Merge branch 'for-linus' of ../linux-2.6-block into block-for-2.6.39/core

This merge creates two set of conflicts.  One is simple context
conflicts caused by removal of throtl_scheduled_delayed_work() in
for-linus and removal of throtl_shutdown_timer_wq() in
for-2.6.39/core.

The other is caused by commit 255bb490c8 (block: blk-flush shouldn't
call directly into q->request_fn() __blk_run_queue()) in for-linus
crashing with FLUSH reimplementation in for-2.6.39/core.  The conflict
isn't trivial but the resolution is straight-forward.

* __blk_run_queue() calls in flush_end_io() and flush_data_end_io()
  should be called with @force_kblockd set to %true.

* elv_insert() in blk_kick_flush() should use
  %ELEVATOR_INSERT_REQUEUE.

Both changes are to avoid invoking ->request_fn() directly from
request completion path and closely match the changes in the commit
255bb490c8.

Signed-off-by: Tejun Heo <tj@kernel.org>

8 files changed, 49 insertions, 38 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index accff29ad674..74d496ccf4d7 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -342,7 +342,7 @@ void blk_start_queue(struct request_queue *q)
         WARN_ON(!irqs_disabled());
 
         queue_flag_clear(QUEUE_FLAG_STOPPED, q);
-        __blk_run_queue(q);
+        __blk_run_queue(q, false);
 }
 EXPORT_SYMBOL(blk_start_queue);
 
@@ -396,13 +396,14 @@ EXPORT_SYMBOL(blk_sync_queue);
 /**
  * __blk_run_queue - run a single device queue
  * @q:  The queue to run
+ * @force_kblockd: Don't run @q->request_fn directly.  Use kblockd.
  *
  * Description:
  *    See @blk_run_queue. This variant must be called with the queue lock
  *    held and interrupts disabled.
  *
  */
-void __blk_run_queue(struct request_queue *q)
+void __blk_run_queue(struct request_queue *q, bool force_kblockd)
 {
         blk_remove_plug(q);
 
@@ -416,7 +417,7 @@ void __blk_run_queue(struct request_queue *q)
          * Only recurse once to avoid overrunning the stack, let the unplug
          * handling reinvoke the handler shortly if we already got there.
          */
-        if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
+        if (!force_kblockd && !queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
                 q->request_fn(q);
                 queue_flag_clear(QUEUE_FLAG_REENTER, q);
         } else {
@@ -439,7 +440,7 @@ void blk_run_queue(struct request_queue *q)
         unsigned long flags;
 
         spin_lock_irqsave(q->queue_lock, flags);
-        __blk_run_queue(q);
+        __blk_run_queue(q, false);
         spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL(blk_run_queue);
@@ -1085,7 +1086,7 @@ void blk_insert_request(struct request_queue *q, struct request *rq,
 
         drive_stat_acct(rq, 1);
         __elv_add_request(q, rq, where, 0);
-        __blk_run_queue(q);
+        __blk_run_queue(q, false);
         spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL(blk_insert_request);
@@ -2642,13 +2643,6 @@ int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
 }
 EXPORT_SYMBOL(kblockd_schedule_work);
 
-int kblockd_schedule_delayed_work(struct request_queue *q,
-                        struct delayed_work *dwork, unsigned long delay)
-{
-        return queue_delayed_work(kblockd_workqueue, dwork, delay);
-}
-EXPORT_SYMBOL(kblockd_schedule_delayed_work);
-
 int __init blk_dev_init(void)
 {
         BUILD_BUG_ON(__REQ_NR_BITS > 8 *
diff --git a/block/blk-flush.c b/block/blk-flush.c
index a867e3f524f3..0bd8c9c5d6e5 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -212,9 +212,14 @@ static void flush_end_io(struct request *flush_rq, int error)
                 queued |= blk_flush_complete_seq(rq, seq, error);
         }
 
-        /* after populating an empty queue, kick it to avoid stall */
+        /*
+         * Moving a request silently to empty queue_head may stall the
+         * queue.  Kick the queue in those cases.  This function is called
+         * from request completion path and calling directly into
+         * request_fn may confuse the driver.  Always use kblockd.
+         */
         if (queued && was_empty)
-                __blk_run_queue(q);
+                __blk_run_queue(q, true);
 }
 
