From 1db97eaa0b482a738c715da6edb023d6f99e50b0 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sun, 2 Sep 2018 15:11:57 -0400 Subject: [PATCH] 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: Trond Myklebust --- fs/nfs/inode.c | 25 ++++++++++++------------- include/linux/nfs_fs.h | 1 + 2 files changed, 13 insertions(+), 13 deletions(-) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index b65aee481d13..09b3b7146ff4 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -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); - return pos; - } while ((pos = list_entry(pos->list.next, typeof(*pos), list)) != head); + if (refcount_inc_not_zero(&pos->count)) + return pos; + } 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); } - 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); diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h index a0831e9d19c9..d2f4f88a0e66 100644 --- a/include/linux/nfs_fs.h +++ b/include/linux/nfs_fs.h @@ -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; -- 2.39.5