Re: [CFT][PATCH] exit/bdflush: Remove the deprecated bdflush system call

Michael Schmitz
2021-06-29T21:45:19Z

On 30/06/21 8:28 am, Eric W. Biederman wrote:
> The bdflush system call has been deprecated for a very long time.
> Recently Michael Schmitz tested[1] and found that the last known
> caller of of the bdflush system call is unaffected by it's removal.
>
> Since the code is not needed delete it.
>
> [1] https://lkml.kernel.org/r/36123b5d-daa0-6c2b-f2d4-a942f069fd54@gmail.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
> ---
>
> I think we have consensus that bdflush can be removed. Can folks please
> verify I have removed it correctly?
>
> Michael could you give me a Tested-by on this patch?
>
> arch/alpha/kernel/syscalls/syscall.tbl | 2 +-
> arch/arm/tools/syscall.tbl | 2 +-
> arch/arm64/include/asm/unistd32.h | 2 +-
> arch/ia64/kernel/syscalls/syscall.tbl | 2 +-
> arch/m68k/kernel/syscalls/syscall.tbl | 2 +-
> arch/microblaze/kernel/syscalls/syscall.tbl | 2 +-
> arch/mips/kernel/syscalls/syscall_o32.tbl | 2 +-
> arch/parisc/kernel/syscalls/syscall.tbl | 2 +-
> arch/powerpc/kernel/syscalls/syscall.tbl | 2 +-
> arch/s390/kernel/syscalls/syscall.tbl | 2 +-
> arch/sh/kernel/syscalls/syscall.tbl | 2 +-
> arch/sparc/kernel/syscalls/syscall.tbl | 2 +-
> arch/x86/entry/syscalls/syscall_32.tbl | 2 +-
> arch/xtensa/kernel/syscalls/syscall.tbl | 2 +-
> fs/buffer.c | 27 -------------------
> include/linux/syscalls.h | 1 -
> include/uapi/linux/capability.h | 1 -
> kernel/sys_ni.c | 1 -
> .../arch/powerpc/entry/syscalls/syscall.tbl | 2 +-
> .../perf/arch/s390/entry/syscalls/syscall.tbl | 2 +-
> 20 files changed, 16 insertions(+), 46 deletions(-)
>
> diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
> index 3000a2e8ee21..85d2bcd9cf36 100644
> --- a/arch/alpha/kernel/syscalls/syscall.tbl
> +++ b/arch/alpha/kernel/syscalls/syscall.tbl
> @@ -230,7 +230,7 @@
> 259 common osf_swapctl sys_ni_syscall
> 260 common osf_memcntl sys_ni_syscall
> 261 common osf_fdatasync sys_ni_syscall
> -300 common bdflush sys_bdflush
> +300 common bdflush sys_ni_syscall
> 301 common sethae sys_sethae
> 302 common mount sys_mount
> 303 common old_adjtimex sys_old_adjtimex
> diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
> index 28e03b5fec00..241988512648 100644
> --- a/arch/arm/tools/syscall.tbl
> +++ b/arch/arm/tools/syscall.tbl
> @@ -147,7 +147,7 @@
> 131 common quotactl sys_quotactl
> 132 common getpgid sys_getpgid
> 133 common fchdir sys_fchdir
> -134 common bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall
> 135 common sysfs sys_sysfs
> 136 common personality sys_personality
> # 137 was sys_afs_syscall
> diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
> index 5dab69d2c22b..a35cd6c4909c 100644
> --- a/arch/arm64/include/asm/unistd32.h
> +++ b/arch/arm64/include/asm/unistd32.h
> @@ -279,7 +279,7 @@ __SYSCALL(__NR_getpgid, sys_getpgid)
> #define __NR_fchdir 133
> __SYSCALL(__NR_fchdir, sys_fchdir)
> #define __NR_bdflush 134
> -__SYSCALL(__NR_bdflush, sys_bdflush)
> +__SYSCALL(__NR_bdflush, sys_ni_syscall)
> #define __NR_sysfs 135
> __SYSCALL(__NR_sysfs, sys_sysfs)
> #define __NR_personality 136
> diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl
> index bb11fe4c875a..7de53a9a2972 100644
> --- a/arch/ia64/kernel/syscalls/syscall.tbl
> +++ b/arch/ia64/kernel/syscalls/syscall.tbl
> @@ -123,7 +123,7 @@
> # 1135 was get_kernel_syms
> # 1136 was query_module
> 113 common quotactl sys_quotactl
> -114 common bdflush sys_bdflush
> +114 common bdflush sys_ni_syscall
> 115 common sysfs sys_sysfs
> 116 common personality sys_personality
> 117 common afs_syscall sys_ni_syscall
> diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
> index 79c2d24c89dd..be5abd9c8c07 100644
> --- a/arch/m68k/kernel/syscalls/syscall.tbl
> +++ b/arch/m68k/kernel/syscalls/syscall.tbl
> @@ -141,7 +141,7 @@
> 131 common quotactl sys_quotactl
> 132 common getpgid sys_getpgid
> 133 common fchdir sys_fchdir
> -134 common bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall
> 135 common sysfs sys_sysfs
> 136 common personality sys_personality
> # 137 was afs_syscall
> diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
> index b11395a20c20..555fd987f4ab 100644
> --- a/arch/microblaze/kernel/syscalls/syscall.tbl
> +++ b/arch/microblaze/kernel/syscalls/syscall.tbl
> @@ -141,7 +141,7 @@
> 131 common quotactl sys_quotactl
> 132 common getpgid sys_getpgid
> 133 common fchdir sys_fchdir
> -134 common bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall
