[PATCH] block: add BLK_FEAT_LBS to check for PAGE_SIZE limit

[Luis Chamberlain <mcgrof@kernel.org>]

The commit titled "block/bdev: lift block size restrictions to 64k"
lifted the block layer's max supported block size to 64k inside the
helper blk_validate_block_size() now that we support large folios on
the block layer. However, block drivers have relied on the call for
queue_limits_commit_update() to validate and ensure the logical block
size < PAGE_SIZE.

We should take time to validate each block driver before enabling
support for larger logical block sizes, so that those that didn't
have support stay that way and don't need modifications.

Li Wang reported this as a regression on LTP via:

testcases/kernel/syscalls/ioctl/ioctl_loop06

Which uses the loopback driver to enable larger logical block sizes
first with LOOP_CONFIGURE and then LOOP_SET_BLOCK_SIZE. While
I see no reason why the loopback block driver can't support
larger logical block sizes than PAGE_SIZE, leave this validation
step as a secondary effort for each block driver.

Reported-by: Li Wang <liwang@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202503101538.84c33cd4-lkp@intel.com
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 block/blk-settings.c   | 4 +++-
 include/linux/blkdev.h | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/blk-settings.c b/block/blk-settings.c
index c44dadc35e1e..5cdd0d7d2af2 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -254,7 +254,9 @@ int blk_validate_limits(struct queue_limits *lim)
 	 */
 	if (!lim->logical_block_size)
 		lim->logical_block_size = SECTOR_SIZE;
-	else if (blk_validate_block_size(lim->logical_block_size)) {
+	else if (blk_validate_block_size(lim->logical_block_size) ||
+		 (lim->logical_block_size > PAGE_SIZE &&
+		   !(lim->features & BLK_FEAT_LBS))) {
 		pr_warn("Invalid logical block size (%d)\n", lim->logical_block_size);
 		return -EINVAL;
 	}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a97428e8bbbe..cdab3731a646 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -341,6 +341,9 @@ typedef unsigned int __bitwise blk_features_t;
 #define BLK_FEAT_ATOMIC_WRITES \
 	((__force blk_features_t)(1u << 16))
 
+/* Supports sector sizes > PAGE_SIZE */
+#define BLK_FEAT_LBS		((__force blk_features_t)(1u << 17))
+
 /*
  * Flags automatically inherited when stacking limits.
  */
-- 
2.47.2