[PATCH v3] common/rc: add _require_blocks_in_file helper

[Joanne Chang <joannechien@google.com>]

generic/735 attempts to create a file with nearly 2^32 blocks. However,
some filesystems have a maximum file block limit below this threshold.
For instance, F2FS is limited to approximately 2^30 blocks due to the
capacity of the inode. So add _require_blocks_in_file helper to skip the
test in such cases.

The helper uses a hardcoded constant instead of a programmatic method,
so that bugs which affect the maximum file size are not masked.

Signed-off-by: Joanne Chang <joannechien@google.com>
---
v2 -> v3: 
- added explanation for using constants to commit message

v1 -> v2:
- changed title from "generic/735: disable for f2fs"
- used a new helper function instead of _exclude_fs as Christoph Hellwig
  suggested

 common/rc         | 16 ++++++++++++++++
 tests/generic/735 |  1 +
 2 files changed, 17 insertions(+)

diff --git a/common/rc b/common/rc
index c3cdc220..e92f4854 100644
--- a/common/rc
+++ b/common/rc
@@ -6120,6 +6120,22 @@ _require_file_attr_special()
 	fi
 }
 
+# Require filesystem to accomodate enough blocks in a file
+_require_blocks_in_file()
+{
+	local blocks=$1
+
+	case $FSTYP in
+	f2fs)
+		if [ $blocks -gt 1057053439 ]; then
+			_notrun "$blocks blocks per file not supported on $FSTYP"
+		fi
+		;;
+	*)
+		;;
+	esac
+}
+
 ################################################################################
 # make sure this script returns success
 /bin/true
diff --git a/tests/generic/735 b/tests/generic/735
index 9bbdf3a1..2fbf125c 100755
--- a/tests/generic/735
+++ b/tests/generic/735
@@ -22,6 +22,7 @@ fi
 _require_odirect
 _require_xfs_io_command "falloc"
 _require_xfs_io_command "finsert"
+_require_blocks_in_file $(( (1 << 32) - 1 ))
 
 dev_size=$((80 * 1024 * 1024))
 _scratch_mkfs_sized $dev_size >>$seqres.full 2>&1
-- 
2.52.0.351.gbe84eed79e-goog