Merge tag '9p-for-5.11-rc1' of git://github.com/martinetd/linux

Pull 9p update from Dominique Martinet:

- fix long-standing limitation on open-unlink-fop pattern

- add refcount to p9_fid (fixes the above and will allow for more
cleanups and simplifications in the future)

* tag '9p-for-5.11-rc1' of git://github.com/martinetd/linux:
9p: Remove unnecessary IS_ERR() check
9p: Uninitialized variable in v9fs_writeback_fid()
9p: Fix writeback fid incorrectly being attached to dentry
9p: apply review requests for fid refcounting
9p: add refcount to p9_fid struct
fs/9p: search open fids first
fs/9p: track open fids
fs/9p: fix create-unlink-getattr idiom

fs/9p/fid.c

···
 }
 
 /**
+ * v9fs_fid_find_inode - search for an open fid off of the inode list
+ * @inode: return a fid pointing to a specific inode
+ * @uid: return a fid belonging to the specified user
+ *
+ */
+
+static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid)
+{
+	struct hlist_head *h;
+	struct p9_fid *fid, *ret = NULL;
+
+	p9_debug(P9_DEBUG_VFS, " inode: %p\n", inode);
+
+	spin_lock(&inode->i_lock);
+	h = (struct hlist_head *)&inode->i_private;
+	hlist_for_each_entry(fid, h, ilist) {
+		if (uid_eq(fid->uid, uid)) {
+			refcount_inc(&fid->count);
+			ret = fid;
+			break;
+		}
+	}
+	spin_unlock(&inode->i_lock);
+	return ret;
+}
+
+/**
+ * v9fs_open_fid_add - add an open fid to an inode
+ * @dentry: inode that the fid is being added to
+ * @fid: fid to add
+ *
+ */
+
+void v9fs_open_fid_add(struct inode *inode, struct p9_fid *fid)
+{
+	spin_lock(&inode->i_lock);
+	hlist_add_head(&fid->ilist, (struct hlist_head *)&inode->i_private);
+	spin_unlock(&inode->i_lock);
+}
+
+
+/**
  * v9fs_fid_find - retrieve a fid that belongs to the specified uid
  * @dentry: dentry to look for fid in
  * @uid: return fid that belongs to the specified user
···
 		 dentry, dentry, from_kuid(&init_user_ns, uid),
 		 any);
 	ret = NULL;
+
+	if (d_inode(dentry))
+		ret = v9fs_fid_find_inode(d_inode(dentry), uid);
+
 	/* we'll recheck under lock if there's anything to look in */
-	if (dentry->d_fsdata) {
+	if (!ret && dentry->d_fsdata) {
 		struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
 		spin_lock(&dentry->d_lock);
 		hlist_for_each_entry(fid, h, dlist) {
 			if (any || uid_eq(fid->uid, uid)) {
 				ret = fid;
+				refcount_inc(&ret->count);
 				break;
 			}
 		}
···
 	fid = v9fs_fid_find(ds, uid, any);
 	if (fid) {
 		/* Found the parent fid do a lookup with that */
-		fid = p9_client_walk(fid, 1, &dentry->d_name.name, 1);
+		struct p9_fid *ofid = fid;
+
+		fid = p9_client_walk(ofid, 1, &dentry->d_name.name, 1);
+		p9_client_clunk(ofid);
 		goto fid_out;
 	}
 	up_read(&v9ses->rename_sem);
···
 		v9fs_fid_add(dentry->d_sb->s_root, fid);
 	}
 	/* If we are root ourself just return that */
-	if (dentry->d_sb->s_root == dentry)
+	if (dentry->d_sb->s_root == dentry) {
+		refcount_inc(&fid->count);
 		return fid;
+	}
 	/*
 	 * Do a multipath walk with attached root.
 	 * When walking parent we need to make sure we
···
 			fid = ERR_PTR(-ENOENT);
 		} else {
 			__add_fid(dentry, fid);
+			refcount_inc(&fid->count);
 			spin_unlock(&dentry->d_lock);
 		}
 	}
···
 struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
 {
 	int err;
-	struct p9_fid *fid;
+	struct p9_fid *fid, *ofid;
 
