From patchwork Sun Nov 19 23:56:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13460707 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 35FF019BAE for ; Sun, 19 Nov 2023 23:56:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Tl5mBXt2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F40F1C433C7; Sun, 19 Nov 2023 23:56:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700438179; bh=EtcwSMC+2X05pmB2XZm956sPJJv7BwUf2YkTNGJ38Es=; h=Subject:From:To:Cc:Date:From; b=Tl5mBXt2ZuhV2UXwJohYFa4npkQ+9I5tbjkfwdfH7ZTJ1VCuqFsw/kcXAtvycd3V2 VtuJhnRWC9unIUrLGgxnyYKsxm73qr7pHT0owU3mJQxvpq1FdB47XEnyzWSchCP+F2 c/XEP6NTBesnOquzS8lEktnLsAEF82RJnVMuK66IajcziI6+HUSqvwifKdYqkiW+8W NE5NLiHEElKQl9VBLnpvFi8kWc9SfU+XHK9ABP7MXYKxqj1i2J3chZnPlbEcSXuYd0 uLwSDQksIE7JqLL/N/esjX4GFxBB01baK+ld2lemvJx8Xtrh6NBglTSLo122A71Zv1 EivHA2HNbM16w== Subject: [PATCH v4] libfs: getdents() should return 0 after reaching EOD From: Chuck Lever To: akpm@linux-foundation.org, brauner@kernel.org, hughd@google.com, jlayton@redhat.com, viro@zeniv.linux.org.uk Cc: Tavian Barnes , Chuck Lever , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Sun, 19 Nov 2023 18:56:17 -0500 Message-ID: <170043792492.4628.15646203084646716134.stgit@bazille.1015granger.net> User-Agent: StGit/1.5 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Chuck Lever The new directory offset helpers don't conform with the convention of getdents() returning no more entries once a directory file descriptor has reached the current end-of-directory. To address this, copy the logic from dcache_readdir() to mark the open directory file descriptor once EOD has been reached. Seeking resets the mark. Reported-by: Tavian Barnes Closes: https://lore.kernel.org/linux-fsdevel/20231113180616.2831430-1-tavianator@tavianator.com/ Fixes: 6faddda69f62 ("libfs: Add directory operations for stable offsets") Signed-off-by: Chuck Lever --- fs/libfs.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) v4 of this patch passes Tavian's reproducer and fstests over NFS and directly on a tmpfs mount. Changes since v3: - Ensure that llseek() resets the EOD mark too Changes since v2: - Go back to marking EOD in the file->private_data field Changes since RFC: - Keep file->private_data stable while directory descriptor remains open diff --git a/fs/libfs.c b/fs/libfs.c index e9440d55073c..c2aa6fd4795c 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -399,6 +399,8 @@ 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; return vfs_setpos(file, offset, U32_MAX); } @@ -428,7 +430,7 @@ 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 inode *inode, struct dir_context *ctx) { struct offset_ctx *so_ctx = inode->i_op->get_offset_ctx(inode); XA_STATE(xas, &so_ctx->xa, ctx->pos); @@ -437,7 +439,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) while (true) { dentry = offset_find_next(&xas); if (!dentry) - break; + return ERR_PTR(-ENOENT); if (!offset_dir_emit(ctx, dentry)) { dput(dentry); @@ -447,6 +449,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) dput(dentry); ctx->pos = xas.xa_index + 1; } + return NULL; } /** @@ -479,7 +482,12 @@ static int offset_readdir(struct file *file, struct dir_context *ctx) if (!dir_emit_dots(file, ctx)) return 0; - offset_iterate_dir(d_inode(dir), ctx); + /* In this case, ->private_data is protected by f_pos_lock */ + if (ctx->pos == 2) + file->private_data = NULL; + else if (file->private_data == ERR_PTR(-ENOENT)) + return 0; + file->private_data = offset_iterate_dir(d_inode(dir), ctx); return 0; }