> On Jul 14, 2016, at 18:58, Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote:
>
> The non-retry error path is currently broken and ends up releasing the
> reference to the layout twice. It also can end up clearing the
> NFS_LAYOUT_FIRST_LAYOUTGET flag twice, causing a race.
>
> In addition, the retry path will fail to decrement the plh_outstanding
> counter.
>
> Fixes: 183d9e7b112aa ("pnfs: rework LAYOUTGET retry handling")
> Cc: stable@xxxxxxxxxxxxxxx # 4.7
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfs/pnfs.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index 0fbe734cc38c..73b0dc90265a 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -1645,6 +1645,7 @@ lookup_again:
> lseg = send_layoutget(lo, ctx, &stateid, &arg, &timeout, gfp_flags);
> trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
> PNFS_UPDATE_LAYOUT_SEND_LAYOUTGET);
> + atomic_dec(&lo->plh_outstanding);
> if (IS_ERR(lseg)) {
> switch(PTR_ERR(lseg)) {
> case -ERECALLCONFLICT:
> @@ -1652,26 +1653,25 @@ lookup_again:
> lseg = NULL;
> /* Fallthrough */
> case -EAGAIN:
> - pnfs_put_layout_hdr(lo);
> - if (first)
> - pnfs_clear_first_layoutget(lo);
> - if (lseg) {
> - trace_pnfs_update_layout(ino, pos, count,
> - iomode, lo, lseg, PNFS_UPDATE_LAYOUT_RETRY);
> - goto lookup_again;
> - }
> - /* Fallthrough */
> + break;
> default:
> if (!nfs_error_is_fatal(PTR_ERR(lseg))) {
> pnfs_layout_clear_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
> lseg = NULL;
> }
> }
> + if (lseg) {
> + pnfs_put_layout_hdr(lo);
Yes, I’m aware I need to move this to after the trace_pnfs_update_layout() below (and before “goto lookup_again”). I managed to send out an earlier version of the patch that is being committed to linux-next.
> + if (first)
> + pnfs_clear_first_layoutget(lo);
> + trace_pnfs_update_layout(ino, pos, count,
> + iomode, lo, lseg, PNFS_UPDATE_LAYOUT_RETRY);
> + goto lookup_again;
> + }
> } else {
> pnfs_layout_clear_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
> }
>
> - atomic_dec(&lo->plh_outstanding);
> out_put_layout_hdr:
> if (first)
> pnfs_clear_first_layoutget(lo);
> --
> 2.7.4
>
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