fs: use mapping_set_error instead of opencoded set_bit

The mapping_set_error() helper sets the correct AS_ flag for the mapping
so there is no reason to open code it.  Use the helper directly.

[akpm@linux-foundation.org: be honest about conversion from -ENXIO to -EIO]
Link: http://lkml.kernel.org/r/20160912111608.2588-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 14d506e..f865c3f 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -398,8 +398,7 @@
 		switch (ret) {
 		case -EDQUOT:
 		case -ENOSPC:
-			set_bit(AS_ENOSPC,
-				&wb->vnode->vfs_inode.i_mapping->flags);
+			mapping_set_error(wb->vnode->vfs_inode.i_mapping, -ENOSPC);
 			break;
 		case -EROFS:
 		case -EIO:
@@ -409,7 +408,7 @@
 		case -ENOMEDIUM:
 		case -ENXIO:
 			afs_kill_pages(wb->vnode, true, first, last);
-			set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
+			mapping_set_error(wb->vnode->vfs_inode.i_mapping, -EIO);
 			break;
 		case -EACCES:
 		case -EPERM: