From patchwork Thu Apr 7 11:21:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12805088 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 F1890C433FE for ; Thu, 7 Apr 2022 11:22:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244749AbiDGLYY (ORCPT ); Thu, 7 Apr 2022 07:24:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48712 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244740AbiDGLYW (ORCPT ); Thu, 7 Apr 2022 07:24:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 07DC922BF5; Thu, 7 Apr 2022 04:22:23 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 9381961E51; Thu, 7 Apr 2022 11:22:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F276CC385A4; Thu, 7 Apr 2022 11:22:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1649330541; bh=ViJgKQTFzYHnPi8m6Ss7n+kb5PGcQiolFLTANzW/oLk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SS8N3QhVt1xJwlPAdXarEat/YG5A0/zaPGiAaagGe8EFNVxIrDYqZ8eHn8R1r6SIV GXVE7ekQea9yD7kYq102E6zgtCnFaNYaVCyuextlQipXY64IGrx4+IibJ8Ra6WqW2a eLAvRFi5nETGyvLtgztb9Ik+65E6XAJRcz6obE7Dccq4Mf7GwrgJ4rNz3ifWvK2ENF Ox+gR3yf5AUqB53gozw7347LnQz6fYAkxGjDsyUuoQT2ZPp2tdRVl9+SHwV2qmMhz8 YGDP9nlcwMxUQvnefOJ3riH1OSbTAilDzeGdKgzf63BZ7tkHuPWX9ESHLVQVVKhQEP R/blhYtrO0T7g== From: Christian Brauner To: Amir Goldstein , Christoph Hellwig , Miklos Szeredi , Al Viro Cc: Christian Brauner , linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Aleksa Sarai , Giuseppe Scrivano , Rodrigo Campos Catelin , Seth Forshee , Luca Bocassi , Lennart Poettering , =?utf-8?q?St=C3=A9phane_Graber?= Subject: [PATCH v5 01/19] fs: add two trivial lookup helpers Date: Thu, 7 Apr 2022 13:21:38 +0200 Message-Id: <20220407112157.1775081-2-brauner@kernel.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220407112157.1775081-1-brauner@kernel.org> References: <20220407112157.1775081-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5757; h=from:subject; bh=ViJgKQTFzYHnPi8m6Ss7n+kb5PGcQiolFLTANzW/oLk=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMST5nfRY+72Rn9F441UOfvOc04bNV3gXV/U/2/a4eMeP+c9z Wm9GdJSyMIhxMciKKbI4tJuEyy3nqdhslKkBM4eVCWQIAxenAEzEV4/hF9Mzp7K9ZvVum5Vvv5jrEH jj1bbwbSzrD+2Nc6qwrtvhl8Hwv1I89tXyzUczEnhsLXi+xymIxIvNfl6dpff+t98W7//N3AA= 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) --- /* v2 */ unchanged /* v3 */ - Christoph Hellwig : - Wrap overly long lines. - Add kerneldoc for lookup_one_positive_unlocked(). /* v4 */ unchanged /* v5 */ unchanged --- fs/namei.c | 69 ++++++++++++++++++++++++++++++++++++------- include/linux/namei.h | 6 ++++ 2 files changed, 65 insertions(+), 10 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 3f1829b3ab5b..d76f4dde6179 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2768,7 +2768,8 @@ 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 @@ -2779,14 +2780,15 @@ 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); @@ -2795,6 +2797,58 @@ 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); /* @@ -2808,12 +2862,7 @@ 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 *);