dm thin: fix discard support to a previously shared block

[deliverable/linux.git] / drivers / md / dm-thin.c

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index ee29037ffc2e74633050b708718ccbe963bf20d1..51e656a3002c1b0184860631b38e63c551162095 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -512,6 +512,7 @@ struct dm_thin_new_mapping {
        unsigned quiesced:1;
        unsigned prepared:1;
        unsigned pass_discard:1;
+       unsigned definitely_not_shared:1;
 
        struct thin_c *tc;
        dm_block_t virt_block;
@@ -683,7 +684,15 @@ static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m)
        cell_defer_no_holder(tc, m->cell2);
 
        if (m->pass_discard)
-               remap_and_issue(tc, m->bio, m->data_block);
+               if (m->definitely_not_shared)
+                       remap_and_issue(tc, m->bio, m->data_block);
+               else {
+                       bool used = false;
+                       if (dm_pool_block_is_used(tc->pool->pmd, m->data_block, &used) || used)
+                               bio_endio(m->bio, 0);
+                       else
+                               remap_and_issue(tc, m->bio, m->data_block);
+               }
        else
                bio_endio(m->bio, 0);
 
@@ -751,13 +760,17 @@ static int ensure_next_mapping(struct pool *pool)
 
 static struct dm_thin_new_mapping *get_next_mapping(struct pool *pool)
 {
-       struct dm_thin_new_mapping *r = pool->next_mapping;
+       struct dm_thin_new_mapping *m = pool->next_mapping;
 
        BUG_ON(!pool->next_mapping);
 
+       memset(m, 0, sizeof(struct dm_thin_new_mapping));
+       INIT_LIST_HEAD(&m->list);
+       m->bio = NULL;
+
        pool->next_mapping = NULL;
 
-       return r;
+       return m;
 }
 
 static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
@@ -769,15 +782,10 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
        struct pool *pool = tc->pool;
        struct dm_thin_new_mapping *m = get_next_mapping(pool);
 
-       INIT_LIST_HEAD(&m->list);
-       m->quiesced = 0;
-       m->prepared = 0;
        m->tc = tc;
        m->virt_block = virt_block;
        m->data_block = data_dest;
        m->cell = cell;
-       m->err = 0;
-       m->bio = NULL;
 
        if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))
                m->quiesced = 1;
@@ -840,15 +848,12 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
        struct pool *pool = tc->pool;
        struct dm_thin_new_mapping *m = get_next_mapping(pool);
 
-       INIT_LIST_HEAD(&m->list);
        m->quiesced = 1;
        m->prepared = 0;
        m->tc = tc;
        m->virt_block = virt_block;
        m->data_block = data_block;
        m->cell = cell;
-       m->err = 0;
-       m->bio = NULL;
 
        /*
         * If the whole block of data is being overwritten or we are not
@@ -1040,12 +1045,12 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
                         */
                        m = get_next_mapping(pool);
                        m->tc = tc;
-                       m->pass_discard = (!lookup_result.shared) && pool->pf.discard_passdown;
+                       m->pass_discard = pool->pf.discard_passdown;
+                       m->definitely_not_shared = !lookup_result.shared;
                        m->virt_block = block;
                        m->data_block = lookup_result.block;
                        m->cell = cell;
                        m->cell2 = cell2;
-                       m->err = 0;
                        m->bio = bio;
 
                        if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) {