From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:48886 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751944AbaKYHYu (ORCPT ); Tue, 25 Nov 2014 02:24:50 -0500 Received: by mail-pa0-f46.google.com with SMTP id lj1so6834pab.33 for ; Mon, 24 Nov 2014 23:24:49 -0800 (PST) Received: from localhost.localdomain.localdomain ([112.23.171.71]) by mx.google.com with ESMTPSA id dp3sm570842pdb.46.2014.11.24.23.24.48 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Nov 2014 23:24:49 -0800 (PST) From: Wang Shilong To: linux-btrfs@vger.kernel.org Subject: [PATCH] Btrfs: deal with all 'subvol=xxx' options once Date: Tue, 25 Nov 2014 15:23:14 +0800 Message-Id: <1416900194-17495-1-git-send-email-wangshilong1991@gmail.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Steps to reproduce: # mkfs.btrfs -f /dev/sdb # mount -t btrfs /dev/sdb /mnt # btrfs sub create /mnt/dir # mount -t btrfs /dev/sdb /mnt -o subvol=dir,subvol=dir It fails with: mount: mount(2) failed: No such file or directory Btrfs deal with subvolume mounting in a recursive way, to avoid looping, it will stripe out 'subvol=xxxx' string, then next loop will stop.Problem here is it only deal one string once, if users specify mount option multiple times. It will loop several times which is not good, and above reproducing steps will also return confusing results. Fix this problem by striping out all 'subvol=xxx' options, only last is valid. Signed-off-by: Wang Shilong --- fs/btrfs/super.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 54bd91e..2b2fa4b 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1115,7 +1115,7 @@ static inline int is_subvolume_inode(struct inode *inode) * subvolid=0 to make sure we get the actual tree root for path walking to the * subvol we want. */ -static char *setup_root_args(char *args) +static char *__setup_root_args(char *args) { unsigned len = strlen(args) + 2 + 1; char *src, *dst, *buf; @@ -1161,6 +1161,24 @@ static char *setup_root_args(char *args) return buf; } +static char *setup_root_args(char *args) +{ + char *p, *new_args; + + p = new_args = __setup_root_args(args); + /* in case users specify subvol=xxx option multiple times */ + while (p) { + p = __setup_root_args(new_args); + if (p) { + kfree(new_args); + new_args = p; + } else { + break; + } + } + return new_args; +} + static struct dentry *mount_subvol(const char *subvol_name, int flags, const char *device_name, char *data) { -- 1.7.12.4