fs: kill BDI_CAP_SWAP_BACKED

This bdi flag isn't too useful - we can determine that a vma is backed by
either swap or shmem trivially in the caller.

This also allows removing the backing_dev_info instaces for swap and shmem
in favor of noop_backing_dev_info.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 10 insertions, 7 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index a271adc93289..1383a8916bc3 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -222,19 +222,22 @@ static long madvise_willneed(struct vm_area_struct *vma,
         struct file *file = vma->vm_file;
 
 #ifdef CONFIG_SWAP
-        if (!file || mapping_cap_swap_backed(file->f_mapping)) {
+        if (!file) {
                 *prev = vma;
-                if (!file)
-                        force_swapin_readahead(vma, start, end);
-                else
-                        force_shm_swapin_readahead(vma, start, end,
-                                                file->f_mapping);
+                force_swapin_readahead(vma, start, end);
                 return 0;
         }
-#endif
 
+        if (shmem_mapping(file->f_mapping)) {
+                *prev = vma;
+                force_shm_swapin_readahead(vma, start, end,
+                                        file->f_mapping);
+                return 0;
+        }
+#else
         if (!file)
                 return -EBADF;
+#endif
 
         if (file->f_mapping->a_ops->get_xip_mem) {
                 /* no bad return value, but ignore advice */