block: add blk_io_schedule() for avoiding task hung in sync dio

Sync dio could be big, or may take long time in discard or in case of
IO failure.

We have prevented task hung in submit_bio_wait() and blk_execute_rq(),
so apply the same trick for prevent task hung from happening in sync dio.

Add helper of blk_io_schedule() and use io_schedule_timeout() to prevent
task hung warning.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Cc: Salman Qazi <sqazi@google.com>
Cc: Jesse Barnes <jsbarnes@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 7cbb7b7..ebd1507 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -255,7 +255,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
                        break;
                if (!(iocb->ki_flags & IOCB_HIPRI) ||
                    !blk_poll(bdev_get_queue(bdev), qc, true))
-                       io_schedule();
+                       blk_io_schedule();
        }
        __set_current_state(TASK_RUNNING);
 
@@ -449,7 +449,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 
                if (!(iocb->ki_flags & IOCB_HIPRI) ||
                    !blk_poll(bdev_get_queue(bdev), qc, true))
-                       io_schedule();
+                       blk_io_schedule();
        }
        __set_current_state(TASK_RUNNING);
 

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 00b4d15..6d5370e 100644 (file)
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -500,7 +500,7 @@ static struct bio *dio_await_one(struct dio *dio)
                spin_unlock_irqrestore(&dio->bio_lock, flags);
                if (!(dio->iocb->ki_flags & IOCB_HIPRI) ||
                    !blk_poll(dio->bio_disk->queue, dio->bio_cookie, true))
-                       io_schedule();
+                       blk_io_schedule();
                /* wake up sets us TASK_RUNNING */
                spin_lock_irqsave(&dio->bio_lock, flags);
                dio->waiter = NULL;

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 20dde5a..fd3bd06 100644 (file)
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -561,7 +561,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
                            !dio->submit.last_queue ||
                            !blk_poll(dio->submit.last_queue,
                                         dio->submit.cookie, true))
-                               io_schedule();
+                               blk_io_schedule();
                }
                __set_current_state(TASK_RUNNING);
        }

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f00bd40..222eb5f 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -27,6 +27,7 @@
 #include <linux/percpu-refcount.h>
 #include <linux/scatterlist.h>
 #include <linux/blkzoned.h>
+#include <linux/sched/sysctl.h>
 
 struct module;
 struct scsi_ioctl_command;
@@ -1827,4 +1828,15 @@ static inline void blk_wake_io_task(struct task_struct *waiter)
                wake_up_process(waiter);
 }
 
+static inline void blk_io_schedule(void)
+{
+       /* Prevent hang_check timer from firing at us during very long I/O */
+       unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;
+
+       if (timeout)
+               io_schedule_timeout(timeout);
+       else
+               io_schedule();
+}
+
 #endif