Ocfs2 devel - Sep 2008 - [PATCH 1/1] OCFS2: add spin lock when accessing inode->i_nlink.

add spin lock when accessing inode->i_nlink in ocfs2_drop_inode().

the patch is against 1.2 svn.

Signed-off-by: Wengang wang <wen.gang.wang at oracle.com>
--
Index: fs/ocfs2/inode.c
==================================================================---
fs/ocfs2/inode.c	(revision 3101)
+++ fs/ocfs2/inode.c	(working copy)
@@ -991,10 +991,12 @@
 	/* Testing ip_orphaned_slot here wouldn't work because we may
 	 * not have gotten a delete_inode vote from any other nodes
 	 * yet. */
+	spin_lock(&oi->ip_lock);
 	if (oi->ip_flags & OCFS2_INODE_MAYBE_ORPHANED) {
 		mlog(0, "Inode was orphaned on another node, clearing nlink.\n");
 		inode->i_nlink = 0;
 	}
+	spin_unlock(&oi->ip_lock);
 
 	generic_drop_inode(inode);

NAK

Firstly ip_lock does not protect inode. Secondly, the field is
protected by inode_lock. Follow the code:

iput (inode_lock taken) => iput_final ==> ocfs2_drop_inode (inode_lock 
still held).

void iput(struct inode *inode)
{
....
                if (atomic_dec_and_lock(&inode->i_count,
&inode_lock))
                        iput_final(inode);
}

static inline void iput_final(struct inode *inode)
{
        struct super_operations *op = inode->i_sb->s_op;
        void (*drop)(struct inode *) = generic_drop_inode;

        if (op && op->drop_inode)
                drop = op->drop_inode;
        drop(inode);
}


wangang wang wrote:
> add spin lock when accessing inode->i_nlink in ocfs2_drop_inode().
>
> the patch is against 1.2 svn.
>
> Signed-off-by: Wengang wang <wen.gang.wang at oracle.com>
> --
> Index: fs/ocfs2/inode.c
> ==================================================================> ---
fs/ocfs2/inode.c	(revision 3101)
> +++ fs/ocfs2/inode.c	(working copy)
> @@ -991,10 +991,12 @@
>  	/* Testing ip_orphaned_slot here wouldn't work because we may
>  	 * not have gotten a delete_inode vote from any other nodes
>  	 * yet. */
> +	spin_lock(&oi->ip_lock);
>  	if (oi->ip_flags & OCFS2_INODE_MAYBE_ORPHANED) {
>  		mlog(0, "Inode was orphaned on another node, clearing
nlink.\n");
>  		inode->i_nlink = 0;
>  	}
> +	spin_unlock(&oi->ip_lock);
>  
>  	generic_drop_inode(inode);
>  
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> http://oss.oracle.com/mailman/listinfo/ocfs2-devel
>