disk: part_efi: add support to repair gpt table

If a gpt table is corrupted (after a power cut
for example), then the gpt table should repaired.
The function gpt_repair_headers check if at least
one gpt table is valid, and then only write the
corrupted gpt table.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>

diff --git a/disk/part_efi.c b/disk/part_efi.c
index f1f3e5b..829ccb6 100644 (file)
--- a/disk/part_efi.c
+++ b/disk/part_efi.c
@@ -705,6 +705,92 @@ int gpt_verify_headers(struct blk_desc *dev_desc, gpt_header *gpt_head,
        return 0;
 }
 
+static void restore_primary_gpt_header(gpt_header *gpt_h, struct blk_desc *dev_desc)
+{
+       u32 calc_crc32;
+       u64 val;
+
+       /* recalculate the values for the Primary GPT Header */
+       val = le64_to_cpu(gpt_h->my_lba);
+       gpt_h->my_lba = gpt_h->alternate_lba;
+       gpt_h->alternate_lba = cpu_to_le64(val);
+       gpt_h->partition_entry_lba = cpu_to_le64(partition_entries_offset(dev_desc));
+
+       gpt_h->header_crc32 = 0;
+
+       calc_crc32 = efi_crc32((const unsigned char *)gpt_h,
+                              le32_to_cpu(gpt_h->header_size));
+       gpt_h->header_crc32 = cpu_to_le32(calc_crc32);
+}
+
+static int write_one_gpt_table(struct blk_desc *dev_desc,
+                              gpt_header *gpt_h, gpt_entry *gpt_e)
+{
+       const int pte_blk_cnt = BLOCK_CNT((gpt_h->num_partition_entries
+                                          * sizeof(gpt_entry)), dev_desc);
+       lbaint_t start;
+       int ret = 0;
+
+       start = le64_to_cpu(gpt_h->my_lba);
+       if (blk_dwrite(dev_desc, start, 1, gpt_h) != 1) {
+               ret = -1;
+               goto out;
+       }
+
+       start = le64_to_cpu(gpt_h->partition_entry_lba);
+       if (blk_dwrite(dev_desc, start, pte_blk_cnt, gpt_e) != pte_blk_cnt) {
+               ret = -1;
+               goto out;
+       }
+
+ out:
+       return ret;
+}
+
+int gpt_repair_headers(struct blk_desc *dev_desc)
+{
+       ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_h1, 1, dev_desc->blksz);
+       ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_h2, 1, dev_desc->blksz);
+       gpt_entry *gpt_e1 = NULL, *gpt_e2 = NULL;
+       int is_gpt1_valid, is_gpt2_valid;
+       int ret = -1;
+
+       is_gpt1_valid = is_gpt_valid(dev_desc, GPT_PRIMARY_PARTITION_TABLE_LBA,
+                                    gpt_h1, &gpt_e1);
+       is_gpt2_valid = is_gpt_valid(dev_desc, dev_desc->lba - 1,
+                                    gpt_h2, &gpt_e2);
+
+       if (is_gpt1_valid && is_gpt2_valid) {
+               ret = 0;
+               goto out;
+       }
+
+       if (is_gpt1_valid && !is_gpt2_valid) {
+               prepare_backup_gpt_header(gpt_h1);
+               ret = write_one_gpt_table(dev_desc, gpt_h1, gpt_e1);
+               goto out;
+       }
+
+       if (!is_gpt1_valid && is_gpt2_valid) {
+               restore_primary_gpt_header(gpt_h2, dev_desc);
+               ret = write_one_gpt_table(dev_desc, gpt_h2, gpt_e2);
+               goto out;
+       }
+
+       if (!is_gpt1_valid && !is_gpt2_valid) {
+               ret = -1;
+               goto out;
+       }
+
+ out:
+       if (is_gpt1_valid)
+               free(gpt_e1);
+       if (is_gpt2_valid)
+               free(gpt_e2);
+
+       return ret;
+}
+
 int gpt_verify_partitions(struct blk_desc *dev_desc,
                          struct disk_partition *partitions, int parts,
                          gpt_header *gpt_head, gpt_entry **gpt_pte)

diff --git a/include/part.h b/include/part.h
index 3a6958d..6f604e7 100644 (file)
--- a/include/part.h
+++ b/include/part.h
@@ -467,6 +467,16 @@ int gpt_verify_headers(struct blk_desc *dev_desc, gpt_header *gpt_head,
                       gpt_entry **gpt_pte);
 
 /**
+ * gpt_repair_headers() - Function to repair the GPT's header
+ *                        and partition table entries (PTE)
+ *
+ * @param dev_desc - block device descriptor
+ *
+ * Return: - '0' on success, otherwise error
+ */
+int gpt_repair_headers(struct blk_desc *dev_desc);
+
+/**
  * gpt_verify_partitions() - Function to check if partitions' name, start and
  *                           size correspond to '$partitions' env variable
  *