1 files changed, 42 insertions, 35 deletions

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index db404a0f7e2c..c09359db3a90 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -33,7 +33,6 @@ struct dm_io_client {
 struct io {
         unsigned long error_bits;
         atomic_t count;
-        struct completion *wait;
         struct dm_io_client *client;
         io_notify_fn callback;
         void *context;
@@ -112,28 +111,27 @@ static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
  * We need an io object to keep track of the number of bios that
  * have been dispatched for a particular io.
  *---------------------------------------------------------------*/
-static void dec_count(struct io *io, unsigned int region, int error)
+static void complete_io(struct io *io)
 {
-        if (error)
-                set_bit(region, &io->error_bits);
+        unsigned long error_bits = io->error_bits;
+        io_notify_fn fn = io->callback;
+        void *context = io->context;
 
-        if (atomic_dec_and_test(&io->count)) {
-                if (io->vma_invalidate_size)
-                        invalidate_kernel_vmap_range(io->vma_invalidate_address,
-                                                     io->vma_invalidate_size);
+        if (io->vma_invalidate_size)
+                invalidate_kernel_vmap_range(io->vma_invalidate_address,
+                                             io->vma_invalidate_size);
 
-                if (io->wait)
-                        complete(io->wait);
+        mempool_free(io, io->client->pool);
+        fn(error_bits, context);
+}
 
-                else {
-                        unsigned long r = io->error_bits;
-                        io_notify_fn fn = io->callback;
-                        void *context = io->context;
+static void dec_count(struct io *io, unsigned int region, int error)
+{
+        if (error)
+                set_bit(region, &io->error_bits);
 
-                        mempool_free(io, io->client->pool);
-                        fn(r, context);
-                }
-        }
+        if (atomic_dec_and_test(&io->count))
+                complete_io(io);
 }
 
 static void endio(struct bio *bio, int error)
@@ -376,41 +374,51 @@ static void dispatch_io(int rw, unsigned int num_regions,
         dec_count(io, 0, 0);
 }
 
+struct sync_io {
+        unsigned long error_bits;
+        struct completion wait;
+};
+
+static void sync_io_complete(unsigned long error, void *context)
+{
+        struct sync_io *sio = context;
+
+        sio->error_bits = error;
+        complete(&sio->wait);
+}
+
 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
                    struct dm_io_region *where, int rw, struct dpages *dp,
                    unsigned long *error_bits)
 {
-        /*
-         * gcc <= 4.3 can't do the alignment for stack variables, so we must
-         * align it on our own.
-         * volatile prevents the optimizer from removing or reusing
-         * "io_" field from the stack frame (allowed in ANSI C).
-         */
-        volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
-        struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));
-        DECLARE_COMPLETION_ONSTACK(wait);
+        struct io *io;
+        struct sync_io sio;
 
         if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
                 WARN_ON(1);
                 return -EIO;
         }
 
+        init_completion(&sio.wait);
+
+        io = mempool_alloc(client->pool, GFP_NOIO);
         io->error_bits = 0;
         atomic_set(&io->count, 1); /* see dispatch_io() */
-        io->wait = &wait;
         io->client = client;
+        io->callback = sync_io_complete;
+        io->context = &sio;
 
         io->vma_invalidate_address = dp->vma_invalidate_address;
         io->vma_invalidate_size = dp->vma_invalidate_size;
 
         dispatch_io(rw, num_regions, where, dp, io, 1);
 
-        wait_for_completion_io(&wait);
+        wait_for_completion_io(&sio.wait);
 
         if (error_bits)
-                *error_bits = io->error_bits;
+                *error_bits = sio.error_bits;
 
-        return io->error_bits ? -EIO : 0;
+        return sio.error_bits ? -EIO : 0;
 }
 
 static int async_io(struct dm_io_client *client, unsigned int num_regions,
@@ -428,7 +436,6 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions,
         io = mempool_alloc(client->pool, GFP_NOIO);
         io->error_bits = 0;
         atomic_set(&io->count, 1); /* see dispatch_io() */
-        io->wait = NULL;
         io->client = client;
         io->callback = fn;
         io->context = context;
@@ -481,9 +488,9 @@ static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
  * New collapsed (a)synchronous interface.
  *
  * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
- * the queue with blk_unplug() some time later or set REQ_SYNC in
-io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
- * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
+ * the queue with blk_unplug() some time later or set REQ_SYNC in io_req->bi_rw.
+ * If you fail to do one of these, the IO will be submitted to the disk after
+ * q->unplug_delay, which defaults to 3ms in blk-settings.c.
  */
 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
           struct dm_io_region *where, unsigned long *sync_error_bits)