[PATCH] dm snapshot: fix freeing pending exception

If a snapshot became invalid while there are outstanding pending_exceptions,
when pending_complete() processes each one it forgets to remove the
corresponding exception from its exception table before freeing it.

Fix this by moving the 'out:' label up one statement so that
remove_exception() is always called.  Then __invalidate_exception() no longer
needs to call it and its 'pe' argument become superfluous.

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

1 files changed, 6 insertions, 10 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 638c8d90da0e..5281e0094072 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -631,8 +631,7 @@ static void error_bios(struct bio *bio)
         }
 }
 
-static void __invalidate_snapshot(struct dm_snapshot *s,
-                                struct pending_exception *pe, int err)
+static void __invalidate_snapshot(struct dm_snapshot *s, int err)
 {
         if (!s->valid)
                 return;
@@ -642,9 +641,6 @@ static void __invalidate_snapshot(struct dm_snapshot *s,
         else if (err == -ENOMEM)
                 DMERR("Invalidating snapshot: Unable to allocate exception.");
 
-        if (pe)
-                remove_exception(&pe->e);
-
         if (s->store.drop_snapshot)
                 s->store.drop_snapshot(&s->store);
 
@@ -701,7 +697,7 @@ static void pending_complete(struct pending_exception *pe, int success)
         if (!success) {
                 /* Read/write error - snapshot is unusable */
                 down_write(&s->lock);
-                __invalidate_snapshot(s, pe, -EIO);
+                __invalidate_snapshot(s, -EIO);
                 error = 1;
                 goto out;
         }
@@ -709,7 +705,7 @@ static void pending_complete(struct pending_exception *pe, int success)
         e = alloc_exception();
         if (!e) {
                 down_write(&s->lock);
-                __invalidate_snapshot(s, pe, -ENOMEM);
+                __invalidate_snapshot(s, -ENOMEM);
                 error = 1;
                 goto out;
         }
@@ -727,9 +723,9 @@ static void pending_complete(struct pending_exception *pe, int success)
          * in-flight exception from the list.
          */
         insert_exception(&s->complete, e);
-        remove_exception(&pe->e);
 
  out:
+        remove_exception(&pe->e);
         snapshot_bios = bio_list_get(&pe->snapshot_bios);
         origin_bios = put_pending_exception(pe);
 
@@ -909,7 +905,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
         if (bio_rw(bio) == WRITE) {
                 pe = __find_pending_exception(s, bio);
                 if (!pe) {
-                        __invalidate_snapshot(s, pe, -ENOMEM);
+                        __invalidate_snapshot(s, -ENOMEM);
                         r = -EIO;
                         goto out_unlock;
                 }
@@ -1035,7 +1031,7 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
 
                 pe = __find_pending_exception(snap, bio);
                 if (!pe) {
-                        __invalidate_snapshot(snap, pe, -ENOMEM);
+                        __invalidate_snapshot(snap, -ENOMEM);
                         goto next_snapshot;
                 }