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

[Shiyang Ruan]

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...@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)
+               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;
@@ -1348,7 +1356,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault 
*vmf, pfn_t *pfnp,
                        count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
                        major = VM_FAULT_MAJOR;
                }
-               error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn);
+               error = dax_iomap_direct_access(&iomap, pos, PAGE_SIZE,
+                                               NULL, &pfn);
                if (error < 0)
                        goto error_finish_iomap;
 
@@ -1566,7 +1575,8 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault 
*vmf, pfn_t *pfnp,
 
        switch (iomap.type) {
        case IOMAP_MAPPED:
-               error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn);
+               error = dax_iomap_direct_access(&iomap, pos, PMD_SIZE,
+                                               NULL, &pfn);
                if (error < 0)
                        goto finish_iomap;
 
-- 
2.30.0