Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754421AbbDIVhA (ORCPT ); Thu, 9 Apr 2015 17:37:00 -0400 Received: from mail-pd0-f182.google.com ([209.85.192.182]:33244 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751790AbbDIVfZ (ORCPT ); Thu, 9 Apr 2015 17:35:25 -0400 From: Omar Sandoval To: Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Qu Wenruo , Omar Sandoval Subject: [PATCH v2 2/6] Btrfs: remove all subvol options before mounting top-level Date: Thu, 9 Apr 2015 14:34:52 -0700 Message-Id: <8ead0eb0e24aac86fae1d748853ed64e3a4161d9.1428614837.git.osandov@osandov.com> X-Mailer: git-send-email 2.3.5 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3476 Lines: 112 Currently, setup_root_args() substitutes 's/subvol=[^,]*/subvolid=0/'. But, this means that if the user passes both a subvol and subvolid for some reason, we won't actually mount the top-level when we recursively mount. For example, consider: mkfs.btrfs -f /dev/sdb mount /dev/sdb /mnt btrfs subvol create /mnt/subvol1 # subvolid=257 btrfs subvol create /mnt/subvol2 # subvolid=258 umount /mnt mount -osubvol=/subvol1,subvolid=258 /dev/sdb /mnt In the final mount, subvol=/subvol1,subvolid=258 becomes subvolid=0,subvolid=258, and the last option takes precedence, so we mount subvol2 and try to look up subvol1 inside of it, which fails. So, instead, do a thorough scan through the argument list and remove any subvol= and subvolid= options, then append subvolid=0 to the end. This implicitly makes subvol= take precedence over subvolid=, but we're about to add a stricter check for that. This also makes setup_root_args() more generic, which we'll need soon. Signed-off-by: Omar Sandoval --- fs/btrfs/super.c | 56 ++++++++++++++++++++------------------------------------ 1 file changed, 20 insertions(+), 36 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index d38be09..bac3c9a 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1129,52 +1129,36 @@ static inline int is_subvolume_inode(struct inode *inode) } /* - * This will strip out the subvol=%s argument for an argument string and add - * subvolid=0 to make sure we get the actual tree root for path walking to the - * subvol we want. + * This will add subvolid=0 to the argument string while removing any subvol= + * and subvolid= arguments to make sure we get the top-level root for path + * walking to the subvol we want. */ static char *setup_root_args(char *args) { - unsigned len = strlen(args) + 2 + 1; - char *src, *dst, *buf; + char *buf, *dst, *sep; - /* - * We need the same args as before, but with this substitution: - * s!subvol=[^,]+!subvolid=0! - * - * Since the replacement string is up to 2 bytes longer than the - * original, allocate strlen(args) + 2 + 1 bytes. - */ - - src = strstr(args, "subvol="); - /* This shouldn't happen, but just in case.. */ - if (!src) - return NULL; + if (!args) + return kstrdup("subvolid=0", GFP_NOFS); - buf = dst = kmalloc(len, GFP_NOFS); + /* The worst case is that we add ",subvolid=0" to the end. */ + buf = dst = kmalloc(strlen(args) + strlen(",subvolid=0") + 1, GFP_NOFS); if (!buf) return NULL; - /* - * If the subvol= arg is not at the start of the string, - * copy whatever precedes it into buf. - */ - if (src != args) { - *src++ = '\0'; - strcpy(buf, args); - dst += strlen(args); + while (1) { + sep = strchrnul(args, ','); + if (!strstarts(args, "subvol=") && + !strstarts(args, "subvolid=")) { + memcpy(dst, args, sep - args); + dst += sep - args; + *dst++ = ','; + } + if (*sep) + args = sep + 1; + else + break; } - strcpy(dst, "subvolid=0"); - dst += strlen("subvolid=0"); - - /* - * If there is a "," after the original subvol=... string, - * copy that suffix into our buffer. Otherwise, we're done. - */ - src = strchr(src, ','); - if (src) - strcpy(dst, src); return buf; } -- 2.3.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/