[PATCH] mke2fs: Disallow bigalloc with with bs < 4096

[Lukas Czerner <lczerner@redhat.com>]

Currently there is nothing preventing user to create file system with
bigalloc feature enabled and block size smaller than 4096 Bytes. However
such combination does not make much sense at all because the whole point
of bigalloc is to have bigger allocation units.

This patch disallow such combination.

Thanks!
-Lukas
---
 misc/mke2fs.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index bbf477a..1f33a20 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -1924,6 +1924,12 @@ profile_error:
 				  "smaller than the block size.\n"));
 			exit(1);
 		}
+		if (EXT2_BLOCK_SIZE(&fs_param) < 4096) {
+			com_err(program_name, 0,
+				_("Bigalloc feature is not supported with "
+				  "block size smaller than 4096 B"));
+			exit(1);
+		}
 	} else if (cluster_size) {
 		com_err(program_name, 0,
 			_("specifying a cluster size requires the "
-- 
1.7.7.6