[PATCH 4/7] configfs: remove d_add() calls before configfs_attach_group()

[NeilBrown]

From: NeilBrown <neil@xxxxxxxxxx>

These d_add() calls cannot be necessary.  The inode given is NULL so all
they do is attach the dentry to the hash table.

If configfs_attach_group() fails, then d_drop() is called so the dentry
will be detached.
If configfs_attach_group() succeeds, then
 configfs_attach_group -> configfs_attach_item ->configfs_create_dir
must have succeeded, so d_instantiate() will have been called and the
dentry hashed there.

So the only effect is that the dentry will be hashed-negative for a
short period which will allow a lookup to find nothing without waiting
for the directory i_rwsem.  I can find no indication that this might be
important.

Adding a dentry as negative, and then later making it positive is an
unusual pattern and appears to be unnecessary, so it is best avoided.

Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
---
 fs/configfs/dir.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 3c88f13f1ca2..145a092171fe 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -715,8 +715,6 @@ static int create_default_group(struct dentry *parent,
 	ret = -ENOMEM;
 	child = d_alloc_name(parent, group->cg_item.ci_name);
 	if (child) {
-		d_add(child, NULL);
-
 		ret = configfs_attach_group(&group->cg_item, child, frag);
 		if (!ret) {
 			sd = child->d_fsdata;
@@ -1901,8 +1899,6 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
 	err = -ENOMEM;
 	dentry = d_alloc_name(root, group->cg_item.ci_name);
 	if (dentry) {
-		d_add(dentry, NULL);
-
 		err = configfs_dirent_exists(dentry);
 		if (!err)
 			err = configfs_attach_group(&group->cg_item,
-- 
2.50.0.107.gf914562f5916.dirty