dm kcopyd: prepare for callback race fix

Use a variable in segment_complete() to point to the dm_kcopyd_client
struct and only release job->pages in run_complete_job() if any are
defined.  These changes are needed by the next patch.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 0a225da21272..9d379070918b 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -297,7 +297,8 @@ static int run_complete_job(struct kcopyd_job *job)
         dm_kcopyd_notify_fn fn = job->fn;
         struct dm_kcopyd_client *kc = job->kc;
 
-        kcopyd_put_pages(kc, job->pages);
+        if (job->pages)
+                kcopyd_put_pages(kc, job->pages);
         mempool_free(job, kc->job_pool);
         fn(read_err, write_err, context);
 
@@ -461,6 +462,7 @@ static void segment_complete(int read_err, unsigned long write_err,
         sector_t progress = 0;
         sector_t count = 0;
         struct kcopyd_job *job = (struct kcopyd_job *) context;
+        struct dm_kcopyd_client *kc = job->kc;
 
         mutex_lock(&job->lock);
 
@@ -490,7 +492,7 @@ static void segment_complete(int read_err, unsigned long write_err,
 
         if (count) {
                 int i;
-                struct kcopyd_job *sub_job = mempool_alloc(job->kc->job_pool,
+                struct kcopyd_job *sub_job = mempool_alloc(kc->job_pool,
                                                            GFP_NOIO);
 
                 *sub_job = *job;