xfsprogs: mkfs manpage fix for -nsize/log

There are two limitations for the mkfs.xfs -nsize/log option:
1) directory block size must be a power of 2.
2) it can't be less than a file system block size.

Current man page don't include the above information. User could
be confused with errors, say "Illegal value xxx for -n size option", but
they can't find out the cause by checking the man page.

The patch adds the two limitations to the manpage.

Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
index 4b147e979fb7bd8576ca527e1140fe028b8da778..fdd38d4b14c90b38d8757021561bfd547d9662ba 100644 (file)
--- a/man/man8/mkfs.xfs.8
+++ b/man/man8/mkfs.xfs.8
@@ -478,6 +478,8 @@ in bytes with
 or as a base two logarithm
 .I value
 .RB "with " log= .
+The block size must be a power of 2 and cannot be less than the
+filesystem block size.
 The default size
 .I value
 for version 2 directories is 4096 bytes (4 KiB),