diff --git a/fs/inode.c b/fs/inode.c
index f356fe2ec2b6..2b5889ff7b36 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -60,6 +60,13 @@ static unsigned int i_hash_shift __ro_after_init;
 static struct hlist_head *inode_hashtable __ro_after_init;
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
 
+/*
+ * This represents the latest fine-grained time that we have handed out as a
+ * timestamp on the system. Tracked as a monotonic value, and converted to the
+ * realtime clock on an as-needed basis.
+ */
+static __cacheline_aligned_in_smp atomic64_t ctime_floor;
+
 /*
  * Empty aops. Can be used for the cases where the user does not
  * define any of the address_space operations.
@@ -2127,19 +2134,72 @@ int file_remove_privs(struct file *file)
 }
 EXPORT_SYMBOL(file_remove_privs);
 
+/**
+ * coarse_ctime - return the current coarse-grained time
+ * @floor: current (monotonic) ctime_floor value
+ *
+ * Get the coarse-grained time, and then determine whether to
+ * return it or the current floor value. Returns the later of the
+ * floor and coarse grained timestamps, converted to realtime
+ * clock value.
+ */
+static ktime_t coarse_ctime(ktime_t floor)
+{
+	ktime_t coarse = ktime_get_coarse();
+
+	/* If coarse time is already newer, return that */
+	if (!ktime_after(floor, coarse))
+		return ktime_get_coarse_real();
+	return ktime_mono_to_real(floor);
+}
+
+/**
+ * current_time - Return FS time (possibly fine-grained)
+ * @inode: inode.
+ *
+ * Return the current time truncated to the time granularity supported by
+ * the fs, as suitable for a ctime/mtime change. If the ctime is flagged
+ * as having been QUERIED, get a fine-grained timestamp.
+ */
+struct timespec64 current_time(struct inode *inode)
+{
+	ktime_t floor = atomic64_read(&ctime_floor);
+	ktime_t now = coarse_ctime(floor);
+	struct timespec64 now_ts = ktime_to_timespec64(now);
+	u32 cns;
+
+	if (!is_mgtime(inode))
+		goto out;
+
+	/* If nothing has queried it, then coarse time is fine */
+	cns = smp_load_acquire(&inode->i_ctime_nsec);
+	if (cns & I_CTIME_QUERIED) {
+		/*
+		 * If there is no apparent change, then
+		 * get a fine-grained timestamp.
+		 */
+		if (now_ts.tv_nsec == (cns & ~I_CTIME_QUERIED))
+			ktime_get_real_ts64(&now_ts);
+	}
+out:
+	return timestamp_truncate(now_ts, inode);
+}
+EXPORT_SYMBOL(current_time);
+
 static int inode_needs_update_time(struct inode *inode)
 {
+	struct timespec64 now, ts;
 	int sync_it = 0;
-	struct timespec64 now = current_time(inode);
-	struct timespec64 ts;
 
 	/* First try to exhaust all avenues to not sync */
 	if (IS_NOCMTIME(inode))
 		return 0;
 
+	now = current_time(inode);
+
 	ts = inode_get_mtime(inode);
 	if (!timespec64_equal(&ts, &now))
-		sync_it = S_MTIME;
+		sync_it |= S_MTIME;
 
 	ts = inode_get_ctime(inode);
 	if (!timespec64_equal(&ts, &now))
@@ -2507,6 +2567,14 @@ void inode_nohighmem(struct inode *inode)
 }
 EXPORT_SYMBOL(inode_nohighmem);
 
+struct timespec64 inode_set_ctime_to_ts(struct inode *inode, struct timespec64 ts)
+{
+	inode->i_ctime_sec = ts.tv_sec;
+	inode->i_ctime_nsec = ts.tv_nsec & ~I_CTIME_QUERIED;
+	return ts;
+}
+EXPORT_SYMBOL(inode_set_ctime_to_ts);
+
 /**
  * timestamp_truncate - Truncate timespec to a granularity
  * @t: Timespec
@@ -2538,38 +2606,87 @@ struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
 }
 EXPORT_SYMBOL(timestamp_truncate);
 
