dm: refactor deferred bio_list processing

Refactor deferred bio_list processing.

 - use separate _merge_pushback_list function
 - move deferred bio list pick up to flush function
 - use bio_list_pop instead of bio_list_get
 - simplify noflush flag use

No real functional change in this patch.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 52427e1..c1ad7d7 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1262,19 +1262,27 @@ EXPORT_SYMBOL_GPL(dm_put);
 /*
  * Process the deferred bios
  */
-static void __flush_deferred_io(struct mapped_device *md, struct bio *c)
+static void __flush_deferred_io(struct mapped_device *md)
 {
-       struct bio *n;
+       struct bio *c;
 
-       while (c) {
-               n = c->bi_next;
-               c->bi_next = NULL;
+       while ((c = bio_list_pop(&md->deferred))) {
                if (__split_bio(md, c))
                        bio_io_error(c);
-               c = n;
        }
 }
 
+static void __merge_pushback_list(struct mapped_device *md)
+{
+       unsigned long flags;
+
+       spin_lock_irqsave(&md->pushback_lock, flags);
+       clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
+       bio_list_merge_head(&md->deferred, &md->pushback);
+       bio_list_init(&md->pushback);
+       spin_unlock_irqrestore(&md->pushback_lock, flags);
+}
+
 /*
  * Swap in a new table (destroying old one).
  */
@@ -1346,9 +1354,7 @@ static void unlock_fs(struct mapped_device *md)
 int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 {
        struct dm_table *map = NULL;
-       unsigned long flags;
        DECLARE_WAITQUEUE(wait, current);
-       struct bio *def;
        int r = -EINVAL;
        int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
        int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
@@ -1378,16 +1384,16 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
                        r = -ENOMEM;
                        goto flush_and_out;
                }
-       }
 
-       /*
-        * Flush I/O to the device.
-        * noflush supersedes do_lockfs, because lock_fs() needs to flush I/Os.
-        */
-       if (do_lockfs && !noflush) {
-               r = lock_fs(md);
-               if (r)
-                       goto out;
+               /*
+                * Flush I/O to the device. noflush supersedes do_lockfs,
+                * because lock_fs() needs to flush I/Os.
+                */
+               if (do_lockfs) {
+                       r = lock_fs(md);
+                       if (r)
+                               goto out;
+               }
        }
 
        /*
@@ -1421,20 +1427,14 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
        down_write(&md->io_lock);
        remove_wait_queue(&md->wait, &wait);
 
-       if (noflush) {
-               spin_lock_irqsave(&md->pushback_lock, flags);
-               clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
-               bio_list_merge_head(&md->deferred, &md->pushback);
-               bio_list_init(&md->pushback);
-               spin_unlock_irqrestore(&md->pushback_lock, flags);
-       }
+       if (noflush)
+               __merge_pushback_list(md);
 
        /* were we interrupted ? */
        r = -EINTR;
        if (atomic_read(&md->pending)) {
                clear_bit(DMF_BLOCK_IO, &md->flags);
-               def = bio_list_get(&md->deferred);
-               __flush_deferred_io(md, def);
+               __flush_deferred_io(md);
                up_write(&md->io_lock);
                unlock_fs(md);
                goto out; /* pushback list is already flushed, so skip flush */
@@ -1454,15 +1454,8 @@ flush_and_out:
                 * flush them before return.
                 */
                down_write(&md->io_lock);
-
-               spin_lock_irqsave(&md->pushback_lock, flags);
-               clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
-               bio_list_merge_head(&md->deferred, &md->pushback);
-               bio_list_init(&md->pushback);
-               spin_unlock_irqrestore(&md->pushback_lock, flags);
-
-               def = bio_list_get(&md->deferred);
-               __flush_deferred_io(md, def);
+               __merge_pushback_list(md);
+               __flush_deferred_io(md);
                up_write(&md->io_lock);
        }
 
@@ -1482,7 +1475,6 @@ out_unlock:
 int dm_resume(struct mapped_device *md)
 {
        int r = -EINVAL;
-       struct bio *def;
        struct dm_table *map = NULL;
 
        mutex_lock(&md->suspend_lock);
@@ -1500,8 +1492,7 @@ int dm_resume(struct mapped_device *md)
        down_write(&md->io_lock);
        clear_bit(DMF_BLOCK_IO, &md->flags);
 
-       def = bio_list_get(&md->deferred);
-       __flush_deferred_io(md, def);
+       __flush_deferred_io(md);
        up_write(&md->io_lock);
 
        unlock_fs(md);