From patchwork Wed Nov 27 15:28:14 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13887140 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 66CB33C488 for ; Wed, 27 Nov 2024 15:28:23 +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=1732721303; cv=none; b=FZDRa6FYoAy2lroZ010Yhg9W675BjyzDUfRZGUcp8GiGZUOL4ywCYTDdBPOy4J+NKhrfL2hVzF7TGD/2dix2qRzxAKN+tAtwE3RhaOpvCnfHSRGcpdrqI+6VFOzCA4nmNYfnzHAbDL5Dx6KMcT3EE1tSgB5CHM1q45e/vtzaPKM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732721303; c=relaxed/simple; bh=yaUgVsYqn/+UqS21Ay0PUdvP+2Ovp6VDQCczLqXNXYo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UJC7ZbltASyM3W7TaRf9ropjRrGaBxD+7rpJM/X0WeXyX7TWmkqSX6aI8UJTLpKh5qkplIWeyicHrSKA1w3ePrWNIzl3s7BXYqd17c/PQwzsw4xJdqYTNgR9bUrQxqGuZZR7rDjJEBZumB/vf1cBL1J47KgOaaDnH5RNVB0uuJ4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VT08HImq; 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="VT08HImq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A88EC4CED3; Wed, 27 Nov 2024 15:28:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732721303; bh=yaUgVsYqn/+UqS21Ay0PUdvP+2Ovp6VDQCczLqXNXYo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VT08HImqWvjHVpg0vUPPxkxWgmyqx6FPQSiQJRMNw0IopFVIATgz4coLvIXaQA5w+ HttmvTm9x2ggjv3ICKFLH2h80s+uaVVrnaMJSjwVnsR2/fYo0lVxOcpflRO32MDlHv A22VX+RXRrBbmm3pQFuLEaAmcJDB4WsVuQQUMC2PBkwbOD/R2h8tkSbikpz8uryCiI MAOIYikg4eQqyojGl+XUy2EA1W/0bAEc4kVDCJtU3EdmX6y+fDI28xs4E9sT8iNdKn JfH0jERkX0EQp1goCDny+sYUW9vwUuytQPtbRZbr5myfCmnE/xuWTfyt5dnYfvMqJW r9ZGIH9IRFzqQ== From: cel@kernel.org To: Hugh Dickens , Christian Brauner , Al Viro Cc: , , yukuai3@huawei.com, yangerkun@huaweicloud.com, Chuck Lever Subject: [RFC PATCH v3 4/5] libfs: Refactor end-of-directory detection for simple_offset directories Date: Wed, 27 Nov 2024 10:28:14 -0500 Message-ID: <20241127152815.151781-5-cel@kernel.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241127152815.151781-1-cel@kernel.org> References: <20241127152815.151781-1-cel@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Chuck Lever This mechanism seems have been misunderstood more than once. Make the code more self-documentary. Signed-off-by: Chuck Lever --- fs/libfs.c | 54 ++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 42 insertions(+), 12 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index a673427d3416..0deff5390abb 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -449,6 +449,34 @@ void simple_offset_destroy(struct offset_ctx *octx) mtree_destroy(&octx->mt); } +static void offset_set_eod(struct file *file) +{ + file->private_data = ERR_PTR(-ENOENT); +} + +static void offset_clear_eod(struct file *file) +{ + file->private_data = NULL; +} + +static bool offset_at_eod(struct file *file) +{ + return file->private_data == ERR_PTR(-ENOENT); +} + +/** + * offset_dir_open - Open a directory descriptor + * @inode: directory to be opened + * @file: struct file to instantiate + * + * Returns zero on success, or a negative errno value. + */ +static int offset_dir_open(struct inode *inode, struct file *file) +{ + offset_clear_eod(file); + return 0; +} + /** * offset_dir_llseek - Advance the read position of a directory descriptor * @file: an open directory whose position is to be updated @@ -474,8 +502,8 @@ static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence) return -EINVAL; } - /* In this case, ->private_data is protected by f_pos_lock */ - file->private_data = NULL; + /* ->private_data is protected by f_pos_lock */ + offset_clear_eod(file); return vfs_setpos(file, offset, LONG_MAX); } @@ -506,15 +534,20 @@ static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry) inode->i_ino, fs_umode_to_dtype(inode->i_mode)); } -static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx) +static void offset_iterate_dir(struct file *file, struct dir_context *ctx) { + struct dentry *dir = file->f_path.dentry; + struct inode *inode = d_inode(dir); struct offset_ctx *octx = inode->i_op->get_offset_ctx(inode); struct dentry *dentry; while (true) { dentry = offset_find_next(octx, ctx->pos); - if (!dentry) - return ERR_PTR(-ENOENT); + if (!dentry) { + /* ->private_data is protected by f_pos_lock */ + offset_set_eod(file); + return; + } if (!offset_dir_emit(ctx, dentry)) { dput(dentry); @@ -524,7 +557,6 @@ static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx) ctx->pos = dentry2offset(dentry) + 1; dput(dentry); } - return NULL; } /** @@ -557,16 +589,14 @@ static int offset_readdir(struct file *file, struct dir_context *ctx) if (!dir_emit_dots(file, ctx)) return 0; - /* In this case, ->private_data is protected by f_pos_lock */ - if (ctx->pos == DIR_OFFSET_MIN) - file->private_data = NULL; - else if (file->private_data == ERR_PTR(-ENOENT)) - return 0; - file->private_data = offset_iterate_dir(d_inode(dir), ctx); + /* ->private_data is protected by f_pos_lock */ + if (!offset_at_eod(file)) + offset_iterate_dir(file, ctx); return 0; } const struct file_operations simple_offset_dir_operations = { + .open = offset_dir_open, .llseek = offset_dir_llseek, .iterate_shared = offset_readdir, .read = generic_read_dir,