[PATCH] common/config: Fix use of MKFS_OPTIONS

[An Long <lan@suse.com>]

_scratch_mkfs_sized() only receive integer number of bytes as a valid
input. But if the MKFS_OPTIONS variable exists, it will use the value of
block size in MKFS_OPTIONS to override input. In case of
MKFS_OPTIONS="-b 4k", would result in blocksize=4 but not 4096. This
will give errors to ext2/3/4 etc, and brings potential bugs to xfs or
btrfs.

Therefore, add validation check to force MKFS_OPTIONS to use pure
integer in bytes for any size value.

Signed-off-by: An Long <lan@suse.com>
---
 README        | 3 ++-
 common/config | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/README b/README
index 80d148be..7c2d3334 100644
--- a/README
+++ b/README
@@ -241,7 +241,8 @@ Misc:
    this option is supported for all filesystems currently only -overlay is
    expected to run without issues. For other filesystems additional patches
    and fixes to the test suite might be needed.
-
+ - If MKFS_OPTIONS is used, the size value must be an integer number of bytes
+   without units. For example, set MKFS_OPTIONS="-b 4096" but not "-b 4k".
 ______________________
 USING THE FSQA SUITE
 ______________________
diff --git a/common/config b/common/config
index de3aba15..ec723ac4 100644
--- a/common/config
+++ b/common/config
@@ -896,5 +896,10 @@ else
 	fi
 fi
 
+# check the size value in $MKFS_OPTIONS is an integer
+if [[ $MKFS_OPTIONS =~ [0-9]+[^0-9\ ] ]] ; then
+        _fatal "error: \$MKFS_OPTIONS: Only number in bytes is allowed, no units."
+fi
+
 # make sure this script returns success
 /bin/true
-- 
2.35.3