sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency

Instead of including the full <linux/signal.h>, we are going to include the
types-only <linux/signal_types.h> header in <linux/sched.h>, to further
decouple the scheduler header from the signal headers.

This means that various files which relied on the full <linux/signal.h> need
to be updated to gain an explicit dependency on it.

Update the code that relies on sched.h's inclusion of the <linux/signal.h> header.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index c35b966..dad395b 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -16,6 +16,7 @@
  * Boston, MA 021110-1307, USA.
  */
 #include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/pagemap.h>
 #include <linux/writeback.h>
 #include <linux/blkdev.h>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 1a131f7..493a654 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -18,6 +18,7 @@
 
 #include <linux/pagemap.h>
 #include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/slab.h>
 #include <linux/math64.h>
 #include <linux/ratelimit.h>
diff --git a/fs/buffer.c b/fs/buffer.c
index 28484b3..9196f2a 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -19,6 +19,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/sched/signal.h>
 #include <linux/syscalls.h>
 #include <linux/fs.h>
 #include <linux/iomap.h>
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index f297a9e..1a3e1b4 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -8,6 +8,7 @@
 #include <linux/slab.h>
 #include <linux/pagevec.h>
 #include <linux/task_io_accounting_ops.h>
+#include <linux/signal.h>
 
 #include "super.h"
 #include "mds_client.h"
diff --git a/fs/dax.c b/fs/dax.c
index 7436c98..de622d4 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -27,6 +27,7 @@
 #include <linux/pagevec.h>
 #include <linux/pmem.h>
 #include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/uio.h>
 #include <linux/vmstat.h>
 #include <linux/pfn_t.h>
diff --git a/fs/ioctl.c b/fs/ioctl.c
index cb9b029..569db68 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -15,6 +15,8 @@
 #include <linux/writeback.h>
 #include <linux/buffer_head.h>
 #include <linux/falloc.h>
+#include <linux/sched/signal.h>
+
 #include "internal.h"
 
 #include <asm/ioctls.h>
diff --git a/fs/iomap.c b/fs/iomap.c
index 0f85f24..3ca1a8e 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -26,6 +26,8 @@
 #include <linux/buffer_head.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/dax.h>
+#include <linux/sched/signal.h>
+
 #include "internal.h"
 
 /*
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index a24e42f..ca1646f 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -42,6 +42,7 @@
 #include <linux/seq_file.h>
 #include <linux/quotaops.h>
 #include <linux/cleancache.h>
+#include <linux/signal.h>
 
 #define CREATE_TRACE_POINTS
 #include "ocfs2_trace.h"