[PATCH] dm snapshot: tidy pending_complete

This patch rearranges the pending_complete() code so that the functional
changes in subsequent patches are clearer.

By consolidating the error and the non-error paths, we can move
error_snapshot_bios() and __flush_bios() in line.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 30 insertions, 46 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index c5449f2504b6..d92980177b5c 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -609,26 +609,6 @@ static void error_bios(struct bio *bio)
         }
 }
 
-static inline void error_snapshot_bios(struct pending_exception *pe)
-{
-        error_bios(bio_list_get(&pe->snapshot_bios));
-}
-
-static struct bio *__flush_bios(struct pending_exception *pe)
-{
-        /*
-         * If this pe is involved in a write to the origin and
-         * it is the last sibling to complete then release
-         * the bios for the original write to the origin.
-         */
-
-        if (pe->primary_pe &&
-            atomic_dec_and_test(&pe->primary_pe->sibling_count))
-                return bio_list_get(&pe->primary_pe->origin_bios);
-
-        return NULL;
-}
-
 static void __invalidate_snapshot(struct dm_snapshot *s,
                                 struct pending_exception *pe, int err)
 {
@@ -656,16 +636,15 @@ static void pending_complete(struct pending_exception *pe, int success)
         struct exception *e;
         struct pending_exception *primary_pe;
         struct dm_snapshot *s = pe->snap;
-        struct bio *flush = NULL;
+        struct bio *origin_bios = NULL;
+        struct bio *snapshot_bios = NULL;
+        int error = 0;
 
         if (!success) {
                 /* Read/write error - snapshot is unusable */
                 down_write(&s->lock);
                 __invalidate_snapshot(s, pe, -EIO);
-                flush = __flush_bios(pe);
-                up_write(&s->lock);
-
-                error_snapshot_bios(pe);
+                error = 1;
                 goto out;
         }
 
@@ -673,42 +652,40 @@ static void pending_complete(struct pending_exception *pe, int success)
         if (!e) {
                 down_write(&s->lock);
                 __invalidate_snapshot(s, pe, -ENOMEM);
-                flush = __flush_bios(pe);
-                up_write(&s->lock);
-
-                error_snapshot_bios(pe);
+                error = 1;
                 goto out;
         }
         *e = pe->e;
 
-        /*
-         * Add a proper exception, and remove the
-         * in-flight exception from the list.
-         */
         down_write(&s->lock);
         if (!s->valid) {
-                flush = __flush_bios(pe);
-                up_write(&s->lock);
-
                 free_exception(e);
-
-                error_snapshot_bios(pe);
+                error = 1;
                 goto out;
         }
 
+        /*
+         * Add a proper exception, and remove the
+         * in-flight exception from the list.
+         */
         insert_exception(&s->complete, e);
         remove_exception(&pe->e);
-        flush = __flush_bios(pe);
-
-        up_write(&s->lock);
-
-        /* Submit any pending write bios */
-        flush_bios(bio_list_get(&pe->snapshot_bios));
 
  out:
+        snapshot_bios = bio_list_get(&pe->snapshot_bios);
+
         primary_pe = pe->primary_pe;
 
         /*
+         * If this pe is involved in a write to the origin and
+         * it is the last sibling to complete then release
+         * the bios for the original write to the origin.
+         */
+        if (primary_pe &&
+            atomic_dec_and_test(&primary_pe->sibling_count))
+                origin_bios = bio_list_get(&primary_pe->origin_bios);
+
+        /*
          * Free the pe if it's not linked to an origin write or if
          * it's not itself a primary pe.
          */
@@ -721,8 +698,15 @@ static void pending_complete(struct pending_exception *pe, int success)
         if (primary_pe && !atomic_read(&primary_pe->sibling_count))
                 free_pending_exception(primary_pe);
 
-        if (flush)
-                flush_bios(flush);
+        up_write(&s->lock);
+
+        /* Submit any pending write bios */
+        if (error)
+                error_bios(snapshot_bios);
+        else
+                flush_bios(snapshot_bios);
+
+        flush_bios(origin_bios);
 }
 
 static void commit_callback(void *context, int success)