Re: [PATCH 04/21] fs: Implement lazy LRU updates for inodes

Nick Piggin
2010-10-21T10:07:15Z

On Thu, Oct 21, 2010 at 11:49:29AM +1100, Dave Chinner wrote:
> } else {
> /*
> - * The inode is clean, unused
> + * The inode is clean. If it is unused, then make sure
> + * that it is put on the LRU correctly as iput_final()
> + * does not move dirty inodes to the LRU and dirty
> + * inodes are removed from the LRU during scanning.
> */
> - list_move(&inode->i_list, &inode_unused);
> + list_del_init(&inode->i_list);
> + if (!atomic_read(&inode->i_count))
> + inode_lru_list_add(inode);

This "optimisation" is surely wrong. How could we have no reference
on the inode at this point?

> -static int can_unuse(struct inode *inode)
> -{
> - if (inode->i_state)
> - return 0;
> - if (inode_has_buffers(inode))
> - return 0;
> - if (atomic_read(&inode->i_count))
> - return 0;
> - if (inode->i_data.nrpages)
> - return 0;
> - return 1;
> -}

Avoiding the reclaim optimisation? As I said, I noticed some increased
scanning in heavy reclaim from removing this.