mmap_seek: print error code and text on failurevendor/openzfs/master

If lseek() returns an unexpected error, it's useful to know the error
code to help connect it to the trouble spot inside the module.

Since the two seek functions should be basically identical, lift them
into a single generic function.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Robert Evans <evansr@google.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #17843

1 files changed, 22 insertions, 13 deletions

diff --git a/tests/zfs-tests/cmd/mmap_seek.c b/tests/zfs-tests/cmd/mmap_seek.c
index 45ba17e36c35..f46980cad111 100644
--- a/tests/zfs-tests/cmd/mmap_seek.c
+++ b/tests/zfs-tests/cmd/mmap_seek.c
@@ -47,25 +47,34 @@
 #endif
 
 static void
+seek_expect(int fd, off_t offset, int whence, off_t expect_offset)
+{
+	errno = 0;
+	off_t seek_offset = lseek(fd, offset, whence);
+	if (seek_offset == expect_offset)
+		return;
+
+	int err = errno;
+	fprintf(stderr, "lseek(fd, %ld, SEEK_%s) = %ld (expected %ld)",
+	    offset, (whence == SEEK_DATA ? "DATA" : "HOLE"),
+	    seek_offset, expect_offset);
+	if (err != 0)
+		fprintf(stderr, " (errno %d [%s])\n", err, strerror(err));
+	else
+		fputc('\n', stderr);
+	exit(2);
+}
+
+static inline void
 seek_data(int fd, off_t offset, off_t expected)
 {
-	off_t data_offset = lseek(fd, offset, SEEK_DATA);
-	if (data_offset != expected) {
-		fprintf(stderr, "lseek(fd, %d, SEEK_DATA) = %d (expected %d)\n",
-		    (int)offset, (int)data_offset, (int)expected);
-		exit(2);
-	}
+	seek_expect(fd, offset, SEEK_DATA, expected);
 }
 
-static void
+static inline void
 seek_hole(int fd, off_t offset, off_t expected)
 {
-	off_t hole_offset = lseek(fd, offset, SEEK_HOLE);
-	if (hole_offset != expected) {
-		fprintf(stderr, "lseek(fd, %d, SEEK_HOLE) = %d (expected %d)\n",
-		    (int)offset, (int)hole_offset, (int)expected);
-		exit(2);
-	}
+	seek_expect(fd, offset, SEEK_HOLE, expected);
 }
 
 int