From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A9C611754B for ; Thu, 11 Apr 2024 18:26:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712859978; cv=none; b=a2qrKDo5V1su/3PU9cf2awVo2Oj4KMQR4vgd2m0TNwe7Z5CMORRj58AHzdYu+J0tPDEMaFv7ihiRAZGnNgiWluhL/B20eoLXPJ5CBA6Qm80SLJUoVkwK/+eAiwrDQRUdCOsAp9dG4GDgzD6xKc/kYUa2XzahveSri0zJ8QBICVg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712859978; c=relaxed/simple; bh=LlHyaLtG1YvNIQ1CFV+T9CQsPAP2A/k5hQvjMmkXKDc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Kk4P+TosGMbNCr7kw7ktv9Hioi72x36J/yYbxFCnQZDSqGtmWa+0qzRMdYC3YRxRD8Cfp6hwbKoaIqgnHxy5ewvLmBZKeQYQ4VfMGCvAhQ5JwyvvMCUbOkyZfrTRC+f+PmpOG/Ln8aR/WDjyN1attxorpq4fkjM9y6vK/7Cff+A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=C5yXbvx1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="C5yXbvx1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC84BC072AA; Thu, 11 Apr 2024 18:26:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712859978; bh=LlHyaLtG1YvNIQ1CFV+T9CQsPAP2A/k5hQvjMmkXKDc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C5yXbvx1jrv9lNmAbJ2EsJBrqXxmBM3eiR6oNKWIRoC1F899cpZHpWNZ++JcVjc73 UzJ0PYbHkJM24Vu/cB52R1Qgd5zLJAdG8Mw5a8WuBGr5v8JEv0KYgTxFqLdfUaTRmk k6mBQ4U7PcWWKdg4xBfY0P0W0uBsK5PIGzY9zfpgr6EIIKMjTsxHEB6LvMg3+eB/fT 4q3++BvbWDyTH8I9F+qxtvnoGVtO3i3wFCB2BmeDkcad/4CSfk5VNuCmDk0FKVzhag patw11ykJaH357nsn2SqEj+/HVgdDL7+gN3Gj0RoVcja31X7iqg+32sHjQmC43MgBW DbV1G7S8X/YdA== From: cel@kernel.org To: Christian Brauner Cc: , Chuck Lever Subject: [PATCH v1 1/2] shmem: Fix shmem_rename2() Date: Thu, 11 Apr 2024 14:26:10 -0400 Message-ID: <20240411182611.203328-2-cel@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240411182611.203328-1-cel@kernel.org> References: <20240411182611.203328-1-cel@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever When renaming onto an existing directory entry, user space expects the replacement entry to have the same directory offset as the original one. The details of handling directory offsets during a rename are moved to fs/libfs.c so that they can be reused by other API consumers. For backporting to stable kernels: use xa_store() rather than mtree_store(), and octx->xa rather than octx->mt. See commit 0e4a862174f2 ("libfs: Convert simple directory offsets to use a Maple Tree") for details. Link: https://gitlab.alpinelinux.org/alpine/aports/-/issues/15966 Fixes: a2e459555c5f ("shmem: stable directory offsets") Signed-off-by: Chuck Lever --- fs/libfs.c | 53 ++++++++++++++++++++++++++++++++++++++++------ include/linux/fs.h | 2 ++ mm/shmem.c | 3 +-- 3 files changed, 50 insertions(+), 8 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index 3a6f2cb364f8..ff767288e5dd 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -295,6 +295,17 @@ int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry) return 0; } +/* + * Internal helper for use when it is known that the tree entry at + * @index is already NULL. + */ +static int simple_offset_store(struct offset_ctx *octx, struct dentry *dentry, + long index) +{ + offset_set(dentry, index); + return mtree_store(&octx->mt, index, dentry, GFP_KERNEL); +} + /** * simple_offset_remove - Remove an entry to a directory's offset map * @octx: directory offset ctx to be updated @@ -345,6 +356,35 @@ int simple_offset_empty(struct dentry *dentry) return ret; } +/** + * simple_offset_rename - handle directory offsets for rename + * @old_dir: parent directory of source entry + * @old_dentry: dentry of source entry + * @new_dir: parent_directory of destination entry + * @new_dentry: dentry of destination + * + * Caller provides appropriate serialization. + * + * Returns zero on success, a negative errno value on failure. + */ +int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir); + struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir); + long new_index = dentry2offset(new_dentry); + + simple_offset_remove(old_ctx, old_dentry); + + /* + * When the destination entry already exists, user space expects + * its directory offset value to be unchanged after the rename. + */ + if (new_index) + return simple_offset_store(new_ctx, old_dentry, new_index); + return simple_offset_add(new_ctx, old_dentry); +} + /** * simple_offset_rename_exchange - exchange rename with directory offsets * @old_dir: parent of dentry being moved @@ -352,6 +392,9 @@ int simple_offset_empty(struct dentry *dentry) * @new_dir: destination parent * @new_dentry: destination dentry * + * This API preserves the directory offset values. Caller provides + * appropriate serialization. + * * Returns zero on success. Otherwise a negative errno is returned and the * rename is rolled back. */ @@ -369,11 +412,11 @@ int simple_offset_rename_exchange(struct inode *old_dir, simple_offset_remove(old_ctx, old_dentry); simple_offset_remove(new_ctx, new_dentry); - ret = simple_offset_add(new_ctx, old_dentry); + ret = simple_offset_store(new_ctx, old_dentry, new_index); if (ret) goto out_restore; - ret = simple_offset_add(old_ctx, new_dentry); + ret = simple_offset_store(old_ctx, new_dentry, old_index); if (ret) { simple_offset_remove(new_ctx, old_dentry); goto out_restore; @@ -388,10 +431,8 @@ int simple_offset_rename_exchange(struct inode *old_dir, return 0; out_restore: - offset_set(old_dentry, old_index); - mtree_store(&old_ctx->mt, old_index, old_dentry, GFP_KERNEL); - offset_set(new_dentry, new_index); - mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL); + (void)simple_offset_store(old_ctx, old_dentry, old_index); + (void)simple_offset_store(new_ctx, new_dentry, new_index); return ret; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 8dfd53b52744..b09f14132110 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3340,6 +3340,8 @@ void simple_offset_init(struct offset_ctx *octx); int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry); void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry); int simple_offset_empty(struct dentry *dentry); +int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry); int simple_offset_rename_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, diff --git a/mm/shmem.c b/mm/shmem.c index 0aad0d9a621b..c0fb65223963 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3473,8 +3473,7 @@ static int shmem_rename2(struct mnt_idmap *idmap, return error; } - simple_offset_remove(shmem_get_offset_ctx(old_dir), old_dentry); - error = simple_offset_add(shmem_get_offset_ctx(new_dir), old_dentry); + error = simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry); if (error) return error; -- 2.44.0