From nobody Wed Dec 17 15:34:45 2025 Received: from mail-lj1-f179.google.com (mail-lj1-f179.google.com [209.85.208.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 314F36E61B; Tue, 7 May 2024 09:37:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715074650; cv=none; b=jciFh5BN+8nBmaLJYNsBBPjQGGApOXTNJZPMf82ugpyyuLmEr6XjyF2NcChcLGbZkLqJ0TXURAiRzNzcLZoJjaNG9p7gT2uT4t1b+8N63KgqFeFlzxVWp5axfewZb9y4jH6I7RdqYxqszDWYDnMdW+VFGJFFIUxGeWoey36cRlY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715074650; c=relaxed/simple; bh=RM8ecK6sFi/vogUypaZKYRK7sq1fWu1V3XPe+SMN4ns=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=dUvTuldosdWabK9MiRXEMo0prrZpdWt+hIv+smMO2qZKktAz0CWVb43ddfUwAVbHBmD6czQNM7YR2eJMaCH9P9VurJx7nZdkU3+JnWrxkb5lCAPiBj/AOe6nyJmaC+hfvu4mXprKObmMGdwcdC/0UH7yyMGgw7gfAg2QdJJrdTc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=byqIhEGF; arc=none smtp.client-ip=209.85.208.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="byqIhEGF" Received: by mail-lj1-f179.google.com with SMTP id 38308e7fff4ca-2e3e1ad0b19so8278301fa.0; Tue, 07 May 2024 02:37:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1715074647; x=1715679447; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=MjEE8E6ryWIUb7zrvHx2Xl9/PlP43pMdw3xy20SDzeY=; b=byqIhEGF+AYkPMr0Eq4GG4rsUCv9z/xTtt5tk9L5hLxpyiDKoUOzf8pKHsYEV8e6zw Nc6Z4nMZe0n52wPuixrNyoeRR0UfZGWiVCT2pRrXh8qLDwZTtB1JnEwlqbHWzmiCwoYh 5U22gpjZXy7qgS0wMdwtK2aXwklHM5YZ62SwiRs/Z1II2VAC7Vff1FLlUJMFQpmgVFZI jRKED76nDGdsYn4x5c+MxfI26aeqYCEBULykQ7saHsYJuUmt7ekJ1bAitia2eMmQS9W9 sUyUrD/mEs15CE9S7o61oIYIjBM3RkLTeCHb9rcxIM3PT7SCDeuiCZaTQfkbmJruRtOl qW9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1715074647; x=1715679447; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=MjEE8E6ryWIUb7zrvHx2Xl9/PlP43pMdw3xy20SDzeY=; b=jENif85rEyobqZmEsrAmVEN02iqnQrdFwxD6fyHhirki+BQhD+UE/GSf53TjHPFIVq M1eBT1yOTdAPcz8Ou5+uKONJifc9FD6iKA8zUQwFUWM/HGVj28tNOaX1lu8wi8/W8vmL thIDkuZSnd0Ry5xaFp/c0hlVpm0Z8F+K4J35hhvTTACdLA2+8yaCPNHCByIi34yO3wAz 2VkADhPZ+GcmPozVbcwl1Q12sHHDKUIf+mxdphABm0u5QMvbWAqvWV8Wr/wrxa39TbTO qL7BJEijzBSkA7VoHYpAGH5Sf5cRcTQYSLpREYAj2ANmBv70HnMRuz6Mw25jJV9/vIC8 lPvg== X-Forwarded-Encrypted: i=1; AJvYcCXdFNUKnvMiF4mxWJ5+oh+ln9X6F5p6+8Uyys5benbxl6kY+CaEbVqU8+9odDbkKP7gqYX+MY8FkQmlQMWMzdKLV8hMTMkD5QPPsqAemN3Gi1oQKXI7C4+fGZ0NoZZtXZTmZd/WD7cn7PazAg== X-Gm-Message-State: AOJu0YxYOJrNz4LvDMc2MGVVuSaqZ7nDBbN+Q9ZtPk2Cd865Jb0wMlZf nJNWapnNqNvQf+6qUUlr8pGa0NiOu3UZyu6gLECGW+MH7j65ej3Z/hD60Q== X-Google-Smtp-Source: AGHT+IG4kP44y9LBnB6Gb0NRCn1Q1gM+S/ffoRVzDyB2qwPMZ8jMbaTmgJKxOHWHznUlcueebE6gcA== X-Received: by 2002:a2e:2406:0:b0:2e2:5fd:7030 with SMTP id k6-20020a2e2406000000b002e205fd7030mr7918797ljk.13.1715074647042; Tue, 07 May 2024 02:37:27 -0700 (PDT) Received: from f.. (cst-prg-20-30.cust.vodafone.cz. [46.135.20.30]) by smtp.gmail.com with ESMTPSA id k8-20020a05600c1c8800b00418a6d62ad0sm22891128wms.34.2024.05.07.02.37.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 May 2024 02:37:26 -0700 (PDT) From: Mateusz Guzik To: ebiggers@kernel.org Cc: tytso@mit.edu, jaegeuk@kernel.org, linux-kernel@vger.kernel.org, linux-fscrypt@vger.kernel.org, Mateusz Guzik Subject: [PATCH] fscrypto: try to avoid refing parent dentry in fscrypt_file_open Date: Tue, 7 May 2024 11:36:53 +0200 Message-ID: <20240507093653.297402-1-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 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" Merely checking if the directory is encrypted happens for every open when using ext4, at the moment refing and unrefing the parent, costing 2 atomics and serializing opens of different files. The most common case of encryption not being used can be checked for with RCU instead. Sample result from open1_processes -t 20 ("Separate file open/close") from will-it-scale on Sapphire Rapids (ops/s): before: 12539898 after: 25575494 (+103%) Arguably a vfs helper would be nice here. Signed-off-by: Mateusz Guzik --- fs/crypto/hooks.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 104771c3d3f6..16328ec14266 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -30,21 +30,32 @@ int fscrypt_file_open(struct inode *inode, struct file *filp) { int err; - struct dentry *dir; + struct dentry *dentry, *dentry_parent; + struct inode *inode_parent; =20 err =3D fscrypt_require_key(inode); if (err) return err; =20 - dir =3D dget_parent(file_dentry(filp)); - if (IS_ENCRYPTED(d_inode(dir)) && - !fscrypt_has_permitted_context(d_inode(dir), inode)) { + dentry =3D file_dentry(filp); + rcu_read_lock(); + dentry_parent =3D READ_ONCE(dentry->d_parent); + inode_parent =3D d_inode_rcu(dentry_parent); + if (inode_parent !=3D NULL && !IS_ENCRYPTED(inode_parent)) { + rcu_read_unlock(); + return 0; + } + rcu_read_unlock(); + + dentry_parent =3D dget_parent(dentry); + if (IS_ENCRYPTED(d_inode(dentry_parent)) && + !fscrypt_has_permitted_context(d_inode(dentry_parent), inode)) { fscrypt_warn(inode, "Inconsistent encryption context (parent directory: %lu)", - d_inode(dir)->i_ino); + d_inode(dentry_parent)->i_ino); err =3D -EPERM; } - dput(dir); + dput(dentry_parent); return err; } EXPORT_SYMBOL_GPL(fscrypt_file_open); --=20 2.39.2