[PATCH v2] swapfile: disable swapon for bs > ps devices

[Luis Chamberlain <mcgrof@kernel.org>]

Devices which have a requirement for bs > ps cannot be supported for
swap as swap still needs work. Now that the block device cache sets the
min order for block devices we need this stop gap otherwise all
swap operations are rejected.

Without this you'll end up with errors on these devices as the swap
code still needs much love to support min order.

With this we at least now put a stop gap of its use, until the
swap subsystem completes its major overhaul:

mkswap: /dev/nvme3n1: warning: wiping old swap signature.
Setting up swapspace version 1, size = 100 GiB (107374178304 bytes)
no label, UUID=6af76b5c-7e7b-4902-b7f7-4c24dde6fa36
swapon: /dev/nvme3n1: swapon failed: Invalid argument

Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 mm/swapfile.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 2eff8b51a945..9e49875ca1fd 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3322,6 +3322,15 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		goto bad_swap_unlock_inode;
 	}
 
+	/*
+	 * The swap subsystem needs a major overhaul to support this.
+	 * It doesn't work yet so just disable it for now.
+	 */
+	if (mapping_min_folio_order(mapping) > 0) {
+		error = -EINVAL;
+		goto bad_swap_unlock_inode;
+	}
+
 	/*
 	 * Read the swap header.
 	 */
-- 
2.47.2