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>

1 files changed, 36 insertions, 26 deletions

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 51b97f07aca3..867ee52121d4 100644
--- 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)