dm thin metadata: only check incompat features on open

Factor out __check_incompat_features and only call it once when we open
the metadata device rather than at the beginning of every transaction.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Joe Thornber <ejt@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 51b97f0..867ee52 100644 (file)
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -537,6 +537,34 @@ bad:
        return r;
 }
 
+static int __check_incompat_features(struct thin_disk_superblock *disk_super,
+                                    struct dm_pool_metadata *pmd)
+{
+       uint32_t features;
+
+       features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
+       if (features) {
+               DMERR("could not access metadata due to unsupported optional features (%lx).",
+                     (unsigned long)features);
+               return -EINVAL;
+       }
+
+       /*
+        * Check for read-only metadata to skip the following RDWR checks.
+        */
+       if (get_disk_ro(pmd->bdev->bd_disk))
+               return 0;
+
+       features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
+       if (features) {
+               DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
+                     (unsigned long)features);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
 static int __open_metadata(struct dm_pool_metadata *pmd)
 {
        int r;
@@ -551,6 +579,13 @@ static int __open_metadata(struct dm_pool_metadata *pmd)
        }
 
        disk_super = dm_block_data(sblock);
+
+       r = __check_incompat_features(disk_super, pmd);
+       if (r < 0) {
+               dm_bm_unlock(sblock);
+               return r;
+       }
+
        r = dm_tm_open_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                               disk_super->metadata_space_map_root,
                               sizeof(disk_super->metadata_space_map_root),
@@ -635,7 +670,6 @@ static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd)
 static int __begin_transaction(struct dm_pool_metadata *pmd)
 {
        int r;
-       u32 features;
        struct thin_disk_superblock *disk_super;
        struct dm_block *sblock;
 
@@ -656,32 +690,8 @@ static int __begin_transaction(struct dm_pool_metadata *pmd)
        pmd->flags = le32_to_cpu(disk_super->flags);
        pmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 
-       features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
-       if (features) {
-               DMERR("could not access metadata due to "
-                     "unsupported optional features (%lx).",
-                     (unsigned long)features);
-               r = -EINVAL;
-               goto out;
-       }
-
-       /*
-        * Check for read-only metadata to skip the following RDWR checks.
-        */
-       if (get_disk_ro(pmd->bdev->bd_disk))
-               goto out;
-
-       features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
-       if (features) {
-               DMERR("could not access metadata RDWR due to "
-                     "unsupported optional features (%lx).",
-                     (unsigned long)features);
-               r = -EINVAL;
-       }
-
-out:
        dm_bm_unlock(sblock);
-       return r;
+       return 0;
 }
 
 static int __write_changed_details(struct dm_pool_metadata *pmd)