Merge tag '9p-for-5.20' of https://github.com/martinetd/linux

Pull 9p updates from Dominique Martinet:

 - a couple of fixes

 - add a tracepoint for fid refcounting

 - some cleanup/followup on fid lookup

 - some cleanup around req refcounting

* tag '9p-for-5.20' of https://github.com/martinetd/linux:
  net/9p: Initialize the iounit field during fid creation
  net: 9p: fix refcount leak in p9_read_work() error handling
  9p: roll p9_tag_remove into p9_req_put
  9p: Add client parameter to p9_req_put()
  9p: Drop kref usage
  9p: Fix some kernel-doc comments
  9p fid refcount: cleanup p9_fid_put calls
  9p fid refcount: add a 9p_fid_ref tracepoint
  9p fid refcount: add p9_fid_get/put wrappers
  9p: Fix minor typo in code comment
  9p: Remove unnecessary variable for old fids while walking from d_parent
  9p: Make the path walk logic more clear about when cloning is required
  9p: Track the root fid with its own variable during lookups

fs/9p/fid.c

@@ -28,14 +28,18 @@ static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
 /**
  * v9fs_fid_add - add a fid to a dentry
  * @dentry: dentry that the fid is being added to
- * @fid: fid to add
+ * @pfid: fid to add, NULLed out
  *
  */
-void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
+void v9fs_fid_add(struct dentry *dentry, struct p9_fid **pfid)
 {
+	struct p9_fid *fid = *pfid;
+
 	spin_lock(&dentry->d_lock);
 	__add_fid(dentry, fid);
 	spin_unlock(&dentry->d_lock);
+
+	*pfid = NULL;
 }
 
 /**
@@ -56,7 +60,7 @@ static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid)
 	h = (struct hlist_head *)&inode->i_private;
 	hlist_for_each_entry(fid, h, ilist) {
 		if (uid_eq(fid->uid, uid)) {
-			refcount_inc(&fid->count);
+			p9_fid_get(fid);
 			ret = fid;
 			break;
 		}
@@ -68,15 +72,19 @@ static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid)
 /**
  * v9fs_open_fid_add - add an open fid to an inode
  * @inode: inode that the fid is being added to
- * @fid: fid to add
+ * @pfid: fid to add, NULLed out
  *
  */
 
-void v9fs_open_fid_add(struct inode *inode, struct p9_fid *fid)
+void v9fs_open_fid_add(struct inode *inode, struct p9_fid **pfid)
 {
+	struct p9_fid *fid = *pfid;
+
 	spin_lock(&inode->i_lock);
 	hlist_add_head(&fid->ilist, (struct hlist_head *)&inode->i_private);
 	spin_unlock(&inode->i_lock);
+
+	*pfid = NULL;
 }
 
 
@@ -104,7 +112,7 @@ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
 		hlist_for_each_entry(fid, h, dlist) {
 			if (any || uid_eq(fid->uid, uid)) {
 				ret = fid;
-				refcount_inc(&ret->count);
+				p9_fid_get(ret);
 				break;
 			}
 		}
@@ -150,9 +158,9 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
 {
 	struct dentry *ds;
 	const unsigned char **wnames, *uname;
-	int i, n, l, clone, access;
+	int i, n, l, access;
 	struct v9fs_session_info *v9ses;
-	struct p9_fid *fid, *old_fid;
+	struct p9_fid *fid, *root_fid, *old_fid;
 
 	v9ses = v9fs_dentry2v9ses(dentry);
 	access = v9ses->flags & V9FS_ACCESS_MASK;
@@ -169,17 +177,17 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
 	fid = v9fs_fid_find(ds, uid, any);
 	if (fid) {
 		/* Found the parent fid do a lookup with that */
-		struct p9_fid *ofid = fid;
+		old_fid = fid;
 
-		fid = p9_client_walk(ofid, 1, &dentry->d_name.name, 1);
-		p9_client_clunk(ofid);
+		fid = p9_client_walk(old_fid, 1, &dentry->d_name.name, 1);
+		p9_fid_put(old_fid);
 		goto fid_out;
 	}
 	up_read(&v9ses->rename_sem);
 
 	/* start from the root and try to do a lookup */
-	fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
-	if (!fid) {
+	root_fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
+	if (!root_fid) {
 		/* the user is not attached to the fs yet */
 		if (access == V9FS_ACCESS_SINGLE)
 			return ERR_PTR(-EPERM);
@@ -194,12 +202,13 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
 		if (IS_ERR(fid))
 			return fid;
 
