Detach sched.h from mm.h

First thing mm.h does is including sched.h solely for can_do_mlock() inline
function which has "current" dereference inside. By dealing with can_do_mlock()
mm.h can be detached from sched.h which is good. See below, why.

This patch
a) removes unconditional inclusion of sched.h from mm.h
b) makes can_do_mlock() normal function in mm/mlock.c
c) exports can_do_mlock() to not break compilation
d) adds sched.h inclusions back to files that were getting it indirectly.
e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were
   getting them indirectly

Net result is:
a) mm.h users would get less code to open, read, preprocess, parse, ... if
   they don't need sched.h
b) sched.h stops being dependency for significant number of files:
   on x86_64 allmodconfig touching sched.h results in recompile of 4083 files,
   after patch it's only 3744 (-8.3%).

Cross-compile tested on

	all arm defconfigs, all mips defconfigs, all powerpc defconfigs,
	alpha alpha-up
	arm
	i386 i386-up i386-defconfig i386-allnoconfig
	ia64 ia64-up
	m68k
	mips
	parisc parisc-up
	powerpc powerpc-up
	s390 s390-up
	sparc sparc-up
	sparc64 sparc64-up
	um-x86_64
	x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfig

as well as my two usual configs.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 7 insertions, 9 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4670ebd1f622..e4183c6c7de3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1,7 +1,6 @@
 #ifndef _LINUX_MM_H
 #define _LINUX_MM_H
 
-#include <linux/sched.h>
 #include <linux/errno.h>
 #include <linux/capability.h>
 
@@ -20,6 +19,7 @@
 
 struct mempolicy;
 struct anon_vma;
+struct user_struct;
 
 #ifndef CONFIG_DISCONTIGMEM          /* Don't use mapnrs, do it properly */
 extern unsigned long max_mapnr;
@@ -717,14 +717,7 @@ extern unsigned long shmem_get_unmapped_area(struct file *file,
                                              unsigned long flags);
 #endif
 
-static inline int can_do_mlock(void)
-{
-        if (capable(CAP_IPC_LOCK))
-                return 1;
-        if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0)
-                return 1;
-        return 0;
-}
+extern int can_do_mlock(void);
 extern int user_shm_lock(size_t, struct user_struct *);
 extern void user_shm_unlock(size_t, struct user_struct *);
 
diff --git a/include/linux/smb_fs.h b/include/linux/smb_fs.h
index 13b3af547864..6b51a48e8995 100644
--- a/include/linux/smb_fs.h
+++ b/include/linux/smb_fs.h
@@ -9,6 +9,7 @@
 #ifndef _LINUX_SMB_FS_H
 #define _LINUX_SMB_FS_H
 
+#include <linux/jiffies.h>
 #include <linux/smb.h>
 
 /*
diff --git a/include/linux/task_io_accounting_ops.h b/include/linux/task_io_accounting_ops.h
index 1218733ec6b5..ff46c6fad79d 100644
--- a/include/linux/task_io_accounting_ops.h
+++ b/include/linux/task_io_accounting_ops.h
@@ -4,6 +4,8 @@
 #ifndef __TASK_IO_ACCOUNTING_OPS_INCLUDED
 #define __TASK_IO_ACCOUNTING_OPS_INCLUDED
 
+#include <linux/sched.h>
+
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 static inline void task_io_account_read(size_t bytes)
 {
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 050915b59576..4ef4d22e5e43 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -4,6 +4,8 @@
 #ifndef WRITEBACK_H
 #define WRITEBACK_H
 
+#include <linux/sched.h>
+
 struct backing_dev_info;
 
 extern spinlock_t inode_lock;