I recently used the yaffs filesystem on the 5.10 kernel and
after using David Russell's suggestion it worked fine.

Signed-off-by: tianyu2 <tianyu2@kernelsoft.com>
---
 yaffs_vfs_multi.c | 26 +++++++++++++++++---------
 yportenv_multi.h  | 13 +++++++------
 2 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/yaffs_vfs_multi.c b/yaffs_vfs_multi.c
index a08e071..d387aaa 100644
--- a/yaffs_vfs_multi.c
+++ b/yaffs_vfs_multi.c
@@ -88,7 +88,9 @@
 #include <linux/interrupt.h>
 #include <linux/string.h>
 #include <linux/ctype.h>
-
+#if (LINUX_VERSION_CODE > KERNEL_VERSION(4, 19, 0))
+#include <linux/blkdev.h>
+#endif
 #if (YAFFS_NEW_FOLLOW_LINK == 1)
 #include <linux/namei.h>
 #endif
@@ -264,18 +266,24 @@ MODULE_PARM(yaffs_gc_control, "i");
 #define page_cache_release put_page
 #endif
 
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(4,12,0))
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 12, 0))
 #define update_dir_time(dir) do {\
 		(dir)->i_ctime = (dir)->i_mtime = CURRENT_TIME; \
 	} while (0)
-#elif (LINUX_VERSION_CODE < KERNEL_VERSION(4,18,0))
+#elif (LINUX_VERSION_CODE < KERNEL_VERSION(4, 18, 0))
 #define update_dir_time(dir) do {\
 		(dir)->i_ctime = (dir)->i_mtime = current_kernel_time(); \
 	} while (0)
-#else
+#elif (LINUX_VERSION_CODE < KERNEL_VERSION(4, 20, 0))
 #define update_dir_time(dir) do {\
 		(dir)->i_ctime = (dir)->i_mtime = current_kernel_time64(); \
 	} while (0)
+#else
+#define update_dir_time(dir) do {\
+		struct timespec64 ltime; \
+		ktime_get_coarse_real_ts64(&ltime); \
+		(dir)->i_ctime = (dir)->i_mtime = ltime; \
+	} while (0)
 #endif
 
 #if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 9, 0))
@@ -2737,12 +2745,12 @@ static int yaffs_remount_fs(struct super_block *sb, int *flags, char *data)
 		return 1;
 	}
 
-	read_only = ((*flags & MS_RDONLY) != 0);
+	read_only = ((*flags & SB_RDONLY) != 0);
 	if (!read_only && !(mtd->flags & MTD_WRITEABLE)) {
 		read_only = 1;
 		printk(KERN_INFO
 			"yaffs: mtd is read only, setting superblock read only");
-		*flags |= MS_RDONLY;
+		*flags |= SB_RDONLY;
 	}
 
 	dev = sb->s_fs_info;
@@ -2914,9 +2922,9 @@ static struct super_block *yaffs_internal_read_super(int yaffs_version,
 
 	sb->s_magic = YAFFS_MAGIC;
 	sb->s_op = &yaffs_super_ops;
-	sb->s_flags |= MS_NOATIME;
+	sb->s_flags |= SB_NOATIME;
 
-	read_only = ((sb->s_flags & MS_RDONLY) != 0);
+	read_only = ((sb->s_flags & SB_RDONLY) != 0);
 
 #ifdef YAFFS_COMPILE_EXPORTFS
 	sb->s_export_op = &yaffs_export_ops;
@@ -2994,7 +3002,7 @@ static struct super_block *yaffs_internal_read_super(int yaffs_version,
 		printk(KERN_INFO
 		       "yaffs: mtd is read only, setting superblock read only\n"
 		);
-		sb->s_flags |= MS_RDONLY;
+		sb->s_flags |= SB_RDONLY;
 	}
 
 	dev = kmalloc(sizeof(struct yaffs_dev), GFP_KERNEL);
diff --git a/yportenv_multi.h b/yportenv_multi.h
index fa5601b..3c3e0a1 100644
--- a/yportenv_multi.h
+++ b/yportenv_multi.h
@@ -63,18 +63,19 @@
 #define YAFFS_LOSTNFOUND_MODE		0700
 
 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2, 5, 0))
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(4,12,0))
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 12, 0))
 #define Y_CURRENT_TIME CURRENT_TIME.tv_sec
-#else
+#elif (LINUX_VERSION_CODE < KERNEL_VERSION(4, 20, 0))
 #define Y_CURRENT_TIME current_kernel_time().tv_sec
+#else
+#define Y_CURRENT_TIME ({\
+		struct timespec64 ltime; \
+		ktime_get_coarse_real_ts64(&ltime); \
+		ltime.tv_sec; })
 #endif
 #define Y_TIME_CONVERT(x) (x).tv_sec
 #else
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(4,12,0))
 #define Y_CURRENT_TIME CURRENT_TIME
-#else
-#define Y_CURRENT_TIME current_kernel_time()
-#endif
 #define Y_TIME_CONVERT(x) (x)
 #endif
 
-- 
2.25.1