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From:   Dominique Martinet <asmadeus@codewreck.org>
To:     Christian Schoenebeck <linux_oss@crudebyte.com>,
        Tyler Hicks <tyhicks@linux.microsoft.com>,
        Eric Van Hensbergen <ericvh@gmail.com>,
        Latchesar Ionkov <lucho@ionkov.net>,
        Dominique Martinet <asmadeus@codewreck.org>
Cc:     v9fs-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: [PATCH 06/06] 9p fid refcount: cleanup p9_fid_put calls
Date:   Sun, 12 Jun 2022 17:53:29 +0900
Message-Id: <20220612085330.1451496-7-asmadeus@codewreck.org>
In-Reply-To: <20220612085330.1451496-1-asmadeus@codewreck.org>
References: <20220612085330.1451496-1-asmadeus@codewreck.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Simplify p9_fid_put cleanup path in many 9p functions since the function
is noop on null or error fids.

Also make the *_add_fid() helpers "steal" the fid by nulling its
pointer, so put after them will be noop.

This should lead to no change of behaviour

Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
---
 fs/9p/fid.c            | 24 +++++++++++------
 fs/9p/fid.h            |  4 +--
 fs/9p/vfs_file.c       |  5 ++--
 fs/9p/vfs_inode.c      | 61 +++++++++++++++++-------------------------
 fs/9p/vfs_inode_dotl.c | 58 +++++++++++++--------------------------
 fs/9p/vfs_super.c      |  2 +-
 6 files changed, 64 insertions(+), 90 deletions(-)

diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index d792499349c4..289a85eae2ae 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -31,11 +31,15 @@ static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
  * @fid: fid to add
  *
  */
-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;
 }
 
 /**
@@ -72,11 +76,15 @@ static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid)
  *
  */
 
-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;
 }
 
 
@@ -189,13 +197,13 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
 		else
 			uname = v9ses->uname;
 
-		root_fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
-					    v9ses->aname);
-		if (IS_ERR(root_fid))
-			return root_fid;
+		fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
+				       v9ses->aname);
+		if (IS_ERR(fid))
+			return fid;
 
-		p9_fid_get(root_fid);
-		v9fs_fid_add(dentry->d_sb->s_root, 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)
diff --git a/fs/9p/fid.h b/fs/9p/fid.h
index 3168dfad510e..8a4e8cd12ca2 100644
--- a/fs/9p/fid.h
+++ b/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);
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 8276f3af35d7..aec43ba83799 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -69,9 +69,10 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 		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 &&
@@ -95,7 +96,7 @@ 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_fid_put(file->private_data);
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 38186d1a1440..1b11a92208fd 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -398,10 +398,8 @@ 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_fid_put(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)
@@ -632,14 +630,12 @@ 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_fid_put(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_fid_put(dfid);
 		goto error;
 	}
 
@@ -650,8 +646,6 @@ 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_fid_put(dfid);
 			goto error;
 		}
 		/*
@@ -662,21 +656,17 @@ 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_fid_put(dfid);
 			goto error;
 		}
-		v9fs_fid_add(dentry, fid);
+		v9fs_fid_add(dentry, &fid);
 		d_instantiate(dentry, inode);
 	}
 	p9_fid_put(dfid);
 	return ofid;
 error:
-	if (ofid)
-		p9_fid_put(ofid);
-
-	if (fid)
-		p9_fid_put(fid);
-
+	p9_fid_put(dfid);
+	p9_fid_put(ofid);
+	p9_fid_put(fid);
 	return ERR_PTR(err);
 }
 
@@ -803,9 +793,9 @@ 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_fid_put(fid);
 	}
@@ -846,7 +836,6 @@ 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;
 	}
 
@@ -881,7 +870,7 @@ 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:
@@ -889,8 +878,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	return err;
 
 error:
-	if (fid)
-		p9_fid_put(fid);
+	p9_fid_put(fid);
 	goto out;
 }
 
@@ -938,9 +926,9 @@ 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)
@@ -957,21 +945,22 @@ 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_fid_put(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_fid_put(dfid);
+	dfid = NULL;
 
 	if (IS_ERR(newdirfid)) {
 		retval = PTR_ERR(newdirfid);
-		goto clunk_olddir;
+		goto error;
 	}
 
 	down_write(&v9ses->rename_sem);
@@ -982,7 +971,7 @@ 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) {
 		/*
@@ -991,14 +980,14 @@ 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))
@@ -1019,12 +1008,10 @@ v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 		d_move(old_dentry, new_dentry);
 	}
 	up_write(&v9ses->rename_sem);
+
+error:
 	p9_fid_put(newdirfid);
-
-clunk_olddir:
 	p9_fid_put(olddirfid);
-
-done:
 	p9_fid_put(oldfid);
 	return retval;
 }
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 09b124fe349c..5cfa4b4f070f 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/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_fid_put(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_fid_put(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_fid_put(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_fid_put(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_fid_put(fid);
-err_clunk_old_fid:
-	if (ofid)
-		p9_fid_put(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 {
 		/*
@@ -457,8 +444,7 @@ static int v9fs_vfs_mkdir_dotl(struct user_namespace *mnt_userns,
 	inc_nlink(dir);
 	v9fs_invalidate_inode_attr(dir);
 error:
-	if (fid)
-		p9_fid_put(fid);
+	p9_fid_put(fid);
 	v9fs_put_acl(dacl, pacl);
 	p9_fid_put(dfid);
 	return err;
@@ -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 */
@@ -770,9 +754,7 @@ v9fs_vfs_symlink_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 	}
 
 error:
-	if (fid)
-		p9_fid_put(fid);
-
+	p9_fid_put(fid);
 	p9_fid_put(dfid);
 	return err;
 }
@@ -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 {
 		/*
@@ -923,8 +902,7 @@ v9fs_vfs_mknod_dotl(struct user_namespace *mnt_userns, struct inode *dir,
 		d_instantiate(dentry, inode);
 	}
 error:
-	if (fid)
-		p9_fid_put(fid);
+	p9_fid_put(fid);
 	v9fs_put_acl(dacl, pacl);
 	p9_fid_put(dfid);
 
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index bf350fad9500..2d9ee073d12c 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -184,7 +184,7 @@ 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);
-- 
2.35.1