 /**
@@ -257,7 +262,7 @@ static bool blk_kick_flush(struct request_queue *q)
         q->flush_rq.end_io = flush_end_io;
 
         q->flush_pending_idx ^= 1;
-        elv_insert(q, &q->flush_rq, ELEVATOR_INSERT_FRONT);
+        elv_insert(q, &q->flush_rq, ELEVATOR_INSERT_REQUEUE);
         return true;
 }
 
@@ -266,9 +271,12 @@ static void flush_data_end_io(struct request *rq, int error)
         struct request_queue *q = rq->q;
         bool was_empty = elv_queue_empty(q);
 
-        /* after populating an empty queue, kick it to avoid stall */
+        /*
+         * After populating an empty queue, kick it to avoid stall.  Read
+         * the comment in flush_end_io().
+         */
         if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error) && was_empty)
-                __blk_run_queue(q);
+                __blk_run_queue(q, true);
 }
 
 /**
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 1a320d2406b0..eec78becb355 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -132,7 +132,7 @@ static void bio_batch_end_io(struct bio *bio, int err)
 }
 
 /**
- * blkdev_issue_zeroout generate number of zero filed write bios
+ * blkdev_issue_zeroout - generate number of zero filed write bios
  * @bdev:       blockdev to issue
  * @sector:     start sector
  * @nr_sects:   number of sectors to write
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index c0f623742165..061dee66e2a6 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -20,6 +20,11 @@ static int throtl_quantum = 32;
 /* Throttling is performed over 100ms slice and after that slice is renewed */
 static unsigned long throtl_slice = HZ/10;      /* 100 ms */
 
+/* A workqueue to queue throttle related work */
+static struct workqueue_struct *kthrotld_workqueue;
+static void throtl_schedule_delayed_work(struct throtl_data *td,
+                                unsigned long delay);
+
 struct throtl_rb_root {
         struct rb_root rb;
         struct rb_node *left;
@@ -345,10 +350,9 @@ static void throtl_schedule_next_dispatch(struct throtl_data *td)
         update_min_dispatch_time(st);
 
         if (time_before_eq(st->min_disptime, jiffies))
-                throtl_schedule_delayed_work(td->queue, 0);
+                throtl_schedule_delayed_work(td, 0);
         else
-                throtl_schedule_delayed_work(td->queue,
-                                (st->min_disptime - jiffies));
+                throtl_schedule_delayed_work(td, (st->min_disptime - jiffies));
 }
 
 static inline void
@@ -815,10 +819,10 @@ void blk_throtl_work(struct work_struct *work)
 }
 
 /* Call with queue lock held */
-void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay)
+static void
+throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay)
 {
 
-        struct throtl_data *td = q->td;
         struct delayed_work *dwork = &td->throtl_work;
 
         if (total_nr_queued(td) > 0) {
@@ -827,12 +831,11 @@ void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay)
                  * Cancel that and schedule a new one.
                  */
                 __cancel_delayed_work(dwork);
-                kblockd_schedule_delayed_work(q, dwork, delay);
+                queue_delayed_work(kthrotld_workqueue, dwork, delay);
                 throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
                                 delay, jiffies);
         }
 }
-EXPORT_SYMBOL(throtl_schedule_delayed_work);
 
 static void
 throtl_destroy_tg(struct throtl_data *td, struct throtl_grp *tg)
@@ -920,7 +923,7 @@ static void throtl_update_blkio_group_read_bps(void *key,
         smp_mb__after_atomic_inc();
 
         /* Schedule a work now to process the limit change */
-        throtl_schedule_delayed_work(td->queue, 0);
+        throtl_schedule_delayed_work(td, 0);
 }
 
 static void throtl_update_blkio_group_write_bps(void *key,
@@ -934,7 +937,7 @@ static void throtl_update_blkio_group_write_bps(void *key,
         smp_mb__before_atomic_inc();
         atomic_inc(&td->limits_changed);
         smp_mb__after_atomic_inc();
-        throtl_schedule_delayed_work(td->queue, 0);
+        throtl_schedule_delayed_work(td, 0);
 }
 
