
>         hlist_add_head(&inode->i_hash, head);
>         spin_unlock(&inode->i_lock);
> +       if (!creating)
> +               inode_sb_list_add(inode);
>  unlock:
>         spin_unlock(&inode_hash_lock);
>
> @@ -1117,12 +1120,12 @@ struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
>         struct inode *inode = ilookup5(sb, hashval, test, data);
>
>         if (!inode) {
> -               struct inode *new = new_inode(sb);
> +               struct inode *new = alloc_inode(sb);
>
>                 if (new) {
>                         inode = inode_insert5(new, hashval, test, set, data);
>                         if (unlikely(inode != new))
> -                               iput(new);
> +                               destroy_inode(new);
>                 }
>         }
>         return inode;
> --
> 2.14.3
>