udf: Add read-only support for 2.50 UDF media

[net-next-2.6.git] / fs / udf / partition.c

diff --git a/fs/udf/partition.c b/fs/udf/partition.c
index b2e6e1eddb901abab27d428d0bc35d36f9690cec..2dfe4be2eeb2f99dc7cd588c37d3df8d37297699 100644 (file)
--- a/fs/udf/partition.c
+++ b/fs/udf/partition.c
@@ -266,3 +266,58 @@ int udf_relocate_blocks(struct super_block *sb, long old_block, long *new_block)
 
        return 0;
 }
+
+static uint32_t udf_try_read_meta(struct inode *inode, uint32_t block,
+                                       uint16_t partition, uint32_t offset)
+{
+       struct super_block *sb = inode->i_sb;
+       struct udf_part_map *map;
+       kernel_lb_addr eloc;
+       uint32_t elen;
+       sector_t ext_offset;
+       struct extent_position epos = {};
+       uint32_t phyblock;
+
+       if (inode_bmap(inode, block, &epos, &eloc, &elen, &ext_offset) !=
+                                               (EXT_RECORDED_ALLOCATED >> 30))
+               phyblock = 0xFFFFFFFF;
+       else {
+               map = &UDF_SB(sb)->s_partmaps[partition];
+               /* map to sparable/physical partition desc */
+               phyblock = udf_get_pblock(sb, eloc.logicalBlockNum,
+                       map->s_partition_num, ext_offset + offset);
+       }
+
+       brelse(epos.bh);
+       return phyblock;
+}
+
+uint32_t udf_get_pblock_meta25(struct super_block *sb, uint32_t block,
+                               uint16_t partition, uint32_t offset)
+{
+       struct udf_sb_info *sbi = UDF_SB(sb);
+       struct udf_part_map *map;
+       struct udf_meta_data *mdata;
+       uint32_t retblk;
+       struct inode *inode;
+
+       udf_debug("READING from METADATA\n");
+
+       map = &sbi->s_partmaps[partition];
+       mdata = &map->s_type_specific.s_metadata;
+       inode = mdata->s_metadata_fe ? : mdata->s_mirror_fe;
+
+       /* We shouldn't mount such media... */
+       BUG_ON(!inode);
+       retblk = udf_try_read_meta(inode, block, partition, offset);
+       if (retblk == 0xFFFFFFFF) {
+               udf_warning(sb, __func__, "error reading from METADATA, "
+                       "trying to read from MIRROR");
+               inode = mdata->s_mirror_fe;
+               if (!inode)
+                       return 0xFFFFFFFF;
+               retblk = udf_try_read_meta(inode, block, partition, offset);
+       }
+
+       return retblk;
+}