sysfs: remove s_sibling hacks

sysfs: remove s_sibling hacks

s_sibling was used for three different purposes:
1) as a linked list of entries in the directory
2) as a linked list of entries to be deleted
3) as a pointer to "struct completion"

This patch removes the hack and introduces new union u which
holds pointers for cases 2) and 3).

This change is needed for the following patch that removes s_sibling at all
and replaces it with a rb tree.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 12 insertions, 12 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 3e937da224d4..a4846979d4e8 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -154,7 +154,6 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
  */
 void sysfs_put_active(struct sysfs_dirent *sd)
 {
-        struct completion *cmpl;
         int v;
 
         if (unlikely(!sd))
@@ -166,10 +165,9 @@ void sysfs_put_active(struct sysfs_dirent *sd)
                 return;
 
         /* atomic_dec_return() is a mb(), we'll always see the updated
-         * sd->s_sibling.
+         * sd->u.completion.
          */
-        cmpl = (void *)sd->s_sibling;
-        complete(cmpl);
+        complete(sd->u.completion);
 }
 
 /**
@@ -183,16 +181,16 @@ static void sysfs_deactivate(struct sysfs_dirent *sd)
         DECLARE_COMPLETION_ONSTACK(wait);
         int v;
 
-        BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
+        BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED));
 
         if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
                 return;
 
-        sd->s_sibling = (void *)&wait;
+        sd->u.completion = (void *)&wait;
 
         rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
         /* atomic_add_return() is a mb(), put_active() will always see
-         * the updated sd->s_sibling.
+         * the updated sd->u.completion.
          */
         v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
 
@@ -201,8 +199,6 @@ static void sysfs_deactivate(struct sysfs_dirent *sd)
                 wait_for_completion(&wait);
         }
 
-        sd->s_sibling = NULL;
-
         lock_acquired(&sd->dep_map, _RET_IP_);
         rwsem_release(&sd->dep_map, 1, _RET_IP_);
 }
@@ -518,7 +514,7 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
         }
 
         sd->s_flags |= SYSFS_FLAG_REMOVED;
-        sd->s_sibling = acxt->removed;
+        sd->u.removed_list = acxt->removed;
         acxt->removed = sd;
 }
 
@@ -542,8 +538,7 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
         while (acxt->removed) {
                 struct sysfs_dirent *sd = acxt->removed;
 
-                acxt->removed = sd->s_sibling;
-                sd->s_sibling = NULL;
+                acxt->removed = sd->u.removed_list;
 
                 sysfs_deactivate(sd);
                 unmap_bin_file(sd);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index fe1a9e8650bf..3c261681713b 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -66,6 +66,11 @@ struct sysfs_dirent {
 
         struct rb_node          name_node;
 
+        union {
+                struct completion       *completion;
+                struct sysfs_dirent     *removed_list;
+        } u;
+
         const void              *s_ns; /* namespace tag */
         union {
                 struct sysfs_elem_dir           s_dir;