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

Michael Schmitz <schmitzmic@xxxxxxxxx> · Wed, 30 Jun 2021 09:45:04 +1200

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@xxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Tested-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
---

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		-				-






