On Thu, Feb 13, 2025 at 03:51:16AM +0000, Al Viro wrote:
> On Thu, Feb 06, 2025 at 04:42:56PM +1100, NeilBrown wrote:
> > nfs_sillyrename(struct inode *dir, struct dentry *dentry)
> > {
> > static unsigned int sillycounter;
> > @@ -447,7 +451,8 @@ nfs_sillyrename(struct inode *dir, struct dentry *dentry)
> > struct dentry *sdentry;
> > struct inode *inode = d_inode(dentry);
> > struct rpc_task *task;
> > - int error = -EBUSY;
> > + struct dentry *base;
> > + int error = -EBUSY;
> >
> > dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
> > dentry, d_count(dentry));
> > @@ -461,10 +466,11 @@ nfs_sillyrename(struct inode *dir, struct dentry *dentry)
> >
> > fileid = NFS_FILEID(d_inode(dentry));
> >
> > + base = d_find_alias(dir);
>
> Huh? That would better be dentry->d_parent and all operations are in
> that directory, so you don't even need to grab a reference...
>
> > sdentry = NULL;
> > do {
> > int slen;
> > - dput(sdentry);
> > +
> > sillycounter++;
> > slen = scnprintf(silly, sizeof(silly),
> > SILLYNAME_PREFIX "%0*llx%0*x",
> > @@ -474,14 +480,19 @@ nfs_sillyrename(struct inode *dir, struct dentry *dentry)
> > dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
> > dentry, silly);
> >
> > - sdentry = lookup_one_len(silly, dentry->d_parent, slen);
> > - /*
> > - * N.B. Better to return EBUSY here ... it could be
> > - * dangerous to delete the file while it's in use.
> > - */
> > - if (IS_ERR(sdentry))
> > - goto out;
> > - } while (d_inode(sdentry) != NULL); /* need negative lookup */
> > + sdentry = lookup_and_lock_one(NULL, silly, slen,
> > + base,
> > + LOOKUP_CREATE | LOOKUP_EXCL
> > + | LOOKUP_RENAME_TARGET
> > + | LOOKUP_PARENT_LOCKED);
> > + } while (PTR_ERR_OR_ZERO(sdentry) == -EEXIST); /* need negative lookup */
>
> What's wrong with sdentry == ERR_PTR(-EEXIST)?
BTW, do you need to mess with NFS_DATA_BLOCKED with that thing in place?
