[RFC PATCH] misc: skip fsx tests when op length not congruent with file allocation unit

[Jeffle Xu <jefflexu@linux.alibaba.com>]

Yes it works. For example in this RFC patch, generic/075 could be
skipped once 'bigalloc' is detected for ext4.

I could fix all related test cases in this way, if it is acceptable to
the community.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 common/rc         | 20 ++++++++++++++++++++
 tests/generic/075 |  3 +++
 2 files changed, 23 insertions(+)

diff --git a/common/rc b/common/rc
index f58a542..92245e0 100644
--- a/common/rc
+++ b/common/rc
@@ -4041,6 +4041,23 @@ _sysfs_dev()
 	min=$(echo "ibase=16; $min" | bc)
 	echo /sys/dev/block/$maj:$min
 }
+		
+_ext4_get_file_block_size()
+{
+	local path="$1"
+	path="$(readlink -m "$path")"
+	local dev=`$DF_PROG $dir | tail -1 | $AWK_PROG '{print $1}'`
+	
+	# The alloc unit size equals block size for ext4 without 'bigalloc'.
+	if ! (tune2fs -l $dev | grep -q 'Cluster size'); then
+		_get_block_size "$path"
+		return
+	fi
+
+	# Otherwise, call tune2fs acquiring cluster size.
+	tune2fs -l $dev | sed -n -e 's/^.*Cluster size:\s*\([0-9]*\).*$/\1/p'
+
+}
 
 # Get the minimum block size of a file.  Usually this is the
 # minimum fs block size, but some filesystems (ocfs2) do block
@@ -4059,6 +4076,9 @@ _get_file_block_size()
 	"xfs")
 		_xfs_get_file_block_size $1
 		;;
+	"ext4")
+		_ext4_get_file_block_size $1
+		;;
 	*)
 		_get_block_size $1
 		;;
diff --git a/tests/generic/075 b/tests/generic/075
index 7467bb7..d269a7c 100755
--- a/tests/generic/075
+++ b/tests/generic/075
@@ -109,6 +109,9 @@ _process_args()
 _supported_fs generic
 _require_test
 
+blksz=$(_get_block_size $TEST_DIR)
+_require_congruent_file_oplen $TEST_DIR $blksz
+
 size10=`expr 10 \* 1024 \* 1024`	# 10 megabytes
 filelen=$size10
 numops1=1000
-- 
1.8.3.1