-	fid = clone_fid(v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0));
+	ofid = v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0);
+	fid = clone_fid(ofid);
 	if (IS_ERR(fid))
 		goto error_out;
+	p9_client_clunk(ofid);
 	/*
 	 * writeback fid will only be used to write back the
 	 * dirty pages. We always request for the open fid in read-write

fs/9p/fid.h

···
 }
 void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid);
 struct p9_fid *v9fs_writeback_fid(struct dentry *dentry);
+void v9fs_open_fid_add(struct inode *inode, struct p9_fid *fid);
 static inline struct p9_fid *clone_fid(struct p9_fid *fid)
 {
 	return IS_ERR(fid) ? fid :  p9_client_walk(fid, 0, NULL, 1);
 }
 static inline struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
 {
-	return clone_fid(v9fs_fid_lookup(dentry));
+	struct p9_fid *fid, *nfid;
+
+	fid = v9fs_fid_lookup(dentry);
+	if (!fid || IS_ERR(fid))
+		return fid;
+
+	nfid = clone_fid(fid);
+	p9_client_clunk(fid);
+	return nfid;
 }
 #endif

fs/9p/vfs_dentry.c

···
 			retval = v9fs_refresh_inode_dotl(fid, inode);
 		else
 			retval = v9fs_refresh_inode(fid, inode);
+		p9_client_clunk(fid);
+
 		if (retval == -ENOENT)
 			return 0;
 		if (retval < 0)

fs/9p/vfs_dir.c

···
 	fid = filp->private_data;
 	p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
 		 inode, filp, fid ? fid->fid : -1);
-	if (fid)
+	if (fid) {
+		spin_lock(&inode->i_lock);
+		hlist_del(&fid->ilist);
+		spin_unlock(&inode->i_lock);
 		p9_client_clunk(fid);
+	}
 	return 0;
 }
 

fs/9p/vfs_file.c

···
 	int err;
 	struct v9fs_inode *v9inode;
 	struct v9fs_session_info *v9ses;
-	struct p9_fid *fid;
+	struct p9_fid *fid, *writeback_fid;
 	int omode;
 
 	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
···
 		 * because we want write after unlink usecase
 		 * to work.
 		 */
-		fid = v9fs_writeback_fid(file_dentry(file));
+		writeback_fid = v9fs_writeback_fid(file_dentry(file));
 		if (IS_ERR(fid)) {
 			err = PTR_ERR(fid);
 			mutex_unlock(&v9inode->v_mutex);
 			goto out_error;
 		}
-		v9inode->writeback_fid = (void *) fid;
+		v9inode->writeback_fid = (void *) writeback_fid;
 	}
 	mutex_unlock(&v9inode->v_mutex);
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 		v9fs_cache_inode_set_cookie(inode, file);
+	v9fs_open_fid_add(inode, fid);
 	return 0;
 out_error:
 	p9_client_clunk(file->private_data);

fs/9p/vfs_inode.c

···
 	inode->i_rdev = rdev;
 	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 	inode->i_mapping->a_ops = &v9fs_addr_operations;
+	inode->i_private = NULL;
 
 	switch (mode & S_IFMT) {
 	case S_IFIFO:
···
 	if (v9fs_proto_dotl(v9ses))
 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
 					    v9fs_at_to_dotl_flags(flags));
+	p9_client_clunk(dfid);
 	if (retval == -EOPNOTSUPP) {
 		/* Try the one based on path */
 		v9fid = v9fs_fid_clone(dentry);
···
 
 		v9fs_invalidate_inode_attr(inode);
 		v9fs_invalidate_inode_attr(dir);
+
+		/* invalidate all fids associated with dentry */
+		/* NOTE: This will not include open fids */
+		dentry->d_op->d_release(dentry);
 	}
 	return retval;
 }
···
 {
 	int err;
 	const unsigned char *name;
-	struct p9_fid *dfid, *ofid, *fid;
+	struct p9_fid *dfid, *ofid = NULL, *fid = NULL;
 	struct inode *inode;
 
 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
 
 	err = 0;
-	ofid = NULL;
-	fid = NULL;
 	name = dentry->d_name.name;
 	dfid = v9fs_parent_fid(dentry);
 	if (IS_ERR(dfid)) {
···
 	if (IS_ERR(ofid)) {
 		err = PTR_ERR(ofid);
 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
+		p9_client_clunk(dfid);
 		return ERR_PTR(err);
 	}
 
