[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>

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index c5449f2..d929801 100644 (file)
--- 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;
        }
 
@@ -673,41 +652,39 @@ 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)