On Tue, Feb 22, 2005 at 09:45:37AM -0500, Trond Myklebust wrote:
> ty den 22.02.2005 Klokka 13:12 (+0100) skreiv Herbert Poetzl:
>
> > diff -NurpP --minimal
> > linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01/fs/namei.c
> > linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01-co0.01/fs/namei.c
> > --- linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01/fs/namei.c
> > 2005-02-13 17:16:55 +0100
> > +++ linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01-co0.01/fs/namei.c
> > 2005-02-19 06:31:50 +0100
> > @@ -1168,6 +1168,24 @@ static inline int may_create(struct inod
> > return permission(dir,MAY_WRITE | MAY_EXEC, nd);
> > }
> >
> > +static inline int mnt_may_create(struct vfsmount *mnt, struct inode *dir,
> > struct dentry *child) {
> > + if (child->d_inode)
> > + return -EEXIST;
> > + if (IS_DEADDIR(dir))
> > + return -ENOENT;
> > + if (MNT_IS_RDONLY(mnt))
> > + return -EROFS;
> > + return 0;
> > +}
> > +
> > +static inline int mnt_may_unlink(struct vfsmount *mnt, struct inode *dir,
> > struct dentry *child) {
> > + if (!child->d_inode)
> > + return -ENOENT;
> > + if (MNT_IS_RDONLY(mnt))
> > + return -EROFS;
> > + return 0;
> > +}
>
> Most of these checks are redundant, since they are already being done
> elsewhere in the code.
> child->d_inode is, for instance checked in may_delete() and in
> may_create.
well, but mnt_may_create() for example is called from
lookup_create() which in turn is (for example) called
from sys_mknod() which doesn't call may_delete() or
may_create() ... did I miss something?
> IS_DEADDIR is also checked in may_create.
ditto ...
> > /*
> > * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
> > * reasons.
> > @@ -1518,23 +1536,28 @@ do_link:
> > struct dentry *lookup_create(struct nameidata *nd, int is_dir)
> > {
> > struct dentry *dentry;
> > + int error;
> >
> > down(&nd->dentry->d_inode->i_sem);
> > - dentry = ERR_PTR(-EEXIST);
> > + error = -EEXIST;
> > if (nd->last_type != LAST_NORM)
> > - goto fail;
> > + goto out;
> > nd->flags &= ~LOOKUP_PARENT;
> > dentry = lookup_hash(&nd->last, nd->dentry);
> > if (IS_ERR(dentry))
> > + goto ret;
> > + error = mnt_may_create(nd->mnt, nd->dentry->d_inode, dentry);
> > + if (error)
> > goto fail;
> > + error = -ENOENT;
> > if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
> > - goto enoent;
> > + goto fail;
> > +ret:
> > return dentry;
> > -enoent:
> > - dput(dentry);
> > - dentry = ERR_PTR(-ENOENT);
> > fail:
> > - return dentry;
> > + dput(dentry);
> > +out:
> > + return ERR_PTR(error);
> > }
>
> What is the value of adding "error"?
> The current code is more efficient, and just as readable.
hmm, a compile test resulted in almost
identical code, but maybe I did miss some
aspect of the efficiency ...
anyway, thanks for the feedback,
Herbert
> Cheers,
> Trond
>
> --
> Trond Myklebust <[EMAIL PROTECTED]>
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