1 files changed, 27 insertions, 324 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 351afe7..6e095a9 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -54,11 +54,6 @@ unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio request
 static struct kmem_cache	*kiocb_cachep;
 static struct kmem_cache	*kioctx_cachep;
 
-static struct workqueue_struct *aio_wq;
-
-static void aio_kick_handler(struct work_struct *);
-static void aio_queue_work(struct kioctx *);
-
 /* aio_setup
  *	Creates the slab caches used by the aio routines, panic on
  *	failure as this is done early during the boot sequence.
@@ -68,9 +63,6 @@ static int __init aio_setup(void)
 	kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 
-	aio_wq = alloc_workqueue("aio", 0, 1);	/* used to limit concurrency */
-	BUG_ON(!aio_wq);
-
 	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
 
 	return 0;
@@ -86,7 +78,6 @@ static void aio_free_ring(struct kioctx *ctx)
 		put_page(info->ring_pages[i]);
 
 	if (info->mmap_size) {
-		BUG_ON(ctx->mm != current->mm);
 		vm_munmap(info->mmap_base, info->mmap_size);
 	}
 
@@ -101,6 +92,7 @@ static int aio_setup_ring(struct kioctx *ctx)
 	struct aio_ring *ring;
 	struct aio_ring_info *info = &ctx->ring_info;
 	unsigned nr_events = ctx->max_reqs;
+	struct mm_struct *mm = current->mm;
 	unsigned long size, populate;
 	int nr_pages;
 
@@ -126,23 +118,22 @@ static int aio_setup_ring(struct kioctx *ctx)
 
 	info->mmap_size = nr_pages * PAGE_SIZE;
 	dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
-	down_write(&ctx->mm->mmap_sem);
+	down_write(&mm->mmap_sem);
 	info->mmap_base = do_mmap_pgoff(NULL, 0, info->mmap_size, 
 					PROT_READ|PROT_WRITE,
 					MAP_ANONYMOUS|MAP_PRIVATE, 0,
 					&populate);
 	if (IS_ERR((void *)info->mmap_base)) {
-		up_write(&ctx->mm->mmap_sem);
+		up_write(&mm->mmap_sem);
 		info->mmap_size = 0;
 		aio_free_ring(ctx);
 		return -EAGAIN;
 	}
 
 	dprintk("mmap address: 0x%08lx\n", info->mmap_base);
-	info->nr_pages = get_user_pages(current, ctx->mm,
-					info->mmap_base, nr_pages, 
+	info->nr_pages = get_user_pages(current, mm, info->mmap_base, nr_pages,
 					1, 0, info->ring_pages, NULL);
-	up_write(&ctx->mm->mmap_sem);
+	up_write(&mm->mmap_sem);
 
 	if (unlikely(info->nr_pages != nr_pages)) {
 		aio_free_ring(ctx);
@@ -206,10 +197,7 @@ static void __put_ioctx(struct kioctx *ctx)
 	unsigned nr_events = ctx->max_reqs;
 	BUG_ON(ctx->reqs_active);
 
-	cancel_delayed_work_sync(&ctx->wq);
 	aio_free_ring(ctx);
-	mmdrop(ctx->mm);
-	ctx->mm = NULL;
 	if (nr_events) {
 		spin_lock(&aio_nr_lock);
 		BUG_ON(aio_nr - nr_events > aio_nr);
@@ -237,7 +225,7 @@ static inline void put_ioctx(struct kioctx *kioctx)
  */
 static struct kioctx *ioctx_alloc(unsigned nr_events)
 {
-	struct mm_struct *mm;
+	struct mm_struct *mm = current->mm;
 	struct kioctx *ctx;
 	int err = -ENOMEM;
 
@@ -256,8 +244,6 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 		return ERR_PTR(-ENOMEM);
 
 	ctx->max_reqs = nr_events;
-	mm = ctx->mm = current->mm;
-	atomic_inc(&mm->mm_count);
 
 	atomic_set(&ctx->users, 2);
 	spin_lock_init(&ctx->ctx_lock);
@@ -265,8 +251,6 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 	init_waitqueue_head(&ctx->wait);
 
