Commit 0de43976 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Convert lookups of the open context to RCU 



Reduce contention on the inode->i_lock by ensuring that we use RCU
when looking up the NFS open context.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 6ba0c4e5

fs/nfs/delegation.c

+6 −5
Original line number Diff line number Diff line
@@ -136,8 +136,8 @@ static int nfs_delegation_claim_opens(struct inode *inode, 
	int err;



again:

	spin_lock(&inode->i_lock);

	list_for_each_entry(ctx, &nfsi->open_files, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {

		state = ctx->state;

		if (state == NULL)

			continue;
@@ -147,8 +147,9 @@ static int nfs_delegation_claim_opens(struct inode *inode, 
			continue;

		if (!nfs4_stateid_match(&state->stateid, stateid))

			continue;

		get_nfs_open_context(ctx);

		spin_unlock(&inode->i_lock);

		if (!get_nfs_open_context(ctx))

			continue;

		rcu_read_unlock();

		sp = state->owner;

		/* Block nfs4_proc_unlck */

		mutex_lock(&sp->so_delegreturn_mutex);
@@ -164,7 +165,7 @@ static int nfs_delegation_claim_opens(struct inode *inode, 
			return err;

		goto again;

	}

	spin_unlock(&inode->i_lock);

	rcu_read_unlock();

	return 0;

}

fs/nfs/inode.c

+15 −20
Original line number Diff line number Diff line
@@ -977,9 +977,9 @@ EXPORT_SYMBOL_GPL(alloc_nfs_open_context); 


struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)

{

	if (ctx != NULL)

		refcount_inc(&ctx->lock_context.count);

	if (ctx != NULL && refcount_inc_not_zero(&ctx->lock_context.count))

		return ctx;

	return NULL;

}

EXPORT_SYMBOL_GPL(get_nfs_open_context);
@@ -988,13 +988,13 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync) 
	struct inode *inode = d_inode(ctx->dentry);

	struct super_block *sb = ctx->dentry->d_sb;



	if (!list_empty(&ctx->list)) {

		if (!refcount_dec_and_lock(&ctx->lock_context.count, &inode->i_lock))

	if (!refcount_dec_and_test(&ctx->lock_context.count))

		return;

		list_del(&ctx->list);

	if (!list_empty(&ctx->list)) {

		spin_lock(&inode->i_lock);

		list_del_rcu(&ctx->list);

		spin_unlock(&inode->i_lock);

	} else if (!refcount_dec_and_test(&ctx->lock_context.count))

		return;

	}

	if (inode != NULL)

		NFS_PROTO(inode)->close_context(ctx, is_sync);

	if (ctx->cred != NULL)
@@ -1002,7 +1002,7 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync) 
	dput(ctx->dentry);

	nfs_sb_deactive(sb);

	kfree(ctx->mdsthreshold);

	kfree(ctx);

	kfree_rcu(ctx, rcu_head);

}



void put_nfs_open_context(struct nfs_open_context *ctx)
@@ -1026,10 +1026,7 @@ void nfs_inode_attach_open_context(struct nfs_open_context *ctx) 
	struct nfs_inode *nfsi = NFS_I(inode);



	spin_lock(&inode->i_lock);

	if (ctx->mode & FMODE_WRITE)

		list_add(&ctx->list, &nfsi->open_files);

	else

		list_add_tail(&ctx->list, &nfsi->open_files);

	list_add_tail_rcu(&ctx->list, &nfsi->open_files);

	spin_unlock(&inode->i_lock);

}

EXPORT_SYMBOL_GPL(nfs_inode_attach_open_context);
@@ -1050,16 +1047,17 @@ struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_c 
	struct nfs_inode *nfsi = NFS_I(inode);

	struct nfs_open_context *pos, *ctx = NULL;



	spin_lock(&inode->i_lock);

	list_for_each_entry(pos, &nfsi->open_files, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(pos, &nfsi->open_files, list) {

		if (cred != NULL && pos->cred != cred)

			continue;

		if ((pos->mode & (FMODE_READ|FMODE_WRITE)) != mode)

			continue;

		ctx = get_nfs_open_context(pos);

		if (ctx)

			break;

	}

	spin_unlock(&inode->i_lock);

	rcu_read_unlock();

	return ctx;

}
@@ -1077,9 +1075,6 @@ void nfs_file_clear_open_context(struct file *filp) 
		if (ctx->error < 0)

			invalidate_inode_pages2(inode->i_mapping);

		filp->private_data = NULL;

		spin_lock(&inode->i_lock);

		list_move_tail(&ctx->list, &NFS_I(inode)->open_files);

		spin_unlock(&inode->i_lock);

		put_nfs_open_context_sync(ctx);

