Commit fadad878 authored by Jens Axboe's avatar Jens Axboe
Browse files

kernel: add CLONE_IO to specifically request sharing of IO contexts 



syslets (or other threads/processes that want io context sharing) can
set this to enforce sharing of io context.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 521f3bbd

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#define CLONE_NEWUSER		0x10000000	/* New user namespace */

#define CLONE_NEWPID		0x20000000	/* New pid namespace */

#define CLONE_NEWNET		0x40000000	/* New network namespace */

#define CLONE_IO		0x80000000	/* Clone io context */



/*

 * Scheduling policies

kernel/fork.c

+10 −4
Original line number Diff line number Diff line
@@ -792,15 +792,21 @@ static int copy_files(unsigned long clone_flags, struct task_struct * tsk) 
	return error;

}



static int copy_io(struct task_struct *tsk)

static int copy_io(unsigned long clone_flags, struct task_struct *tsk)

{

#ifdef CONFIG_BLOCK

	struct io_context *ioc = current->io_context;



	if (!ioc)

		return 0;



	if (ioprio_valid(ioc->ioprio)) {

	/*

	 * Share io context with parent, if CLONE_IO is set

	 */

	if (clone_flags & CLONE_IO) {

		tsk->io_context = ioc_task_link(ioc);

		if (unlikely(!tsk->io_context))

			return -ENOMEM;

	} else if (ioprio_valid(ioc->ioprio)) {

		tsk->io_context = alloc_io_context(GFP_KERNEL, -1);

		if (unlikely(!tsk->io_context))

			return -ENOMEM;
@@ -1176,7 +1182,7 @@ 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)))

	if ((retval = copy_io(clone_flags, p)))

		goto bad_fork_cleanup_namespaces;

	retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);

	if (retval)