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Commit 02e1215f authored by Jeff Layton's avatar Jeff Layton Committed by J. Bruce Fields
Browse files

nfsd: Avoid taking state_lock while holding inode lock in nfsd_break_one_deleg 



state_lock is a heavily contended global lock. We don't want to grab
that while simultaneously holding the inode->i_lock.

Add a new per-nfs4_file lock that we can use to protect the
per-nfs4_file delegation list. Hold that while walking the list in the
break_deleg callback and queue the workqueue job for each one.

The workqueue job can then take the state_lock and do the list
manipulations without the i_lock being held prior to starting the
rpc call.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: default avatarJeff Layton <jlayton@primarydata.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent e8051c83

fs/nfsd/nfs4callback.c

+21 −4
Original line number Diff line number Diff line
@@ -933,7 +933,7 @@ void nfsd4_shutdown_callback(struct nfs4_client *clp) 
	set_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags);

	/*

	 * Note this won't actually result in a null callback;

	 * instead, nfsd4_do_callback_rpc() will detect the killed

	 * instead, nfsd4_run_cb_null() will detect the killed

	 * client, destroy the rpc client, and stop:

	 */

	do_probe_callback(clp);
@@ -1011,10 +1011,9 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb) 
		run_nfsd4_cb(cb);

}



void

nfsd4_do_callback_rpc(struct work_struct *w)

static void

nfsd4_run_callback_rpc(struct nfsd4_callback *cb)

{

	struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback, cb_work);

	struct nfs4_client *clp = cb->cb_clp;

	struct rpc_clnt *clnt;
@@ -1032,6 +1031,24 @@ nfsd4_do_callback_rpc(struct work_struct *w) 
			cb->cb_ops, cb);

}



void

nfsd4_run_cb_null(struct work_struct *w)

{

	struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback,

							cb_work);

	nfsd4_run_callback_rpc(cb);

}



void

nfsd4_run_cb_recall(struct work_struct *w)

{

	struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback,

							cb_work);



	nfsd4_prepare_cb_recall(cb->cb_op);

	nfsd4_run_callback_rpc(cb);

}



void nfsd4_cb_recall(struct nfs4_delegation *dp)

{

	struct nfsd4_callback *cb = &dp->dl_recall;

fs/nfsd/nfs4state.c

+38 −20
Original line number Diff line number Diff line
@@ -254,6 +254,8 @@ static void nfsd4_free_file(struct nfs4_file *f) 
static inline void

put_nfs4_file(struct nfs4_file *fi)

{

	might_lock(&state_lock);



	if (atomic_dec_and_lock(&fi->fi_ref, &state_lock)) {

		hlist_del(&fi->fi_hash);

		spin_unlock(&state_lock);
@@ -554,6 +556,8 @@ static void block_delegations(struct knfsd_fh *fh) 
	u32 hash;

	struct bloom_pair *bd = &blocked_delegations;



	lockdep_assert_held(&state_lock);



	hash = arch_fast_hash(&fh->fh_base, fh->fh_size, 0);



	__set_bit(hash&255, bd->set[bd->new]);
@@ -592,7 +596,7 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv 
	fh_copy_shallow(&dp->dl_fh, &current_fh->fh_handle);

	dp->dl_time = 0;

	atomic_set(&dp->dl_count, 1);

	INIT_WORK(&dp->dl_recall.cb_work, nfsd4_do_callback_rpc);

	INIT_WORK(&dp->dl_recall.cb_work, nfsd4_run_cb_recall);

	return dp;

}
@@ -640,7 +644,9 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp) 
	lockdep_assert_held(&state_lock);



	dp->dl_stid.sc_type = NFS4_DELEG_STID;

	spin_lock(&fp->fi_lock);

	list_add(&dp->dl_perfile, &fp->fi_delegations);

	spin_unlock(&fp->fi_lock);

	list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations);

}
@@ -648,14 +654,18 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp) 
static void

unhash_delegation(struct nfs4_delegation *dp)

