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authorJens Axboe <jens.axboe@oracle.com>2008-01-24 08:54:47 +0100
committerJens Axboe <jens.axboe@oracle.com>2008-01-28 10:50:36 +0100
commitfadad878cc0640cc9cd5569998bf54b693f7b38b (patch)
tree9ad8c65d458d45f970f7e78cd1512c0e7da58def
parentio_context sharing - anticipatory changes (diff)
downloadlinux-dev-fadad878cc0640cc9cd5569998bf54b693f7b38b.tar.xz
linux-dev-fadad878cc0640cc9cd5569998bf54b693f7b38b.zip
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: Jens Axboe <jens.axboe@oracle.com>
-rw-r--r--include/linux/sched.h1
-rw-r--r--kernel/fork.c14
2 files changed, 11 insertions, 4 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 80837e7d527e..2d0546e884ea 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 1987c57abb08..314f5101d2b0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -792,15 +792,21 @@ out:
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)