From patchwork Tue Nov 26 15:54:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13886130 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 81F7D1DAC90 for ; Tue, 26 Nov 2024 15:54:57 +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=1732636497; cv=none; b=Ib+bHzlRxst1aHYdMg61XvTav9HlLRbNequ5zhOiQr0p1Y2kNQy7F/sgNt3VDYKJW2ChhgFYa/sfQZWBxBALl74c5f/I0mqpOjvH1qUise7ZABBiw5KUg/9GYnjPiepoV+Yh6CI4Onn/vZqGYfTVxot/7Q07SbU20/UqwD3kuOI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732636497; c=relaxed/simple; bh=tMz/47mxpsuDcyrl6vBlEBAasdrsXvapQPHriWB0vcU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MKz2+praieyHTE+uy13S6ydoAy1uX/iH7WsslJPfxBkZro48yPhWl0lNd8N/8gRMzPhOEPY1vso83MxDrhTfIHrpSz2SAz6MoRKO2AZY05+4sbXd8VpWWGiyB9UuaPsLF1Lmw2nU/oru9tHGILJNlXtJ4IUpthxzb62Tnt7aqO8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SsK6NV8j; 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="SsK6NV8j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3AA74C4CED3; Tue, 26 Nov 2024 15:54:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732636497; bh=tMz/47mxpsuDcyrl6vBlEBAasdrsXvapQPHriWB0vcU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SsK6NV8jA66kTudkpuY9LMmdM8pQatvG2B2mhSyAac4M/AEOF25/vatqmM9Falwci yj7mYfpwIf2l+hqSnEoF+aP5ks6Sa9qzjw4ccEmVHYRy4GL0VFDkDcsJNEqWotFeud presvLu/aV0ui65cWMC7eg09NrL7cNa2Nq2ua9M6mxyMZYUPfoiJYim0q/GAjg3Md5 VO5R3CDpPk9qijalnRWIXExd8XetVGsblXaetFQ8LqpSTHEuyY/f27mhUzno/q2yQp FjMxtZUy+R4esvZFh/CugOAt1+qwdk6nNVWCiKHQe0RHfsWh95kIV/HLyZBzAJto/H HCyI48l739NTg== From: cel@kernel.org To: Hugh Dickens , Christian Brauner , Al Viro Cc: , , yukuai3@huawei.com, yangerkun@huaweicloud.com, Chuck Lever Subject: [RFC PATCH v2 4/5] libfs: Refactor end-of-directory detection for simple_offset directories Date: Tue, 26 Nov 2024 10:54:43 -0500 Message-ID: <20241126155444.2556-5-cel@kernel.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241126155444.2556-1-cel@kernel.org> References: <20241126155444.2556-1-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 e6c46b13fc71..be641a84047a 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -453,6 +453,34 @@ 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 @@ -478,8 +506,8 @@ 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); } @@ -510,15 +538,20 @@ 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); @@ -528,7 +561,6 @@ static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx) ctx->pos = dentry2offset(dentry) + 1; dput(dentry); } - return NULL; } /** @@ -561,16 +593,14 @@ 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,