[PATCH] initramfs: use vfs_stat/lstat directly

From: Arnd Bergmann
Date: Tue Mar 14 2017 - 17:50:42 EST


sys_newlstat is a system call implementation that is meant for user
space, and that copies kernel-internal data structure to the user
format, which is not needed for in-kernel users.

Further, as we rearrange the system call implementation so we can
extend it with 64-bit time_t, the prototype for sys_newlstat changes.

This changes the initramfs code to use vfs_lstat directly, to get
it out of the way of the time_t changes, and make it slightly more
efficient in the process. Along the same lines we also replace
sys_stat and sys_stat64 with vfs_stat.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
Submitted before in June 2016, but no reply.

Andrew or Al, could one of you pick this up for v4.12?
---
init/do_mounts.h | 22 ++++------------------
init/initramfs.c | 12 ++++++------
2 files changed, 10 insertions(+), 24 deletions(-)

diff --git a/init/do_mounts.h b/init/do_mounts.h
index 067af1d9e8b6..282d65bfd674 100644
--- a/init/do_mounts.h
+++ b/init/do_mounts.h
@@ -19,29 +19,15 @@ static inline int create_dev(char *name, dev_t dev)
return sys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));
}

-#if BITS_PER_LONG == 32
static inline u32 bstat(char *name)
{
- struct stat64 stat;
- if (sys_stat64(name, &stat) != 0)
+ struct kstat stat;
+ if (vfs_stat(name, &stat) != 0)
return 0;
- if (!S_ISBLK(stat.st_mode))
+ if (!S_ISBLK(stat.mode))
return 0;
- if (stat.st_rdev != (u32)stat.st_rdev)
- return 0;
- return stat.st_rdev;
-}
-#else
-static inline u32 bstat(char *name)
-{
- struct stat stat;
- if (sys_newstat(name, &stat) != 0)
- return 0;
- if (!S_ISBLK(stat.st_mode))
- return 0;
- return stat.st_rdev;
+ return stat.rdev;
}
-#endif

#ifdef CONFIG_BLK_DEV_RAM

diff --git a/init/initramfs.c b/init/initramfs.c
index 7eb7cb7cb9b9..83d514d0e69d 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -312,10 +312,10 @@ static int __init maybe_link(void)

static void __init clean_path(char *path, umode_t fmode)
{
- struct stat st;
+ struct kstat st;

- if (!sys_newlstat(path, &st) && (st.st_mode ^ fmode) & S_IFMT) {
- if (S_ISDIR(st.st_mode))
+ if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
+ if (S_ISDIR(st.mode))
sys_rmdir(path);
else
sys_unlink(path);
@@ -581,13 +581,13 @@ static void __init clean_rootfs(void)
num = sys_getdents64(fd, dirp, BUF_SIZE);
while (num > 0) {
while (num > 0) {
- struct stat st;
+ struct kstat st;
int ret;

- ret = sys_newlstat(dirp->d_name, &st);
+ ret = vfs_lstat(dirp->d_name, &st);
WARN_ON_ONCE(ret);
if (!ret) {
- if (S_ISDIR(st.st_mode))
+ if (S_ISDIR(st.mode))
sys_rmdir(dirp->d_name);
else
sys_unlink(dirp->d_name);
--
2.9.0