On Wed, Feb 13, 2019 at 2:22 AM Jan Kara <jack@xxxxxxx> wrote:
>
> On Tue 12-02-19 13:24:56, Dan Williams wrote:
> > The checks in __bdev_dax_supported() helped mitigate a potential data
> > corruption bug in the pmem driver's handling of section alignment
> > padding. Strengthen the checks, including checking the end of the range,
> > to validate the dev_pagemap, Xarray entries, and sector-to-pfn
> > translation established for pmem namespaces.
> >
> > Cc: Jan Kara <jack@xxxxxxx>
> > Cc: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> > ---
> > drivers/dax/super.c | 39 +++++++++++++++++++++++++++++----------
> > 1 file changed, 29 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> > index 6e928f37d084..a27395cfcec6 100644
> > --- a/drivers/dax/super.c
> > +++ b/drivers/dax/super.c
> > @@ -86,12 +86,14 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
> > {
> > struct dax_device *dax_dev;
> > bool dax_enabled = false;
> > + pgoff_t pgoff, pgoff_end;
> > struct request_queue *q;
> > - pgoff_t pgoff;
> > - int err, id;
> > - pfn_t pfn;
> > - long len;
> > char buf[BDEVNAME_SIZE];
> > + void *kaddr, *end_kaddr;
> > + pfn_t pfn, end_pfn;
> > + sector_t last_page;
> > + long len, len2;
> > + int err, id;
> >
> > if (blocksize != PAGE_SIZE) {
> > pr_debug("%s: error: unsupported blocksize for dax\n",
> > @@ -113,6 +115,15 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
> > return false;
> > }
> >
> > + last_page = ALIGN_DOWN(part_nr_sects_read(bdev->bd_part)
> > + - PAGE_SIZE / 512, PAGE_SIZE / 512);
>
> Why not just (i_size_read(bdev->bd_inode) - 1) >> PAGE_SHIFT?
Because that would be too elegant and straightforward?
> Otherwise the patch looks good to me.
Thanks, I'll fix up the last page calculation.