 	INIT_LIST_HEAD(&ctx->active_reqs);
-	INIT_LIST_HEAD(&ctx->run_list);
-	INIT_DELAYED_WORK(&ctx->wq, aio_kick_handler);
 
 	if (aio_setup_ring(ctx) < 0)
 		goto out_freectx;
@@ -287,14 +271,13 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 	spin_unlock(&mm->ioctx_lock);
 
 	dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
-		ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
+		ctx, ctx->user_id, mm, ctx->ring_info.nr);
 	return ctx;
 
 out_cleanup:
 	err = -EAGAIN;
 	aio_free_ring(ctx);
 out_freectx:
-	mmdrop(mm);
 	kmem_cache_free(kioctx_cachep, ctx);
 	dprintk("aio: error allocating ioctx %d\n", err);
 	return ERR_PTR(err);
@@ -391,8 +374,6 @@ void exit_aio(struct mm_struct *mm)
 		 * as indicator that it needs to unmap the area,
 		 * just set it to 0; aio_free_ring() is the only
 		 * place that uses ->mmap_size, so it's safe.
-		 * That way we get all munmap done to current->mm -
-		 * all other callers have ctx->mm == current->mm.
 		 */
 		ctx->ring_info.mmap_size = 0;
 		put_ioctx(ctx);
@@ -426,7 +407,6 @@ static struct kiocb *__aio_get_req(struct kioctx *ctx)
 	req->ki_dtor = NULL;
 	req->private = NULL;
 	req->ki_iovec = NULL;
-	INIT_LIST_HEAD(&req->ki_run_list);
 	req->ki_eventfd = NULL;
 
 	return req;
@@ -611,281 +591,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
 	return ret;
 }
 
