kill d_instantiate_no_diralias()

The only user is fuse_create_new_entry(), and there it's used to
mitigate the same mkdir/open-by-handle race as in nfs_mkdir().
The same solution applies - unhash the mkdir argument, then
call d_splice_alias() and if that returns a reference to preexisting
alias, dput() and report success.  ->mkdir() argument left unhashed
negative with the preexisting alias moved in the right place is just
fine from the ->mkdir() callers point of view.

Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 11 insertions, 4 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 56231b31f806..4bbae6ac75c3 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -539,6 +539,7 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
 {
 	struct fuse_entry_out outarg;
 	struct inode *inode;
+	struct dentry *d;
 	int err;
 	struct fuse_forget_link *forget;
 
@@ -570,11 +571,17 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
 	}
 	kfree(forget);
 
-	err = d_instantiate_no_diralias(entry, inode);
-	if (err)
-		return err;
+	d_drop(entry);
+	d = d_splice_alias(inode, entry);
+	if (IS_ERR(d))
+		return PTR_ERR(d);
 
-	fuse_change_entry_timeout(entry, &outarg);
+	if (d) {
+		fuse_change_entry_timeout(d, &outarg);
+		dput(d);
+	} else {
+		fuse_change_entry_timeout(entry, &outarg);
+	}
 	fuse_invalidate_attr(dir);
 	return 0;