dm snapshot: refactor __find_pending_exception

Move looking-up of a pending exception from __find_pending_exception to another
function.

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

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 65ff82ff124e29a3c7cfedf276df89646fcbc2ac..87a2803ba6bd6ef259fca34622638495651e3ce3 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -972,6 +972,17 @@ static void start_copy(struct dm_snap_pending_exception *pe)
                    &src, 1, &dest, 0, copy_callback, pe);
 }
 
+static struct dm_snap_pending_exception *
+__lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk)
+{
+       struct dm_snap_exception *e = lookup_exception(&s->pending, chunk);
+
+       if (!e)
+               return NULL;
+
+       return container_of(e, struct dm_snap_pending_exception, e);
+}
+
 /*
  * Looks to see if this snapshot already has a pending exception
  * for this chunk, otherwise it allocates a new one and inserts
@@ -983,20 +994,9 @@ static void start_copy(struct dm_snap_pending_exception *pe)
 static struct dm_snap_pending_exception *
 __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
 {
-       struct dm_snap_exception *e;
-       struct dm_snap_pending_exception *pe;
+       struct dm_snap_pending_exception *pe, *pe2;
        chunk_t chunk = sector_to_chunk(s, bio->bi_sector);
 
-       /*
-        * Is there a pending exception for this already ?
-        */
-       e = lookup_exception(&s->pending, chunk);
-       if (e) {
-               /* cast the exception to a pending exception */
-               pe = container_of(e, struct dm_snap_pending_exception, e);
-               goto out;
-       }
-
        /*
         * Create a new pending exception, we don't want
         * to hold the lock while we do this.
@@ -1010,11 +1010,10 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
                return NULL;
        }
 
-       e = lookup_exception(&s->pending, chunk);
-       if (e) {
+       pe2 = __lookup_pending_exception(s, chunk);
+       if (pe2) {
                free_pending_exception(pe);
-               pe = container_of(e, struct dm_snap_pending_exception, e);
-               goto out;
+               return pe2;
        }
 
        pe->e.old_chunk = chunk;
@@ -1032,7 +1031,6 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
        get_pending_exception(pe);
        insert_exception(&s->pending, &pe->e);
 
- out:
        return pe;
 }
 
@@ -1083,11 +1081,14 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
         * writeable.
         */
        if (bio_rw(bio) == WRITE) {
-               pe = __find_pending_exception(s, bio);
+               pe = __lookup_pending_exception(s, chunk);
                if (!pe) {
-                       __invalidate_snapshot(s, -ENOMEM);
-                       r = -EIO;
-                       goto out_unlock;
+                       pe = __find_pending_exception(s, bio);
+                       if (!pe) {
+                               __invalidate_snapshot(s, -ENOMEM);
+                               r = -EIO;
+                               goto out_unlock;
+                       }
                }
 
                remap_exception(s, &pe->e, bio, chunk);
@@ -1217,10 +1218,13 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
                if (e)
                        goto next_snapshot;
 
-               pe = __find_pending_exception(snap, bio);
+               pe = __lookup_pending_exception(snap, chunk);
                if (!pe) {
-                       __invalidate_snapshot(snap, -ENOMEM);
-                       goto next_snapshot;
+                       pe = __find_pending_exception(snap, bio);
+                       if (!pe) {
+                               __invalidate_snapshot(snap, -ENOMEM);
+                               goto next_snapshot;
+                       }
                }
 
                if (!primary_pe) {