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Subject回复: [PATCH 1/7] fsdax: Output address in da x iomap pfn() and rename it
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> hi,
>
> > 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@cn.fujitsu.com>
> > ---
> > fs/dax.c | 20 +++++++++++++++-----
> > 1 file changed, 15 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/dax.c b/fs/dax.c
> > index 5b47834f2e1b..b012b2db7ba2 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -998,8 +998,8 @@ static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
> > return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
> > }
> >
> > -static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
> > - pfn_t *pfnp)
> > +static int dax_iomap_direct_access(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;
> > @@ -1011,11 +1011,13 @@ static int dax_iomap_pfn(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)
> Should this be "if (!*pfnp)"?

pfnp may be NULL if we only need a kaddr output.
`dax_iomap_direct_access(iomap, pos, size, &kaddr, NULL);`

So, it's a NULL pointer check here.


--
Thanks,
Ruan Shiyang.

>
> Regards,
> Xiaoguang Wang
> > + goto out_check_addr;
> > rc = -EINVAL;
> > if (PFN_PHYS(length) < size)
> > goto out;
> > @@ -1025,6 +1027,12 @@ static int dax_iomap_pfn(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;
>
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