回复: [PATCH 1/7] fsdax: Output address in dax_iomap_pfn() and rename it

hi,

quoted

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 <redacted>
---
  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

quoted

+             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;