{

	struct nfs4_file *fp = dp->dl_file;



	spin_lock(&state_lock);

	list_del_init(&dp->dl_perclnt);

	list_del_init(&dp->dl_perfile);

	list_del_init(&dp->dl_recall_lru);

	spin_lock(&fp->fi_lock);

	list_del_init(&dp->dl_perfile);

	spin_unlock(&fp->fi_lock);

	spin_unlock(&state_lock);

	if (dp->dl_file) {

		nfs4_put_deleg_lease(dp->dl_file);

		put_nfs4_file(dp->dl_file);

	if (fp) {

		nfs4_put_deleg_lease(fp);

		put_nfs4_file(fp);

		dp->dl_file = NULL;

	}

}
@@ -1677,7 +1687,7 @@ static struct nfs4_client *create_client(struct xdr_netobj name, 
		spin_unlock(&nn->client_lock);

		return NULL;

	}

	INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_do_callback_rpc);

	INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_run_cb_null);

	clp->cl_time = get_seconds();

	clear_bit(0, &clp->cl_cb_slot_busy);

	copy_verf(clp, verf);
@@ -3079,30 +3089,38 @@ nfs4_share_conflict(struct svc_fh *current_fh, unsigned int deny_type) 
	return ret;

}



static void nfsd_break_one_deleg(struct nfs4_delegation *dp)

void nfsd4_prepare_cb_recall(struct nfs4_delegation *dp)

{

	struct nfs4_client *clp = dp->dl_stid.sc_client;

	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);



	lockdep_assert_held(&state_lock);

	/* We're assuming the state code never drops its reference

	 * without first removing the lease.  Since we're in this lease

	 * callback (and since the lease code is serialized by the kernel

	 * lock) we know the server hasn't removed the lease yet, we know

	 * it's safe to take a reference: */

	atomic_inc(&dp->dl_count);



	/*

	 * We can't do this in nfsd_break_deleg_cb because it is

	 * already holding inode->i_lock

	 */

	spin_lock(&state_lock);

	block_delegations(&dp->dl_fh);

	/*

	 * If the dl_time != 0, then we know that it has already been

	 * queued for a lease break. Don't queue it again.

	 */

	if (dp->dl_time == 0) {

		list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);

		dp->dl_time = get_seconds();

		list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);

	}

	spin_unlock(&state_lock);

}



	block_delegations(&dp->dl_fh);



static void nfsd_break_one_deleg(struct nfs4_delegation *dp)

{

	/*

	 * We're assuming the state code never drops its reference

	 * without first removing the lease.  Since we're in this lease

	 * callback (and since the lease code is serialized by the kernel

	 * lock) we know the server hasn't removed the lease yet, we know

	 * it's safe to take a reference.

	 */

	atomic_inc(&dp->dl_count);

	nfsd4_cb_recall(dp);

}
@@ -3127,11 +3145,11 @@ static void nfsd_break_deleg_cb(struct file_lock *fl) 
	 */

	fl->fl_break_time = 0;



	spin_lock(&state_lock);

	fp->fi_had_conflict = true;

	spin_lock(&fp->fi_lock);

	list_for_each_entry(dp, &fp->fi_delegations, dl_perfile)

		nfsd_break_one_deleg(dp);

	spin_unlock(&state_lock);

	spin_unlock(&fp->fi_lock);

}



static

fs/nfsd/state.h

+3 −1
Original line number Diff line number Diff line
@@ -436,7 +436,8 @@ extern struct nfs4_client_reclaim *nfsd4_find_reclaim_client(const char *recdir, 
extern __be32 nfs4_check_open_reclaim(clientid_t *clid,

		struct nfsd4_compound_state *cstate, struct nfsd_net *nn);

extern int set_callback_cred(void);

void nfsd4_do_callback_rpc(struct work_struct *w);

void nfsd4_run_cb_null(struct work_struct *w);

void nfsd4_run_cb_recall(struct work_struct *w);

extern void nfsd4_probe_callback(struct nfs4_client *clp);

extern void nfsd4_probe_callback_sync(struct nfs4_client *clp);

extern void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *);
@@ -444,6 +445,7 @@ extern void nfsd4_cb_recall(struct nfs4_delegation *dp); 
extern int nfsd4_create_callback_queue(void);

extern void nfsd4_destroy_callback_queue(void);

extern void nfsd4_shutdown_callback(struct nfs4_client *);

extern void nfsd4_prepare_cb_recall(struct nfs4_delegation *dp);

extern void nfs4_put_delegation(struct nfs4_delegation *dp);

extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(const char *name,

							struct nfsd_net *nn);