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

[Shiyang Ruan]

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.f...@fujitsu.com>
Reviewed-by: Christoph Hellwig <h...@lst.de>
Reviewed-by: Ritesh Harjani <rite...@linux.ibm.com>
Reviewed-by: Dan Williams <dan.j.willi...@intel.com>

Could've sworn I reviewed this a few revisions ago...

Oh, sorry, Maybe I missed that.

Reviewed-by: Darrick J. Wong <djw...@kernel.org>

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