fs/afs: use new return type vm_fault_t

Use new return type vm_fault_t for fault handler in struct
vm_operations_struct.  For now, this is just documenting that the
function returns a VM_FAULT value rather than an errno.  Once all
instances are converted, vm_fault_t will become a distinct type.

See 1c8f4220 ("mm: change return type to vm_fault_t") for reference.

Link: http://lkml.kernel.org/r/20180702152017.GA3780@jordon-HP-15-Notebook-PCSigned-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/afs/internal.h

@@ -21,6 +21,7 @@
 #include <linux/fscache.h>
 #include <linux/backing-dev.h>
 #include <linux/uuid.h>
+#include <linux/mm_types.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 #include <net/sock.h>
@@ -1076,7 +1077,7 @@ extern int afs_writepages(struct address_space *, struct writeback_control *);
 extern void afs_pages_written_back(struct afs_vnode *, struct afs_call *);
 extern ssize_t afs_file_write(struct kiocb *, struct iov_iter *);
 extern int afs_fsync(struct file *, loff_t, loff_t, int);
-extern int afs_page_mkwrite(struct vm_fault *);
+extern vm_fault_t afs_page_mkwrite(struct vm_fault *vmf);
 extern void afs_prune_wb_keys(struct afs_vnode *);
 extern int afs_launder_page(struct page *);
 

fs/afs/write.c

@@ -753,7 +753,7 @@ int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  * notification that a previously read-only page is about to become writable
  * - if it returns an error, the caller will deliver a bus error signal
  */
-int afs_page_mkwrite(struct vm_fault *vmf)
+vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 {
 	struct file *file = vmf->vma->vm_file;
 	struct inode *inode = file_inode(file);