 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
 	if (err < 0) {
 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
+		p9_client_clunk(dfid);
 		goto error;
 	}
 
···
 			p9_debug(P9_DEBUG_VFS,
 				   "p9_client_walk failed %d\n", err);
 			fid = NULL;
+			p9_client_clunk(dfid);
 			goto error;
 		}
 		/*
···
 			err = PTR_ERR(inode);
 			p9_debug(P9_DEBUG_VFS,
 				   "inode creation failed %d\n", err);
+			p9_client_clunk(dfid);
 			goto error;
 		}
 		v9fs_fid_add(dentry, fid);
 		d_instantiate(dentry, inode);
 	}
+	p9_client_clunk(dfid);
 	return ofid;
 error:
 	if (ofid)
···
 	 */
 	name = dentry->d_name.name;
 	fid = p9_client_walk(dfid, 1, &name, 1);
+	p9_client_clunk(dfid);
 	if (fid == ERR_PTR(-ENOENT))
 		inode = NULL;
 	else if (IS_ERR(fid))
···
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid, *inode_fid;
 	struct dentry *res = NULL;
+	struct inode *inode;
 
 	if (d_in_lookup(dentry)) {
 		res = v9fs_vfs_lookup(dir, dentry, 0);
···
 	}
 
 	v9fs_invalidate_inode_attr(dir);
-	v9inode = V9FS_I(d_inode(dentry));
+	inode = d_inode(dentry);
+	v9inode = V9FS_I(inode);
 	mutex_lock(&v9inode->v_mutex);
 	if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
 	    !v9inode->writeback_fid &&
···
 	file->private_data = fid;
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 		v9fs_cache_inode_set_cookie(d_inode(dentry), file);
+	v9fs_open_fid_add(inode, fid);
 
 	file->f_mode |= FMODE_CREATED;
 out:
···
 	struct inode *old_inode;
 	struct inode *new_inode;
 	struct v9fs_session_info *v9ses;
-	struct p9_fid *oldfid;
+	struct p9_fid *oldfid, *dfid;
 	struct p9_fid *olddirfid;
 	struct p9_fid *newdirfid;
 	struct p9_wstat wstat;
···
 	if (IS_ERR(oldfid))
 		return PTR_ERR(oldfid);
 
-	olddirfid = clone_fid(v9fs_parent_fid(old_dentry));
+	dfid = v9fs_parent_fid(old_dentry);
+	olddirfid = clone_fid(dfid);
+	if (dfid && !IS_ERR(dfid))
+		p9_client_clunk(dfid);
+
 	if (IS_ERR(olddirfid)) {
 		retval = PTR_ERR(olddirfid);
 		goto done;
 	}
 
-	newdirfid = clone_fid(v9fs_parent_fid(new_dentry));
+	dfid = v9fs_parent_fid(new_dentry);
+	newdirfid = clone_fid(dfid);
+	p9_client_clunk(dfid);
+
 	if (IS_ERR(newdirfid)) {
 		retval = PTR_ERR(newdirfid);
 		goto clunk_olddir;
···
 	p9_client_clunk(olddirfid);
 
 done:
+	p9_client_clunk(oldfid);
 	return retval;
 }
 
···
 		return PTR_ERR(fid);
 
 	st = p9_client_stat(fid);
+	p9_client_clunk(fid);
 	if (IS_ERR(st))
 		return PTR_ERR(st);
 
···
 
 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
 {
-	int retval;
+	int retval, use_dentry = 0;
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid = NULL;
 	struct p9_wstat wstat;
···
 		fid = iattr->ia_file->private_data;
 		WARN_ON(!fid);
 	}
-	if (!fid)
+	if (!fid) {
 		fid = v9fs_fid_lookup(dentry);
+		use_dentry = 1;
+	}
 	if(IS_ERR(fid))
 		return PTR_ERR(fid);
 
···
 		filemap_write_and_wait(d_inode(dentry)->i_mapping);
 
 	retval = p9_client_wstat(fid, &wstat);
+
+	if (use_dentry)
+		p9_client_clunk(fid);
+
 	if (retval < 0)
 		return retval;
 