	}

}

fs/nfs/nfs4proc.c

+24 −6
Original line number Diff line number Diff line
@@ -1933,23 +1933,41 @@ nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data) 
	return ret;

}



static struct nfs_open_context *nfs4_state_find_open_context(struct nfs4_state *state)

static struct nfs_open_context *

nfs4_state_find_open_context_mode(struct nfs4_state *state, fmode_t mode)

{

	struct nfs_inode *nfsi = NFS_I(state->inode);

	struct nfs_open_context *ctx;



	spin_lock(&state->inode->i_lock);

	list_for_each_entry(ctx, &nfsi->open_files, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {

		if (ctx->state != state)

			continue;

		get_nfs_open_context(ctx);

		spin_unlock(&state->inode->i_lock);

		if ((ctx->mode & mode) != mode)

			continue;

		if (!get_nfs_open_context(ctx))

			continue;

		rcu_read_unlock();

		return ctx;

	}

	spin_unlock(&state->inode->i_lock);

	rcu_read_unlock();

	return ERR_PTR(-ENOENT);

}



static struct nfs_open_context *

nfs4_state_find_open_context(struct nfs4_state *state)

{

	struct nfs_open_context *ctx;



	ctx = nfs4_state_find_open_context_mode(state, FMODE_READ|FMODE_WRITE);

	if (!IS_ERR(ctx))

		return ctx;

	ctx = nfs4_state_find_open_context_mode(state, FMODE_WRITE);

	if (!IS_ERR(ctx))

		return ctx;

	return nfs4_state_find_open_context_mode(state, FMODE_READ);

}



static struct nfs4_opendata *nfs4_open_recoverdata_alloc(struct nfs_open_context *ctx,

		struct nfs4_state *state, enum open_claim_type4 claim)

{

fs/nfs/nfs4state.c

+6 −6
Original line number Diff line number Diff line
@@ -1437,8 +1437,8 @@ void nfs_inode_find_state_and_recover(struct inode *inode, 
	struct nfs4_state *state;

	bool found = false;



	spin_lock(&inode->i_lock);

	list_for_each_entry(ctx, &nfsi->open_files, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {

		state = ctx->state;

		if (state == NULL)

			continue;
@@ -1456,7 +1456,7 @@ void nfs_inode_find_state_and_recover(struct inode *inode, 
		    nfs4_state_mark_reclaim_nograce(clp, state))

			found = true;

	}

	spin_unlock(&inode->i_lock);

	rcu_read_unlock();



	nfs_inode_find_delegation_state_and_recover(inode, stateid);

	if (found)
@@ -1469,13 +1469,13 @@ static void nfs4_state_mark_open_context_bad(struct nfs4_state *state) 
	struct nfs_inode *nfsi = NFS_I(inode);

	struct nfs_open_context *ctx;



	spin_lock(&inode->i_lock);

	list_for_each_entry(ctx, &nfsi->open_files, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {

		if (ctx->state != state)

			continue;

		set_bit(NFS_CONTEXT_BAD, &ctx->flags);

	}

	spin_unlock(&inode->i_lock);

	rcu_read_unlock();

}



static void nfs4_state_mark_recovery_failed(struct nfs4_state *state, int error)

fs/nfs/pnfs.c

+4 −1
Original line number Diff line number Diff line
@@ -1339,6 +1339,7 @@ bool pnfs_roc(struct inode *ino, 
	if (!nfs_have_layout(ino))

		return false;

retry:

	rcu_read_lock();

	spin_lock(&ino->i_lock);

	lo = nfsi->layout;

	if (!lo || !pnfs_layout_is_valid(lo) ||
@@ -1349,6 +1350,7 @@ bool pnfs_roc(struct inode *ino, 
	pnfs_get_layout_hdr(lo);

	if (test_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags)) {

		spin_unlock(&ino->i_lock);

		rcu_read_unlock();

		wait_on_bit(&lo->plh_flags, NFS_LAYOUT_RETURN,

				TASK_UNINTERRUPTIBLE);

		pnfs_put_layout_hdr(lo);
@@ -1362,7 +1364,7 @@ bool pnfs_roc(struct inode *ino, 
		skip_read = true;

	}



	list_for_each_entry(ctx, &nfsi->open_files, list) {

	list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {

		state = ctx->state;

		if (state == NULL)

			continue;
@@ -1410,6 +1412,7 @@ bool pnfs_roc(struct inode *ino, 


out_noroc:

	spin_unlock(&ino->i_lock);

	rcu_read_unlock();

	pnfs_layoutcommit_inode(ino, true);

	if (roc) {

		struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;