- * superblock does not go away while we are working on it. It returns
- * false if a reference was not gained, and returns true with the s_umount
- * lock held in read mode if a reference is gained. On successful return,
- * the caller must drop the s_umount lock and the passive reference when
- * done.
+ * filesystem is not shut down while we are working on it. It returns
+ * false if we cannot acquire s_umount or if we lose the race and
+ * filesystem already got into shutdown, and returns true with the s_umount
+ * lock held in read mode in case of success. On successful return,
+ * the caller must drop the s_umount lock when done.
+ *
+ * Note that unlike get_super() et.al. this one does *not* bump ->s_count.
+ * The reason why it's safe is that we are OK with doing trylock instead
+ * of down_read(). There's a couple of places that are OK with that, but
+ * it's very much not a general-purpose interface.