-		refcount_inc(&fid->count);
-		v9fs_fid_add(dentry->d_sb->s_root, fid);
+		root_fid = p9_fid_get(fid);
+		v9fs_fid_add(dentry->d_sb->s_root, &fid);
 	}
 	/* If we are root ourself just return that */
 	if (dentry->d_sb->s_root == dentry)
-		return fid;
+		return root_fid;
+
 	/*
 	 * Do a multipath walk with attached root.
 	 * When walking parent we need to make sure we
@@ -211,19 +220,20 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
 		fid = ERR_PTR(n);
 		goto err_out;
 	}
-	old_fid = fid;
-	clone = 1;
+	fid = root_fid;
+	old_fid = root_fid;
 	i = 0;
 	while (i < n) {
 		l = min(n - i, P9_MAXWELEM);
 		/*
 		 * We need to hold rename lock when doing a multipath
-		 * walk to ensure none of the patch component change
+		 * walk to ensure none of the path components change
 		 */
-		fid = p9_client_walk(fid, l, &wnames[i], clone);
+		fid = p9_client_walk(old_fid, l, &wnames[i],
+				     old_fid == root_fid /* clone */);
 		/* non-cloning walk will return the same fid */
 		if (fid != old_fid) {
-			p9_client_clunk(old_fid);
+			p9_fid_put(old_fid);
 			old_fid = fid;
 		}
 		if (IS_ERR(fid)) {
@@ -231,7 +241,6 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
 			goto err_out;
 		}
 		i += l;
-		clone = 0;
 	}
 	kfree(wnames);
 fid_out:
@@ -239,11 +248,11 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
 		spin_lock(&dentry->d_lock);
 		if (d_unhashed(dentry)) {
 			spin_unlock(&dentry->d_lock);
-			p9_client_clunk(fid);
+			p9_fid_put(fid);
 			fid = ERR_PTR(-ENOENT);
 		} else {
 			__add_fid(dentry, fid);
-			refcount_inc(&fid->count);
+			p9_fid_get(fid);
 			spin_unlock(&dentry->d_lock);
 		}
 	}
@@ -300,7 +309,7 @@ struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
 	fid = clone_fid(ofid);
 	if (IS_ERR(fid))
 		goto error_out;
-	p9_client_clunk(ofid);
+	p9_fid_put(ofid);
 	/*
 	 * writeback fid will only be used to write back the
 	 * dirty pages. We always request for the open fid in read-write
@@ -309,7 +318,7 @@ struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
 	 */
 	err = p9_client_open(fid, O_RDWR);
 	if (err < 0) {
-		p9_client_clunk(fid);
+		p9_fid_put(fid);
 		fid = ERR_PTR(err);
 		goto error_out;
 	}

fs/9p/fid.h

@@ -13,9 +13,9 @@ static inline struct p9_fid *v9fs_parent_fid(struct dentry *dentry)
 {
 	return v9fs_fid_lookup(dentry->d_parent);
 }
-void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid);
+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);
+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);
@@ -29,7 +29,7 @@ static inline struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
 		return fid;
 
 	nfid = clone_fid(fid);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	return nfid;
 }
 #endif

fs/9p/vfs_addr.c

@@ -73,7 +73,7 @@ static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
 		BUG_ON(!fid);
 	}
 
-	refcount_inc(&fid->count);
+	p9_fid_get(fid);
 	rreq->netfs_priv = fid;
 	return 0;
 }
@@ -86,7 +86,7 @@ static void v9fs_free_request(struct netfs_io_request *rreq)
 {
 	struct p9_fid *fid = rreq->netfs_priv;
 
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 }
 
 /**

fs/9p/vfs_dentry.c

@@ -54,7 +54,7 @@ static void v9fs_dentry_release(struct dentry *dentry)
 	p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
 		 dentry, dentry);
 	hlist_for_each_safe(p, n, (struct hlist_head *)&dentry->d_fsdata)
-		p9_client_clunk(hlist_entry(p, struct p9_fid, dlist));
+		p9_fid_put(hlist_entry(p, struct p9_fid, dlist));
 	dentry->d_fsdata = NULL;
 }
 
@@ -85,7 +85,7 @@ static int v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 			retval = v9fs_refresh_inode_dotl(fid, inode);
 		else
 			retval = v9fs_refresh_inode(fid, inode);
-		p9_client_clunk(fid);
+		p9_fid_put(fid);
 
 		if (retval == -ENOENT)
 			return 0;

fs/9p/vfs_dir.c

@@ -218,7 +218,7 @@ int v9fs_dir_release(struct inode *inode, struct file *filp)
 		spin_lock(&inode->i_lock);
 		hlist_del(&fid->ilist);
 		spin_unlock(&inode->i_lock);
-		p9_client_clunk(fid);
+		p9_fid_put(fid);
 	}
 
 	if ((filp->f_mode & FMODE_WRITE)) {

fs/9p/vfs_file.c

@@ -63,15 +63,16 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
 		err = p9_client_open(fid, omode);
 		if (err < 0) {
-			p9_client_clunk(fid);
+			p9_fid_put(fid);
 			return err;
 		}
 		if ((file->f_flags & O_APPEND) &&
 			(!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
 			generic_file_llseek(file, 0, SEEK_END);
+
+		file->private_data = fid;
 	}
 
