dax: Remove dead zeroing code from fault handlers

Now that all filesystems zero out blocks allocated for a fault handler,
we can just remove the zeroing from the handler itself. Also add checks
that no filesystem returns to us unwritten or new buffer.

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

diff --git a/fs/dax.c b/fs/dax.c
index 83e7894d86d853574e9863a3239bae7344fdf6e1..ccb8bc399d7867275dbf75f5941a921f40c118f8 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -587,11 +587,6 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
                error = PTR_ERR(dax.addr);
                goto out;
        }
-
-       if (buffer_unwritten(bh) || buffer_new(bh)) {
-               clear_pmem(dax.addr, PAGE_SIZE);
-               wmb_pmem();
-       }
        dax_unmap_atomic(bdev, &dax);
 
        error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false,
@@ -722,7 +717,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
        }
 
        /* Filesystem should not return unwritten buffers to us! */
-       WARN_ON_ONCE(buffer_unwritten(&bh));
+       WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
        error = dax_insert_mapping(inode, &bh, vma, vmf);
 
  out:
@@ -854,7 +849,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
                if (get_block(inode, block, &bh, 1) != 0)
                        return VM_FAULT_SIGBUS;
                alloc = true;
-               WARN_ON_ONCE(buffer_unwritten(&bh));
+               WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
        }
 
        bdev = bh.b_bdev;
@@ -953,14 +948,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
                        dax_pmd_dbg(&bh, address, "pfn not in memmap");
                        goto fallback;
                }
-
-               if (buffer_unwritten(&bh) || buffer_new(&bh)) {
-                       clear_pmem(dax.addr, PMD_SIZE);
-                       wmb_pmem();
-                       count_vm_event(PGMAJFAULT);
-                       mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
-                       result |= VM_FAULT_MAJOR;
-               }
                dax_unmap_atomic(bdev, &dax);
 
                /*