2017-04-20 18:42:05

by Trond Myklebust

[permalink] [raw]
Subject: [PATCH] NFSv4: Fix a hang in OPEN related to server reboot

If the server fails to return the attributes as part of an OPEN
reply, and then reboots, we can end up hanging. The reason is that
the client attempts to send a GETATTR in order to pick up the
missing OPEN call, but fails to release the slot first, causing
reboot recovery to deadlock.

Signed-off-by: Trond Myklebust <[email protected]>
Fixes: 2e80dbe7ac51a ("NFSv4.1: Close callback races for OPEN, LAYOUTGET...")
Cc: [email protected] # v4.8+
---
fs/nfs/nfs4proc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 4e52ac773d1f..6e9ff2d9a5bf 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2300,8 +2300,10 @@ static int _nfs4_proc_open(struct nfs4_opendata *data)
if (status != 0)
return status;
}
- if (!(o_res->f_attr->valid & NFS_ATTR_FATTR))
+ if (!(o_res->f_attr->valid & NFS_ATTR_FATTR)) {
+ nfs4_sequence_free_slot(&o_res->seq_res);
nfs4_proc_getattr(server, &o_res->fh, o_res->f_attr, o_res->f_label);
+ }
return 0;
}

--
2.9.3