openfs.c (ext2fs_open): Fix bug which caused us to pass the

	wrong group_block to ext2fs_descriptor_block_loc if we're
	using the backup superblock/block group descriptors.
	(ext2fs_descriptor_block_loc): If we're using the backup
	superblock descriptors, use the backup descriptor block in
	the next block group.

diff --git a/lib/ext2fs/ChangeLog b/lib/ext2fs/ChangeLog
index 57e1d85..5f7d43b 100644 (file)
--- a/lib/ext2fs/ChangeLog
+++ b/lib/ext2fs/ChangeLog
@@ -1,3 +1,12 @@
+2002-10-31  Theodore Ts'o  <tytso@mit.edu>
+
+       * openfs.c (ext2fs_open): Fix bug which caused us to pass the
+               wrong group_block to ext2fs_descriptor_block_loc if we're
+               using the backup superblock/block group descriptors.
+               (ext2fs_descriptor_block_loc): If we're using the backup
+               superblock descriptors, use the backup descriptor block in
+               the next block group.
+
 2002-10-30  Theodore Ts'o  <tytso@mit.edu>
 
        * alloc_tables.c (ext2fs_allocate_group_table): Allocate the inode

diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index 4dcae98..eb5a7dc 100644 (file)
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -33,6 +33,7 @@ blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
 {
        int     bg;
        int     has_super = 0;
+       int     ret_blk;
 
        if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
            (i < fs->super->s_first_meta_bg))
@@ -41,8 +42,21 @@ blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
        bg = (fs->blocksize / sizeof (struct ext2_group_desc)) * i;
        if (ext2fs_bg_has_super(fs, bg))
                has_super = 1;
-       return (fs->super->s_first_data_block + has_super + 
-               (bg * fs->super->s_blocks_per_group));
+       ret_blk = (fs->super->s_first_data_block + has_super + 
+                  (bg * fs->super->s_blocks_per_group));
+       /*
+        * If group_block is not the normal value, we're trying to use
+        * the backup group descriptors and superblock --- so use the
+        * alternate location of the second block group in the
+        * metablock group.  Ideally we should be testing each bg
+        * descriptor block individually for correctness, but we don't
+        * have the infrastructure in place to do that.
+        */
+       if (group_block != fs->super->s_first_data_block &&
+           ((ret_blk + fs->super->s_blocks_per_group) <
+            fs->super->s_blocks_count))
+               ret_blk += fs->super->s_blocks_per_group;
+       return ret_blk;
 }
 
 /*
@@ -120,7 +134,7 @@ errcode_t ext2fs_open(const char *name, int flags, int superblock,
                        goto cleanup;
                }
                io_channel_set_blksize(fs->io, block_size);
-               group_block = superblock + 1;
+               group_block = superblock;
                fs->orig_super = 0;
        } else {
                io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);