dm: move wait queue declaration

Move wait queue declaration and unplug to dm_wait_for_completion.

The purpose is to minimize duplicate code in the further patches.

The patch reorders functions a little bit. It doesn't change any
functionality. For proper non-deadlock operation, add_wait_queue must
happen before set_current_state(interruptible) and before the test for
!atomic_read(&md->pending).

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f570372..7867d90 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1377,6 +1377,11 @@ EXPORT_SYMBOL_GPL(dm_put);
 static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
 {
        int r = 0;
+       DECLARE_WAITQUEUE(wait, current);
+
+       dm_unplug_all(md->queue);
+
+       add_wait_queue(&md->wait, &wait);
 
        while (1) {
                set_current_state(interruptible);
@@ -1395,6 +1400,8 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
        }
        set_current_state(TASK_RUNNING);
 
+       remove_wait_queue(&md->wait, &wait);
+
        return r;
 }
 
@@ -1501,7 +1508,6 @@ static void unlock_fs(struct mapped_device *md)
 int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 {
        struct dm_table *map = NULL;
-       DECLARE_WAITQUEUE(wait, current);
        int r = 0;
        int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
        int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
@@ -1551,20 +1557,14 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
        down_write(&md->io_lock);
        set_bit(DMF_BLOCK_IO, &md->flags);
 
-       add_wait_queue(&md->wait, &wait);
        up_write(&md->io_lock);
 
-       /* unplug */
-       if (map)
-               dm_table_unplug_all(map);
-
        /*
         * Wait for the already-mapped ios to complete.
         */
        r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
 
        down_write(&md->io_lock);
-       remove_wait_queue(&md->wait, &wait);
 
        if (noflush)
                clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);