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>

1 files changed, 29 insertions, 38 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 52427e15189b..c1ad7d77dbcd 100644
--- 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);