Re: [PATCH] nilfs2: fix data loss with mmap()

From: Andrew Morton
Date: Thu Sep 18 2014 - 15:17:14 EST


On Thu, 18 Sep 2014 23:56:25 +0900 Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> wrote:

> From: Andreas Rohner <andreas.rohner@xxxxxxx>
>
> This bug leads to reproducible silent data loss, despite the use of
> msync(), sync() and a clean unmount of the file system. It is easily
> reproducible with the following script:
>
> ...
>
> --- a/fs/nilfs2/inode.c
> +++ b/fs/nilfs2/inode.c
> @@ -219,10 +219,10 @@ static int nilfs_writepage(struct page *page, struct writeback_control *wbc)
>
> static int nilfs_set_page_dirty(struct page *page)
> {
> + struct inode *inode = page->mapping->host;
> int ret = __set_page_dirty_nobuffers(page);
>
> if (page_has_buffers(page)) {
> - struct inode *inode = page->mapping->host;
> unsigned nr_dirty = 0;
> struct buffer_head *bh, *head;
>
> @@ -245,6 +245,10 @@ static int nilfs_set_page_dirty(struct page *page)
>
> if (nr_dirty)
> nilfs_set_file_dirty(inode, nr_dirty);
> + } else if (ret) {
> + unsigned nr_dirty = 1 << (PAGE_SHIFT - inode->i_blkbits);

It's quite cosmetic, but it is conventional to use PAGE_CACHE_SHIFT here.
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