Re: [PATCH try #2] fuse: fix error case in fuse_readpages

[Andrew Morton <akpm@osdl.org>]

On Thu, 10 Aug 2006 11:28:48 +0200
Miklos Szeredi <miklos@szeredi.hu> wrote:

> From: Alexander Zarochentsev <zam@namesys.com>
> 
> Don't let fuse_readpages leave the @pages list not empty when exiting
> on error.
> 

Oh dear.  read_cache_pages_release_page() is not a readahead thing.  It is
a dhowells fscache thing.

> 
> Index: linux/fs/fuse/file.c
> ===================================================================
> --- linux.orig/fs/fuse/file.c	2006-08-10 09:41:12.000000000 +0200
> +++ linux/fs/fuse/file.c	2006-08-10 11:13:35.000000000 +0200
> @@ -395,14 +395,16 @@ static int fuse_readpages(struct file *f
>  	struct fuse_readpages_data data;
>  	int err;
>  
> +	err = -EIO;
>  	if (is_bad_inode(inode))
> -		return -EIO;
> +		goto clean_pages_up;
>  
>  	data.file = file;
>  	data.inode = inode;
>  	data.req = fuse_get_req(fc);
> +	err = PTR_ERR(data.req);
>  	if (IS_ERR(data.req))
> -		return PTR_ERR(data.req);
> +		goto clean_pages_up;
>  
>  	err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
>  	if (!err) {
> @@ -412,6 +414,10 @@ static int fuse_readpages(struct file *f
>  			fuse_put_request(fc, data.req);
>  	}
>  	return err;
> +
> +clean_pages_up:
> +	put_pages_list(pages);
> +	return err;
>  }
>  
>  static size_t fuse_send_write(struct fuse_req *req, struct file *file,
> Index: linux/mm/readahead.c
> ===================================================================
> --- linux.orig/mm/readahead.c	2006-08-10 09:41:14.000000000 +0200
> +++ linux/mm/readahead.c	2006-08-10 11:12:27.000000000 +0200
> @@ -147,13 +147,7 @@ int read_cache_pages(struct address_spac
>  		if (!pagevec_add(&lru_pvec, page))
>  			__pagevec_lru_add(&lru_pvec);
>  		if (ret) {
> -			while (!list_empty(pages)) {
> -				struct page *victim;
> -
> -				victim = list_to_page(pages);
> -				list_del(&victim->lru);
> -				page_cache_release(victim);
> -			}
> +			put_pages_list(pages);
>  			break;
>  		}
>  	}

So I shall drop the above hunk for now.

> Index: linux/include/linux/mm.h
> ===================================================================
> --- linux.orig/include/linux/mm.h	2006-08-10 11:06:05.000000000 +0200
> +++ linux/include/linux/mm.h	2006-08-10 11:12:46.000000000 +0200
> @@ -336,6 +336,7 @@ static inline void init_page_count(struc
>  }
>  
>  void put_page(struct page *page);
> +void put_pages_list(struct list_head *pages);
>  
>  void split_page(struct page *page, unsigned int order);
>  
> Index: linux/mm/swap.c
> ===================================================================
> --- linux.orig/mm/swap.c	2006-08-10 11:02:34.000000000 +0200
> +++ linux/mm/swap.c	2006-08-10 11:18:59.000000000 +0200
> @@ -54,6 +54,24 @@ void put_page(struct page *page)
>  }
>  EXPORT_SYMBOL(put_page);
>  
> +/**
> + * Release page list.  Currently used by read_cache_pages() and related
> + * cleanup code.
> + *
> + * @pages: list of pages threaded on page->lru
> + */
> +void put_pages_list(struct list_head *pages)
> +{
> +	while (!list_empty(pages)) {
> +		struct page *victim;
> +
> +		victim = list_entry(pages->prev, struct page, lru);
> +		list_del(&victim->lru);
> +		page_cache_release(victim);
> +	}
> +}
> +EXPORT_SYMBOL(put_pages_list);
> +
>  /*
>   * Writeback is about to end against a page which has been marked for immediate
>   * reclaim.  If it still appears to be reclaimable, move it to the tail of the