linux-kernel - Re: [PATCH v2 (v4.18 regression fix)] vfs: don't evict uninitialized inode

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Message-ID: <20180719214519.GA23379@ZenIV.linux.org.uk>
Date:   Thu, 19 Jul 2018 22:45:20 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Miklos Szeredi <mszeredi@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 (v4.18 regression fix)] vfs: don't evict uninitialized
 inode

On Wed, Jul 18, 2018 at 01:18:33PM +0100, Al Viro wrote:

> BTW, why have you left generic_readlink() sitting around?  AFAICS,
> it could've been folded into the only remaining caller just as
> you've made it static in late 2016...  I'll fold it in;
> just curious what was the reason for not doing that back then...

BTW^2:
const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)
{
        const char *res = ERR_PTR(-EINVAL);
        struct inode *inode = d_inode(dentry);

        if (d_is_symlink(dentry)) {
                res = ERR_PTR(security_inode_readlink(dentry));
                if (!res)
                        res = inode->i_op->get_link(dentry, inode, done);
        }
        return res;
}
hits a method call that is not needed in the majority of cases.  Is there
any subtle reason why it shouldn't be

const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)
{
        const char *res = ERR_PTR(-EINVAL);
        struct inode *inode = d_inode(dentry);

        if (d_is_symlink(dentry)) {
                res = ERR_PTR(security_inode_readlink(dentry));
                if (!res)
			res = inode->i_link;
		if (!res)
                        res = inode->i_op->get_link(dentry, inode, done);
        }
        return res;
}
instead?