Remove struct task_struct::io_wait

Hell knows what happened in commit 63b05203af57e7de4f3bb63b8b81d43bc196d32b
during 2.6.9 development.  Commit introduced io_wait field which remained
write-only than and still remains write-only.

Also garbage collect macros which "use" io_wait.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 2 insertions, 34 deletions

diff --git a/fs/aio.c b/fs/aio.c
index d02f43b50a3d..f12db415c0f6 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -710,18 +710,9 @@ static ssize_t aio_run_iocb(struct kiocb *iocb)
 
         /*
          * Now we are all set to call the retry method in async
-         * context. By setting this thread's io_wait context
-         * to point to the wait queue entry inside the currently
-         * running iocb for the duration of the retry, we ensure
-         * that async notification wakeups are queued by the
-         * operation instead of blocking waits, and when notified,
-         * cause the iocb to be kicked for continuation (through
-         * the aio_wake_function callback).
+         * context.
          */
-        BUG_ON(current->io_wait != NULL);
-        current->io_wait = &iocb->ki_wait;
         ret = retry(iocb);
-        current->io_wait = NULL;
 
         if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
                 BUG_ON(!list_empty(&iocb->ki_wait.task_list));
@@ -1508,10 +1499,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb)
  *      Simply triggers a retry of the operation via kick_iocb.
  *
  *      This callback is specified in the wait queue entry in
- *      a kiocb (current->io_wait points to this wait queue
- *      entry when an aio operation executes; it is used
- *      instead of a synchronous wait when an i/o blocking
- *      condition is encountered during aio).
+ *      a kiocb.
  *
  * Note:
  * This routine is executed with the wait queue lock held.
diff --git a/include/linux/aio.h b/include/linux/aio.h
index d10e608f232d..7ef8de662001 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -232,18 +232,6 @@ int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                 __put_ioctx(kioctx);                                    \
 } while (0)
 
-#define in_aio() (unlikely(!is_sync_wait(current->io_wait)))
-
-/* may be used for debugging */
-#define warn_if_async()                                                 \
-do {                                                                    \
-        if (in_aio()) {                                                 \
-                printk(KERN_ERR "%s(%s:%d) called in async context!\n", \
-                        __FUNCTION__, __FILE__, __LINE__);              \
-                dump_stack();                                           \
-        }                                                               \
-} while (0)
-
 #define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 
 #include <linux/aio_abi.h>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c204ab0d4df1..269b234609b8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1110,13 +1110,6 @@ struct task_struct {
 
         unsigned long ptrace_message;
         siginfo_t *last_siginfo; /* For ptrace use.  */
-/*
- * current io wait handle: wait queue entry to use for io waits
- * If this thread is processing aio, this points at the waitqueue
- * inside the currently handled kiocb. It may be NULL (i.e. default
- * to a stack based synchronous wait) if its doing sync IO.
- */
-        wait_queue_t *io_wait;
 #ifdef CONFIG_TASK_XACCT
 /* i/o counters(bytes read/written, #syscalls */
         u64 rchar, wchar, syscr, syscw;
diff --git a/kernel/fork.c b/kernel/fork.c
index 7e455a93a75a..125246fc75a5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1084,7 +1084,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         p->security = NULL;
 #endif
         p->io_context = NULL;
-        p->io_wait = NULL;
         p->audit_context = NULL;
         cpuset_fork(p);
 #ifdef CONFIG_NUMA