common: Introduce get_block_size() helper

Currently many tests and other functions uses it's own way to get block
size of the file system. Introduce get_block_size(), a generic way to
get block size of mounted file system and use that instead.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

common/attr

@@ -249,7 +249,7 @@ _sort_getfattr_output()
 if [ "$FSTYP" == "xfs" -o "$FSTYP" == "udf" ]; then
 	MAX_ATTRS=1000
 else # Assume max ~1 block of attrs
-	BLOCK_SIZE=`stat -f $TEST_DIR | grep "Block size" | cut -d " " -f3`
+	BLOCK_SIZE=`get_block_size $TEST_DIR`
 	# user.attribute_XXX="value.XXX" is about 32 bytes; leave some overhead
 	let MAX_ATTRS=$BLOCK_SIZE/40
 fi
@@ -260,7 +260,7 @@ export MAX_ATTRS
 if [ "$FSTYP" == "xfs" -o "$FSTYP" == "udf" -o "$FSTYP" == "btrfs" ]; then
 	MAX_ATTRVAL_SIZE=64
 else # Assume max ~1 block of attrs
-	BLOCK_SIZE=`stat -f $TEST_DIR | grep "Block size" | cut -d " " -f3`
+	BLOCK_SIZE=`get_block_size $TEST_DIR`
 	# leave a little overhead
 	let MAX_ATTRVAL_SIZE=$BLOCK_SIZE-256
 fi

common/punch

@@ -557,7 +557,7 @@ _test_generic_punch()
 	if [ "$remove_testfile" ]; then
 		rm -f $testfile
 	fi
-	block_size=`stat -f $TEST_DIR | grep "Block size" | cut -d " " -f3`
+	block_size=`get_block_size $TEST_DIR`
 	$XFS_IO_PROG -f -c "truncate $block_size" \
 		-c "pwrite 0 $block_size" $sync_cmd \
 		-c "$zero_cmd 128 128" \

common/rc

@@ -2542,6 +2542,15 @@ _short_dev()
 	echo `basename $(_real_dev $1)`
 }
 
+get_block_size()
+{
+	if [ -z $1 ] || [ ! -d $1 ]; then
+		echo "Missing mount point argument for get_block_size"
+		exit 1
+	fi
+	echo `stat -f -c %S $1`
+}
+
 init_rc
 
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