[PATCH 09/10] btrfs: dax support for cow_page/mmap_private and shared

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgold...@suse.com>

Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com>
---
 fs/btrfs/dax.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/dax.c b/fs/btrfs/dax.c
index 88017f8799d1..6d68d39cc5da 100644
--- a/fs/btrfs/dax.c
+++ b/fs/btrfs/dax.c
@@ -198,10 +198,13 @@ vm_fault_t btrfs_dax_fault(struct vm_fault *vmf)
        pfn_t pfn;
        struct address_space *mapping = vmf->vma->vm_file->f_mapping;
        XA_STATE(xas, &mapping->i_pages, vmf->pgoff);
+       unsigned long vaddr = vmf->address;
        struct inode *inode = mapping->host;
        loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
        void *entry = NULL;
        vm_fault_t ret = 0;
+       struct extent_map *em;
+       struct dax_device *dax_dev;
 
        if (pos > i_size_read(inode)) {
                ret = VM_FAULT_SIGBUS;
@@ -214,21 +217,33 @@ vm_fault_t btrfs_dax_fault(struct vm_fault *vmf)
                goto out;
        }
 
-       if (!vmf->cow_page) {
+        em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, pos, PAGE_SIZE, 0);
+       if (em->block_start != EXTENT_MAP_HOLE)
+               dax_dev = fs_dax_get_by_bdev(em->bdev);
+
+       if (vmf->cow_page) {
+               sector_t sector;
+               if (em->block_start == EXTENT_MAP_HOLE) {
+                       clear_user_highpage(vmf->cow_page, vaddr);
+                       goto out;
+               }
+               sector = (get_start_sect(em->bdev) << 9) + (em->block_start + 
(pos - em->start));
+               sector >>= 9;
+               ret = copy_user_dax(em->bdev, dax_dev, sector, PAGE_SIZE, 
vmf->cow_page, vaddr);
+               goto out;
+       } else {
                sector_t sector;
-               struct extent_map *em;
-                em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, pos, PAGE_SIZE, 
0);
                if (em->block_start == EXTENT_MAP_HOLE) {
                        ret = dax_load_hole(&xas, mapping, entry, vmf);
                        goto out;
                }
                sector = ((get_start_sect(em->bdev) << 9) +
                          (em->block_start + (pos - em->start))) >> 9;
-               ret = dax_pfn(fs_dax_get_by_bdev(em->bdev), em->bdev, sector, 
PAGE_SIZE, &pfn);
+               ret = dax_pfn(dax_dev, em->bdev, sector, PAGE_SIZE, &pfn);
                if (ret)
                        goto out;
                dax_insert_entry(&xas, mapping, vmf, entry, pfn, 0, false);
-               ret = vmf_insert_mixed(vmf->vma, vmf->address, pfn);
+               ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
        }
 out:
        if (entry)
-- 
2.16.4