[LTP] [PATCH 1/2] libswap: add known swap supported fs check

[Li Wang]

This introduce an enhancement to the library's is_swap_supported
function to check for filesystem compatibility before attempting
to create and enable a swap file.  A list of supported filesystems
is added (ext2, ext3, ext4, xfs, vfat, exfat, ntfs), and a check
against this list is performed to ensure that the swap operations
are only attempted on known compatible filesystems.

If the make_swapfile function fails, the error handling is now
more descriptive: it distinguishes between failures due to the
filesystem not supporting swap files and other types of failures.
Similarly, when attempting to enable the swap file with swapon,
the patch ensures that clearer error messages are provided in
cases where the operation is not supported by the filesystem.

Signed-off-by: Li Wang <liwang@redhat.com>
---
 libs/libltpswap/libswap.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/libs/libltpswap/libswap.c b/libs/libltpswap/libswap.c
index d014325e5..5f9622aca 100644
--- a/libs/libltpswap/libswap.c
+++ b/libs/libltpswap/libswap.c
@@ -12,6 +12,17 @@
 #include "libswap.h"
 #include "lapi/syscalls.h"
 
+static const char *const swap_supported_fs[] = {
+	"ext2",
+	"ext3",
+	"ext4",
+	"xfs",
+	"vfat",
+	"exfat",
+	"ntfs",
+	NULL
+};
+
 /*
  * Make a swap file
  */
@@ -39,23 +50,31 @@ int make_swapfile(const char *swapfile, int safe)
  */
 void is_swap_supported(const char *filename)
 {
+	int i, sw_support = 0;
 	int fibmap = tst_fibmap(filename);
 	long fs_type = tst_fs_type(filename);
 	const char *fstype = tst_fs_type_name(fs_type);
 
-	int ret = make_swapfile(filename, 1);
-	if (ret != 0) {
-		if (fibmap == 1)
-			tst_brk(TCONF, "mkswap on %s not supported", fstype);
-		else
-			tst_brk(TFAIL, "mkswap on %s failed", fstype);
+	for (i = 0; swap_supported_fs[i]; i++) {
+		if (!strcmp(fstype, swap_supported_fs[i])) {
+			sw_support = 1;
+			break;
+		}
 	}
 
+       int ret = make_swapfile(filename, 1);
+       if (ret != 0) {
+               if (fibmap == 1 && sw_support == 0)
+                       tst_brk(TCONF, "mkswap on %s not supported", fstype);
+               else
+                       tst_brk(TFAIL, "mkswap on %s failed", fstype);
+       }
+
 	TEST(tst_syscall(__NR_swapon, filename, 0));
 	if (TST_RET == -1) {
 		if (errno == EPERM)
 			tst_brk(TCONF, "Permission denied for swapon()");
-		else if (fibmap == 1 && errno == EINVAL)
+		else if (fibmap == 1 && errno == EINVAL && sw_support == 0)
 			tst_brk(TCONF, "Swapfile on %s not implemented", fstype);
 		else
 			tst_brk(TFAIL | TTERRNO, "swapon() on %s failed", fstype);
-- 
2.40.1