| Message ID | 06c7c949626acd419d77d611a65ca5427d6cf866.1488054759.git.bosrsf04@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, 25 Feb 2017, Brian Ashworth wrote: > The pivot_root syscall is not needed on systems that do not use > any intermediate filesystem. Allowing for pivot_root to be > ommitted from the kernel will aid in the tinification efforts. > > Without CONFIG_PIVOT_ROOT_SYSCALL set > add/remove: 0/2 grow/shrink: 1/0 up/down: 45/-707 (-662) > function old new delta > attach_recursive_mnt 349 394 +45 > attach_mnt 71 - -71 > sys_pivot_root 636 - -636 > Total: Before=1899893, After=1899231, chg -0.03% A -0.03% size difference doesn't seem much. To bring up a more realistic scenario for tinification statistics, you could start from "make tinyconfig" instead. > Signed-off-by: Brian Ashworth <bosrsf04@gmail.com> > --- > fs/namespace.c | 2 ++ > init/Kconfig | 10 ++++++++++ > kernel/sys_ni.c | 1 + > 3 files changed, 13 insertions(+) I agree that this is a much more interesting diffstat than the previous one. Acked-by: Nicolas Pitre <nico@linaro.org> > diff --git a/fs/namespace.c b/fs/namespace.c > index 487ba30bb5c6..5e24a08bfb36 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -3058,6 +3058,7 @@ bool path_is_under(const struct path *path1, const struct path *path2) > } > EXPORT_SYMBOL(path_is_under); > > +#ifdef CONFIG_PIVOT_ROOT_SYSCALL > /* > * pivot_root Semantics: > * Moves the root file system of the current process to the directory put_old, > @@ -3180,6 +3181,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, > out0: > return error; > } > +#endif /* CONFIG_PIVOT_ROOT_SYSCALL */ > > static void __init init_mount_tree(void) > { > diff --git a/init/Kconfig b/init/Kconfig > index 8c39615165b7..4ea9ab25ec30 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1450,6 +1450,16 @@ config SYSCTL_SYSCALL > > If unsure say N here. > > +config PIVOT_ROOT_SYSCALL > + bool "Pivot_root syscall support" if EXPERT > + default y > + help > + pivot_root is a system call that allows the root to be moved and > + replaced by another root. This is needed for intermediate file > + systems such as initrd. > + > + If unsure say Y here. > + > config POSIX_TIMERS > bool "Posix Clocks & timers" if EXPERT > default y > diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c > index 8acef8576ce9..7bd207571f87 100644 > --- a/kernel/sys_ni.c > +++ b/kernel/sys_ni.c > @@ -178,6 +178,7 @@ cond_syscall(sys_setfsgid); > cond_syscall(sys_capget); > cond_syscall(sys_capset); > cond_syscall(sys_copy_file_range); > +cond_syscall(sys_pivot_root); > > /* arch-specific weak syscall entries */ > cond_syscall(sys_pciconfig_read); > -- > 2.11.1 > >
Thanks for the ack on this. Whose tree should this patch go through?
diff --git a/fs/namespace.c b/fs/namespace.c index 487ba30bb5c6..5e24a08bfb36 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3058,6 +3058,7 @@ bool path_is_under(const struct path *path1, const struct path *path2) } EXPORT_SYMBOL(path_is_under); +#ifdef CONFIG_PIVOT_ROOT_SYSCALL /* * pivot_root Semantics: * Moves the root file system of the current process to the directory put_old, @@ -3180,6 +3181,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, out0: return error; } +#endif /* CONFIG_PIVOT_ROOT_SYSCALL */ static void __init init_mount_tree(void) { diff --git a/init/Kconfig b/init/Kconfig index 8c39615165b7..4ea9ab25ec30 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1450,6 +1450,16 @@ config SYSCTL_SYSCALL If unsure say N here. +config PIVOT_ROOT_SYSCALL + bool "Pivot_root syscall support" if EXPERT + default y + help + pivot_root is a system call that allows the root to be moved and + replaced by another root. This is needed for intermediate file + systems such as initrd. + + If unsure say Y here. + config POSIX_TIMERS bool "Posix Clocks & timers" if EXPERT default y diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 8acef8576ce9..7bd207571f87 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -178,6 +178,7 @@ cond_syscall(sys_setfsgid); cond_syscall(sys_capget); cond_syscall(sys_capset); cond_syscall(sys_copy_file_range); +cond_syscall(sys_pivot_root); /* arch-specific weak syscall entries */ cond_syscall(sys_pciconfig_read);
The pivot_root syscall is not needed on systems that do not use any intermediate filesystem. Allowing for pivot_root to be ommitted from the kernel will aid in the tinification efforts. Without CONFIG_PIVOT_ROOT_SYSCALL set add/remove: 0/2 grow/shrink: 1/0 up/down: 45/-707 (-662) function old new delta attach_recursive_mnt 349 394 +45 attach_mnt 71 - -71 sys_pivot_root 636 - -636 Total: Before=1899893, After=1899231, chg -0.03% Signed-off-by: Brian Ashworth <bosrsf04@gmail.com> --- fs/namespace.c | 2 ++ init/Kconfig | 10 ++++++++++ kernel/sys_ni.c | 1 + 3 files changed, 13 insertions(+)