ext4: fix online resize bug

There is a bug when we are trying to verify that the reserve inode's
double indirect blocks point back to the primary gdt blocks.  The fix is
obvious, we need to mod the gdb count by the addr's per block.  This was
verified using the same testcase as with the ext3 equivalent of this
patch.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 9f086a6a472b1c13359334d6966caaa6a90d4ea1..9ecb92f68543ab12f5531a7cf4cb2c6233d2258e 100644 (file)
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -563,7 +563,8 @@ static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
        }
 
        blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
-       data = (__le32 *)dind->b_data + EXT4_SB(sb)->s_gdb_count;
+       data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
+                                        EXT4_ADDR_PER_BLOCK(sb));
        end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 
        /* Get each reserved primary GDT block and verify it holds backups */