···
 		return ERR_PTR(-EBADF);
 
 	st = p9_client_stat(fid);
+	p9_client_clunk(fid);
 	if (IS_ERR(st))
 		return ERR_CAST(st);
 

fs/9p/vfs_inode_dotl.c

···
 
 	/* instantiate inode and assign the unopened fid to the dentry */
 	fid = p9_client_walk(dfid, 1, &name, 1);
+	p9_client_clunk(dfid);
 	if (IS_ERR(fid)) {
 		err = PTR_ERR(fid);
 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
···
 	file->private_data = ofid;
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 		v9fs_cache_inode_set_cookie(inode, file);
+	v9fs_open_fid_add(inode, ofid);
 	file->f_mode |= FMODE_CREATED;
 out:
 	v9fs_put_acl(dacl, pacl);
···
 	err = p9_client_mkdir_dotl(dfid, name, mode, gid, &qid);
 	if (err < 0)
 		goto error;
-
 	fid = p9_client_walk(dfid, 1, &name, 1);
 	if (IS_ERR(fid)) {
 		err = PTR_ERR(fid);
···
 	if (fid)
 		p9_client_clunk(fid);
 	v9fs_put_acl(dacl, pacl);
+	p9_client_clunk(dfid);
 	return err;
 }
 
···
 	 */
 
 	st = p9_client_getattr_dotl(fid, P9_STATS_ALL);
+	p9_client_clunk(fid);
 	if (IS_ERR(st))
 		return PTR_ERR(st);
 
···
 
 int v9fs_vfs_setattr_dotl(struct dentry *dentry, struct iattr *iattr)
 {
-	int retval;
+	int retval, use_dentry = 0;
 	struct p9_fid *fid = NULL;
 	struct p9_iattr_dotl p9attr;
 	struct inode *inode = d_inode(dentry);
···
 		fid = iattr->ia_file->private_data;
 		WARN_ON(!fid);
 	}
-	if (!fid)
+	if (!fid) {
 		fid = v9fs_fid_lookup(dentry);
+		use_dentry = 1;
+	}
 	if (IS_ERR(fid))
 		return PTR_ERR(fid);
 
···
 		filemap_write_and_wait(inode->i_mapping);
 
 	retval = p9_client_setattr(fid, &p9attr);
-	if (retval < 0)
+	if (retval < 0) {
+		if (use_dentry)
+			p9_client_clunk(fid);
 		return retval;
+	}
 
 	if ((iattr->ia_valid & ATTR_SIZE) &&
 	    iattr->ia_size != i_size_read(inode))
···
 	if (iattr->ia_valid & ATTR_MODE) {
 		/* We also want to update ACL when we update mode bits */
 		retval = v9fs_acl_chmod(inode, fid);
-		if (retval < 0)
+		if (retval < 0) {
+			if (use_dentry)
+				p9_client_clunk(fid);
 			return retval;
+		}
 	}
+	if (use_dentry)
+		p9_client_clunk(fid);
+
 	return 0;
 }
 
···
 	if (fid)
 		p9_client_clunk(fid);
 
+	p9_client_clunk(dfid);
 	return err;
 }
 
···
 		return PTR_ERR(dfid);
 
 	oldfid = v9fs_fid_lookup(old_dentry);
-	if (IS_ERR(oldfid))
+	if (IS_ERR(oldfid)) {
+		p9_client_clunk(dfid);
 		return PTR_ERR(oldfid);
+	}
 
 	err = p9_client_link(dfid, oldfid, dentry->d_name.name);
 
+	p9_client_clunk(dfid);
+	p9_client_clunk(oldfid);
 	if (err < 0) {
 		p9_debug(P9_DEBUG_VFS, "p9_client_link failed %d\n", err);
 		return err;
···
 			return PTR_ERR(fid);
 
 		v9fs_refresh_inode_dotl(fid, d_inode(old_dentry));
+		p9_client_clunk(fid);
 	}
 	ihold(d_inode(old_dentry));
 	d_instantiate(dentry, d_inode(old_dentry));
···
 	if (fid)
 		p9_client_clunk(fid);
 	v9fs_put_acl(dacl, pacl);
+	p9_client_clunk(dfid);
+
 	return err;
 }
 
···
 	if (IS_ERR(fid))
 		return ERR_CAST(fid);
 	retval = p9_client_readlink(fid, &target);
+	p9_client_clunk(fid);
 	if (retval)
 		return ERR_PTR(retval);
 	set_delayed_call(done, kfree_link, target);

fs/9p/vfs_super.c

···
 	}
 	res = simple_statfs(dentry, buf);
 done:
+	p9_client_clunk(fid);
 	return res;
 }
 

fs/9p/xattr.c

···
 		       void *buffer, size_t buffer_size)
 {
 	struct p9_fid *fid;
+	int ret;
 