-	file->private_data = fid;
 	mutex_lock(&v9inode->v_mutex);
 	if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
 	    !v9inode->writeback_fid &&
@@ -95,10 +96,10 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 		fscache_use_cookie(v9fs_inode_cookie(v9inode),
 				   file->f_mode & FMODE_WRITE);
-	v9fs_open_fid_add(inode, fid);
+	v9fs_open_fid_add(inode, &fid);
 	return 0;
 out_error:
-	p9_client_clunk(file->private_data);
+	p9_fid_put(file->private_data);
 	file->private_data = NULL;
 	return err;
 }

fs/9p/vfs_inode.c

@@ -399,10 +399,8 @@ void v9fs_evict_inode(struct inode *inode)
 
 	fscache_relinquish_cookie(v9fs_inode_cookie(v9inode), false);
 	/* clunk the fid stashed in writeback_fid */
-	if (v9inode->writeback_fid) {
-		p9_client_clunk(v9inode->writeback_fid);
-		v9inode->writeback_fid = NULL;
-	}
+	p9_fid_put(v9inode->writeback_fid);
+	v9inode->writeback_fid = NULL;
 }
 
 static int v9fs_test_inode(struct inode *inode, void *data)
@@ -569,7 +567,7 @@ static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
 	if (v9fs_proto_dotl(v9ses))
 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
 					    v9fs_at_to_dotl_flags(flags));
-	p9_client_clunk(dfid);
+	p9_fid_put(dfid);
 	if (retval == -EOPNOTSUPP) {
 		/* Try the one based on path */
 		v9fid = v9fs_fid_clone(dentry);
@@ -633,14 +631,12 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 	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);
+		goto error;
 	}
 
 	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;
 	}
 
@@ -651,8 +647,6 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 			err = PTR_ERR(fid);
 			p9_debug(P9_DEBUG_VFS,
 				   "p9_client_walk failed %d\n", err);
-			fid = NULL;
-			p9_client_clunk(dfid);
 			goto error;
 		}
 		/*
@@ -663,21 +657,17 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 			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);
+		v9fs_fid_add(dentry, &fid);
 		d_instantiate(dentry, inode);
 	}
-	p9_client_clunk(dfid);
+	p9_fid_put(dfid);
 	return ofid;
 error:
-	if (ofid)
-		p9_client_clunk(ofid);
-
-	if (fid)
-		p9_client_clunk(fid);
-
+	p9_fid_put(dfid);
+	p9_fid_put(ofid);
+	p9_fid_put(fid);
 	return ERR_PTR(err);
 }
 
@@ -708,7 +698,7 @@ v9fs_vfs_create(struct user_namespace *mnt_userns, struct inode *dir,
 		return PTR_ERR(fid);
 
 	v9fs_invalidate_inode_attr(dir);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 
 	return 0;
 }
@@ -744,7 +734,7 @@ static int v9fs_vfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 	}
 
 	if (fid)
-		p9_client_clunk(fid);
+		p9_fid_put(fid);
 
 	return err;
 }
@@ -785,7 +775,7 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 	 */
 	name = dentry->d_name.name;
 	fid = p9_client_walk(dfid, 1, &name, 1);
-	p9_client_clunk(dfid);
+	p9_fid_put(dfid);
 	if (fid == ERR_PTR(-ENOENT))
 		inode = NULL;
 	else if (IS_ERR(fid))
@@ -804,11 +794,11 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 	res = d_splice_alias(inode, dentry);
 	if (!IS_ERR(fid)) {
 		if (!res)
-			v9fs_fid_add(dentry, fid);
+			v9fs_fid_add(dentry, &fid);
 		else if (!IS_ERR(res))
-			v9fs_fid_add(res, fid);
+			v9fs_fid_add(res, &fid);
 		else
-			p9_client_clunk(fid);
+			p9_fid_put(fid);
 	}
 	return res;
 }
@@ -847,7 +837,6 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 						v9fs_proto_dotu(v9ses)));
 	if (IS_ERR(fid)) {
 		err = PTR_ERR(fid);
-		fid = NULL;
 		goto error;
 	}
 
