zfs_sync: return error when pool suspends

If the pool is suspended, we'll just block in zil_commit(). If the
system is shutting down, blocking wouldn't help anyone. So, we should
keep this test for now, but at least return an error for anyone who is
actually interested.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Paul Dagnelie <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Closes #17420

Author: robn

module/os/linux/zfs/zfs_vfsops.c

@@ -279,12 +279,13 @@ zfs_sync(struct super_block *sb, int wait, cred_t *cr)
 		return (err);
 
 	/*
-	 * If the system is shutting down, then skip any
-	 * filesystems which may exist on a suspended pool.
+	 * If the pool is suspended, just return an error. This is to help
+	 * with shutting down with pools suspended, as we don't want to block
+	 * in that case.
 	 */
 	if (spa_suspended(zfsvfs->z_os->os_spa)) {
 		zfs_exit(zfsvfs, FTAG);
-		return (0);
+		return (SET_ERROR(EIO));
 	}
 
 	zil_commit(zfsvfs->z_log, 0);