[PATCH 5/8] sysfs: implement symlink auto-rename

[Tejun Heo <htejun@gmail.com>]

When a sysfs_node or one of its ancestors is renamed, automatically
rename symlinks pointing to it according to the name format together.

Note that as links created with kobject based sysfs_create_link()
aren't chained on its target, they aren't renamed automatically.  This
is for backward compatibility.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 fs/sysfs/dir.c |   45 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 4a04cb4..eac8fef 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -1196,6 +1196,7 @@ static int sysfs_prep_rename(struct sysfs_rename_context *rcxt,
 {
 	struct sysfs_rcxt_rename_ent *rent;
 	struct sysfs_rcxt_mutex_ent *ment;
+	struct sysfs_dirent *cur;
 	int rc;
 
 	INIT_LIST_HEAD(&rcxt->mutexes);
@@ -1220,6 +1221,50 @@ static int sysfs_prep_rename(struct sysfs_rename_context *rcxt,
 		goto err;
 
 	/*
+	 * prep links pointing to @sd and its children
+	 */
+	cur = NULL;
+	while ((cur = sysfs_tree_walk_next(sd, cur))) {
+		struct sysfs_dirent *link;
+
+		if (sysfs_type(cur) != SYSFS_DIR)
+			continue;
+
+		for (link = cur->s_dir.links; link; link = link->s_link.next) {
+			const char *link_new_name;
+			int copied;
+
+			rc = sysfs_link_name(link->s_link.name_fmt,
+					     link->s_link.target,
+					     &link_new_name,
+					     sd, new_parent, new_name);
+			if (rc < 0)
+				goto err;
+			copied = rc;
+
+			if (!strcmp(link->s_name, link_new_name)) {
+				if (copied)
+					kfree(link_new_name);
+				continue;
+			}
+
+			rc = -ENOMEM;
+			rent = sysfs_rcxt_add(rcxt, link, link->s_parent);
+			if (!rent) {
+				mutex_unlock(&sysfs_mutex);
+				goto err;
+			}
+
+			rent->new_name = link_new_name;
+			rent->new_name_copied = copied;
+
+			rc = sysfs_rcxt_get_dentries(rcxt, rent);
+			if (rc)
+				goto err;
+		}
+	}
+
+	/*
 	 * lock all i_mutexes
 	 */
  try_lock:
-- 
1.5.0.3