[PATCH v4 07/12] selftests/mm: Skip map_populate on weird filesystems

[Brendan Jackman <jackmanb@google.com>]

It seems that 9pfs does not allow truncating unlinked files, Mark Brown
has noted that NFS may also behave this way.

It doesn't seem quite right to call this a "bug" but it's probably a
special enough case that it makes sense for the test to just SKIP if it
happens.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 tools/testing/selftests/mm/map_populate.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/mm/map_populate.c b/tools/testing/selftests/mm/map_populate.c
index 5c8a53869b1bd287b09a250edf628a66c25c2439..433e54fb634f793f2eb4c53ba6b791045c9f4986 100644
--- a/tools/testing/selftests/mm/map_populate.c
+++ b/tools/testing/selftests/mm/map_populate.c
@@ -87,6 +87,13 @@ int main(int argc, char **argv)
 	BUG_ON(!ftmp, "tmpfile()");
 
 	ret = ftruncate(fileno(ftmp), MMAP_SZ);
+	if (ret < 0 && errno == ENOENT) {
+		/*
+		 * This probably means tmpfile() made a file on a filesystem
+		 * that doesn't handle temporary files the way we want.
+		 */
+		ksft_exit_skip("ftruncate(fileno(tmpfile())) gave ENOENT, weird filesystem?\n");
+	}
 	BUG_ON(ret, "ftruncate()");
 
 	smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,

-- 
2.49.0.rc0.332.g42c0ae87b1-goog