libext2fs: Improve flex_bg inode table placement algorithm
When trying to find the best place for the inode table in the last
flex block group, use the true size for the flex_bg's portion of the
inode table instead of the worst case required size of the inode table
fragment if the file system is resized. This fixes a corner case
where if the size of the filesystem is just big enough that there is
only room for a single block group in the last flex_bg, and that
partial block group is too small for the full portion of the inode
table, the inode table is placed in the very first block group:
Group 64: (Blocks 2097152-2099199) [INODE_UNINIT, ITABLE_ZEROED]
Checksum 0xd305, unused inodes 8080
Block bitmap at 2097152 (+0), Inode bitmap at 2097168 (+16)
Inode table at 8626-9130 (+4292878770)
^^^^^^^^^
Thanks to Vyacheslav Dubeyko for pointing this out.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/lib/ext2fs/alloc_tables.c b/lib/ext2fs/alloc_tables.c
index 8547ad6..55e6174 100644
--- a/lib/ext2fs/alloc_tables.c
+++ b/lib/ext2fs/alloc_tables.c
@@ -181,6 +181,8 @@
blk_t prev_block = 0;
if (group && fs->group_desc[group-1].bg_inode_table)
prev_block = fs->group_desc[group-1].bg_inode_table;
+ if (last_grp == fs->group_desc_count)
+ rem_grps = last_grp - group;
group_blk = flexbg_offset(fs, group, prev_block, bmap,
flexbg_size * 2,
fs->inode_blocks_per_group *