[Ocfs2-devel] [PATCH 2/2] ocfs2: fix ocfs2 corrupt when iputting an inode

[Joseph Qi <jiangqi903@gmail.com>]

On 2020/5/26 15:55, Wangyan wrote:
> In this condition, it will cause an bug on error.
> ocfs2_mkdir()
>   ->ocfs2_mknod()
>     ->ocfs2_mknod_locked()
>       ->__ocfs2_mknod_locked()
>         //Assume inode->i_generation is genN.
>         ->inode->i_generation = osb->s_next_generation++;
>         // The inode lockres has been initialized.
>         ->ocfs2_populate_inode()
>         ->ocfs2_create_new_inode_locks()
>             ->An error happened, returned value is non-zero
>       // free the start_bit x in bg_blkno
>       ->ocfs2_free_suballoc_bits()
>     ->...  /* Another process execute mkdir success in this place,
>               and it occupied the start_bit x in bg_blkno
>               which has been freed before. Its inode->i_generation
>               is genN + 1 */
>     ->iput(inode)
>       ->evict()
>         ->ocfs2_evict_inode()
>           ->ocfs2_delete_inode()
>             ->ocfs2_inode_lock()
>               ->ocfs2_inode_lock_update()
>                 /* Bug on here, genN != genN + 1 */
>                 ->mlog_bug_on_msg(inode->i_generation !=
>                   le32_to_cpu(fe->i_generation))
> 
> So, we need not to reclaim the inode when the inode->ip_inode_lockres
> has been initialized. It will be freed in iput().
> 
> Signed-off-by: Yan Wang <wangyan122@huawei.com>
> Reviewed-by: Jun Piao <piaojun@huawei.com>
> ---
>  fs/ocfs2/namei.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
> index e61fdd8972ec..5302992d2bee 100644
> --- a/fs/ocfs2/namei.c
> +++ b/fs/ocfs2/namei.c
> @@ -640,7 +640,8 @@ static int ocfs2_mknod_locked(struct ocfs2_super *osb,
>  	status = __ocfs2_mknod_locked(dir, inode, dev, new_fe_bh,
>  				    parent_fe_bh, handle, inode_ac,
>  				    fe_blkno, suballoc_loc, suballoc_bit);
> -	if (status < 0) {
> +	if (status < 0 && !(OCFS2_I(inode)->ip_inode_lockres.l_flags &
> +				OCFS2_LOCK_INITIALIZED)) {

Each condition in separate line may be better:

if (status < 0 &&
    !(OCFS2_I(inode)->ip_inode_lockres.l_flags & OCFS2_LOCK_INITIALIZED))

And you've missed a fixed tag:
Fixes: b1529a41f777 ("ocfs2: should reclaim the inode if '__ocfs2_mknod_locked' returns an error")

Thanks,
Joseph

>  		u64 bg_blkno = ocfs2_which_suballoc_group(fe_blkno, suballoc_bit);
>  		int tmp = ocfs2_free_suballoc_bits(handle, inode_ac->ac_inode,
>  				inode_ac->ac_bh, suballoc_bit, bg_blkno, 1);
>