-/*
- * Queue up a kiocb to be retried. Assumes that the kiocb
- * has already been marked as kicked, and places it on
- * the retry run list for the corresponding ioctx, if it
- * isn't already queued. Returns 1 if it actually queued
- * the kiocb (to tell the caller to activate the work
- * queue to process it), or 0, if it found that it was
- * already queued.
- */
-static inline int __queue_kicked_iocb(struct kiocb *iocb)
-{
-	struct kioctx *ctx = iocb->ki_ctx;
-
-	assert_spin_locked(&ctx->ctx_lock);
-
-	if (list_empty(&iocb->ki_run_list)) {
-		list_add_tail(&iocb->ki_run_list,
-			&ctx->run_list);
-		return 1;
-	}
-	return 0;
-}
-
-/* aio_run_iocb
- *	This is the core aio execution routine. It is
- *	invoked both for initial i/o submission and
- *	subsequent retries via the aio_kick_handler.
- *	Expects to be invoked with iocb->ki_ctx->lock
- *	already held. The lock is released and reacquired
- *	as needed during processing.
- *
- * Calls the iocb retry method (already setup for the
- * iocb on initial submission) for operation specific
- * handling, but takes care of most of common retry
- * execution details for a given iocb. The retry method
- * needs to be non-blocking as far as possible, to avoid
- * holding up other iocbs waiting to be serviced by the
- * retry kernel thread.
- *
- * The trickier parts in this code have to do with
- * ensuring that only one retry instance is in progress
- * for a given iocb at any time. Providing that guarantee
- * simplifies the coding of individual aio operations as
- * it avoids various potential races.
- */
-static ssize_t aio_run_iocb(struct kiocb *iocb)
-{
-	struct kioctx	*ctx = iocb->ki_ctx;
-	ssize_t (*retry)(struct kiocb *);
-	ssize_t ret;
-
-	if (!(retry = iocb->ki_retry)) {
-		printk("aio_run_iocb: iocb->ki_retry = NULL\n");
-		return 0;
-	}
-
-	/*
-	 * We don't want the next retry iteration for this
-	 * operation to start until this one has returned and
-	 * updated the iocb state. However, wait_queue functions
-	 * can trigger a kick_iocb from interrupt context in the
-	 * meantime, indicating that data is available for the next
-	 * iteration. We want to remember that and enable the
-	 * next retry iteration _after_ we are through with
-	 * this one.
-	 *
-	 * So, in order to be able to register a "kick", but
-	 * prevent it from being queued now, we clear the kick
-	 * flag, but make the kick code *think* that the iocb is
-	 * still on the run list until we are actually done.
-	 * When we are done with this iteration, we check if
-	 * the iocb was kicked in the meantime and if so, queue
-	 * it up afresh.
-	 */
-
-	kiocbClearKicked(iocb);
-
-	/*
-	 * This is so that aio_complete knows it doesn't need to
-	 * pull the iocb off the run list (We can't just call
-	 * INIT_LIST_HEAD because we don't want a kick_iocb to
-	 * queue this on the run list yet)
-	 */
-	iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
-	spin_unlock_irq(&ctx->ctx_lock);
-
-	/* Quit retrying if the i/o has been cancelled */
-	if (kiocbIsCancelled(iocb)) {
-		ret = -EINTR;
-		aio_complete(iocb, ret, 0);
-		/* must not access the iocb after this */
-		goto out;
-	}
-
-	/*
-	 * Now we are all set to call the retry method in async
-	 * context.
-	 */
-	ret = retry(iocb);
-
-	if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
-		/*
-		 * There's no easy way to restart the syscall since other AIO's
-		 * may be already running. Just fail this IO with EINTR.
-		 */
-		if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
-			     ret == -ERESTARTNOHAND || ret == -ERESTART_RESTARTBLOCK))
-			ret = -EINTR;
-		aio_complete(iocb, ret, 0);
-	}
-out:
-	spin_lock_irq(&ctx->ctx_lock);
-
-	if (-EIOCBRETRY == ret) {
-		/*
-		 * OK, now that we are done with this iteration
-		 * and know that there is more left to go,
-		 * this is where we let go so that a subsequent
-		 * "kick" can start the next iteration
-		 */
-
-		/* will make __queue_kicked_iocb succeed from here on */
-		INIT_LIST_HEAD(&iocb->ki_run_list);
-		/* we must queue the next iteration ourselves, if it
-		 * has already been kicked */
-		if (kiocbIsKicked(iocb)) {
-			__queue_kicked_iocb(iocb);
-
-			/*
-			 * __queue_kicked_iocb will always return 1 here, because
-			 * iocb->ki_run_list is empty at this point so it should
-			 * be safe to unconditionally queue the context into the
-			 * work queue.
-			 */
-			aio_queue_work(ctx);
-		}
-	}
-	return ret;
-}
-
-/*
- * __aio_run_iocbs:
- * 	Process all pending retries queued on the ioctx
- * 	run list.
- * Assumes it is operating within the aio issuer's mm
- * context.
- */
-static int __aio_run_iocbs(struct kioctx *ctx)
-{
-	struct kiocb *iocb;
-	struct list_head run_list;
-
-	assert_spin_locked(&ctx->ctx_lock);
-
-	list_replace_init(&ctx->run_list, &run_list);
-	while (!list_empty(&run_list)) {
-		iocb = list_entry(run_list.next, struct kiocb,
-			ki_run_list);
-		list_del(&iocb->ki_run_list);
-		/*
-		 * Hold an extra reference while retrying i/o.
-		 */
-		iocb->ki_users++;       /* grab extra reference */
-		aio_run_iocb(iocb);
-		__aio_put_req(ctx, iocb);
- 	}
-	if (!list_empty(&ctx->run_list))
-		return 1;
-	return 0;
-}
-
-static void aio_queue_work(struct kioctx * ctx)
-{
-	unsigned long timeout;
-	/*
-	 * if someone is waiting, get the work started right
-	 * away, otherwise, use a longer delay
-	 */
-	smp_mb();
-	if (waitqueue_active(&ctx->wait))
-		timeout = 1;
-	else
-		timeout = HZ/10;
-	queue_delayed_work(aio_wq, &ctx->wq, timeout);
-}
-
-/*
- * aio_run_all_iocbs:
- *	Process all pending retries queued on the ioctx
- *	run list, and keep running them until the list
- *	stays empty.
- * Assumes it is operating within the aio issuer's mm context.
- */
-static inline void aio_run_all_iocbs(struct kioctx *ctx)
-{
-	spin_lock_irq(&ctx->ctx_lock);
-	while (__aio_run_iocbs(ctx))
-		;
-	spin_unlock_irq(&ctx->ctx_lock);
-}
-
-/*
- * aio_kick_handler:
- * 	Work queue handler triggered to process pending
- * 	retries on an ioctx. Takes on the aio issuer's
- *	mm context before running the iocbs, so that
- *	copy_xxx_user operates on the issuer's address
- *      space.
- * Run on aiod's context.
- */
-static void aio_kick_handler(struct work_struct *work)
-{
-	struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
-	mm_segment_t oldfs = get_fs();
-	struct mm_struct *mm;
-	int requeue;
-
-	set_fs(USER_DS);
-	use_mm(ctx->mm);
-	spin_lock_irq(&ctx->ctx_lock);
-	requeue =__aio_run_iocbs(ctx);
-	mm = ctx->mm;
-	spin_unlock_irq(&ctx->ctx_lock);
- 	unuse_mm(mm);
-	set_fs(oldfs);
-	/*
-	 * we're in a worker thread already; no point using non-zero delay
-	 */
-	if (requeue)
-		queue_delayed_work(aio_wq, &ctx->wq, 0);
-}
-
-
-/*
- * Called by kick_iocb to queue the kiocb for retry
- * and if required activate the aio work queue to process
- * it
- */
-static void try_queue_kicked_iocb(struct kiocb *iocb)
-{
- 	struct kioctx	*ctx = iocb->ki_ctx;
-	unsigned long flags;
-	int run = 0;
-
-	spin_lock_irqsave(&ctx->ctx_lock, flags);
-	/* set this inside the lock so that we can't race with aio_run_iocb()
-	 * testing it and putting the iocb on the run list under the lock */
-	if (!kiocbTryKick(iocb))
-		run = __queue_kicked_iocb(iocb);
-	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
-	if (run)
-		aio_queue_work(ctx);
-}
-
-/*
- * kick_iocb:
- *      Called typically from a wait queue callback context
- *      to trigger a retry of the iocb.
- *      The retry is usually executed by aio workqueue
- *      threads (See aio_kick_handler).
- */
-void kick_iocb(struct kiocb *iocb)
-{
-	/* sync iocbs are easy: they can only ever be executing from a 
-	 * single context. */
-	if (is_sync_kiocb(iocb)) {
-		kiocbSetKicked(iocb);
-	        wake_up_process(iocb->ki_obj.tsk);
-		return;
-	}
-
-	try_queue_kicked_iocb(iocb);
-}
-EXPORT_SYMBOL(kick_iocb);
-
 /* aio_complete
  *	Called when the io request on the given iocb is complete.
  *	Returns true if this is the last user of the request.  The 
@@ -926,9 +631,6 @@ int aio_complete(struct kiocb *iocb, long res, long res2)
 	 */
 	spin_lock_irqsave(&ctx->ctx_lock, flags);
 
