dm thin metadata: Add support for a pre-commit callback

Add support for one pre-commit callback which is run right before the
metadata are committed.

This allows the thin provisioning target to run a callback before the
metadata are committed and is required by the next commit.

Cc: stable@vger.kernel.org
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 4c68a7b93d5edab9192a3ce9c24fcdc79b7e1acf..b88d6d701f5bb26bec60314164b4cd07926fab51 100644 (file)
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -188,6 +188,15 @@ struct dm_pool_metadata {
        unsigned long flags;
        sector_t data_block_size;
 
+       /*
+        * Pre-commit callback.
+        *
+        * This allows the thin provisioning target to run a callback before
+        * the metadata are committed.
+        */
+       dm_pool_pre_commit_fn pre_commit_fn;
+       void *pre_commit_context;
+
        /*
         * We reserve a section of the metadata for commit overhead.
         * All reported space does *not* include this.
@@ -826,6 +835,14 @@ static int __commit_transaction(struct dm_pool_metadata *pmd)
        if (unlikely(!pmd->in_service))
                return 0;
 
+       if (pmd->pre_commit_fn) {
+               r = pmd->pre_commit_fn(pmd->pre_commit_context);
+               if (r < 0) {
+                       DMERR("pre-commit callback failed");
+                       return r;
+               }
+       }
+
        r = __write_changed_details(pmd);
        if (r < 0)
                return r;
@@ -892,6 +909,8 @@ struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
        pmd->in_service = false;
        pmd->bdev = bdev;
        pmd->data_block_size = data_block_size;
+       pmd->pre_commit_fn = NULL;
+       pmd->pre_commit_context = NULL;
 
        r = __create_persistent_data_objects(pmd, format_device);
        if (r) {
@@ -2044,6 +2063,16 @@ int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
        return r;
 }
 
+void dm_pool_register_pre_commit_callback(struct dm_pool_metadata *pmd,
+                                         dm_pool_pre_commit_fn fn,
+                                         void *context)
+{
+       pmd_write_lock_in_core(pmd);
+       pmd->pre_commit_fn = fn;
+       pmd->pre_commit_context = context;
+       pmd_write_unlock(pmd);
+}
+
 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd)
 {
        int r = -EINVAL;

diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h
index f6be0d733c20267f569b72ab14314d0565425e80..7ef56bd2a7e33974469196486bdf05c9b4bedda3 100644 (file)
--- a/drivers/md/dm-thin-metadata.h
+++ b/drivers/md/dm-thin-metadata.h
@@ -230,6 +230,13 @@ bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd);
  */
 void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd);
 
+/* Pre-commit callback */
+typedef int (*dm_pool_pre_commit_fn)(void *context);
+
+void dm_pool_register_pre_commit_callback(struct dm_pool_metadata *pmd,
+                                         dm_pool_pre_commit_fn fn,
+                                         void *context);
+
 /*----------------------------------------------------------------*/
 
 #endif