[PATCH] dm snapshot: fix metadata writing when suspending

When suspending a device-mapper device, dm_suspend() sleeps until all
necessary I/O is completed.  This state is triggered by a callback from
persistent_commit().  But some I/O can still be issued *after* the callback
(to prepare the next metadata area for use if the current one is full).  This
patch delays the callback until after that I/O is complete.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
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, 10 insertions, 10 deletions

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 002417da122..99cdffa7fbf 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -536,6 +536,16 @@ static void persistent_commit(struct exception_store *store,
                 if (r)
                         ps->valid = 0;
 
+                /*
+                 * Have we completely filled the current area ?
+                 */
+                if (ps->current_committed == ps->exceptions_per_area) {
+                        ps->current_committed = 0;
+                        r = zero_area(ps, ps->current_area + 1);
+                        if (r)
+                                ps->valid = 0;
+                }
+
                 for (i = 0; i < ps->callback_count; i++) {
                         cb = ps->callbacks + i;
                         cb->callback(cb->context, r == 0 ? 1 : 0);
@@ -543,16 +553,6 @@ static void persistent_commit(struct exception_store *store,
 
                 ps->callback_count = 0;
         }
-
-        /*
-         * Have we completely filled the current area ?
-         */
-        if (ps->current_committed == ps->exceptions_per_area) {
-                ps->current_committed = 0;
-                r = zero_area(ps, ps->current_area + 1);
-                if (r)
-                        ps->valid = 0;
-        }
 }
 
 static void persistent_drop(struct exception_store *store)