-/**
- * current_time - Return FS time
- * @inode: inode.
- *
- * Return the current time truncated to the time granularity supported by
- * the fs.
- *
- * Note that inode and inode->sb cannot be NULL.
- * Otherwise, the function warns and returns time without truncation.
- */
-struct timespec64 current_time(struct inode *inode)
-{
-	struct timespec64 now;
-
-	ktime_get_coarse_real_ts64(&now);
-	return timestamp_truncate(now, inode);
-}
-EXPORT_SYMBOL(current_time);
-
 /**
  * inode_set_ctime_current - set the ctime to current_time
  * @inode: inode
  *
- * Set the inode->i_ctime to the current value for the inode. Returns
- * the current value that was assigned to i_ctime.
+ * Set the inode's ctime to the current value for the inode. Returns the
+ * current value that was assigned. If this is not a multigrain inode, then we
+ * just set it to whatever the coarse_ctime is.
+ *
+ * If it is multigrain, then we first see if the coarse-grained timestamp is
+ * distinct from what we have. If so, then we'll just use that. If we have to
+ * get a fine-grained timestamp, then do so, and try to swap it into the floor.
+ * We accept the new floor value regardless of the outcome of the cmpxchg.
+ * After that, we try to swap the new value into i_ctime_nsec. Again, we take
+ * the resulting ctime, regardless of the outcome of the swap.
  */
 struct timespec64 inode_set_ctime_current(struct inode *inode)
 {
-	struct timespec64 now = current_time(inode);
+	ktime_t now, floor = atomic64_read(&ctime_floor);
+	struct timespec64 now_ts;
+	u32 cns, cur;
+
+	now = coarse_ctime(floor);
 
-	inode_set_ctime_to_ts(inode, now);
-	return now;
+	/* Just return that if this is not a multigrain fs */
+	if (!is_mgtime(inode)) {
+		now_ts = timestamp_truncate(ktime_to_timespec64(now), inode);
+		inode_set_ctime_to_ts(inode, now_ts);
+		goto out;
+	}
+
+	/*
+	 * We only need a fine-grained time if someone has queried it,
+	 * and the current coarse grained time isn't later than what's
+	 * already there.
+	 */
+	cns = smp_load_acquire(&inode->i_ctime_nsec);
+	if (cns & I_CTIME_QUERIED) {
+		ktime_t ctime = ktime_set(inode->i_ctime_sec, cns & ~I_CTIME_QUERIED);
+
+		if (!ktime_after(now, ctime)) {
+			ktime_t old, fine;
+
+			/* Get a fine-grained time */
+			fine = ktime_get();
+
+			/*
+			 * If the cmpxchg works, we take the new floor value. If
+			 * not, then that means that someone else changed it after we
+			 * fetched it but before we got here. That value is just
+			 * as good, so keep it.
+			 */
+			old = floor;
+			if (!atomic64_try_cmpxchg(&ctime_floor, &old, fine))
+				fine = old;
+			now = ktime_mono_to_real(fine);
+		}
+	}
+	now_ts = timestamp_truncate(ktime_to_timespec64(now), inode);
+	cur = cns;
+retry:
+	/* Try to swap the nsec value into place. */
+	if (try_cmpxchg(&inode->i_ctime_nsec, &cur, now_ts.tv_nsec)) {
+		/* If swap occurred, then we're (mostly) done */
+		inode->i_ctime_sec = now_ts.tv_sec;
+	} else {
+		/*
+		 * Was the change due to someone marking the old ctime QUERIED?
+		 * If so then retry the swap. This can only happen once since
+		 * the only way to clear I_CTIME_QUERIED is to stamp the inode
+		 * with a new ctime.
+		 */
+		if (!(cns & I_CTIME_QUERIED) && (cns | I_CTIME_QUERIED) == cur) {
+			cns = cur;
+			goto retry;
+		}
+		/* Otherwise, keep the existing ctime */
+		now_ts.tv_sec = inode->i_ctime_sec;
+		now_ts.tv_nsec = cur & ~I_CTIME_QUERIED;
+	}
+out:
+	return now_ts;
 }
 EXPORT_SYMBOL(inode_set_ctime_current);
 
diff --git a/fs/stat.c b/fs/stat.c
index 6f65b3456cad..df7fdd3afed9 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -26,6 +26,32 @@
 #include "internal.h"
 #include "mount.h"
 
