Commit 0f32ab8c authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

fs: add ksys_unlink() wrapper; remove in-kernel calls to sys_unlink() 

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

In the near future, all callers of ksys_unlink() should be converted to
call do_unlinkat() directly or, at least, to operate on regular kernel
pointers.

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: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 447016e9

include/linux/syscalls.h

+11 −0
Original line number Diff line number Diff line
@@ -954,4 +954,15 @@ int ksys_chroot(const char __user *filename); 
ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count);

int ksys_chdir(const char __user *filename);



/*

 * The following kernel syscall equivalents are just wrappers to fs-internal

 * functions. Therefore, provide stubs to be inlined at the callsites.

 */

extern long do_unlinkat(int dfd, struct filename *name);



static inline long ksys_unlink(const char __user *pathname)

{

	return do_unlinkat(AT_FDCWD, getname(pathname));

}



#endif

init/do_mounts.h

+1 −1
Original line number Diff line number Diff line
@@ -16,7 +16,7 @@ extern int root_mountflags; 


static inline int create_dev(char *name, dev_t dev)

{

	sys_unlink(name);

	ksys_unlink(name);

	return sys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));

}

init/do_mounts_initrd.c

+2 −2
Original line number Diff line number Diff line
@@ -128,11 +128,11 @@ bool __init initrd_load(void) 
		 * mounted in the normal path.

		 */

		if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {

			sys_unlink("/initrd.image");

			ksys_unlink("/initrd.image");

			handle_initrd();

			return true;

		}

	}

	sys_unlink("/initrd.image");

	ksys_unlink("/initrd.image");

	return false;

}

init/do_mounts_rd.c

+1 −1
Original line number Diff line number Diff line
@@ -288,7 +288,7 @@ noclose_input: 
	sys_close(out_fd);

out:

	kfree(buf);

	sys_unlink("/dev/ram");

	ksys_unlink("/dev/ram");

	return res;

}

init/initramfs.c

+2 −2
Original line number Diff line number Diff line
@@ -319,7 +319,7 @@ static void __init clean_path(char *path, umode_t fmode) 
		if (S_ISDIR(st.mode))

			sys_rmdir(path);

		else

			sys_unlink(path);

			ksys_unlink(path);

	}

}
@@ -591,7 +591,7 @@ static void __init clean_rootfs(void) 
				if (S_ISDIR(st.mode))

					sys_rmdir(dirp->d_name);

				else

					sys_unlink(dirp->d_name);

					ksys_unlink(dirp->d_name);

			}



			num -= dirp->d_reclen;

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