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From:   Yang Xu <xuyang2018.jy@fujitsu.com>
To:     <david@fromorbit.com>, <djwong@kernel.org>, <brauner@kernel.org>
CC:     <linux-fsdevel@vger.kernel.org>, <ceph-devel@vger.kernel.org>,
        <linux-nfs@vger.kernel.org>, <linux-xfs@vger.kernel.org>,
        <viro@zeniv.linux.org.uk>, <jlayton@kernel.org>,
        Yang Xu <xuyang2018.jy@fujitsu.com>
Subject: [PATCH v3 5/7] fs: Add new helper prepare_mode
Date:   Fri, 15 Apr 2022 19:02:21 +0800
Message-ID: <1650020543-24908-5-git-send-email-xuyang2018.jy@fujitsu.com>
In-Reply-To: <1650020543-24908-1-git-send-email-xuyang2018.jy@fujitsu.com>
References: <1650020543-24908-1-git-send-email-xuyang2018.jy@fujitsu.com>
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Precedence: bulk

As Christian Brauner suggested, add a new helper calls inode_sgid_strip()
and does the umask stripping as well and then call it in all these places.

This api is introduced to support strip file's S_ISGID mode on vfs instead
of on underlying filesystem.

Suggested-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 include/linux/fs.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4a617aaab6f6..8c2f4cde974b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3458,6 +3458,15 @@ static inline bool dir_relax_shared(struct inode *inode)
 	return !IS_DEADDIR(inode);
 }
 
+static inline void prepare_mode(struct user_namespace *mnt_userns,
+				const struct inode *dir, umode_t *mode)
+{
+	inode_sgid_strip(mnt_userns, dir, mode);
+
+	if (!IS_POSIXACL(dir))
+		*mode &= ~current_umask();
+}
+
 extern bool path_noexec(const struct path *path);
 extern void inode_nohighmem(struct inode *inode);
 
-- 
2.27.0