ext4: use EXT4_BAD_INO for buddy cache to avoid colliding with valid inode #

Signed-off-by: Yu Jian <yujian@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 70d1b3e64284ebbabcbf8d0c8f448a83f2cd2119..e41620b56e5384375bb1526d8316a0317dd6793e 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2342,7 +2342,11 @@ static int ext4_mb_init_backend(struct super_block *sb)
                ext4_msg(sb, KERN_ERR, "can't get new inode");
                goto err_freesgi;
        }
-       sbi->s_buddy_cache->i_ino = get_next_ino();
+       /* To avoid potentially colliding with an valid on-disk inode number,
+        * use EXT4_BAD_INO for the buddy cache inode number.  This inode is
+        * not in the inode hash, so it should never be found by iget(), but
+        * this will avoid confusion if it ever shows up during debugging. */
+       sbi->s_buddy_cache->i_ino = EXT4_BAD_INO;
        EXT4_I(sbi->s_buddy_cache)->i_disksize = 0;
        for (i = 0; i < ngroups; i++) {
                desc = ext4_get_group_desc(sb, i, NULL);