Re: [PATCH] flexfiles/pNFS: fix NULL checks on result of ff_layout_choose_ds_for_read

["Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>]

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----- Original Message -----
> From: "Dan Carpenter" <dan.carpenter@linaro.org>
> To: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
> Cc: "trondmy" <trondmy@kernel.org>, "anna schumaker" <anna.schumaker@oracle.com>, "linux-nfs"
> <linux-nfs@vger.kernel.org>
> Sent: Thursday, 28 August, 2025 16:38:29
> Subject: Re: [PATCH] flexfiles/pNFS: fix NULL checks on result of ff_layout_choose_ds_for_read

> On Thu, Aug 28, 2025 at 03:38:43PM +0200, Tigran Mkrtchyan wrote:
>> Recent commit f06bedfa62d5 ("pNFS/flexfiles: don't attempt pnfs on fatal DS
>> errors") has changed the error return type of ff_layout_choose_ds_for_read()
>> from
>> NULL to an error pointer. However, not all code paths have been updated
>> to match the change. Thus, some non-NULL checks will accept error pointers
>> as a valid return value.
>> 
>> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
>> Fixes: f06bedfa62d5 ("pNFS/flexfiles: don't attempt pnfs on fatal DS errors")
>> Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
>> ---
> 
> This is still not complete.
> 
>  1073  static void ff_layout_resend_pnfs_read(struct nfs_pgio_header *hdr)
>  1074  {
>  1075          u32 idx = hdr->pgio_mirror_idx + 1;
>  1076          u32 new_idx = 0;
>  1077
>  1078          if (ff_layout_choose_any_ds_for_read(hdr->lseg, idx, &new_idx))
>                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This should be:
> 
>	struct nfs4_pnfs_ds *ds;
> 
>	ds = ff_layout_choose_any_ds_for_read(hdr->lseg, idx, &new_idx);
>	if (IS_ERR(ds))
>		pnfs_error_mark_layout_for_return(hdr->inode, hdr->lseg);
>	else
>		ff_layout_send_layouterror(hdr->lseg);


Yeah, makes sense. Thanks!

Tigran.
> 
>  1079                  ff_layout_send_layouterror(hdr->lseg);
>  1080          else
>  1081                  pnfs_error_mark_layout_for_return(hdr->inode, hdr->lseg);
>  1082          pnfs_read_resend_pnfs(hdr, new_idx);
>  1083  }
> 
> Also the continue in ff_layout_choose_ds_for_read() still needs to be
> fixed as I mentioned earlier.
> 
> regards,
> dan carpenter

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