@@ -882,7 +871,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 		fscache_use_cookie(v9fs_inode_cookie(v9inode),
 				   file->f_mode & FMODE_WRITE);
-	v9fs_open_fid_add(inode, fid);
+	v9fs_open_fid_add(inode, &fid);
 
 	file->f_mode |= FMODE_CREATED;
 out:
@@ -890,8 +879,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	return err;
 
 error:
-	if (fid)
-		p9_client_clunk(fid);
+	p9_fid_put(fid);
 	goto out;
 }
 
@@ -939,9 +927,9 @@ v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 	struct inode *old_inode;
 	struct inode *new_inode;
 	struct v9fs_session_info *v9ses;
-	struct p9_fid *oldfid, *dfid;
-	struct p9_fid *olddirfid;
-	struct p9_fid *newdirfid;
+	struct p9_fid *oldfid = NULL, *dfid = NULL;
+	struct p9_fid *olddirfid = NULL;
+	struct p9_fid *newdirfid = NULL;
 	struct p9_wstat wstat;
 
 	if (flags)
@@ -958,21 +946,22 @@ v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 
 	dfid = v9fs_parent_fid(old_dentry);
 	olddirfid = clone_fid(dfid);
-	if (dfid && !IS_ERR(dfid))
-		p9_client_clunk(dfid);
+	p9_fid_put(dfid);
+	dfid = NULL;
 
 	if (IS_ERR(olddirfid)) {
 		retval = PTR_ERR(olddirfid);
-		goto done;
+		goto error;
 	}
 
 	dfid = v9fs_parent_fid(new_dentry);
 	newdirfid = clone_fid(dfid);
-	p9_client_clunk(dfid);
+	p9_fid_put(dfid);
+	dfid = NULL;
 
 	if (IS_ERR(newdirfid)) {
 		retval = PTR_ERR(newdirfid);
-		goto clunk_olddir;
+		goto error;
 	}
 
 	down_write(&v9ses->rename_sem);
@@ -983,7 +972,7 @@ v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 			retval = p9_client_rename(oldfid, newdirfid,
 						  new_dentry->d_name.name);
 		if (retval != -EOPNOTSUPP)
-			goto clunk_newdir;
+			goto error_locked;
 	}
 	if (old_dentry->d_parent != new_dentry->d_parent) {
 		/*
@@ -992,14 +981,14 @@ v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 
 		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
 		retval = -EXDEV;
-		goto clunk_newdir;
+		goto error_locked;
 	}
 	v9fs_blank_wstat(&wstat);
 	wstat.muid = v9ses->uname;
 	wstat.name = new_dentry->d_name.name;
 	retval = p9_client_wstat(oldfid, &wstat);
 
-clunk_newdir:
+error_locked:
 	if (!retval) {
 		if (new_inode) {
 			if (S_ISDIR(new_inode->i_mode))
@@ -1020,13 +1009,11 @@ v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 		d_move(old_dentry, new_dentry);
 	}
 	up_write(&v9ses->rename_sem);
-	p9_client_clunk(newdirfid);
-
-clunk_olddir:
-	p9_client_clunk(olddirfid);
 
-done:
-	p9_client_clunk(oldfid);
+error:
+	p9_fid_put(newdirfid);
+	p9_fid_put(olddirfid);
+	p9_fid_put(oldfid);
 	return retval;
 }
 
@@ -1060,7 +1047,7 @@ v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 		return PTR_ERR(fid);
 
 	st = p9_client_stat(fid);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	if (IS_ERR(st))
 		return PTR_ERR(st);
 
@@ -1136,7 +1123,7 @@ static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
 	retval = p9_client_wstat(fid, &wstat);
 
 	if (use_dentry)
-		p9_client_clunk(fid);
+		p9_fid_put(fid);
 
 	if (retval < 0)
 		return retval;
@@ -1261,7 +1248,7 @@ static const char *v9fs_vfs_get_link(struct dentry *dentry,
 		return ERR_CAST(fid);
 
 	st = p9_client_stat(fid);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	if (IS_ERR(st))
 		return ERR_CAST(st);
 
@@ -1308,7 +1295,7 @@ static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
 		return PTR_ERR(fid);
 
 	v9fs_invalidate_inode_attr(dir);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	return 0;
 }
 
@@ -1364,7 +1351,7 @@ v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
 		v9fs_refresh_inode(oldfid, d_inode(old_dentry));
 		v9fs_invalidate_inode_attr(dir);
 	}
-	p9_client_clunk(oldfid);
+	p9_fid_put(oldfid);
 	return retval;
 }
 

fs/9p/vfs_inode_dotl.c

@@ -238,7 +238,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	struct inode *inode;
 	struct p9_fid *fid = NULL;
 	struct v9fs_inode *v9inode;
-	struct p9_fid *dfid, *ofid, *inode_fid;
+	struct p9_fid *dfid = NULL, *ofid = NULL, *inode_fid = NULL;
 	struct v9fs_session_info *v9ses;
 	struct posix_acl *pacl = NULL, *dacl = NULL;
 	struct dentry *res = NULL;
@@ -274,7 +274,6 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	if (IS_ERR(ofid)) {
 		err = PTR_ERR(ofid);
 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
-		p9_client_clunk(dfid);
 		goto out;
 	}
 
