diff options
| -rw-r--r-- | drivers/md/dm.c | 40 |
1 files changed, 32 insertions, 8 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index bb97ec8d6644..9746c1eb9ef7 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1434,18 +1434,21 @@ static void dm_wq_work(struct work_struct *work) down_write(&md->io_lock); - while (1) { + while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) { spin_lock_irq(&md->deferred_lock); c = bio_list_pop(&md->deferred); spin_unlock_irq(&md->deferred_lock); if (!c) { - clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); clear_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags); break; } + up_write(&md->io_lock); + __split_and_process_bio(md, c); + + down_write(&md->io_lock); } up_write(&md->io_lock); @@ -1453,8 +1456,9 @@ static void dm_wq_work(struct work_struct *work) static void dm_queue_flush(struct mapped_device *md) { + clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); + smp_mb__after_clear_bit(); queue_work(md->wq, &md->work); - flush_workqueue(md->wq); } /* @@ -1572,22 +1576,36 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) } /* - * First we set the DMF_QUEUE_IO_TO_THREAD flag so no more ios - * will be mapped. + * Here we must make sure that no processes are submitting requests + * to target drivers i.e. no one may be executing + * __split_and_process_bio. This is called from dm_request and + * dm_wq_work. + * + * To get all processes out of __split_and_process_bio in dm_request, + * we take the write lock. To prevent any process from reentering + * __split_and_process_bio from dm_request, we set + * DMF_QUEUE_IO_TO_THREAD. + * + * To quiesce the thread (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND + * and call flush_workqueue(md->wq). flush_workqueue will wait until + * dm_wq_work exits and DMF_BLOCK_IO_FOR_SUSPEND will prevent any + * further calls to __split_and_process_bio from dm_wq_work. */ down_write(&md->io_lock); set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags); - up_write(&md->io_lock); + flush_workqueue(md->wq); + /* - * Wait for the already-mapped ios to complete. + * At this point no more requests are entering target request routines. + * We call dm_wait_for_completion to wait for all existing requests + * to finish. */ r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE); down_write(&md->io_lock); - if (noflush) clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); up_write(&md->io_lock); @@ -1600,6 +1618,12 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) goto out; /* pushback list is already flushed, so skip flush */ } + /* + * If dm_wait_for_completion returned 0, the device is completely + * quiescent now. There is no request-processing activity. All new + * requests are being added to md->deferred list. + */ + dm_table_postsuspend_targets(map); set_bit(DMF_SUSPENDED, &md->flags); |