switch fput to task_work_add

... and schedule_work() for interrupt/kernel_thread callers
(and yes, now it *is* OK to call from interrupt).

We are guaranteed that __fput() will be done before we return
to userland (or exit).  Note that for fput() from a kernel
thread we get an async behaviour; it's almost always OK, but
sometimes you might need to have __fput() completed before
you do anything else.  There are two mechanisms for that -
a general barrier (flush_delayed_fput()) and explicit
__fput_sync().  Both should be used with care (as was the
case for fput() from kernel threads all along).  See comments
in fs/file_table.c for details.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 1 deletions

diff --git a/init/main.c b/init/main.c
index b5cc0a7c4708..3f151f6c6da7 100644
--- a/init/main.c
+++ b/init/main.c
@@ -68,6 +68,7 @@
 #include <linux/shmem_fs.h>
 #include <linux/slab.h>
 #include <linux/perf_event.h>
+#include <linux/file.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -804,8 +805,8 @@ static noinline int init_post(void)
         system_state = SYSTEM_RUNNING;
         numa_default_policy();
 
-
         current->signal->flags |= SIGNAL_UNKILLABLE;
+        flush_delayed_fput();
 
         if (ramdisk_execute_command) {
                 run_init_process(ramdisk_execute_command);