@@ -286,38 +285,34 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	if (err) {
 		p9_debug(P9_DEBUG_VFS, "Failed to get acl values in creat %d\n",
 			 err);
-		p9_client_clunk(dfid);
-		goto error;
+		goto out;
 	}
 	err = p9_client_create_dotl(ofid, name, v9fs_open_to_dotl_flags(flags),
 				    mode, gid, &qid);
 	if (err < 0) {
 		p9_debug(P9_DEBUG_VFS, "p9_client_open_dotl failed in creat %d\n",
 			 err);
-		p9_client_clunk(dfid);
-		goto error;
+		goto out;
 	}
 	v9fs_invalidate_inode_attr(dir);
 
 	/* 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);
-		fid = NULL;
-		goto error;
+		goto out;
 	}
 	inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n", err);
-		goto error;
+		goto out;
 	}
 	/* Now set the ACL based on the default value */
 	v9fs_set_create_acl(inode, fid, dacl, pacl);
 
-	v9fs_fid_add(dentry, fid);
+	v9fs_fid_add(dentry, &fid);
 	d_instantiate(dentry, inode);
 
 	v9inode = V9FS_I(inode);
@@ -336,7 +331,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 		if (IS_ERR(inode_fid)) {
 			err = PTR_ERR(inode_fid);
 			mutex_unlock(&v9inode->v_mutex);
-			goto err_clunk_old_fid;
+			goto out;
 		}
 		v9inode->writeback_fid = (void *) inode_fid;
 	}
@@ -344,25 +339,20 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	/* Since we are opening a file, assign the open fid to the file */
 	err = finish_open(file, dentry, generic_file_open);
 	if (err)
-		goto err_clunk_old_fid;
+		goto out;
 	file->private_data = ofid;
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 		fscache_use_cookie(v9fs_inode_cookie(v9inode),
 				   file->f_mode & FMODE_WRITE);
-	v9fs_open_fid_add(inode, ofid);
+	v9fs_open_fid_add(inode, &ofid);
 	file->f_mode |= FMODE_CREATED;
 out:
+	p9_fid_put(dfid);
+	p9_fid_put(ofid);
+	p9_fid_put(fid);
 	v9fs_put_acl(dacl, pacl);
 	dput(res);
 	return err;
-
-error:
-	if (fid)
-		p9_client_clunk(fid);
-err_clunk_old_fid:
-	if (ofid)
-		p9_client_clunk(ofid);
-	goto out;
 }
 
 /**
@@ -400,7 +390,6 @@ static int v9fs_vfs_mkdir_dotl(struct user_namespace *mnt_userns,
 	if (IS_ERR(dfid)) {
 		err = PTR_ERR(dfid);
 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
-		dfid = NULL;
 		goto error;
 	}
 
@@ -422,7 +411,6 @@ static int v9fs_vfs_mkdir_dotl(struct user_namespace *mnt_userns,
 		err = PTR_ERR(fid);
 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n",
 			 err);
-		fid = NULL;
 		goto error;
 	}
 
@@ -435,10 +423,9 @@ static int v9fs_vfs_mkdir_dotl(struct user_namespace *mnt_userns,
 				 err);
 			goto error;
 		}
-		v9fs_fid_add(dentry, fid);
+		v9fs_fid_add(dentry, &fid);
 		v9fs_set_create_acl(inode, fid, dacl, pacl);
 		d_instantiate(dentry, inode);
-		fid = NULL;
 		err = 0;
 	} else {
 		/*
@@ -457,10 +444,9 @@ static int v9fs_vfs_mkdir_dotl(struct user_namespace *mnt_userns,
 	inc_nlink(dir);
 	v9fs_invalidate_inode_attr(dir);
 error:
-	if (fid)
-		p9_client_clunk(fid);
+	p9_fid_put(fid);
 	v9fs_put_acl(dacl, pacl);
-	p9_client_clunk(dfid);
+	p9_fid_put(dfid);
 	return err;
 }
 
@@ -489,7 +475,7 @@ v9fs_vfs_getattr_dotl(struct user_namespace *mnt_userns,
 	 */
 
 	st = p9_client_getattr_dotl(fid, P9_STATS_ALL);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	if (IS_ERR(st))
 		return PTR_ERR(st);
 
@@ -603,7 +589,7 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 	retval = p9_client_setattr(fid, &p9attr);
 	if (retval < 0) {
 		if (use_dentry)
-			p9_client_clunk(fid);
+			p9_fid_put(fid);
 		return retval;
 	}
 
@@ -619,12 +605,12 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 		retval = v9fs_acl_chmod(inode, fid);
 		if (retval < 0) {
 			if (use_dentry)
-				p9_client_clunk(fid);
+				p9_fid_put(fid);
 			return retval;
 		}
 	}
 	if (use_dentry)
-		p9_client_clunk(fid);
+		p9_fid_put(fid);
 
 	return 0;
 }
@@ -743,7 +729,6 @@ v9fs_vfs_symlink_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 			err = PTR_ERR(fid);
 			p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n",
 				 err);
-			fid = NULL;
 			goto error;
 		}
 