 static void throtl_update_blkio_group_read_iops(void *key,
@@ -948,7 +951,7 @@ static void throtl_update_blkio_group_read_iops(void *key,
         smp_mb__before_atomic_inc();
         atomic_inc(&td->limits_changed);
         smp_mb__after_atomic_inc();
-        throtl_schedule_delayed_work(td->queue, 0);
+        throtl_schedule_delayed_work(td, 0);
 }
 
 static void throtl_update_blkio_group_write_iops(void *key,
@@ -962,7 +965,7 @@ static void throtl_update_blkio_group_write_iops(void *key,
         smp_mb__before_atomic_inc();
         atomic_inc(&td->limits_changed);
         smp_mb__after_atomic_inc();
-        throtl_schedule_delayed_work(td->queue, 0);
+        throtl_schedule_delayed_work(td, 0);
 }
 
 static void throtl_shutdown_wq(struct request_queue *q)
@@ -1135,6 +1138,10 @@ void blk_throtl_exit(struct request_queue *q)
 
 static int __init throtl_init(void)
 {
+        kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
+        if (!kthrotld_workqueue)
+                panic("Failed to create kthrotld\n");
+
         blkio_policy_register(&blkio_policy_throtl);
         return 0;
 }
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3202c7e87fb3..89dc745c7d94 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3324,7 +3324,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                             cfqd->busy_queues > 1) {
                                 cfq_del_timer(cfqd, cfqq);
                                 cfq_clear_cfqq_wait_request(cfqq);
-                                __blk_run_queue(cfqd->queue);
+                                __blk_run_queue(cfqd->queue, false);
                         } else {
                                 cfq_blkiocg_update_idle_time_stats(
                                                 &cfqq->cfqg->blkg);
@@ -3339,7 +3339,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                  * this new queue is RT and the current one is BE
                  */
                 cfq_preempt_queue(cfqd, cfqq);
-                __blk_run_queue(cfqd->queue);
+                __blk_run_queue(cfqd->queue, false);
         }
 }
 
@@ -3700,7 +3700,7 @@ static void cfq_kick_queue(struct work_struct *work)
         struct request_queue *q = cfqd->queue;
 
         spin_lock_irq(q->queue_lock);
-        __blk_run_queue(cfqd->queue);
+        __blk_run_queue(cfqd->queue, false);
         spin_unlock_irq(q->queue_lock);
 }
 
diff --git a/block/elevator.c b/block/elevator.c
index f98e92edc937..fabf3675c913 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -602,7 +602,7 @@ void elv_quiesce_start(struct request_queue *q)
          */
         elv_drain_elevator(q);
         while (q->rq.elvpriv) {
-                __blk_run_queue(q);
+                __blk_run_queue(q, false);
                 spin_unlock_irq(q->queue_lock);
                 msleep(10);
                 spin_lock_irq(q->queue_lock);
@@ -651,7 +651,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
                  *   with anything.  There's no point in delaying queue
                  *   processing.
                  */
-                __blk_run_queue(q);
+                __blk_run_queue(q, false);
                 break;
 
         case ELEVATOR_INSERT_SORT:
diff --git a/block/genhd.c b/block/genhd.c
index 73d85a8e3c85..3e2b57b55e38 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1355,7 +1355,7 @@ int invalidate_partition(struct gendisk *disk, int partno)
         struct block_device *bdev = bdget_disk(disk, partno);
         if (bdev) {
                 fsync_bdev(bdev);
-                res = __invalidate_device(bdev);
+                res = __invalidate_device(bdev, true);
                 bdput(bdev);
         }
         return res;
diff --git a/block/ioctl.c b/block/ioctl.c
index 9049d460fa89..1124cd297263 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -294,9 +294,11 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
                         return -EINVAL;
                 if (get_user(n, (int __user *) arg))
                         return -EFAULT;
-                if (!(mode & FMODE_EXCL) &&
-                    blkdev_get(bdev, mode | FMODE_EXCL, &bdev) < 0)
-                        return -EBUSY;
+                if (!(mode & FMODE_EXCL)) {
+                        bdgrab(bdev);
+                        if (blkdev_get(bdev, mode | FMODE_EXCL, &bdev) < 0)
+                                return -EBUSY;
+                }
                 ret = set_blocksize(bdev, n);
                 if (!(mode & FMODE_EXCL))
                         blkdev_put(bdev, mode | FMODE_EXCL);