diff options
| -rw-r--r-- | fs/nfsd/nfs4state.c | 52 | ||||
| -rw-r--r-- | fs/nfsd/state.h | 3 |
2 files changed, 26 insertions, 29 deletions
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 0198328c0e8..106e8fa63cd 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -3168,6 +3168,12 @@ grace_disallows_io(struct inode *inode) return locks_in_grace() && mandatory_lock(inode); } +/* Returns true iff a is later than b: */ +static bool stateid_generation_after(stateid_t *a, stateid_t *b) +{ + return (s32)a->si_generation - (s32)b->si_generation > 0; +} + static int check_stateid_generation(stateid_t *in, stateid_t *ref, bool has_session) { /* @@ -3175,25 +3181,25 @@ static int check_stateid_generation(stateid_t *in, stateid_t *ref, bool has_sess * when it is zero. */ if (has_session && in->si_generation == 0) - goto out; + return nfs_ok; + + if (in->si_generation == ref->si_generation) + return nfs_ok; /* If the client sends us a stateid from the future, it's buggy: */ - if (in->si_generation > ref->si_generation) + if (stateid_generation_after(in, ref)) return nfserr_bad_stateid; /* - * The following, however, can happen. For example, if the - * client sends an open and some IO at the same time, the open - * may bump si_generation while the IO is still in flight. - * Thanks to hard links and renames, the client never knows what - * file an open will affect. So it could avoid that situation - * only by serializing all opens and IO from the same open - * owner. To recover from the old_stateid error, the client - * will just have to retry the IO: + * However, we could see a stateid from the past, even from a + * non-buggy client. For example, if the client sends a lock + * while some IO is outstanding, the lock may bump si_generation + * while the IO is still in flight. The client could avoid that + * situation by waiting for responses on all the IO requests, + * but better performance may result in retrying IO that + * receives an old_stateid error if requests are rarely + * reordered in flight: */ - if (in->si_generation < ref->si_generation) - return nfserr_old_stateid; -out: - return nfs_ok; + return nfserr_old_stateid; } static int is_delegation_stateid(stateid_t *stateid) @@ -3353,16 +3359,9 @@ nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, ret = nfserr_bad_stateid; goto out; } - if (stateid->si_generation != 0) { - if (stateid->si_generation < stp->st_stateid.si_generation) { - ret = nfserr_old_stateid; - goto out; - } - if (stateid->si_generation > stp->st_stateid.si_generation) { - ret = nfserr_bad_stateid; - goto out; - } - } + ret = check_stateid_generation(stateid, &stp->st_stateid, 1); + if (ret) + goto out; if (stp->st_type == NFS4_OPEN_STID) { ret = nfserr_locks_held; @@ -3439,11 +3438,6 @@ nfs4_preprocess_seqid_op(struct nfsd4_compound_state *cstate, u32 seqid, return nfserr_bad_stateid; } - /* - * We now validate the seqid and stateid generation numbers. - * For the moment, we ignore the possibility of - * generation number wraparound. - */ if (!nfsd4_has_session(cstate) && seqid != sop->so_seqid) goto check_replay; diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index a06f55bd38b..c425717715f 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -293,6 +293,9 @@ static inline void update_stateid(stateid_t *stateid) { stateid->si_generation++; + /* Wraparound recommendation from 3530bis-13 9.1.3.2: */ + if (stateid->si_generation == 0) + stateid->si_generation = 1; } /* A reasonable value for REPLAY_ISIZE was estimated as follows: |