Re: [PATCH] Fix shrink_dcache_parent() against shrink_dcache_memory() race (3rd updated patch)]

[Jan Blunck <jblunck@suse.de>]

On Fri, Mar 10, Neil Brown wrote:

> -static void prune_dcache(int count)
> +static void prune_dcache(int count, struct super_block *sb)
>  {
>  	spin_lock(&dcache_lock);
>  	for (; count ; count--) {
> @@ -417,8 +425,10 @@ static void prune_dcache(int count)
>   			spin_unlock(&dentry->d_lock);
>  			continue;
>  		}
> -		/* If the dentry was recently referenced, don't free it. */
> -		if (dentry->d_flags & DCACHE_REFERENCED) {
> +		/* If the dentry was recently referenced, or is for
> +		 * a unmounting filesystem, don't free it. */
> +		if ((dentry->d_flags & DCACHE_REFERENCED) ||
> +		    (dentry->d_sb != sb && dentry->d_sb->s_root == NULL)) {
>  			dentry->d_flags &= ~DCACHE_REFERENCED;
>   			list_add(&dentry->d_lru, &dentry_unused);
>   			dentry_stat.nr_unused++;

You have to down_read the rw-semaphore sb->s_umount since sb->s_root is
protected by it :(

Regards,
	Jan

-- 
Jan Blunck                                               jblunck@suse.de
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