X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=fs%2Finode.c;h=64bf28cf05cde859ab0b72abd4a30cbdc7e3912b;hb=f7c3bf8fa7e5a8e45f4a8e82be6466157854b59b;hp=0f1e3b563c47209cd9a09dd1591f6b08d0bd43d4;hpb=7a30bdd99f37352b188575b27924c407c6ddff9e;p=linux.git

diff --git a/fs/inode.c b/fs/inode.c
index 0f1e3b563c47..64bf28cf05cd 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2166,6 +2166,37 @@ struct timespec64 timespec64_trunc(struct timespec64 t, unsigned gran)
 }
 EXPORT_SYMBOL(timespec64_trunc);
 
+/**
+ * timestamp_truncate - Truncate timespec to a granularity
+ * @t: Timespec
+ * @inode: inode being updated
+ *
+ * Truncate a timespec to the granularity supported by the fs
+ * containing the inode. Always rounds down. gran must
+ * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
+ */
+struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	unsigned int gran = sb->s_time_gran;
+
+	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);
+	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))
+		t.tv_nsec = 0;
+
+	/* Avoid division in the common cases 1 ns and 1 s. */
+	if (gran == 1)
+		; /* nothing */
+	else if (gran == NSEC_PER_SEC)
+		t.tv_nsec = 0;
+	else if (gran > 1 && gran < NSEC_PER_SEC)
+		t.tv_nsec -= t.tv_nsec % gran;
+	else
+		WARN(1, "invalid file time granularity: %u", gran);
+	return t;
+}
+EXPORT_SYMBOL(timestamp_truncate);
+
 /**
  * current_time - Return FS time
  * @inode: inode.
@@ -2187,7 +2218,7 @@ struct timespec64 current_time(struct inode *inode)
 		return now;
 	}
 
-	return timespec64_trunc(now, inode->i_sb->s_time_gran);
+	return timestamp_truncate(now, inode);
 }
 EXPORT_SYMBOL(current_time);