ioprio: move io priority from task_struct to io_context

This is where it belongs and then it doesn't take up space for a
process that doesn't do IO.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 27 insertions, 5 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 39d22b3357d..2a86c9dff74 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -51,6 +51,7 @@
 #include <linux/random.h>
 #include <linux/tty.h>
 #include <linux/proc_fs.h>
+#include <linux/blkdev.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -791,6 +792,26 @@ out:
         return error;
 }
 
+static int copy_io(struct task_struct *tsk)
+{
+#ifdef CONFIG_BLOCK
+        struct io_context *ioc = current->io_context;
+
+        if (!ioc)
+                return 0;
+
+        if (ioprio_valid(ioc->ioprio)) {
+                tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
+                if (unlikely(!tsk->io_context))
+                        return -ENOMEM;
+
+                tsk->io_context->task = tsk;
+                tsk->io_context->ioprio = ioc->ioprio;
+        }
+#endif
+        return 0;
+}
+
 /*
  *      Helper to unshare the files of the current task.
  *      We don't want to expose copy_files internals to
@@ -1156,15 +1177,17 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                 goto bad_fork_cleanup_mm;
         if ((retval = copy_namespaces(clone_flags, p)))
                 goto bad_fork_cleanup_keys;
+        if ((retval = copy_io(p)))
+                goto bad_fork_cleanup_namespaces;
         retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
         if (retval)
-                goto bad_fork_cleanup_namespaces;
+                goto bad_fork_cleanup_io;
 
         if (pid != &init_struct_pid) {
                 retval = -ENOMEM;
                 pid = alloc_pid(task_active_pid_ns(p));
                 if (!pid)
-                        goto bad_fork_cleanup_namespaces;
+                        goto bad_fork_cleanup_io;
 
                 if (clone_flags & CLONE_NEWPID) {
                         retval = pid_ns_prepare_proc(task_active_pid_ns(p));
@@ -1234,9 +1257,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         /* Need tasklist lock for parent etc handling! */
         write_lock_irq(&tasklist_lock);
 
-        /* for sys_ioprio_set(IOPRIO_WHO_PGRP) */
-        p->ioprio = current->ioprio;
-
         /*
          * The task hasn't been attached yet, so its cpus_allowed mask will
          * not be changed, nor will its assigned CPU.
@@ -1328,6 +1348,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 bad_fork_free_pid:
         if (pid != &init_struct_pid)
                 free_pid(pid);
+bad_fork_cleanup_io:
+        put_io_context(p->io_context);
 bad_fork_cleanup_namespaces:
         exit_task_namespaces(p);
 bad_fork_cleanup_keys: