Re: [PATCH] tmpfs: don't undo fallocate past its last page

[Brandon Philips <brandon@ifup.co>]

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On Mon, May 16, 2016 at 4:59 AM Vlastimil Babka <vbabka@suse.cz> wrote:

> On 05/08/2016 03:16 PM, Anthony Romano wrote:
> > When fallocate is interrupted it will undo a range that extends one byte
> > past its range of allocated pages. This can corrupt an in-use page by
> > zeroing out its first byte. Instead, undo using the inclusive byte range.
> > Signed-off-by: Anthony Romano <anthony.romano@coreos.com>
>
> Looks like a stable candidate patch. Can you point out the commit that
> introduced the bug, for the Fixes: tag?
>

Bumping this thread as I don't think this patch has gotten picked up. And
cc'ing folks from 1635f6a74152f1dcd1b888231609d64875f0a81a.

Thank you,

Brandon


> > ---
> >   mm/shmem.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/shmem.c b/mm/shmem.c
> > index 719bd6b..f0f9405 100644
> > --- a/mm/shmem.c
> > +++ b/mm/shmem.c
> > @@ -2238,7 +2238,7 @@ static long shmem_fallocate(struct file *file, int
> mode, loff_t offset,
> >                       /* Remove the !PageUptodate pages we added */
> >                       shmem_undo_range(inode,
> >                               (loff_t)start << PAGE_SHIFT,
> > -                             (loff_t)index << PAGE_SHIFT, true);
> > +                             ((loff_t)index << PAGE_SHIFT) - 1, true);
> >                       goto undone;
> >               }
> >
> >
>
>

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