From patchwork Tue Jun 7 10:08:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12871686 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BB34C43334 for ; Tue, 7 Jun 2022 10:09:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240156AbiFGKJK (ORCPT ); Tue, 7 Jun 2022 06:09:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231395AbiFGKJK (ORCPT ); Tue, 7 Jun 2022 06:09:10 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E17B97E1C2; Tue, 7 Jun 2022 03:09:08 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 8C802B81ED8; Tue, 7 Jun 2022 10:09:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48430C34119; Tue, 7 Jun 2022 10:09:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654596546; bh=xaJ3XEVmM6xTga7+v67FnseXxdXUgT36op+OI2WndPE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kJ0nrtIX9XMJyc1HZUJ9MkWIktv1umLVymLhDNAKzC4nWFkjIE3B+ciVl2PXYp3tY sIqdslVUtGOC5jxjefZBuCN7nHTw/ejEIZ8cp9FonkJSfLHrzFQv2EOBQmTxiRhKr3 7EvHjy95PZCe4ftvnQ9LQUu06HCeGz9h7yBwazC7dHsbKZvUAqDXcl96wNhfUeSlGh YTGJ0e2fkFathfAgtffN1xbOsr00XKIyvG5saYABqwVFXZWp7oMMvg20qH7oAvS2ND TxJkzuXQvQACHSqPpNQu7OLGsHocHS2JYndnI8oE7ZAiiqwH6ar5tbniXF4/+QIfyB XIQOuoh56RE0Q== From: Christian Brauner To: Greg KH Cc: Christian Brauner , Amir Goldstein , Miklos Szeredi , Giuseppe Scrivano , Christoph Hellwig , linux-fsdevel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 5.15.y 1/2] fs: add two trivial lookup helpers Date: Tue, 7 Jun 2022 12:08:38 +0200 Message-Id: <20220607100840.1686673-1-brauner@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <165451869522688@kroah.com> References: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5734; h=from:subject; bh=xaJ3XEVmM6xTga7+v67FnseXxdXUgT36op+OI2WndPE=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSTNV15Q8vfH1XJpsb1+Ao0K+fY/lvQv6rnkovx9+u/AFWpf ZleIdJSyMIhxMciKKbI4tJuEyy3nqdhslKkBM4eVCWQIAxenAExkuR7D/xgxfl2zFKv5S8+sP9K6hn /Zv38NTQyX0hQfbY9R++kxU5OR4RhPxuHtnLlCq3nNtYpK35TWx9cktCXY7Lw1o3u67GF9JgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Similar to the addition of lookup_one() add a version of lookup_one_unlocked() and lookup_one_positive_unlocked() that take idmapped mounts into account. This is required to port overlay to support idmapped base layers. Cc: Tested-by: Giuseppe Scrivano Reviewed-by: Amir Goldstein Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi Signed-off-by: Christian Brauner (Microsoft) --- fs/namei.c | 70 ++++++++++++++++++++++++++++++++++++------- include/linux/namei.h | 6 ++++ 2 files changed, 66 insertions(+), 10 deletions(-) base-commit: 207ca688162d4d77129981a8b4352114b97a52b5 diff --git a/fs/namei.c b/fs/namei.c index 8882a70dc119..2ea15d043412 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2718,7 +2718,8 @@ struct dentry *lookup_one(struct user_namespace *mnt_userns, const char *name, EXPORT_SYMBOL(lookup_one); /** - * lookup_one_len_unlocked - filesystem helper to lookup single pathname component + * lookup_one_unlocked - filesystem helper to lookup single pathname component + * @mnt_userns: idmapping of the mount the lookup is performed from * @name: pathname component to lookup * @base: base directory to lookup from * @len: maximum length @len should be interpreted to @@ -2729,14 +2730,15 @@ EXPORT_SYMBOL(lookup_one); * Unlike lookup_one_len, it should be called without the parent * i_mutex held, and will take the i_mutex itself if necessary. */ -struct dentry *lookup_one_len_unlocked(const char *name, - struct dentry *base, int len) +struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns, + const char *name, struct dentry *base, + int len) { struct qstr this; int err; struct dentry *ret; - err = lookup_one_common(&init_user_ns, name, base, len, &this); + err = lookup_one_common(mnt_userns, name, base, len, &this); if (err) return ERR_PTR(err); @@ -2745,6 +2747,59 @@ struct dentry *lookup_one_len_unlocked(const char *name, ret = lookup_slow(&this, base, 0); return ret; } +EXPORT_SYMBOL(lookup_one_unlocked); + +/** + * lookup_one_positive_unlocked - filesystem helper to lookup single + * pathname component + * @mnt_userns: idmapping of the mount the lookup is performed from + * @name: pathname component to lookup + * @base: base directory to lookup from + * @len: maximum length @len should be interpreted to + * + * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns + * known positive or ERR_PTR(). This is what most of the users want. + * + * Note that pinned negative with unlocked parent _can_ become positive at any + * time, so callers of lookup_one_unlocked() need to be very careful; pinned + * positives have >d_inode stable, so this one avoids such problems. + * + * Note that this routine is purely a helper for filesystem usage and should + * not be called by generic code. + * + * The helper should be called without i_mutex held. + */ +struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns, + const char *name, + struct dentry *base, int len) +{ + struct dentry *ret = lookup_one_unlocked(mnt_userns, name, base, len); + + if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { + dput(ret); + ret = ERR_PTR(-ENOENT); + } + return ret; +} +EXPORT_SYMBOL(lookup_one_positive_unlocked); + +/** + * lookup_one_len_unlocked - filesystem helper to lookup single pathname component + * @name: pathname component to lookup + * @base: base directory to lookup from + * @len: maximum length @len should be interpreted to + * + * Note that this routine is purely a helper for filesystem usage and should + * not be called by generic code. + * + * Unlike lookup_one_len, it should be called without the parent + * i_mutex held, and will take the i_mutex itself if necessary. + */ +struct dentry *lookup_one_len_unlocked(const char *name, + struct dentry *base, int len) +{ + return lookup_one_unlocked(&init_user_ns, name, base, len); +} EXPORT_SYMBOL(lookup_one_len_unlocked); /* @@ -2758,12 +2813,7 @@ EXPORT_SYMBOL(lookup_one_len_unlocked); struct dentry *lookup_positive_unlocked(const char *name, struct dentry *base, int len) { - struct dentry *ret = lookup_one_len_unlocked(name, base, len); - if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { - dput(ret); - ret = ERR_PTR(-ENOENT); - } - return ret; + return lookup_one_positive_unlocked(&init_user_ns, name, base, len); } EXPORT_SYMBOL(lookup_positive_unlocked); diff --git a/include/linux/namei.h b/include/linux/namei.h index e89329bb3134..caeb08a98536 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -69,6 +69,12 @@ extern struct dentry *lookup_one_len(const char *, struct dentry *, int); extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); struct dentry *lookup_one(struct user_namespace *, const char *, struct dentry *, int); +struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns, + const char *name, struct dentry *base, + int len); +struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns, + const char *name, + struct dentry *base, int len); extern int follow_down_one(struct path *); extern int follow_down(struct path *);