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SubjectRe: [PATCH 15/23] mm, fs: avoid page allocation beyond i_size on read
On Sun,  4 Aug 2013 05:17:17 +0300 "Kirill A. Shutemov"
<kirill.shutemov@linux.intel.com> wrote:

> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> I've noticed that we allocated unneeded page for cache on read beyond
> i_size. Simple test case (I checked it on ramfs):
>
> $ touch testfile
> $ cat testfile
>
> It triggers 'no_cached_page' code path in do_generic_file_read().
>
> Looks like it's regression since commit a32ea1e. Let's fix it.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: NeilBrown <neilb@suse.de>
> ---
> mm/filemap.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 066bbff..c31d296 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1163,6 +1163,10 @@ static void do_generic_file_read(struct file *filp, loff_t *ppos,
> loff_t isize;
> unsigned long nr, ret;
>
> + isize = i_size_read(inode);
> + if (!isize || index > (isize - 1) >> PAGE_CACHE_SHIFT)
> + goto out;
> +
> cond_resched();
> find_page:
> page = find_get_page(mapping, index);

Looks good to me.

Acked-by: NeilBrown <neilb@suse.de>

Thanks,
NeilBrown
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