 	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
 		 name, buffer_size);
 	fid = v9fs_fid_lookup(dentry);
 	if (IS_ERR(fid))
 		return PTR_ERR(fid);
+	ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
+	p9_client_clunk(fid);
 
-	return v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
+	return ret;
 }
 
 /*
···
 int v9fs_xattr_set(struct dentry *dentry, const char *name,
 		   const void *value, size_t value_len, int flags)
 {
-	struct p9_fid *fid = v9fs_fid_lookup(dentry);
-	return v9fs_fid_xattr_set(fid, name, value, value_len, flags);
+	int ret;
+	struct p9_fid *fid;
+
+	fid  = v9fs_fid_lookup(dentry);
+	if (IS_ERR(fid))
+		return PTR_ERR(fid);
+	ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
+	p9_client_clunk(fid);
+	return ret;
 }
 
 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,

include/net/9p/client.h

···
  *
  * TODO: This needs lots of explanation.
  */
+enum fid_source {
+	FID_FROM_OTHER,
+	FID_FROM_INODE,
+	FID_FROM_DENTRY,
+};
 
 struct p9_fid {
 	struct p9_client *clnt;
 	u32 fid;
+	refcount_t count;
 	int mode;
 	struct p9_qid qid;
 	u32 iounit;
···
 	void *rdir;
 
 	struct hlist_node dlist;	/* list of all fids attached to a dentry */
+	struct hlist_node ilist;
 };
 
 /**

net/9p/client.c

···
 	fid->clnt = clnt;
 	fid->rdir = NULL;
 	fid->fid = 0;
+	refcount_set(&fid->count, 1);
 
 	idr_preload(GFP_KERNEL);
 	spin_lock_irq(&clnt->lock);
···
 			    GFP_NOWAIT);
 	spin_unlock_irq(&clnt->lock);
 	idr_preload_end();
-
 	if (!ret)
 		return fid;
 
···
 
 	p9_debug(P9_DEBUG_9P, ">>> TWALK fids %d,%d nwname %ud wname[0] %s\n",
 		 oldfid->fid, fid->fid, nwname, wnames ? wnames[0] : NULL);
-
 	req = p9_client_rpc(clnt, P9_TWALK, "ddT", oldfid->fid, fid->fid,
 								nwname, wnames);
 	if (IS_ERR(req)) {
···
 	if (nwname)
 		memmove(&fid->qid, &wqids[nwqids - 1], sizeof(struct p9_qid));
 	else
-		fid->qid = oldfid->qid;
+		memmove(&fid->qid, &oldfid->qid, sizeof(struct p9_qid));
 
 	kfree(wqids);
 	return fid;
···
 		p9_is_proto_dotl(clnt) ? "RLOPEN" : "ROPEN",  qid.type,
 		(unsigned long long)qid.path, qid.version, iounit);
 
+	memmove(&fid->qid, &qid, sizeof(struct p9_qid));
 	fid->mode = mode;
 	fid->iounit = iounit;
 
···
 			(unsigned long long)qid->path,
 			qid->version, iounit);
 
+	memmove(&ofid->qid, qid, sizeof(struct p9_qid));
 	ofid->mode = mode;
 	ofid->iounit = iounit;
 
···
 				(unsigned long long)qid.path,
 				qid.version, iounit);
 
+	memmove(&fid->qid, &qid, sizeof(struct p9_qid));
 	fid->mode = mode;
 	fid->iounit = iounit;
 
···
 	struct p9_req_t *req;
 	int retries = 0;
 
-	if (!fid) {
-		pr_warn("%s (%d): Trying to clunk with NULL fid\n",
+	if (!fid || IS_ERR(fid)) {
+		pr_warn("%s (%d): Trying to clunk with invalid fid\n",
 			__func__, task_pid_nr(current));
 		dump_stack();
 		return 0;
 	}
+	if (!refcount_dec_and_test(&fid->count))
+		return 0;
 
 again:
 	p9_debug(P9_DEBUG_9P, ">>> TCLUNK fid %d (try %d)\n", fid->fid,