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x-vs=clean score=0 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfKTLDOhfF+nyXnuVViomYvKPc8yXVWzzcYxWFf50wbC1sZI9ODmdp9al+19a0G9evo5XqtCMckwAB2KsoPzgVqjsOJN5VW+tFyrwwZ62cz21EbD1pDWN GVRreDeNCquYykJcjXtIhz5+5iwi8x4lPGsR9Xi5UwSKf9p6sqen2IlnklG59f3/UZD/6CApwWwY47ezM+5YfhHpyr2/3kP+UlsQpKWpHbvgaQzv2lX/Cm5u X-CM-Analysis: v=2.3 cv=WaUilXpX c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=xqWC_Br6kY4A:10 a=VUJBJC2UJ8kA:10 a=fxJcL_dCAAAA:8 a=VwQbUJbxAAAA:8 a=V5zyGy9ClZnDF-sAG1AA:9 a=x8gzFH9gYPwA:10 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751923AbeEFWsp (ORCPT ); Sun, 6 May 2018 18:48:45 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:36312 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752121AbeEFWsP (ORCPT ); Sun, 6 May 2018 18:48:15 -0400 X-Google-Smtp-Source: AB8JxZp22rxbpwd302zoMP2f/1QcbW41okTbS/fbqqIfwqor0EeTxj7gMWm3BYdomaAH5d92zD/VOQ== From: Christian Brauner To: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: torvalds@linux-foundation.org, tglx@linutronix.de, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, pombredanne@nexb.com, linux-api@vger.kernel.org, Christian Brauner Subject: [PATCH 6/6 v1] statfs: add ST_PRIVATE Date: Mon, 7 May 2018 00:47:04 +0200 Message-Id: <20180506224704.14669-7-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180506224704.14669-1-christian.brauner@ubuntu.com> References: <20180506224704.14669-1-christian.brauner@ubuntu.com> Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Currently userspace can only determine whether a mountpoint is private by parsing /proc//mountinfo. It would be convenient to simply retrieve this property with a statvfs() call. This let's userspace avoid costly parsing, supports cases where /proc is not mounted, and supports usecases where file descriptors to mountpoints are passed between processes that are inspected via fstatvfs(). A mountpoint is considered ST_PRIVATE iff and it is neither ST_SLAVE nor ST_SHARED. Signed-off-by: Christian Brauner --- v0->v1: * non-functional changes: extend commit message --- fs/statfs.c | 2 ++ include/linux/statfs.h | 1 + 2 files changed, 3 insertions(+) diff --git a/fs/statfs.c b/fs/statfs.c index 35ad0402c9a3..899e899ee84c 100644 --- a/fs/statfs.c +++ b/fs/statfs.c @@ -58,6 +58,8 @@ static int calculate_f_flags(struct vfsmount *mnt) if (IS_MNT_SLAVE(real_mount(mnt))) flags |= ST_SLAVE; + else if (!(flags & ST_SHARED)) + flags |= ST_PRIVATE; return flags; } diff --git a/include/linux/statfs.h b/include/linux/statfs.h index 048127effaad..663fa5498a7d 100644 --- a/include/linux/statfs.h +++ b/include/linux/statfs.h @@ -41,6 +41,7 @@ struct kstatfs { #define ST_NODIRATIME (1<<11) /* do not update directory access times */ #define ST_RELATIME (1<<12) /* update atime relative to mtime/ctime */ #define ST_UNBINDABLE (1<<17) /* change to unbindable */ +#define ST_PRIVATE (1<<18) /* change to private */ #define ST_SLAVE (1<<19) /* change to slave */ #define ST_SHARED (1<<20) /* change to shared */ -- 2.17.0