From patchwork Sat Jan 27 17:56:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 13534235 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 C391B2E414; Sat, 27 Jan 2024 17:56:47 +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=1706378207; cv=none; b=Wvfozsons3jWbNtJv/g1mep1uGUhtFwYMkK/KUmxkKdsDJ1H683CpAIYRjxKTG/2DJJha5JU5ZU/Bp9WYrkC+3NGO3JQfBajSwZJaPzku06Qh2CaqPNGd3DFfkd+MRHqUVE4dlMOlgdpsNZU2kJ63M2ksTupSSXJEmFHQXppoCU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706378207; c=relaxed/simple; bh=pEnNZrXen7VnxSjfx0NojxEko5L+OzfrIM99xt+zBOg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=CKtjBD8W8V591jRc1PY7ifR2Y2LX+O6EuuuG8e6831loinXsQbP96WirSF3POxrNOiH5Z9RWyV1ItAv8TFBEza3Zv5aQJAw+c2yZun2dui9ljiqB+hTWt75uvxPa5ncxHS/97N50LF8eNgJM0sHh0rrcm+aXhSsPzFteqKp9kQA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CopMizgS; 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="CopMizgS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 660C9C43394; Sat, 27 Jan 2024 17:56:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706378207; bh=pEnNZrXen7VnxSjfx0NojxEko5L+OzfrIM99xt+zBOg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CopMizgSrSMLM+mWKdUrnkb+ODSVdIxFTuMgTGl54VcP83jzv0iQpxEM7cTyU/wRj 1WjU+cAg96oQxqhn/G6WsIE6i3NBiUVn0waCz1BHeeVbal8eRj5lN+mwjrwINtyopQ rNJB0xMsATWTmVTDmHS2JADqzySdWcpynm5uQI2PX3xra8iq+I7OFQRz7r7JoPpnMn raZoYI3gBaCWrT7SUL1AuhQZNKqXGSXhJYzjoN43LIoZ9mlMRC9gVxmgBP81lt1Xxs 5xYJ44IlwajfyDLqyrWYQc/Fz0tBnrzEqOgRa0Sk4a3ejXj76olreyJHiZEHvuShBT luQVK1SsMubMA== From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Cc: stable@vger.kernel.org, Filipe Manana , Ian Johnson , David Sterba Subject: [PATCH 3/4 for 6.1 stable] btrfs: refresh dir last index during a rewinddir(3) call Date: Sat, 27 Jan 2024 17:56:33 +0000 Message-Id: <9f532a81d33cfd2e241403fc2c861b85bada1b62.1706377319.git.fdmanana@suse.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Filipe Manana commit e60aa5da14d01fed8411202dbe4adf6c44bd2a57 upstream. When opening a directory we find what's the index of its last entry and then store it in the directory's file handle private data (struct btrfs_file_private::last_index), so that in the case new directory entries are added to a directory after an opendir(3) call we don't end up in an infinite loop (see commit 9b378f6ad48c ("btrfs: fix infinite directory reads")) when calling readdir(3). However once rewinddir(3) is called, POSIX states [1] that any new directory entries added after the previous opendir(3) call, must be returned by subsequent calls to readdir(3): "The rewinddir() function shall reset the position of the directory stream to which dirp refers to the beginning of the directory. It shall also cause the directory stream to refer to the current state of the corresponding directory, as a call to opendir() would have done." We currently don't refresh the last_index field of the struct btrfs_file_private associated to the directory, so after a rewinddir(3) we are not returning any new entries added after the opendir(3) call. Fix this by finding the current last index of the directory when llseek is called against the directory. This can be reproduced by the following C program provided by Ian Johnson: #include #include int main(void) { DIR *dir = opendir("test"); FILE *file; file = fopen("test/1", "w"); fwrite("1", 1, 1, file); fclose(file); file = fopen("test/2", "w"); fwrite("2", 1, 1, file); fclose(file); rewinddir(dir); struct dirent *entry; while ((entry = readdir(dir))) { printf("%s\n", entry->d_name); } closedir(dir); return 0; } Reported-by: Ian Johnson Link: https://lore.kernel.org/linux-btrfs/YR1P0S.NGASEG570GJ8@ianjohnson.dev/ Fixes: 9b378f6ad48c ("btrfs: fix infinite directory reads") CC: stable@vger.kernel.org # 6.5+ Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/inode.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 6f388fee0eee..aeae04b5cef4 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6049,6 +6049,19 @@ static int btrfs_opendir(struct inode *inode, struct file *file) return 0; } +static loff_t btrfs_dir_llseek(struct file *file, loff_t offset, int whence) +{ + struct btrfs_file_private *private = file->private_data; + int ret; + + ret = btrfs_get_dir_last_index(BTRFS_I(file_inode(file)), + &private->last_index); + if (ret) + return ret; + + return generic_file_llseek(file, offset, whence); +} + struct dir_entry { u64 ino; u64 offset; @@ -11429,7 +11442,7 @@ static const struct inode_operations btrfs_dir_inode_operations = { }; static const struct file_operations btrfs_dir_file_operations = { - .llseek = generic_file_llseek, + .llseek = btrfs_dir_llseek, .read = generic_read_dir, .iterate_shared = btrfs_real_readdir, .open = btrfs_opendir,