Configure out file locking features

This patch adds the CONFIG_FILE_LOCKING option which allows to remove
support for advisory locks. With this patch enabled, the flock()
system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl()
and NFS support are disabled. These features are not necessarly needed
on embedded systems. It allows to save ~11 Kb of kernel code and data:

   text          data     bss     dec     hex filename
1125436        118764  212992 1457192  163c28 vmlinux.old
1114299        118564  212992 1445855  160fdf vmlinux
 -11137    -200       0  -11337   -2C49 +/-

This patch has originally been written by Matt Mackall
<mpm@selenic.com>, and is part of the Linux Tiny project.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: matthew@wil.cx
Cc: linux-fsdevel@vger.kernel.org
Cc: mpm@selenic.com
Cc: akpm@linux-foundation.org
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

2 files changed, 6 insertions, 1 deletions

diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 08d6e1bb99ac..503d8d4eb80a 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -125,6 +125,7 @@ cond_syscall(sys_vm86old);
 cond_syscall(sys_vm86);
 cond_syscall(compat_sys_ipc);
 cond_syscall(compat_sys_sysctl);
+cond_syscall(sys_flock);
 
 /* arch-specific weak syscall entries */
 cond_syscall(sys_pciconfig_read);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 50ec0886fa3d..4588b2cf2ecb 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -97,7 +97,7 @@ static int sixty = 60;
 static int neg_one = -1;
 #endif
 
-#ifdef CONFIG_MMU
+#if defined(CONFIG_MMU) && defined(CONFIG_FILE_LOCKING)
 static int two = 2;
 #endif
 
@@ -1261,6 +1261,7 @@ static struct ctl_table fs_table[] = {
                 .extra1         = &minolduid,
                 .extra2         = &maxolduid,
         },
+#ifdef CONFIG_FILE_LOCKING
         {
                 .ctl_name       = FS_LEASES,
                 .procname       = "leases-enable",
@@ -1269,6 +1270,7 @@ static struct ctl_table fs_table[] = {
                 .mode           = 0644,
                 .proc_handler   = &proc_dointvec,
         },
+#endif
 #ifdef CONFIG_DNOTIFY
         {
                 .ctl_name       = FS_DIR_NOTIFY,
@@ -1280,6 +1282,7 @@ static struct ctl_table fs_table[] = {
         },
 #endif
 #ifdef CONFIG_MMU
+#ifdef CONFIG_FILE_LOCKING
         {
                 .ctl_name       = FS_LEASE_TIME,
                 .procname       = "lease-break-time",
@@ -1291,6 +1294,7 @@ static struct ctl_table fs_table[] = {
                 .extra1         = &zero,
                 .extra2         = &two,
         },
+#endif
         {
                 .procname       = "aio-nr",
                 .data           = &aio_nr,