Subject: Re: linux-next: manual merge of the pidfd tree with the vfs tree

From: Stephen Rothwell <[email-masked]>
Date: Mon, 22 Feb 2021 09:51:40 +1100

Hi all,

On Mon, 15 Feb 2021 08:05:21 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> On Mon, 25 Jan 2021 17:00:54 +1100 Stephen Rothwell <[email-masked]> wrote:
> >
> > Today's linux-next merge of the pidfd tree got a conflict in:
> > 
> >   fs/namei.c
> > 
> > between commit:
> > 
> >   e36cffed20a3 ("fs: make unlazy_walk() error handling consistent")
> >   1e8f44f159b3 ("do_tmpfile(): don't mess with finish_open()")
> > 
> > from the vfs tree and commit:
> > 
> >   47291baa8ddf ("namei: make permission helpers idmapped mount aware")
> >   ba73d98745be ("namei: handle idmapped mounts in may_*() helpers")
> >   549c7297717c ("fs: make helpers idmap mount aware")
> > 
> > from the pidfd tree.
> > 
> > I fixed it up (see below) and can carry the fix as necessary. This
> > is now fixed as far as linux-next is concerned, but any non trivial
> > conflicts should be mentioned to your upstream maintainer when your tree
> > is submitted for merging.  You may also want to consider cooperating
> > with the maintainer of the conflicting tree to minimise any particularly
> > complex conflicts.
> > 
> > diff --cc fs/namei.c
> > index 4cae88733a5c,dbf53b325ac9..000000000000
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@@ -1568,14 -1639,18 +1644,16 @@@ static struct dentry *lookup_slow(cons
> >   	return res;
> >   }
> >   
> > - static inline int may_lookup(struct nameidata *nd)
> > + static inline int may_lookup(struct user_namespace *mnt_userns,
> > + 			     struct nameidata *nd)
> >   {
> >   	if (nd->flags & LOOKUP_RCU) {
> > - 		int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
> > + 		int err = inode_permission(mnt_userns, nd->inode,
> > + 					   MAY_EXEC | MAY_NOT_BLOCK);
> >  -		if (err != -ECHILD)
> >  +		if (err != -ECHILD || !try_to_unlazy(nd))
> >   			return err;
> >  -		if (unlazy_walk(nd))
> >  -			return -ECHILD;
> >   	}
> > - 	return inode_permission(nd->inode, MAY_EXEC);
> > + 	return inode_permission(mnt_userns, nd->inode, MAY_EXEC);
> >   }
> >   
> >   static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq)
> > @@@ -3324,9 -3453,11 +3453,9 @@@ static int do_tmpfile(struct nameidata 
> >   	path.dentry = child;
> >   	audit_inode(nd->name, child, 0);
> >   	/* Don't check for other permissions, the inode was just created */
> > - 	error = may_open(&path, 0, op->open_flag);
> > + 	error = may_open(mnt_userns, &path, 0, op->open_flag);
> >  -	if (error)
> >  -		goto out2;
> >  -	file->f_path.mnt = path.mnt;
> >  -	error = finish_open(file, child, NULL);
> >  +	if (!error)
> >  +		error = vfs_open(&path, file);
> >   out2:
> >   	mnt_drop_write(path.mnt);
> >   out:  
> 
> With the merge window about to open, this is a reminder that this
> conflict still exists.
> 
> Those vfs tree commits have also been merged into the block tree.

This is now a conflict between the pidfd tree and Linus' tree.
-- 
Cheers,
Stephen Rothwell