Re: [PATCH 10/13] [RFC] Bugs in new pnfs write path

[Benny Halevy <bhalevy@panasas.com>]

On 2011-05-21 13:33, Boaz Harrosh wrote:
> 1. In nfs4_write_done_cb: data->write_done_cb comes with a NULL.

what's the call path?

>    Just as a guess I call nfs4_write_done_cb() just above it
>    it looked like the right thing todo. With that in, I'm able
>    to write things to file When converting pnfs.c:258 to a WARN_ON.
> 
>    Benny we might want to set data->write_done_cb somewhere in the
>    none-rpc path? where is it best to do that?

we're not supposed to get there in the non-rpc path...
The non-rpc drivers must call pnfs_ld_write_done.

> 
> 2. In pnfs_ld_write_done:
> 	put_lseg(data->lseg);
> 	data->lseg = NULL;
>    was done before the call to pnfs_set_layoutcommit()
>    which trys to get_lseg() on that same data->lseg.

good catch, thanks!

> 
> 3. In pnfs_ld_write_done:
>    data->mds_ops->rpc_call_done(NULL, data);
>    crashes with a NULL task. Just pass it with &data->task

As we don't go through nfs_initiate_write data->task is not initialized.
Where's the crash exactly?
We better fix it than fake a task structure...

Benny

> 
>    Which calls for a cleanup. There is bunch of functions
>    with [task, write_data] API. And the task is always
>    write_data->task
> 
> Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
> ---
>  fs/nfs/nfs4proc.c |    3 ++-
>  fs/nfs/pnfs.c     |   10 ++++++----
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 759523a..1a53187 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -3250,7 +3250,8 @@ static int nfs4_write_done(struct rpc_task *task, struct nfs_write_data *data)
>  {
>  	if (!nfs4_sequence_done(task, &data->res.seq_res))
>  		return -EAGAIN;
> -	return data->write_done_cb(task, data);
> +	return data->write_done_cb ? data->write_done_cb(task, data) :
> +		nfs4_write_done_cb(task, data);
>  }
>  
>  /* Reset the the nfs_write_data to send the write to the MDS. */
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index 17d0c4c..b04cdb4 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -255,7 +255,7 @@ put_lseg_common(struct pnfs_layout_segment *lseg)
>  {
>  	struct inode *inode = lseg->pls_layout->plh_inode;
>  
> -	BUG_ON(test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
> + 	WARN_ON(test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
>  	list_del_init(&lseg->pls_list);
>  	if (list_empty(&lseg->pls_layout->plh_segs)) {
>  		set_bit(NFS_LAYOUT_DESTROYED, &lseg->pls_layout->plh_flags);
> @@ -1124,15 +1124,17 @@ pnfs_ld_write_done(struct nfs_write_data *data)
>  {
>  	int status;
>  
> -	put_lseg(data->lseg);
> -	data->lseg = NULL;
>  	if (!data->pnfs_error) {
>  		pnfs_set_layoutcommit(data);
> -		data->mds_ops->rpc_call_done(NULL, data);
> +		data->mds_ops->rpc_call_done(&data->task, data);
>  		data->mds_ops->rpc_release(data);
> +		put_lseg(data->lseg);
> +		data->lseg = NULL;
>  		return 0;
>  	}
>  
> +	put_lseg(data->lseg);
> +	data->lseg = NULL;
>  	dprintk("%s: pnfs_error=%d, retry via MDS\n", __func__,
>  		data->pnfs_error);
>  	status = nfs_initiate_write(data, NFS_CLIENT(data->inode), data->mds_ops, NFS_FILE_SYNC);