@@ -755,9 +740,8 @@ v9fs_vfs_symlink_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 				 err);
 			goto error;
 		}
-		v9fs_fid_add(dentry, fid);
+		v9fs_fid_add(dentry, &fid);
 		d_instantiate(dentry, inode);
-		fid = NULL;
 		err = 0;
 	} else {
 		/* Not in cached mode. No need to populate inode with stat */
@@ -770,10 +754,8 @@ v9fs_vfs_symlink_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 	}
 
 error:
-	if (fid)
-		p9_client_clunk(fid);
-
-	p9_client_clunk(dfid);
+	p9_fid_put(fid);
+	p9_fid_put(dfid);
 	return err;
 }
 
@@ -803,14 +785,14 @@ v9fs_vfs_link_dotl(struct dentry *old_dentry, struct inode *dir,
 
 	oldfid = v9fs_fid_lookup(old_dentry);
 	if (IS_ERR(oldfid)) {
-		p9_client_clunk(dfid);
+		p9_fid_put(dfid);
 		return PTR_ERR(oldfid);
 	}
 
 	err = p9_client_link(dfid, oldfid, dentry->d_name.name);
 
-	p9_client_clunk(dfid);
-	p9_client_clunk(oldfid);
+	p9_fid_put(dfid);
+	p9_fid_put(oldfid);
 	if (err < 0) {
 		p9_debug(P9_DEBUG_VFS, "p9_client_link failed %d\n", err);
 		return err;
@@ -826,7 +808,7 @@ v9fs_vfs_link_dotl(struct dentry *old_dentry, struct inode *dir,
 			return PTR_ERR(fid);
 
 		v9fs_refresh_inode_dotl(fid, d_inode(old_dentry));
-		p9_client_clunk(fid);
+		p9_fid_put(fid);
 	}
 	ihold(d_inode(old_dentry));
 	d_instantiate(dentry, d_inode(old_dentry));
@@ -866,7 +848,6 @@ v9fs_vfs_mknod_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 	if (IS_ERR(dfid)) {
 		err = PTR_ERR(dfid);
 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
-		dfid = NULL;
 		goto error;
 	}
 
@@ -891,7 +872,6 @@ v9fs_vfs_mknod_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 		err = PTR_ERR(fid);
 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n",
 			 err);
-		fid = NULL;
 		goto error;
 	}
 
@@ -905,9 +885,8 @@ v9fs_vfs_mknod_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 			goto error;
 		}
 		v9fs_set_create_acl(inode, fid, dacl, pacl);
-		v9fs_fid_add(dentry, fid);
+		v9fs_fid_add(dentry, &fid);
 		d_instantiate(dentry, inode);
-		fid = NULL;
 		err = 0;
 	} else {
 		/*
@@ -923,10 +902,9 @@ v9fs_vfs_mknod_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 		d_instantiate(dentry, inode);
 	}
 error:
-	if (fid)
-		p9_client_clunk(fid);
+	p9_fid_put(fid);
 	v9fs_put_acl(dacl, pacl);
-	p9_client_clunk(dfid);
+	p9_fid_put(dfid);
 
 	return err;
 }
@@ -956,7 +934,7 @@ v9fs_vfs_get_link_dotl(struct dentry *dentry,
 	if (IS_ERR(fid))
 		return ERR_CAST(fid);
 	retval = p9_client_readlink(fid, &target);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	if (retval)
 		return ERR_PTR(retval);
 	set_delayed_call(done, kfree_link, target);

fs/9p/vfs_super.c

@@ -184,13 +184,13 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
 	retval = v9fs_get_acl(inode, fid);
 	if (retval)
 		goto release_sb;
-	v9fs_fid_add(root, fid);
+	v9fs_fid_add(root, &fid);
 
 	p9_debug(P9_DEBUG_VFS, " simple set mount, return 0\n");
 	return dget(sb->s_root);
 
 clunk_fid:
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	v9fs_session_close(v9ses);
 free_session:
 	kfree(v9ses);
@@ -203,7 +203,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
 	 * attached the fid to dentry so it won't get clunked
 	 * automatically.
 	 */
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	deactivate_locked_super(sb);
 	return ERR_PTR(retval);
 }
@@ -270,7 +270,7 @@ static int v9fs_statfs(struct dentry *dentry, struct kstatfs *buf)
 	}
 	res = simple_statfs(dentry, buf);
 done:
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	return res;
 }
 

fs/9p/xattr.c

@@ -44,7 +44,7 @@ ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
 		if (err)
 			retval = err;
 	}
-	p9_client_clunk(attr_fid);
+	p9_fid_put(attr_fid);
 	return retval;
 }
 
