Changes in / [32254d6:f455de0] in mainline

File:

• uspace/lib/ext4/src/superblock.c (modified) (1 diff)

uspace/lib/ext4/src/superblock.c

@@ -1215 +1215 @@
         uint64_t first_block = EXT4_SUPERBLOCK_OFFSET / phys_block_size;
 
-        /* Compute number of block to write */
-        size_t block_count = EXT4_SUPERBLOCK_SIZE / phys_block_size;
-
-        /* Check alignment */
-        if (EXT4_SUPERBLOCK_SIZE % phys_block_size)
-                block_count++;
-
-        /* Write data */
-        return block_write_direct(service_id, first_block, block_count, sb);
+        if (phys_block_size <= EXT4_SUPERBLOCK_SIZE) {
+                /* Superblock is a multiple of physical block sizes */
+                size_t block_count = EXT4_SUPERBLOCK_SIZE / phys_block_size;
+                return block_write_direct(service_id, first_block, block_count, sb);
+        }
+
+        /*
+         * Superblock fills only a part of the physical block,
+         * but we can only overwrite an entire physical block.
+         */
+        void *tmp_sb = malloc(phys_block_size);
+        if (tmp_sb == NULL)
+                return ENOMEM;
+
+        /* Preserve physical block data */
+        rc = block_read_direct(service_id, first_block, 1, tmp_sb);
+        if (rc == EOK) {
+                /* Write the superblock */
+                void *sb_pos = tmp_sb + EXT4_SUPERBLOCK_OFFSET % phys_block_size;
+                memcpy(sb_pos, sb, EXT4_SUPERBLOCK_SIZE);
+
+                /* Write physical block to device */
+                rc = block_write_direct(service_id, first_block, 1, tmp_sb);
+        }
+
+        free(tmp_sb);
+        return rc;
 }