> 135 common sysfs sys_sysfs
> 136 common personality sys_personality
> 137 common afs_syscall sys_ni_syscall
> diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
> index d560c467a8c6..2c6b10db3bd5 100644
> --- a/arch/mips/kernel/syscalls/syscall_o32.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
> @@ -145,7 +145,7 @@
> 131 o32 quotactl sys_quotactl
> 132 o32 getpgid sys_getpgid
> 133 o32 fchdir sys_fchdir
> -134 o32 bdflush sys_bdflush
> +134 o32 bdflush sys_ni_syscall
> 135 o32 sysfs sys_sysfs
> 136 o32 personality sys_personality sys_32_personality
> 137 o32 afs_syscall sys_ni_syscall
> diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
> index aabc37f8cae3..51c156cb00f1 100644
> --- a/arch/parisc/kernel/syscalls/syscall.tbl
> +++ b/arch/parisc/kernel/syscalls/syscall.tbl
> @@ -147,7 +147,7 @@
> 131 common quotactl sys_quotactl
> 132 common getpgid sys_getpgid
> 133 common fchdir sys_fchdir
> -134 common bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall
> 135 common sysfs sys_sysfs
> 136 32 personality parisc_personality
> 136 64 personality sys_personality
> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
> index 8f052ff4058c..2518e4e6dccf 100644
> --- a/arch/powerpc/kernel/syscalls/syscall.tbl
> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
> @@ -176,7 +176,7 @@
> 131 nospu quotactl sys_quotactl
> 132 common getpgid sys_getpgid
> 133 common fchdir sys_fchdir
> -134 common bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall
> 135 common sysfs sys_sysfs
> 136 32 personality sys_personality ppc64_personality
> 136 64 personality ppc64_personality
> diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
> index 0690263df1dd..ffcf03714f12 100644
> --- a/arch/s390/kernel/syscalls/syscall.tbl
> +++ b/arch/s390/kernel/syscalls/syscall.tbl
> @@ -122,7 +122,7 @@
> 131 common quotactl sys_quotactl sys_quotactl
> 132 common getpgid sys_getpgid sys_getpgid
> 133 common fchdir sys_fchdir sys_fchdir
> -134 common bdflush sys_bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall sys_ni_syscall
> 135 common sysfs sys_sysfs sys_sysfs
> 136 common personality sys_s390_personality sys_s390_personality
> 137 common afs_syscall - -
> diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
> index 0b91499ebdcf..6e7305066a70 100644
> --- a/arch/sh/kernel/syscalls/syscall.tbl
> +++ b/arch/sh/kernel/syscalls/syscall.tbl
> @@ -141,7 +141,7 @@
> 131 common quotactl sys_quotactl
> 132 common getpgid sys_getpgid
> 133 common fchdir sys_fchdir
> -134 common bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall
> 135 common sysfs sys_sysfs
> 136 common personality sys_personality
> # 137 was afs_syscall
> diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
> index e34cc30ef22c..bf330dda7c61 100644
> --- a/arch/sparc/kernel/syscalls/syscall.tbl
> +++ b/arch/sparc/kernel/syscalls/syscall.tbl
> @@ -270,7 +270,7 @@
> 222 common delete_module sys_delete_module
> 223 common get_kernel_syms sys_ni_syscall
> 224 common getpgid sys_getpgid
> -225 common bdflush sys_bdflush
> +225 common bdflush sys_ni_syscall
> 226 common sysfs sys_sysfs
> 227 common afs_syscall sys_nis_syscall
> 228 common setfsuid sys_setfsuid16
> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> index 4bbc267fb36b..a21a72763d58 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -145,7 +145,7 @@
> 131 i386 quotactl sys_quotactl
> 132 i386 getpgid sys_getpgid
> 133 i386 fchdir sys_fchdir
> -134 i386 bdflush sys_bdflush
> +134 i386 bdflush sys_ni_syscall
> 135 i386 sysfs sys_sysfs
> 136 i386 personality sys_personality
> 137 i386 afs_syscall
> diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
> index fd2f30227d96..db4e3d09b249 100644
> --- a/arch/xtensa/kernel/syscalls/syscall.tbl
> +++ b/arch/xtensa/kernel/syscalls/syscall.tbl
> @@ -223,7 +223,7 @@
> # 205 was old nfsservctl
> 205 common nfsservctl sys_ni_syscall
> 206 common _sysctl sys_ni_syscall
> -207 common bdflush sys_bdflush
> +207 common bdflush sys_ni_syscall
> 208 common uname sys_newuname
> 209 common sysinfo sys_sysinfo
> 210 common init_module sys_init_module
> diff --git a/fs/buffer.c b/fs/buffer.c
> index ea48c01fb76b..04ddff76c860 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -3292,33 +3292,6 @@ int try_to_free_buffers(struct page *page)
> }
> EXPORT_SYMBOL(try_to_free_buffers);
>
> -/*
> - * There are no bdflush tunables left. But distributions are
> - * still running obsolete flush daemons, so we terminate them here.
