linux-kernel - [PATCH] init/do_mounts.c: replace sys_mount() to do

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Date:	Tue, 17 Aug 2010 21:37:23 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] init/do_mounts.c: replace sys_mount() to do_mount()

sys_mount() just copies all (string) arguments from user space to kernel
and calls do_mount(). In this case we have all args in kernel already so
there is no need to call sys_mount(). One thing we should take care is
'data' have to be in a page unless it is NULL. Do it manually.

Signed-off-by: Namhyung Kim <namhyung@...il.com>
---
 init/do_mounts.c |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/init/do_mounts.c b/init/do_mounts.c
index 02e3ca4..8eabff6 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -217,7 +217,21 @@ static void __init get_fs_names(char *page)
 
 static int __init do_mount_root(char *name, char *fs, int flags, void *data)
 {
-	int err = sys_mount(name, "/root", fs, flags, data);
+	int err;
+	unsigned long data_page = 0;
+
+	if (data) {
+		/* data should be in a page */
+		data_page = __get_free_page(GFP_KERNEL);
+		if (!data_page)
+			return -ENOMEM;
+		strlcpy((char *) data_page, data, PAGE_SIZE);
+	}
+
+	err = do_mount(name, "/root", fs, flags, (void *) data_page);
+
+	if (data_page)
+		free_page(data_page);
 	if (err)
 		return err;
 
@@ -417,6 +431,6 @@ void __init prepare_namespace(void)
 	mount_root();
 out:
 	devtmpfs_mount("dev");
-	sys_mount(".", "/", NULL, MS_MOVE, NULL);
+	do_mount(".", "/", NULL, MS_MOVE, NULL);
 	sys_chroot(".");
 }
-- 
1.7.0.4

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