[RFC v2 13/14] xfs: add an experimental CONFIG_XFS_LBS option

["Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>]

From: Pankaj Raghav <p.raghav@samsung.com>

Add an experimental CONFIG_XFS_LBS option to enable LBS support in XFS.
Retain the ASSERT for PAGE_SHIFT if CONFIG_XFS_LBS is not enabled.

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 fs/xfs/Kconfig     | 11 +++++++++++
 fs/xfs/xfs_mount.c |  4 +++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/Kconfig b/fs/xfs/Kconfig
index 567fb37274d3..6b0db2f7dc13 100644
--- a/fs/xfs/Kconfig
+++ b/fs/xfs/Kconfig
@@ -216,3 +216,14 @@ config XFS_ASSERT_FATAL
 	  result in warnings.
 
 	  This behavior can be modified at runtime via sysfs.
+
+config XFS_LBS
+	bool "XFS large block size support (EXPERIMENTAL)"
+	depends on XFS_FS
+	help
+	  Set Y to enable support for filesystem block size > system's
+	  base page size.
+
+	  This feature is considered EXPERIMENTAL.  Use with caution!
+
+	  If unsure, say N.
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index bfbaaecaf668..596aa2cdefbc 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -131,11 +131,13 @@ xfs_sb_validate_fsb_count(
 	xfs_sb_t	*sbp,
 	uint64_t	nblocks)
 {
-	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
 	ASSERT(sbp->sb_blocklog >= BBSHIFT);
 	unsigned long mapping_count;
 	uint64_t bytes = nblocks << sbp->sb_blocklog;
 
+	if (!IS_ENABLED(CONFIG_XFS_LBS))
+		ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
+
 	mapping_count = bytes >> PAGE_SHIFT;
 
 	/* Limited by ULONG_MAX of page cache index */
-- 
2.43.0