Re: [PATCH v9 1/8] fsdax: Output address in dax_iomap_pfn() and rename it

[Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>]

On 2021/9/16 8:09, Darrick J. Wong wrote:
> On Wed, Sep 15, 2021 at 06:44:54PM +0800, Shiyang Ruan wrote:
> > Add address output in dax_iomap_pfn() in order to perform a memcpy() in
> > CoW case.  Since this function both output address and pfn, rename it to
> > dax_iomap_direct_access().
> >
> > Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
> > Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> > Reviewed-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
> > Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>
> Could've sworn I reviewed this a few revisions ago...

Oh, sorry, Maybe I missed that.

> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>

Thanks!

--
Ruan

> --D
>
> > ---
> >   fs/dax.c | 16 ++++++++++++----
> >   1 file changed, 12 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/dax.c b/fs/dax.c
> > index 4e3e5a283a91..8b482a58acae 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -1010,8 +1010,8 @@ static sector_t dax_iomap_sector(const struct iomap *iomap, loff_t pos)
> >   	return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
> >   }
> >   
> > -static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
> > -			 pfn_t *pfnp)
> > +static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
> > +		size_t size, void **kaddr, pfn_t *pfnp)
> >   {
> >   	const sector_t sector = dax_iomap_sector(iomap, pos);
> >   	pgoff_t pgoff;
> > @@ -1023,11 +1023,13 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
> >   		return rc;
> >   	id = dax_read_lock();
> >   	length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
> > -				   NULL, pfnp);
> > +				   kaddr, pfnp);
> >   	if (length < 0) {
> >   		rc = length;
> >   		goto out;
> >   	}
> > +	if (!pfnp)
> > +		goto out_check_addr;
> >   	rc = -EINVAL;
> >   	if (PFN_PHYS(length) < size)
> >   		goto out;
> > @@ -1037,6 +1039,12 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
> >   	if (length > 1 && !pfn_t_devmap(*pfnp))
> >   		goto out;
> >   	rc = 0;
> > +
> > +out_check_addr:
> > +	if (!kaddr)
> > +		goto out;
> > +	if (!*kaddr)
> > +		rc = -EFAULT;
> >   out:
> >   	dax_read_unlock(id);
> >   	return rc;
> > @@ -1401,7 +1409,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
> >   		return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
> >   	}
> >   
> > -	err = dax_iomap_pfn(&iter->iomap, pos, size, &pfn);
> > +	err = dax_iomap_direct_access(&iter->iomap, pos, size, NULL, &pfn);
> >   	if (err)
> >   		return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);
> >   
> > --
> > 2.33.0