block: Add Kconfig help which notes that ext4 needs CONFIG_LBD

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/Kconfig b/block/Kconfig
index ac0956f..0cbb3b8 100644 (file)
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -36,6 +36,12 @@ config LBD
          This option also enables support for single files larger than
          2TB.
 
+         The ext4 filesystem requires that this feature be enabled in
+         order to support filesystems that have the huge_file feature
+         enabled.    Otherwise, it will refuse to mount any filesystems
+         that use the huge_file feature, which is enabled by default
+         by mke2fs.ext4.   The GFS2 filesystem also requires this feature.
+
          If unsure, say N.
 
 config BLK_DEV_IO_TRACE