+/**
+ * fill_mg_cmtime - Fill in the mtime and ctime and flag ctime as QUERIED
+ * @stat: where to store the resulting values
+ * @request_mask: STATX_* values requested
+ * @inode: inode from which to grab the c/mtime
+ *
+ * Given @inode, grab the ctime and mtime out if it and store the result
+ * in @stat. When fetching the value, flag it as queried so the next write
+ * will ensure a distinct timestamp.
+ */
+void fill_mg_cmtime(struct kstat *stat, u32 request_mask, struct inode *inode)
+{
+	atomic_t *pcn = (atomic_t *)&inode->i_ctime_nsec;
+
+	/* If neither time was requested, then don't report them */
+	if (!(request_mask & (STATX_CTIME|STATX_MTIME))) {
+		stat->result_mask &= ~(STATX_CTIME|STATX_MTIME);
+		return;
+	}
+
+	stat->mtime = inode_get_mtime(inode);
+	stat->ctime.tv_sec = inode->i_ctime_sec;
+	stat->ctime.tv_nsec = ((u32)atomic_fetch_or(I_CTIME_QUERIED, pcn)) & ~I_CTIME_QUERIED;
+}
+EXPORT_SYMBOL(fill_mg_cmtime);
+
 /**
  * generic_fillattr - Fill in the basic attributes from the inode struct
  * @idmap:		idmap of the mount the inode was found from
@@ -58,8 +84,14 @@ void generic_fillattr(struct mnt_idmap *idmap, u32 request_mask,
 	stat->rdev = inode->i_rdev;
 	stat->size = i_size_read(inode);
 	stat->atime = inode_get_atime(inode);
-	stat->mtime = inode_get_mtime(inode);
-	stat->ctime = inode_get_ctime(inode);
+
+	if (is_mgtime(inode)) {
+		fill_mg_cmtime(stat, request_mask, inode);
+	} else {
+		stat->ctime = inode_get_ctime(inode);
+		stat->mtime = inode_get_mtime(inode);
+	}
+
 	stat->blksize = i_blocksize(inode);
 	stat->blocks = inode->i_blocks;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dc9f9c4b2572..f873f6c58669 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1608,6 +1608,17 @@ static inline struct timespec64 inode_set_mtime(struct inode *inode,
 	return inode_set_mtime_to_ts(inode, ts);
 }
 
+/*
+ * Multigrain timestamps
+ *
+ * Conditionally use fine-grained ctime and mtime timestamps when there
+ * are users actively observing them via getattr. The primary use-case
+ * for this is NFS clients that use the ctime to distinguish between
+ * different states of the file, and that are often fooled by multiple
+ * operations that occur in the same coarse-grained timer tick.
+ */
+#define I_CTIME_QUERIED		((u32)BIT(31))
+
 static inline time64_t inode_get_ctime_sec(const struct inode *inode)
 {
 	return inode->i_ctime_sec;
@@ -1615,7 +1626,7 @@ static inline time64_t inode_get_ctime_sec(const struct inode *inode)
 
 static inline long inode_get_ctime_nsec(const struct inode *inode)
 {
-	return inode->i_ctime_nsec;
+	return inode->i_ctime_nsec & ~I_CTIME_QUERIED;
 }
 
 static inline struct timespec64 inode_get_ctime(const struct inode *inode)
@@ -1626,13 +1637,7 @@ static inline struct timespec64 inode_get_ctime(const struct inode *inode)
 	return ts;
 }
 
-static inline struct timespec64 inode_set_ctime_to_ts(struct inode *inode,
-						      struct timespec64 ts)
-{
-	inode->i_ctime_sec = ts.tv_sec;
-	inode->i_ctime_nsec = ts.tv_nsec;
-	return ts;
-}
+struct timespec64 inode_set_ctime_to_ts(struct inode *inode, struct timespec64 ts);
 
 /**
  * inode_set_ctime - set the ctime in the inode
@@ -2490,6 +2495,7 @@ struct file_system_type {
 #define FS_USERNS_MOUNT		8	/* Can be mounted by userns root */
 #define FS_DISALLOW_NOTIFY_PERM	16	/* Disable fanotify permission events */
 #define FS_ALLOW_IDMAP         32      /* FS has been updated to handle vfs idmappings. */
+#define FS_MGTIME		64	/* FS uses multigrain timestamps */
 #define FS_RENAME_DOES_D_MOVE	32768	/* FS will handle d_move() during rename() internally. */
 	int (*init_fs_context)(struct fs_context *);
 	const struct fs_parameter_spec *parameters;
@@ -2513,6 +2519,17 @@ struct file_system_type {
 
 #define MODULE_ALIAS_FS(NAME) MODULE_ALIAS("fs-" NAME)
 
+/**
+ * is_mgtime: is this inode using multigrain timestamps
+ * @inode: inode to test for multigrain timestamps
+ *
+ * Return true if the inode uses multigrain timestamps, false otherwise.
+ */
+static inline bool is_mgtime(const struct inode *inode)
+{
+	return inode->i_sb->s_type->fs_flags & FS_MGTIME;
+}
+
 extern struct dentry *mount_bdev(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data,
 	int (*fill_super)(struct super_block *, void *, int));
@@ -3252,6 +3269,7 @@ extern void page_put_link(void *);
 extern int page_symlink(struct inode *inode, const char *symname, int len);
 extern const struct inode_operations page_symlink_inode_operations;
 extern void kfree_link(void *);
+void fill_mg_cmtime(struct kstat *stat, u32 request_mask, struct inode *inode);
 void generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct kstat *);
 void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
 extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
