syslets can set this to enforce sharing of io context.
Signed-off-by: Jens Axboe <[EMAIL PROTECTED]>
---
include/linux/sched.h | 1 +
kernel/fork.c | 14 ++++++++++----
2 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 638250c..b6dbcd6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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
diff --git a/kernel/fork.c b/kernel/fork.c
index 4cfb0f4..e7eec39 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -792,14 +792,20 @@ out:
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;
@@ -1166,7 +1172,7 @@ 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)
--
1.5.4.rc2.84.gf85fd
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