[LTP] [PATCH] swapon: commit swapfile caches to disk

[Li Wang <liwang@redhat.com>]

Testcase include swapon(8) fails on mainline kernel-v4.17+ as:
  swapon01    1  TFAIL  :  swapon01.c:47: Failed to turn on swapfile: TEST_ERRNO=EINVAL(22): Invalid argument
  swapon02    4  TFAIL  :  swapon02.c:91: swapon(2) failed to produce expected error: 16, errno: EBUSY and got 22.
  swapon03    1  TFAIL  :  swapon03.c:243: Failed to setup swaps
  swapoff01   1  TBROK  :  swapoff01.c:64: Failed to turn on the swap file, skipping test iteration

And dmesg shows that:
  [  128.698981] swapon: file is not committed

The error located in IOMAP_F_DIRTY(linux/fs/iomap.c) checking, which means
this swapfile have uncommitted metadata in caches. After adding sync() to
the end of all mkswap opertaion, these errors were gone.

linux/fs/iomap.c:
	static loff_t iomap_swapfile_activate_actor(
		struct inode *inode,
		loff_t pos,
		loff_t count,
		void *data,
		struct iomap *iomap)
	{
		struct iomap_swapfile_info *isi = data;
		int error;
		...

		/* No uncommitted metadata or shared blocks. */
		if (iomap->flags & IOMAP_F_DIRTY) {
			pr_err("swapon: file is not committed\n");
			return -EINVAL;
		}
		...
	}
									}
Signed-off-by: Li Wang <liwang@redhat.com>
---

Notes:
    The new changes about swapfile activation function were merged in kernel-4.17
    recently, so we didn't hit this failures before.

 testcases/kernel/syscalls/swapoff/swapoff01.c | 2 ++
 testcases/kernel/syscalls/swapoff/swapoff02.c | 2 ++
 testcases/kernel/syscalls/swapon/libswapon.c  | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/testcases/kernel/syscalls/swapoff/swapoff01.c b/testcases/kernel/syscalls/swapoff/swapoff01.c
index a63e661..b587b0d 100644
--- a/testcases/kernel/syscalls/swapoff/swapoff01.c
+++ b/testcases/kernel/syscalls/swapoff/swapoff01.c
@@ -105,6 +105,8 @@ static void setup(void)
 
 	if (system("mkswap swapfile01 > tmpfile 2>&1") != 0)
 		tst_brkm(TBROK, cleanup, "Failed to make swapfile");
+
+	sync();
 }
 
 static void cleanup(void)
diff --git a/testcases/kernel/syscalls/swapoff/swapoff02.c b/testcases/kernel/syscalls/swapoff/swapoff02.c
index b5c6312..d8c5889 100644
--- a/testcases/kernel/syscalls/swapoff/swapoff02.c
+++ b/testcases/kernel/syscalls/swapoff/swapoff02.c
@@ -154,6 +154,8 @@ static void setup(void)
 
 	if (tst_fill_file("./swapfile01", 0x00, 1024, 1))
 		tst_brkm(TBROK, cleanup, "Failed to create swapfile");
+
+	sync();
 }
 
 static void cleanup(void)
diff --git a/testcases/kernel/syscalls/swapon/libswapon.c b/testcases/kernel/syscalls/swapon/libswapon.c
index cf6a988..49fa5ed 100644
--- a/testcases/kernel/syscalls/swapon/libswapon.c
+++ b/testcases/kernel/syscalls/swapon/libswapon.c
@@ -46,4 +46,6 @@ void make_swapfile(void (cleanup)(void), const char *swapfile)
 	argv[2] = NULL;
 
 	tst_run_cmd(cleanup, argv, "/dev/null", "/dev/null", 0);
+
+	sync();
 }
-- 
1.9.3