Commit fadad878 authored by Jens Axboe's avatar Jens Axboe

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 <>
parent 521f3bbd
......@@ -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
......@@ -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)
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)
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