@@ -71,7 +71,7 @@ ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
 	if (IS_ERR(fid))
 		return PTR_ERR(fid);
 	ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 
 	return ret;
 }
@@ -98,7 +98,7 @@ int v9fs_xattr_set(struct dentry *dentry, const char *name,
 	if (IS_ERR(fid))
 		return PTR_ERR(fid);
 	ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
-	p9_client_clunk(fid);
+	p9_fid_put(fid);
 	return ret;
 }
 
@@ -128,7 +128,7 @@ int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 			 retval);
 	else
 		p9_client_write(fid, 0, &from, &retval);
-	err = p9_client_clunk(fid);
+	err = p9_fid_put(fid);
 	if (!retval && err)
 		retval = err;
 	return retval;

include/net/9p/client.h

@@ -11,6 +11,7 @@
 
 #include <linux/utsname.h>
 #include <linux/idr.h>
+#include <linux/tracepoint-defs.h>
 
 /* Number of requests per row */
 #define P9_ROW_MAXTAG 255
@@ -76,7 +77,7 @@ enum p9_req_status_t {
 struct p9_req_t {
 	int status;
 	int t_err;
-	struct kref refcount;
+	refcount_t refcount;
 	wait_queue_head_t wq;
 	struct p9_fcall tc;
 	struct p9_fcall rc;
@@ -227,15 +228,55 @@ struct p9_req_t *p9_tag_lookup(struct p9_client *c, u16 tag);
 
 static inline void p9_req_get(struct p9_req_t *r)
 {
-	kref_get(&r->refcount);
+	refcount_inc(&r->refcount);
 }
 
 static inline int p9_req_try_get(struct p9_req_t *r)
 {
-	return kref_get_unless_zero(&r->refcount);
+	return refcount_inc_not_zero(&r->refcount);
 }
 
-int p9_req_put(struct p9_req_t *r);
+int p9_req_put(struct p9_client *c, struct p9_req_t *r);
+
+/* We cannot have the real tracepoints in header files,
+ * use a wrapper function */
+DECLARE_TRACEPOINT(9p_fid_ref);
+void do_trace_9p_fid_get(struct p9_fid *fid);
+void do_trace_9p_fid_put(struct p9_fid *fid);
+
+/* fid reference counting helpers:
+ *  - fids used for any length of time should always be referenced through
+ *    p9_fid_get(), and released with p9_fid_put()
+ *  - v9fs_fid_lookup() or similar will automatically call get for you
+ *    and also require a put
+ *  - the *_fid_add() helpers will stash the fid in the inode,
+ *    at which point it is the responsibility of evict_inode()
+ *    to call the put
+ *  - the last put will automatically send a clunk to the server
+ */
+static inline struct p9_fid *p9_fid_get(struct p9_fid *fid)
+{
+	if (tracepoint_enabled(9p_fid_ref))
+		do_trace_9p_fid_get(fid);
+
+	refcount_inc(&fid->count);
+
+	return fid;
+}
+
+static inline int p9_fid_put(struct p9_fid *fid)
+{
+	if (!fid || IS_ERR(fid))
+		return 0;
+
+	if (tracepoint_enabled(9p_fid_ref))
+		do_trace_9p_fid_put(fid);
+
+	if (!refcount_dec_and_test(&fid->count))
+		return 0;
+
+	return p9_client_clunk(fid);
+}
 
 void p9_client_cb(struct p9_client *c, struct p9_req_t *req, int status);
 

include/trace/events/9p.h

@@ -77,6 +77,13 @@
 		EM( P9_TWSTAT,		"P9_TWSTAT" )			\
 		EMe(P9_RWSTAT,		"P9_RWSTAT" )
 
+
+#define P9_FID_REFTYPE							\
+		EM( P9_FID_REF_CREATE,	"create " )			\
+		EM( P9_FID_REF_GET,	"get    " )			\
+		EM( P9_FID_REF_PUT,	"put    " )			\
+		EMe(P9_FID_REF_DESTROY,	"destroy" )
+
 /* Define EM() to export the enums to userspace via TRACE_DEFINE_ENUM() */
 #undef EM
 #undef EMe
@@ -84,6 +91,21 @@
 #define EMe(a, b)	TRACE_DEFINE_ENUM(a);
 
 P9_MSG_T
+P9_FID_REFTYPE
+
+/* And also use EM/EMe to define helper enums -- once */
+#ifndef __9P_DECLARE_TRACE_ENUMS_ONLY_ONCE
+#define __9P_DECLARE_TRACE_ENUMS_ONLY_ONCE
+#undef EM
+#undef EMe
+#define EM(a, b)	a,
+#define EMe(a, b)	a
+
+enum p9_fid_reftype {
+	P9_FID_REFTYPE
+} __mode(byte);
+
+#endif
 
 /*
  * Now redefine the EM() and EMe() macros to map the enums to the strings
@@ -96,6 +118,8 @@ P9_MSG_T
 
