sysfs: move s_active functions to fs/sysfs/dir.c

These functions are about to receive more complexity and doesn't
really need to be inlined in the first place.  Move them from
fs/sysfs/sysfs.h to fs/sysfs/dir.c.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 88 insertions, 0 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 06dff2c30c9b..f5f0b936f181 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -20,6 +20,94 @@ spinlock_t kobj_sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
 static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
 static DEFINE_IDA(sysfs_ino_ida);
 
+/**
+ *      sysfs_get_active - get an active reference to sysfs_dirent
+ *      @sd: sysfs_dirent to get an active reference to
+ *
+ *      Get an active reference of @sd.  This function is noop if @sd
+ *      is NULL.
+ *
+ *      RETURNS:
+ *      Pointer to @sd on success, NULL on failure.
+ */
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
+{
+        if (sd) {
+                if (unlikely(!down_read_trylock(&sd->s_active)))
+                        sd = NULL;
+        }
+        return sd;
+}
+
+/**
+ *      sysfs_put_active - put an active reference to sysfs_dirent
+ *      @sd: sysfs_dirent to put an active reference to
+ *
+ *      Put an active reference to @sd.  This function is noop if @sd
+ *      is NULL.
+ */
+void sysfs_put_active(struct sysfs_dirent *sd)
+{
+        if (sd)
+                up_read(&sd->s_active);
+}
+
+/**
+ *      sysfs_get_active_two - get active references to sysfs_dirent and parent
+ *      @sd: sysfs_dirent of interest
+ *
+ *      Get active reference to @sd and its parent.  Parent's active
+ *      reference is grabbed first.  This function is noop if @sd is
+ *      NULL.
+ *
+ *      RETURNS:
+ *      Pointer to @sd on success, NULL on failure.
+ */
+struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
+{
+        if (sd) {
+                if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
+                        return NULL;
+                if (unlikely(!sysfs_get_active(sd))) {
+                        sysfs_put_active(sd->s_parent);
+                        return NULL;
+                }
+        }
+        return sd;
+}
+
+/**
+ *      sysfs_put_active_two - put active references to sysfs_dirent and parent
+ *      @sd: sysfs_dirent of interest
+ *
+ *      Put active references to @sd and its parent.  This function is
+ *      noop if @sd is NULL.
+ */
+void sysfs_put_active_two(struct sysfs_dirent *sd)
+{
+        if (sd) {
+                sysfs_put_active(sd);
+                sysfs_put_active(sd->s_parent);
+        }
+}
+
+/**
+ *      sysfs_deactivate - deactivate sysfs_dirent
+ *      @sd: sysfs_dirent to deactivate
+ *
+ *      Deny new active references and drain existing ones.  s_active
+ *      will be unlocked when the sysfs_dirent is released.
+ */
+void sysfs_deactivate(struct sysfs_dirent *sd)
+{
+        down_write_nested(&sd->s_active, SYSFS_S_ACTIVE_DEACTIVATE);
+
+        /* s_active will be unlocked by the thread doing the final put
+         * on @sd.  Lie to lockdep.
+         */
+        rwsem_release(&sd->s_active.dep_map, 1, _RET_IP_);
+}
+
 static int sysfs_alloc_ino(ino_t *pino)
 {
         int ino, rc;