mke2fs: clarify documentation about bigalloc in the man page

Addresses-Debian-Bug: #669730

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index 9679780..fea50da 100644 (file)
--- a/misc/mke2fs.8.in
+++ b/misc/mke2fs.8.in
@@ -190,9 +190,11 @@ test is used instead of a fast read-only test.
 .B \-C " cluster-size"
 Specify the size of cluster in bytes for filesystems using the bigalloc
 feature.  Valid cluster-size values are from 2048 to 256M bytes per
-cluster.  By default (if bigalloc is enabled and no cluster size is
-otherwise specified using this option), the cluster size will be 16
-times the block size.
+cluster.  This can only be specified if the bigalloc feature is
+enabled.  (See the
+.B ext4 (5)
+man page for more details about bigalloc.)   The default cluster size if
+bigalloc is enabled is 16 times the block size.
 .TP
 .B \-D
 Use direct I/O when writing to the disk.  This avoids mke2fs dirtying a