 #define show_9p_op(type)						\
 	__print_symbolic(type, P9_MSG_T)
+#define show_9p_fid_reftype(type)					\
+	__print_symbolic(type, P9_FID_REFTYPE)
 
 TRACE_EVENT(9p_client_req,
 	    TP_PROTO(struct p9_client *clnt, int8_t type, int tag),
@@ -168,6 +192,30 @@ TRACE_EVENT(9p_protocol_dump,
 		      __entry->tag, 0, __entry->line, 16, __entry->line + 16)
  );
 
+
+TRACE_EVENT(9p_fid_ref,
+	    TP_PROTO(struct p9_fid *fid, __u8 type),
+
+	    TP_ARGS(fid, type),
+
+	    TP_STRUCT__entry(
+		    __field(	int,	fid		)
+		    __field(	int,	refcount	)
+		    __field(	__u8, type	)
+		    ),
+
+	    TP_fast_assign(
+		    __entry->fid = fid->fid;
+		    __entry->refcount = refcount_read(&fid->count);
+		    __entry->type = type;
+		    ),
+
+	    TP_printk("%s fid %d, refcount %d",
+		      show_9p_fid_reftype(__entry->type),
+		      __entry->fid, __entry->refcount)
+);
+
+
 #endif /* _TRACE_9P_H */
 
 /* This part must be outside protection */

net/9p/trans_fd.c

@@ -343,6 +343,7 @@ static void p9_read_work(struct work_struct *work)
 			p9_debug(P9_DEBUG_ERROR,
 				 "No recv fcall for tag %d (req %p), disconnecting!\n",
 				 m->rc.tag, m->rreq);
+			p9_req_put(m->client, m->rreq);
 			m->rreq = NULL;
 			err = -EIO;
 			goto error;
@@ -378,7 +379,7 @@ static void p9_read_work(struct work_struct *work)
 		m->rc.sdata = NULL;
 		m->rc.offset = 0;
 		m->rc.capacity = 0;
-		p9_req_put(m->rreq);
+		p9_req_put(m->client, m->rreq);
 		m->rreq = NULL;
 	}
 
@@ -492,7 +493,7 @@ static void p9_write_work(struct work_struct *work)
 	m->wpos += err;
 	if (m->wpos == m->wsize) {
 		m->wpos = m->wsize = 0;
-		p9_req_put(m->wreq);
+		p9_req_put(m->client, m->wreq);
 		m->wreq = NULL;
 	}
 
@@ -695,7 +696,7 @@ static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req)
 	if (req->status == REQ_STATUS_UNSENT) {
 		list_del(&req->req_list);
 		req->status = REQ_STATUS_FLSHD;
-		p9_req_put(req);
+		p9_req_put(client, req);
 		ret = 0;
 	}
 	spin_unlock(&client->lock);
@@ -722,7 +723,7 @@ static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req)
 	list_del(&req->req_list);
 	req->status = REQ_STATUS_FLSHD;
 	spin_unlock(&client->lock);
-	p9_req_put(req);
+	p9_req_put(client, req);
 
 	return 0;
 }
@@ -883,12 +884,12 @@ static void p9_conn_destroy(struct p9_conn *m)
 	p9_mux_poll_stop(m);
 	cancel_work_sync(&m->rq);
 	if (m->rreq) {
-		p9_req_put(m->rreq);
+		p9_req_put(m->client, m->rreq);
 		m->rreq = NULL;
 	}
 	cancel_work_sync(&m->wq);
 	if (m->wreq) {
-		p9_req_put(m->wreq);
+		p9_req_put(m->client, m->wreq);
 		m->wreq = NULL;
 	}
 

net/9p/trans_rdma.c

@@ -350,7 +350,7 @@ send_done(struct ib_cq *cq, struct ib_wc *wc)
 			    c->busa, c->req->tc.size,
 			    DMA_TO_DEVICE);
 	up(&rdma->sq_sem);
-	p9_req_put(c->req);
+	p9_req_put(client, c->req);
 	kfree(c);
 }
 

net/9p/trans_virtio.c

@@ -199,7 +199,7 @@ static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
 /* Reply won't come, so drop req ref */
 static int p9_virtio_cancelled(struct p9_client *client, struct p9_req_t *req)
 {
-	p9_req_put(req);
+	p9_req_put(client, req);
 	return 0;
 }
 
@@ -557,7 +557,7 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
 	kvfree(out_pages);
 	if (!kicked) {
 		/* reply won't come */
-		p9_req_put(req);
+		p9_req_put(client, req);
 	}
 	return err;
 }

net/9p/trans_xen.c

@@ -163,7 +163,7 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
 	ring->intf->out_prod = prod;
 	spin_unlock_irqrestore(&ring->lock, flags);
 	notify_remote_via_irq(ring->irq);
-	p9_req_put(p9_req);
+	p9_req_put(client, p9_req);
 
 	return 0;
 }