From nobody Sat Oct 4 01:42:18 2025 Received: from neil.brown.name (neil.brown.name [103.29.64.221]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2CD8D28F4; Fri, 22 Aug 2025 00:11:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.29.64.221 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755821485; cv=none; b=KbLpQnzGkMlCuyvaeKLs955Nv5/E1htCbe0mqnO+6aITf91Z81qwzJgNpObrepcXJbpNBYZNEmwZhnY5haNK4uXhGQSBkkuws3DTeCyGiV9V9s1b5cBy6ke8NgaVeU/5vCfS+KyEK7ahMyqPE8Z9ltDd2XnonA9nP3xAy0Ej1Ac= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755821485; c=relaxed/simple; bh=Xm0u+m9SfyNz7nxDbcIx4KNkfWnzX+pGkAKYdilO22I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wc3NJxa2J7jFhfqWqGINO0EkfI4fAjSEw4I0ES4aBMacOWuY9i8AQSr4QHTs9FXA2sUobtz3MiLRH+HqqoNcFu5j1tLJO8uBBeHOsIS6hjq5fOvAA4dqqv/jYTyWJioZTMffMh6QyEbe7XpQSCvuZj3qCYkvuUPG0hcgy0qBElU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=brown.name; spf=pass smtp.mailfrom=neil.brown.name; arc=none smtp.client-ip=103.29.64.221 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=brown.name Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=neil.brown.name Received: from 196.186.233.220.static.exetel.com.au ([220.233.186.196] helo=home.neil.brown.name) by neil.brown.name with esmtp (Exim 4.95) (envelope-from ) id 1upFNB-006nav-13; Fri, 22 Aug 2025 00:11:14 +0000 From: NeilBrown To: Alexander Viro , Christian Brauner Cc: Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 07/16] VFS: introduce end_dirop() and end_dirop_mkdir() Date: Fri, 22 Aug 2025 10:00:25 +1000 Message-ID: <20250822000818.1086550-8-neil@brown.name> X-Mailer: git-send-email 2.50.0.107.gf914562f5916.dirty In-Reply-To: <20250822000818.1086550-1-neil@brown.name> References: <20250822000818.1086550-1-neil@brown.name> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" end_dirop() is the partner of start_dirop(). It drops the lock and releases the reference on the dentry. It *is* exported and can be used by all callers. As vfs_mkdir() drops the dentry on error we cannot use end_dirop() as that won't unlock when the dentry IS_ERR(). For those cases we have end_dirop_mkdir(). end_dirop() can always be called on the result of start_dirop(), but not after vfs_mkdir(). end_dirop_mkdir() can only be called on the result of start_dirop() if that was not an error, and can calso be called on the result of vfs_mkdir(). We we change vfs_mkdir() to drop the lock when it drops the dentry, end_dirop_mkdir() can be discarded. Signed-off-by: NeilBrown --- fs/namei.c | 50 +++++++++++++++++++++++++++++++++++-------- include/linux/namei.h | 3 +++ 2 files changed, 44 insertions(+), 9 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 4f1eddaff63f..8121550f20aa 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2778,6 +2778,43 @@ static struct dentry *start_dirop(struct dentry *par= ent, struct qstr *name, return dentry; } =20 +/** + * end_dirop - signal completion of a dirop + * @de - the dentry which was returned by start_dirop or similar. + * + * If the de is an error, nothing happens. Otherwise any lock taken to + * protect the dentry is dropped and the dentry itself is release (dput()). + */ +void end_dirop(struct dentry *de) +{ + if (!IS_ERR(de)) { + inode_unlock(de->d_parent->d_inode); + dput(de); + } +} +EXPORT_SYMBOL(end_dirop); + +/** + * end_dirop_mkdir - signal completion of a dirop which could have been vf= s_mkdir + * @de - the dentry which was returned by start_dirop or similar. + * @parent - the parent in which the mkdir happened. + * + * Because vfs_mkdir() dput()s the dentry on failure, end_dirop() cannot be + * used with it. Instead this function must be used, and it must not be c= aller + * if the original lookup failed. + * + * If de is an error the parent is unlocked, else this behaves the same as + * end_dirop(). + */ +void end_dirop_mkdir(struct dentry *de, struct dentry *parent) +{ + if (IS_ERR(de)) + inode_unlock(parent->d_inode); + else + end_dirop(de); +} +EXPORT_SYMBOL(end_dirop_mkdir); + /* does lookup, returns the object with parent locked */ static struct dentry *__kern_path_locked(int dfd, struct filename *name, s= truct path *path) { @@ -4174,9 +4211,8 @@ static struct dentry *filename_create(int dfd, struct= filename *name, =20 return dentry; fail: - dput(dentry); + end_dirop(dentry); dentry =3D ERR_PTR(error); - inode_unlock(path->dentry->d_inode); out_drop_write: if (!error) mnt_drop_write(path->mnt); @@ -4198,9 +4234,7 @@ EXPORT_SYMBOL(kern_path_create); =20 void done_path_create(struct path *path, struct dentry *dentry) { - if (!IS_ERR(dentry)) - dput(dentry); - inode_unlock(path->dentry->d_inode); + end_dirop_mkdir(dentry, path->dentry); mnt_drop_write(path->mnt); path_put(path); } @@ -4540,8 +4574,7 @@ int do_rmdir(int dfd, struct filename *name) goto exit4; error =3D vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode, dentry); exit4: - dput(dentry); - inode_unlock(path.dentry->d_inode); + end_dirop(dentry); exit3: mnt_drop_write(path.mnt); exit2: @@ -4674,8 +4707,7 @@ int do_unlinkat(int dfd, struct filename *name) error =3D vfs_unlink(mnt_idmap(path.mnt), path.dentry->d_inode, dentry, &delegated_inode); exit3: - dput(dentry); - inode_unlock(path.dentry->d_inode); + end_dirop(dentry); } if (inode) iput(inode); /* truncate the inode here */ diff --git a/include/linux/namei.h b/include/linux/namei.h index 5d085428e471..bd0cba118540 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -81,6 +81,9 @@ struct dentry *lookup_one_positive_unlocked(struct mnt_id= map *idmap, struct qstr *name, struct dentry *base); =20 +void end_dirop(struct dentry *de); +void end_dirop_mkdir(struct dentry *de, struct dentry *parent); + extern int follow_down_one(struct path *); extern int follow_down(struct path *path, unsigned int flags); extern int follow_up(struct path *); --=20 2.50.0.107.gf914562f5916.dirty