dax: Use new dax zero page method for zeroing a page

Use new dax native zero page method for zeroing page if I/O is page
aligned. Otherwise fall back to direct_access() + memcpy().

This gets rid of one of the depenendency on block device in dax path.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20200228163456.1587-6-vgoyal@redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/fs/dax.c b/fs/dax.c
index 35da144..98ba375 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1038,47 +1038,40 @@ static vm_fault_t dax_load_hole(struct xa_state *xas,
        return ret;
 }
 
-static bool dax_range_is_aligned(struct block_device *bdev,
-                                unsigned int offset, unsigned int length)
-{
-       unsigned short sector_size = bdev_logical_block_size(bdev);
-
-       if (!IS_ALIGNED(offset, sector_size))
-               return false;
-       if (!IS_ALIGNED(length, sector_size))
-               return false;
-
-       return true;
-}
-
 int __dax_zero_page_range(struct block_device *bdev,
                struct dax_device *dax_dev, sector_t sector,
                unsigned int offset, unsigned int size)
 {
-       if (dax_range_is_aligned(bdev, offset, size)) {
-               sector_t start_sector = sector + (offset >> 9);
+       pgoff_t pgoff;
+       long rc, id;
+       void *kaddr;
+       bool page_aligned = false;
 
-               return blkdev_issue_zeroout(bdev, start_sector,
-                               size >> 9, GFP_NOFS, 0);
-       } else {
-               pgoff_t pgoff;
-               long rc, id;
-               void *kaddr;
 
-               rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
-               if (rc)
-                       return rc;
+       if (IS_ALIGNED(sector << SECTOR_SHIFT, PAGE_SIZE) &&
+           IS_ALIGNED(size, PAGE_SIZE))
+               page_aligned = true;
+
+       rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
+       if (rc)
+               return rc;
 
-               id = dax_read_lock();
+       id = dax_read_lock();
+
+       if (page_aligned)
+               rc = dax_zero_page_range(dax_dev, pgoff, size >> PAGE_SHIFT);
+       else
                rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);
-               if (rc < 0) {
-                       dax_read_unlock(id);
-                       return rc;
-               }
+       if (rc < 0) {
+               dax_read_unlock(id);
+               return rc;
+       }
+
+       if (!page_aligned) {
                memset(kaddr + offset, 0, size);
                dax_flush(dax_dev, kaddr + offset, size);
-               dax_read_unlock(id);
        }
+       dax_read_unlock(id);
        return 0;
 }
 EXPORT_SYMBOL_GPL(__dax_zero_page_range);