> - *
> - * Use of bdflush() is deprecated and will be removed in a future kernel.
> - * The `flush-X' kernel threads fully replace bdflush daemons and this call.
> - */
> -SYSCALL_DEFINE2(bdflush, int, func, long, data)
> -{
> - static int msg_count;
> -
> - if (!capable(CAP_SYS_ADMIN))
> - return -EPERM;
> -
> - if (msg_count < 5) {
> - msg_count++;
> - printk(KERN_INFO
> - "warning: process `%s' used the obsolete bdflush"
> - " system call\n", current->comm);
> - printk(KERN_INFO "Fix your initscripts?\n");
> - }
> -
> - if (func == 1)
> - do_exit(0);
> - return 0;
> -}
> -
> /*
> * Buffer-head allocation
> */
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index 050511e8f1f8..1bd6e05ea116 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -1157,7 +1157,6 @@ asmlinkage long sys_ustat(unsigned dev, struct ustat __user *ubuf);
> asmlinkage long sys_vfork(void);
> asmlinkage long sys_recv(int, void __user *, size_t, unsigned);
> asmlinkage long sys_send(int, void __user *, size_t, unsigned);
> -asmlinkage long sys_bdflush(int func, long data);
> asmlinkage long sys_oldumount(char __user *name);
> asmlinkage long sys_uselib(const char __user *library);
> asmlinkage long sys_sysfs(int option,
> diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
> index 2ddb4226cd23..463d1ba2232a 100644
> --- a/include/uapi/linux/capability.h
> +++ b/include/uapi/linux/capability.h
> @@ -243,7 +243,6 @@ struct vfs_ns_cap_data {
> /* Allow examination and configuration of disk quotas */
> /* Allow setting the domainname */
> /* Allow setting the hostname */
> -/* Allow calling bdflush() */
> /* Allow mount() and umount(), setting up new smb connection */
> /* Allow some autofs root ioctls */
> /* Allow nfsservctl */
> diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
> index 0ea8128468c3..adf4d66ffae2 100644
> --- a/kernel/sys_ni.c
> +++ b/kernel/sys_ni.c
> @@ -414,7 +414,6 @@ COND_SYSCALL(epoll_wait);
> COND_SYSCALL(recv);
> COND_SYSCALL_COMPAT(recv);
> COND_SYSCALL(send);
> -COND_SYSCALL(bdflush);
> COND_SYSCALL(uselib);
>
> /* optional: time32 */
> diff --git a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
> index 2e68fbb57cc6..ab72dec9dadb 100644
> --- a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
> +++ b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
> @@ -176,7 +176,7 @@
> 131 nospu quotactl sys_quotactl
> 132 common getpgid sys_getpgid
> 133 common fchdir sys_fchdir
> -134 common bdflush sys_bdflush
> +134 common bdflush sys_ni_syscall
> 135 common sysfs sys_sysfs
> 136 32 personality sys_personality ppc64_personality
> 136 64 personality ppc64_personality
> diff --git a/tools/perf/arch/s390/entry/syscalls/syscall.tbl b/tools/perf/arch/s390/entry/syscalls/syscall.tbl
> index 7e4a2aba366d..f2eba775e676 100644
> --- a/tools/perf/arch/s390/entry/syscalls/syscall.tbl
> +++ b/tools/perf/arch/s390/entry/syscalls/syscall.tbl
> @@ -122,7 +122,7 @@
> 131 common quotactl sys_quotactl sys_quotactl
> 132 common getpgid sys_getpgid sys_getpgid
> 133 common fchdir sys_fchdir sys_fchdir
> -134 common bdflush sys_bdflush sys_bdflush
> +134 common bdflush - -
> 135 common sysfs sys_sysfs sys_sysfs
> 136 common personality sys_s390_personality sys_s390_personality
> 137 common afs_syscall - -