Re: [rfc][patch 1/3] fs: new truncate sequence

Miklos Szeredi
2009-07-06T17:22:15Z

> Index: linux-2.6/mm/truncate.c
> ===================================================================
> --- linux-2.6.orig/mm/truncate.c
> +++ linux-2.6/mm/truncate.c
> @@ -465,3 +465,79 @@ int invalidate_inode_pages2(struct addre
> return invalidate_inode_pages2_range(mapping, 0, -1);
> }
> EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
> +
> +/**
> + * truncate_pagecache - unmap mappings "freed" by truncate() syscall
> + * @inode: inode
> + * @old: old file offset
> + * @new: new file offset
> + *
> + * inode's new i_size must already be written before truncate_pagecache
> + * is called.
> + */
> +void truncate_pagecache(struct inode * inode, loff_t old, loff_t new)
> +{
> + VM_BUG_ON(inode->i_size != new);

This is not true for fuse (and NFS?) as i_size isn't protected by
i_mutex during attribute revalidation, and so it can change during the
truncate.

Thanks,
Miklos