[PATCH 13/25] sysfs: Simply sysfs_get_dentry

[ebiederm@xmission.com (Eric W. Biederman)]

Now that we know the sysfs tree structure cannot change under us
simplfy sysfs_get_dentry.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/sysfs/dir.c |   48 ++++++------------------------------------------
 1 files changed, 6 insertions(+), 42 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e0f49b7..a9bdb12 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -784,71 +784,35 @@ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent *cur;
 	struct dentry *parent_dentry, *dentry;
-	int i, depth;
 
 	/* Find the first parent which has valid dentry.
 	 */
-	mutex_lock(&sysfs_mutex);
- restart:
-
 	dentry = NULL;
-	depth = 0;
 	cur = sd;
 	while (!(dentry = __sysfs_get_dentry(sysfs_sb, cur))) {
 		if (cur->s_flags & SYSFS_FLAG_REMOVED) {
 			dentry = ERR_PTR(-ENOENT);
-			depth = 0;
 			break;
 		}
 		cur = cur->s_parent;
-		depth++;
 	}
 
 	/* from the found dentry, look up depth times */
-	while (depth--) {
-		/* find and get depth'th ancestor */
-		for (cur = sd, i = 0; cur && i < depth; i++)
+	while (dentry->d_fsdata != sd) {
+		/* Find the first ancestor I have not looked up */
+		cur = sd;
+		while (cur->s_parent != dentry->d_fsdata)
 			cur = cur->s_parent;
 
-		/* This can happen if tree structure was modified due
-		 * to move/rename.  Restart.
-		 */
-		if (i != depth) {
-			dput(dentry);
-			goto restart;
-		}
-
-		sysfs_get(cur);
-
-		mutex_unlock(&sysfs_mutex);
-
 		/* look it up */
 		parent_dentry = dentry;
 		dentry = lookup_one_len_kern(cur->s_name, parent_dentry,
 					     strlen(cur->s_name));
 		dput(parent_dentry);
 
-		if (IS_ERR(dentry)) {
-			sysfs_put(cur);
-			return dentry;
-		}
-
-		mutex_lock(&sysfs_mutex);
-
-		/* This, again, can happen if tree structure has
-		 * changed and we looked up the wrong thing.  Restart.
-		 */
-		if (dentry->d_fsdata != cur) {
-			dput(dentry);
-			sysfs_put(cur);
-			goto restart;
-		}
-
-
-		sysfs_put(cur);
+		if (IS_ERR(dentry))
+			break;
 	}
-
-	mutex_unlock(&sysfs_mutex);
 	return dentry;
 }
 
-- 
1.5.1.1.181.g2de0