From: Trond Myklebust Date: Sun, 8 Jul 2007 14:11:36 -0400 NFSv4: Don't call OPEN if we already have an open stateid for a file If we already have a stateid with the correct open mode for a given file, then we can reuse that stateid instead of re-issuing an OPEN call without violating the close-to-open caching semantics. Signed-off-by: Trond Myklebust --- fs/nfs/nfs4proc.c | 49 +++++++++++++++++++++++++++++++++++++++++-------- 1 files changed, 41 insertions(+), 8 deletions(-) diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index ea332e8..1de0766 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -324,6 +324,24 @@ static int nfs4_wait_for_completion_rpc_task(struct rpc_task *task) return ret; } +static int can_open_cached(struct nfs4_state *state, int mode) +{ + int ret = 0; + switch (mode & (FMODE_READ|FMODE_WRITE|O_EXCL)) { + case FMODE_READ: + ret |= test_bit(NFS_O_RDONLY_STATE, &state->flags) != 0; + ret |= test_bit(NFS_O_RDWR_STATE, &state->flags) != 0; + break; + case FMODE_WRITE: + ret |= test_bit(NFS_O_WRONLY_STATE, &state->flags) != 0; + ret |= test_bit(NFS_O_RDWR_STATE, &state->flags) != 0; + break; + case FMODE_READ|FMODE_WRITE: + ret |= test_bit(NFS_O_RDWR_STATE, &state->flags) != 0; + } + return ret; +} + static int can_open_delegated(struct nfs_delegation *delegation, mode_t open_flags) { if ((delegation->type & open_flags) != open_flags) @@ -407,7 +425,7 @@ static void nfs4_return_incompatible_delegation(struct inode *inode, mode_t open nfs_inode_return_delegation(inode); } -static struct nfs4_state *nfs4_try_open_delegated(struct nfs4_opendata *opendata) +static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata) { struct nfs4_state *state = opendata->state; struct nfs_inode *nfsi = NFS_I(state->inode); @@ -418,9 +436,19 @@ static struct nfs4_state *nfs4_try_open_delegated(struct nfs4_opendata *opendata rcu_read_lock(); delegation = rcu_dereference(nfsi->delegation); - if (delegation == NULL) - goto out_unlock; for (;;) { + if (can_open_cached(state, open_mode)) { + spin_lock(&state->owner->so_lock); + if (can_open_cached(state, open_mode)) { + update_open_stateflags(state, open_mode); + spin_unlock(&state->owner->so_lock); + rcu_read_unlock(); + goto out_return_state; + } + spin_unlock(&state->owner->so_lock); + } + if (delegation == NULL) + break; if (!can_open_delegated(delegation, open_mode)) break; /* Save the delegation */ @@ -434,8 +462,9 @@ static struct nfs4_state *nfs4_try_open_delegated(struct nfs4_opendata *opendata ret = -EAGAIN; rcu_read_lock(); delegation = rcu_dereference(nfsi->delegation); + /* If no delegation, try a cached open */ if (delegation == NULL) - break; + continue; /* Is the delegation still valid? */ if (memcmp(stateid.data, delegation->stateid.data, sizeof(stateid.data)) != 0) continue; @@ -443,7 +472,6 @@ static struct nfs4_state *nfs4_try_open_delegated(struct nfs4_opendata *opendata update_open_stateid(state, NULL, &stateid, open_mode); goto out_return_state; } -out_unlock: rcu_read_unlock(); out: return ERR_PTR(ret); @@ -461,7 +489,7 @@ static struct nfs4_state *nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data int ret; if (!data->rpc_done) { - state = nfs4_try_open_delegated(data); + state = nfs4_try_open_cached(data); goto out; } @@ -775,13 +803,14 @@ static void nfs4_open_prepare(struct rpc_task *task, void *calldata) if (data->state != NULL) { struct nfs_delegation *delegation; + if (can_open_cached(data->state, data->o_arg.open_flags & (FMODE_READ|FMODE_WRITE|O_EXCL))) + goto out_no_action; rcu_read_lock(); delegation = rcu_dereference(NFS_I(data->state->inode)->delegation); if (delegation != NULL && (delegation->flags & NFS_DELEGATION_NEED_RECLAIM) == 0) { rcu_read_unlock(); - task->tk_action = NULL; - return; + goto out_no_action; } rcu_read_unlock(); } @@ -792,6 +821,10 @@ static void nfs4_open_prepare(struct rpc_task *task, void *calldata) msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_OPEN_NOATTR]; data->timestamp = jiffies; rpc_call_setup(task, &msg, 0); + return; +out_no_action: + task->tk_action = NULL; + } static void nfs4_open_done(struct rpc_task *task, void *calldata)