libfs: improve path_from_stashed()

Right now we pass a bunch of info that is fs specific which doesn't make
a lot of sense and it bleeds fs sepcific details into the generic
helper. nsfs and pidfs have slightly different needs when initializing
inodes. Add simple operations that are stashed in sb->s_fs_info that
both can implement. This also allows us to get rid of cleaning up
references in the caller. All in all path_from_stashed() becomes way
simpler.

Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 21 insertions, 3 deletions

diff --git a/fs/pidfs.c b/fs/pidfs.c
index d38b7a184994..8fd71a00be9c 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -193,6 +193,26 @@ static const struct dentry_operations pidfs_dentry_operations = {
 	.d_prune	= stashed_dentry_prune,
 };
 
+static void pidfs_init_inode(struct inode *inode, void *data)
+{
+	inode->i_private = data;
+	inode->i_flags |= S_PRIVATE;
+	inode->i_mode |= S_IRWXU;
+	inode->i_op = &pidfs_inode_operations;
+	inode->i_fop = &pidfs_file_operations;
+}
+
+static void pidfs_put_data(void *data)
+{
+	struct pid *pid = data;
+	put_pid(pid);
+}
+
+static const struct stashed_operations pidfs_stashed_ops = {
+	.init_inode = pidfs_init_inode,
+	.put_data = pidfs_put_data,
+};
+
 static int pidfs_init_fs_context(struct fs_context *fc)
 {
 	struct pseudo_fs_context *ctx;
@@ -203,6 +223,7 @@ static int pidfs_init_fs_context(struct fs_context *fc)
 
 	ctx->ops = &pidfs_sops;
 	ctx->dops = &pidfs_dentry_operations;
+	fc->s_fs_info = (void *)&pidfs_stashed_ops;
 	return 0;
 }
 
@@ -225,10 +246,7 @@ struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags)
 	* for pseudo filesystems.
 	 */
 	ret = path_from_stashed(&pid->stashed, pid->ino, pidfs_mnt,
-				&pidfs_file_operations, &pidfs_inode_operations,
 				get_pid(pid), &path);
-	if (ret <= 0)
-		put_pid(pid);
 	if (ret < 0)
 		return ERR_PTR(ret);