[PATCH 1/2] devpts: remove unneeded inode_lock in mknod_ptmx

[Christian Brauner]

Afaict, the mknod_ptmx() call is a no-op on subsequent calls and the first
call is done before we unlock the suberblock. If I'm not mistaken this is
exactly parallel to what Al pointed out for binderfs 29ef1c8e16a
("binderfs: drop lock in binderfs_binder_ctl_create"). In both filesystems
it should not be necessary to take inode_lock() in there. Let's remove it
and remove the goto.

Cc: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner <christ...@brauner.io>
---
 fs/devpts/inode.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index c53814539070..8fa1492f9712 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -325,7 +325,6 @@ static int parse_mount_options(char *data, int op, struct 
pts_mount_opts *opts)
 static int mknod_ptmx(struct super_block *sb)
 {
        int mode;
-       int rc = -ENOMEM;
        struct dentry *dentry;
        struct inode *inode;
        struct dentry *root = sb->s_root;
@@ -334,18 +333,14 @@ static int mknod_ptmx(struct super_block *sb)
        kuid_t ptmx_uid = current_fsuid();
        kgid_t ptmx_gid = current_fsgid();
 
-       inode_lock(d_inode(root));
-
        /* If we have already created ptmx node, return */
-       if (fsi->ptmx_dentry) {
-               rc = 0;
-               goto out;
-       }
+       if (fsi->ptmx_dentry)
+               return 0;
 
        dentry = d_alloc_name(root, "ptmx");
        if (!dentry) {
                pr_err("Unable to alloc dentry for ptmx node\n");
-               goto out;
+               return -ENOMEM;
        }
 
        /*
@@ -355,7 +350,7 @@ static int mknod_ptmx(struct super_block *sb)
        if (!inode) {
                pr_err("Unable to alloc inode for ptmx node\n");
                dput(dentry);
-               goto out;
+               return -ENOMEM;
        }
 
        inode->i_ino = 2;
@@ -369,10 +364,8 @@ static int mknod_ptmx(struct super_block *sb)
        d_add(dentry, inode);
 
        fsi->ptmx_dentry = dentry;
-       rc = 0;
-out:
-       inode_unlock(d_inode(root));
-       return rc;
+
+       return 0;
 }
 
 static void update_ptmx_mode(struct pts_fs_info *fsi)
-- 
2.20.1