NFSv4: Ensure that we recover from the OPEN + OPEN_CONFIRM BAD_STATEID race

 If the server is in the unconfirmed OPEN state for a given open owner
 and receives a second OPEN for the same open owner, it will cancel the
 state of the first request and set up an OPEN_CONFIRM for the second.

 This can cause a race that is discussed in rfc3530 on page 181.

 The following patch allows the client to recover by retrying the
 original open request.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a8be9af610ac29d96042efe6dee321a9d1adaee6..ff378126ccd768fc39710f16a0eab0483156990c 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -785,6 +785,16 @@ static struct nfs4_state *nfs4_do_open(struct inode *dir, struct dentry *dentry,
                        exception.retry = 1;
                        continue;
                }
+               /*
+                * BAD_STATEID on OPEN means that the server cancelled our
+                * state before it received the OPEN_CONFIRM.
+                * Recover by retrying the request as per the discussion
+                * on Page 181 of RFC3530.
+                */
+               if (status == -NFS4ERR_BAD_STATEID) {
+                       exception.retry = 1;
+                       continue;
+               }
                res = ERR_PTR(nfs4_handle_exception(NFS_SERVER(dir),
                                        status, &exception));
        } while (exception.retry);