dm thin metadata: wrap superblock locking

Introduce wrappers to handle write locking the superblock
appropriately.

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>

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 4aadeae3af67cc9bc8b4a3009e1d6624eb8c63ff..dd3a89b1bf6fa070cf8f240ead71203b6aa20092 100644 (file)
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -343,6 +343,20 @@ static int subtree_equal(void *context, void *value1_le, void *value2_le)
 
 /*----------------------------------------------------------------*/
 
+static int superblock_lock_zero(struct dm_pool_metadata *pmd,
+                               struct dm_block **sblock)
+{
+       return dm_bm_write_lock_zero(pmd->bm, THIN_SUPERBLOCK_LOCATION,
+                                    &sb_validator, sblock);
+}
+
+static int superblock_lock(struct dm_pool_metadata *pmd,
+                          struct dm_block **sblock)
+{
+       return dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
+                               &sb_validator, sblock);
+}
+
 static int superblock_all_zeroes(struct dm_block_manager *bm, int *result)
 {
        int r;
@@ -430,22 +444,11 @@ static int init_pmd(struct dm_pool_metadata *pmd,
                        r = PTR_ERR(data_sm);
                        goto bad;
                }
-
-               /*
-                * We cycle the superblock to let the validator do its stuff.
-                */
-               r = dm_bm_write_lock_zero(bm, THIN_SUPERBLOCK_LOCATION, &sb_validator, &sblock);
-               if (r < 0) {
-                       DMERR("couldn't lock superblock");
-                       goto bad;
-               }
-
-               dm_bm_unlock(sblock);
-
        } else {
                struct thin_disk_superblock *disk_super;
 
-               r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION, &sb_validator, &sblock);
+               r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION,
+                                   &sb_validator, &sblock);
                if (r < 0) {
                        DMERR("couldn't read superblock");
                        return r;
@@ -628,8 +631,7 @@ static int __commit_transaction(struct dm_pool_metadata *pmd)
        if (r < 0)
                return r;
 
-       r = dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
-                            &sb_validator, &sblock);
+       r = superblock_lock(pmd, &sblock);
        if (r)
                return r;
 
@@ -709,8 +711,7 @@ struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
        /*
         * Create.
         */
-       r = dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
-                            &sb_validator, &sblock);
+       r = superblock_lock_zero(pmd, &sblock);
        if (r)
                goto bad;
 
@@ -1126,8 +1127,7 @@ static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
        /*
         * Write the held root into the superblock.
         */
-       r = dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
-                            &sb_validator, &sblock);
+       r = superblock_lock(pmd, &sblock);
        if (r) {
                dm_tm_dec(pmd->tm, held_root);
                return r;
@@ -1157,8 +1157,7 @@ static int __release_metadata_snap(struct dm_pool_metadata *pmd)
        struct dm_block *sblock, *copy;
        dm_block_t held_root;
 
-       r = dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
-                            &sb_validator, &sblock);
+       r = superblock_lock(pmd, &sblock);
        if (r)
                return r;