From: Trond Myklebust trond.myklebust@hammerspace.com
[ Upstream commit e20772cbdf463c12088837e5a08bde1b876bfd25 ]
If NFS_LAYOUT_RETURN_REQUESTED is set, but there is no value set for the layout plh_return_seq, we can end up in a livelock loop in which every layout segment retrieved by a new call to layoutget is immediately invalidated by pnfs_layout_need_return(). To get around this, we should just set plh_return_seq to the current value of the layout stateid's seqid.
Fixes: d474f96104bd ("NFS: Don't return layout segments that are in use") Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/pnfs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index ef14ea0b6ab8..da5cacad6979 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -347,11 +347,15 @@ pnfs_set_plh_return_info(struct pnfs_layout_hdr *lo, enum pnfs_iomode iomode, iomode = IOMODE_ANY; lo->plh_return_iomode = iomode; set_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags); - if (seq != 0) { - WARN_ON_ONCE(lo->plh_return_seq != 0 && lo->plh_return_seq != seq); + /* + * We must set lo->plh_return_seq to avoid livelocks with + * pnfs_layout_need_return() + */ + if (seq == 0) + seq = be32_to_cpu(lo->plh_stateid.seqid); + if (!lo->plh_return_seq || pnfs_seqid_is_newer(seq, lo->plh_return_seq)) lo->plh_return_seq = seq; - pnfs_barrier_update(lo, seq); - } + pnfs_barrier_update(lo, seq); }
static void