NFS: Add an iocounter wait function for async RPC tasks
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@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 3ffbffe..3e7b2e6 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -218,6 +218,7 @@
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 f536106..ad92b40 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -102,6 +102,35 @@
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
@@ -385,8 +414,11 @@
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 1b29915..9aa044e 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -76,6 +76,7 @@
#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 b34097c..2a70f34 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -222,6 +222,7 @@
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 6f01e28..247cc3d 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -141,6 +141,7 @@
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