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Commit 1db97eaa authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Convert lookups of the lock context to RCU 



Speed up lookups of an existing lock context by avoiding the inode->i_lock,
and using RCU instead.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 28ced9a8

fs/nfs/inode.c

+12 −13
Original line number Diff line number Diff line
@@ -857,15 +857,14 @@ static void nfs_init_lock_context(struct nfs_lock_context *l_ctx) 


static struct nfs_lock_context *__nfs_find_lock_context(struct nfs_open_context *ctx)

{

	struct nfs_lock_context *head = &ctx->lock_context;

	struct nfs_lock_context *pos = head;

	struct nfs_lock_context *pos;



	do {

	list_for_each_entry_rcu(pos, &ctx->lock_context.list, list) {

		if (pos->lockowner != current->files)

			continue;

		refcount_inc(&pos->count);

		if (refcount_inc_not_zero(&pos->count))

			return pos;

	} while ((pos = list_entry(pos->list.next, typeof(*pos), list)) != head);

	}

	return NULL;

}
@@ -874,10 +873,10 @@ struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx) 
	struct nfs_lock_context *res, *new = NULL;

	struct inode *inode = d_inode(ctx->dentry);



	spin_lock(&inode->i_lock);

	rcu_read_lock();

	res = __nfs_find_lock_context(ctx);

	rcu_read_unlock();

	if (res == NULL) {

		spin_unlock(&inode->i_lock);

		new = kmalloc(sizeof(*new), GFP_KERNEL);

		if (new == NULL)

			return ERR_PTR(-ENOMEM);
@@ -885,14 +884,14 @@ struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx) 
		spin_lock(&inode->i_lock);

		res = __nfs_find_lock_context(ctx);

		if (res == NULL) {

			list_add_tail(&new->list, &ctx->lock_context.list);

			list_add_tail_rcu(&new->list, &ctx->lock_context.list);

			new->open_context = ctx;

			res = new;

			new = NULL;

		}

	}

		spin_unlock(&inode->i_lock);

		kfree(new);

	}

	return res;

}

EXPORT_SYMBOL_GPL(nfs_get_lock_context);
@@ -904,9 +903,9 @@ void nfs_put_lock_context(struct nfs_lock_context *l_ctx) 


	if (!refcount_dec_and_lock(&l_ctx->count, &inode->i_lock))

		return;

	list_del(&l_ctx->list);

	list_del_rcu(&l_ctx->list);

	spin_unlock(&inode->i_lock);

	kfree(l_ctx);

	kfree_rcu(l_ctx, rcu_head);

}

EXPORT_SYMBOL_GPL(nfs_put_lock_context);

include/linux/nfs_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ struct nfs_lock_context { 
	struct nfs_open_context *open_context;

	fl_owner_t lockowner;

	atomic_t io_count;

	struct rcu_head	rcu_head;

};



struct nfs4_state;