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Commit 6ee41268 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent aac00a8d

fs/nfs/nfs4proc.c

+41 −8
Original line number Diff line number Diff line
@@ -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)