-	if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
-		list_del_init(&iocb->ki_run_list);
-
 	/*
 	 * cancelled requests don't get events, userland was given one
 	 * when the event got cancelled.
@@ -1083,13 +785,11 @@ static int read_events(struct kioctx *ctx,
 	int			i = 0;
 	struct io_event		ent;
 	struct aio_timeout	to;
-	int			retry = 0;
 
 	/* needed to zero any padding within an entry (there shouldn't be 
 	 * any, but C is fun!
 	 */
 	memset(&ent, 0, sizeof(ent));
-retry:
 	ret = 0;
 	while (likely(i < nr)) {
 		ret = aio_read_evt(ctx, &ent);
@@ -1119,13 +819,6 @@ retry:
 
 	/* End fast path */
 
-	/* racey check, but it gets redone */
-	if (!retry && unlikely(!list_empty(&ctx->run_list))) {
-		retry = 1;
-		aio_run_all_iocbs(ctx);
-		goto retry;
-	}
-
 	init_timeout(&to);
 	if (timeout) {
 		struct timespec	ts;
@@ -1349,7 +1042,7 @@ static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
 	/* If we managed to write some out we return that, rather than
 	 * the eventual error. */
 	if (opcode == IOCB_CMD_PWRITEV
-	    && ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY
+	    && ret < 0 && ret != -EIOCBQUEUED
 	    && iocb->ki_nbytes - iocb->ki_left)
 		ret = iocb->ki_nbytes - iocb->ki_left;
 
@@ -1591,18 +1284,28 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	 * don't see ctx->dead set here, io_destroy() waits for our IO to
 	 * finish.
 	 */
-	if (ctx->dead) {
-		spin_unlock_irq(&ctx->ctx_lock);
+	if (ctx->dead)
 		ret = -EINVAL;
+	spin_unlock_irq(&ctx->ctx_lock);
+	if (ret)
 		goto out_put_req;
+
+	if (unlikely(kiocbIsCancelled(req)))
+		ret = -EINTR;
+	else
+		ret = req->ki_retry(req);
+
+	if (ret != -EIOCBQUEUED) {
+		/*
+		 * There's no easy way to restart the syscall since other AIO's
+		 * may be already running. Just fail this IO with EINTR.
+		 */
+		if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
+			     ret == -ERESTARTNOHAND ||
+			     ret == -ERESTART_RESTARTBLOCK))
+			ret = -EINTR;
+		aio_complete(req, ret, 0);
 	}
-	aio_run_iocb(req);
-	if (!list_empty(&ctx->run_list)) {
-		/* drain the run list */
-		while (__aio_run_iocbs(ctx))
-			;
-	}
-	spin_unlock_irq(&ctx->ctx_lock);
 
 	aio_put_req(req);	/* drop extra ref to req */
 	return 0;