bdi: remove BDI_CAP_SYNCHRONOUS_IO BDI_CAP_SYNCHRONOUS_IO is only checked in the swap code, and used to decided if ->rw_page can be used on a block device. Just check up for the method instead. The only complication is that zram needs a second set of block_device_operations as it can switch between modes that actually support ->rw_page and those who don't. Signed-off-by: Christoph Hellwig <[email protected]> Reviewed-by: Jan Kara <[email protected]> Reviewed-by: Johannes Thumshirn <[email protected]> Signed-off-by: Jens Axboe <[email protected]>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index b90f869..96a7c47 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c

@@ -3240,7 +3240,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
 		p->flags |= SWP_STABLE_WRITES;
 
-	if (bdi_cap_synchronous_io(inode_to_bdi(inode)))
+	if (p->bdev && p->bdev->bd_disk->fops->rw_page)
 		p->flags |= SWP_SYNCHRONOUS_IO;
 
 	if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {