fs: add ksys_rmdir() wrapper; remove in-kernel calls to sys_rmdir()

Using this wrapper allows us to avoid the in-kernel calls to the
sys_rmdir() syscall. The ksys_ prefix denotes that this function is meant
as a drop-in replacement for the syscall. In particular, it uses the same
calling convention as sys_rmdir().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

diff --git a/fs/internal.h b/fs/internal.h
index df262f4..0eda35f 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -55,6 +55,7 @@ extern void __init chrdev_init(void);
 extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
 extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
                           const char *, unsigned int, struct path *);
+long do_rmdir(int dfd, const char __user *pathname);
 long do_unlinkat(int dfd, struct filename *name);
 
 /*

diff --git a/fs/namei.c b/fs/namei.c
index 524e829..8545151 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3872,7 +3872,7 @@ out:
 }
 EXPORT_SYMBOL(vfs_rmdir);
 
-static long do_rmdir(int dfd, const char __user *pathname)
+long do_rmdir(int dfd, const char __user *pathname)
 {
        int error = 0;
        struct filename *name;

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 7cbfb41..746043a 100644 (file)
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -965,4 +965,11 @@ static inline long ksys_unlink(const char __user *pathname)
        return do_unlinkat(AT_FDCWD, getname(pathname));
 }
 
+extern long do_rmdir(int dfd, const char __user *pathname);
+
+static inline long ksys_rmdir(const char __user *pathname)
+{
+       return do_rmdir(AT_FDCWD, pathname);
+}
+
 #endif

diff --git a/init/initramfs.c b/init/initramfs.c
index 08eb551..73bbb22 100644 (file)
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -317,7 +317,7 @@ static void __init clean_path(char *path, umode_t fmode)
 
        if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
                if (S_ISDIR(st.mode))
-                       sys_rmdir(path);
+                       ksys_rmdir(path);
                else
                        ksys_unlink(path);
        }
@@ -589,7 +589,7 @@ static void __init clean_rootfs(void)
                        WARN_ON_ONCE(ret);
                        if (!ret) {
                                if (S_ISDIR(st.mode))
-                                       sys_rmdir(dirp->d_name);
+                                       ksys_rmdir(dirp->d_name);
                                else
                                        ksys_unlink(dirp->d_name);
                        }