vfs: Add timestamp_truncate() api
timespec_trunc() function is used to truncate a
filesystem timestamp to the right granularity.
But, the function does not clamp tv_sec part of the
timestamps according to the filesystem timestamp limits.
The replacement api: timestamp_truncate() also alters the
signature of the function to accommodate filesystem
timestamp clamping according to flesystem limits.
Note that the tv_nsec part is set to 0 if tv_sec is not within
the range supported for the filesystem.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
diff --git a/fs/inode.c b/fs/inode.c
index 0f1e3b5..64bf28c 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2167,6 +2167,37 @@ 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);