On Tue, 2017-04-11 at 12:50 -0400, Benjamin Coddington wrote:
> By sleeping on a new NFS Unlock-On-Close waitqueue, rpc tasks may wait for
> a lock context's iocounter to reach zero. The rpc waitqueue is only woken
> when the open_context has the NFS_CONTEXT_UNLOCK flag set in order to
> mitigate spurious wake-ups for any iocounter reaching zero.
>
> Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
> ---
> fs/nfs/client.c | 1 +
> fs/nfs/pagelist.c | 34 +++++++++++++++++++++++++++++++++-
> include/linux/nfs_fs.h | 1 +
> include/linux/nfs_fs_sb.h | 1 +
> include/linux/nfs_page.h | 1 +
> 5 files changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 91a8d610ba0f..c335c6dce285 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -218,6 +218,7 @@ static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
> static void pnfs_init_server(struct nfs_server *server)
> {
> rpc_init_wait_queue(&server->roc_rpcwaitq, "pNFS ROC");
> + rpc_init_wait_queue(&server->uoc_rpcwaitq, "NFS UOC");
> }
>
> #else
> diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> index 6e629b856a00..3487d215cee1 100644
> --- a/fs/nfs/pagelist.c
> +++ b/fs/nfs/pagelist.c
> @@ -115,6 +115,35 @@ nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
> TASK_KILLABLE);
> }
>
> +/**
> + * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
> + * to complete
> + * @task: the rpc_task that should wait
> + * @l_ctx: nfs_lock_context with io_counter to check
> + *
> + * Returns true if there is outstanding I/O to wait on and the
> + * task has been put to sleep.
> + */
> +bool
> +nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
> +{
> + struct inode *inode = d_inode(l_ctx->open_context->dentry);
> + bool ret = false;
> +
> + if (atomic_read(&l_ctx->io_count) > 0) {
> + rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
> + ret = true;
> + }
> +
> + if (atomic_read(&l_ctx->io_count) == 0) {
> + rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
> + ret = false;
> + }
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
> +
> /*
> * nfs_page_group_lock - lock the head of the page group
> * @req - request in group that is to be locked
> @@ -398,8 +427,11 @@ static void nfs_clear_request(struct nfs_page *req)
> req->wb_page = NULL;
> }
> if (l_ctx != NULL) {
> - if (atomic_dec_and_test(&l_ctx->io_count))
> + if (atomic_dec_and_test(&l_ctx->io_count)) {
> wake_up_atomic_t(&l_ctx->io_count);
> + if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
> + rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
> + }
> nfs_put_lock_context(l_ctx);
> req->wb_lock_context = NULL;
> }
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index f1da8c8dd473..3ce3e42beead 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -76,6 +76,7 @@ struct nfs_open_context {
> #define NFS_CONTEXT_ERROR_WRITE (0)
> #define NFS_CONTEXT_RESEND_WRITES (1)
> #define NFS_CONTEXT_BAD (2)
> +#define NFS_CONTEXT_UNLOCK (3)
> int error;
>
> struct list_head list;
> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
> index b34097c67848..2a70f34dffe8 100644
> --- a/include/linux/nfs_fs_sb.h
> +++ b/include/linux/nfs_fs_sb.h
> @@ -222,6 +222,7 @@ struct nfs_server {
> u32 mountd_version;
> unsigned short mountd_port;
> unsigned short mountd_protocol;
> + struct rpc_wait_queue uoc_rpcwaitq;
> };
>
> /* Server capabilities */
> diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
> index 957049f72290..81105e473750 100644
> --- a/include/linux/nfs_page.h
> +++ b/include/linux/nfs_page.h
> @@ -141,6 +141,7 @@ extern int nfs_page_group_lock(struct nfs_page *, bool);
> extern void nfs_page_group_lock_wait(struct nfs_page *);
> extern void nfs_page_group_unlock(struct nfs_page *);
> extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int);
> +extern bool nfs_async_iocounter_wait(struct rpc_task *, struct nfs_lock_context *);
>
> /*
> * Lock the page of an asynchronous request
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
