dm thin metadata: stop tracking need for commit

Remove an optimisation that tracks whether or not a thin metadata commit
is needed.

If dm_pool_commit_metadata() is called and no changes have been made
to the metadata then this optimisation avoided writing to disk.

Removing because we're going to do something better later.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 2 insertions, 38 deletions

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index afd84cacca4b..c8f36227fd7b 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -178,7 +178,6 @@ struct dm_pool_metadata {
 
         struct rw_semaphore root_lock;
         uint32_t time;
-        int need_commit;
         dm_block_t root;
         dm_block_t details_root;
         struct list_head thin_devices;
@@ -479,7 +478,6 @@ static int init_pmd(struct dm_pool_metadata *pmd,
 
         init_rwsem(&pmd->root_lock);
         pmd->time = 0;
-        pmd->need_commit = 0;
         pmd->details_root = 0;
         pmd->trans_id = 0;
         pmd->flags = 0;
@@ -504,11 +502,6 @@ static int __begin_transaction(struct dm_pool_metadata *pmd)
         struct dm_block *sblock;
 
         /*
-         * __maybe_commit_transaction() resets these
-         */
-        WARN_ON(pmd->need_commit);
-
-        /*
          * We re-read the superblock every time.  Shouldn't need to do this
          * really.
          */
@@ -583,8 +576,6 @@ static int __write_changed_details(struct dm_pool_metadata *pmd)
                         list_del(&td->list);
                         kfree(td);
                 }
-
-                pmd->need_commit = 1;
         }
 
         return 0;
@@ -609,9 +600,6 @@ static int __commit_transaction(struct dm_pool_metadata *pmd)
         if (r < 0)
                 return r;
 
-        if (!pmd->need_commit)
-                return r;
-
         r = dm_sm_commit(pmd->data_sm);
         if (r < 0)
                 return r;
@@ -650,11 +638,7 @@ static int __commit_transaction(struct dm_pool_metadata *pmd)
         if (r < 0)
                 goto out_locked;
 
-        r = dm_tm_commit(pmd->tm, sblock);
-        if (!r)
-                pmd->need_commit = 0;
-
-        return r;
+        return dm_tm_commit(pmd->tm, sblock);
 
 out_locked:
         dm_bm_unlock(sblock);
@@ -744,7 +728,6 @@ struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
         }
 
         pmd->flags = 0;
-        pmd->need_commit = 1;
         r = dm_pool_commit_metadata(pmd);
         if (r < 0) {
                 DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
@@ -1042,8 +1025,6 @@ static int __delete_device(struct dm_pool_metadata *pmd, dm_thin_id dev)
         if (r)
                 return r;
 
-        pmd->need_commit = 1;
-
         return 0;
 }
 
@@ -1071,7 +1052,6 @@ int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
         }
 
         pmd->trans_id = new_id;
-        pmd->need_commit = 1;
         up_write(&pmd->root_lock);
 
         return 0;
@@ -1113,8 +1093,6 @@ static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
 
                 dm_tm_dec(pmd->tm, held_root);
                 dm_tm_unlock(pmd->tm, copy);
-                pmd->need_commit = 1;
-
                 return -EBUSY;
         }
 
@@ -1140,16 +1118,12 @@ static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
                              &sb_validator, &sblock);
         if (r) {
                 dm_tm_dec(pmd->tm, held_root);
-                pmd->need_commit = 1;
                 return r;
         }
 
         disk_super = dm_block_data(sblock);
         disk_super->held_root = cpu_to_le64(held_root);
         dm_bm_unlock(sblock);
-
-        pmd->need_commit = 1;
-
         return 0;
 }
 
@@ -1179,7 +1153,6 @@ static int __release_metadata_snap(struct dm_pool_metadata *pmd)
         disk_super = dm_block_data(sblock);
         held_root = le64_to_cpu(disk_super->held_root);
         disk_super->held_root = cpu_to_le64(0);
-        pmd->need_commit = 1;
 
         dm_bm_unlock(sblock);
 
@@ -1317,7 +1290,6 @@ static int __insert(struct dm_thin_device *td, dm_block_t block,
         struct dm_pool_metadata *pmd = td->pmd;
         dm_block_t keys[2] = { td->id, block };
 
-        pmd->need_commit = 1;
         value = cpu_to_le64(pack_block_time(data_block, pmd->time));
         __dm_bless_for_disk(&value);
 
@@ -1358,7 +1330,6 @@ static int __remove(struct dm_thin_device *td, dm_block_t block)
 
         td->mapped_blocks--;
         td->changed = 1;
-        pmd->need_commit = 1;
 
         return 0;
 }
@@ -1379,10 +1350,7 @@ int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result)
         int r;
 
         down_write(&pmd->root_lock);
-
         r = dm_sm_new_block(pmd->data_sm, result);
-        pmd->need_commit = 1;
-
         up_write(&pmd->root_lock);
 
         return r;
@@ -1519,11 +1487,7 @@ static int __resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
                 return -EINVAL;
         }
 
-        r = dm_sm_extend(pmd->data_sm, new_count - old_count);
+        return dm_sm_extend(pmd->data_sm, new_count - old_count);