NFS: Add functionality to allow waiting on all outstanding reads to complete
This will later allow NFS locking code to wait for readahead to complete
before releasing byte range locks.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 7f09330..29cfb7a 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -84,6 +84,55 @@
kmem_cache_free(nfs_page_cachep, p);
}
+static void
+nfs_iocounter_inc(struct nfs_io_counter *c)
+{
+ atomic_inc(&c->io_count);
+}
+
+static void
+nfs_iocounter_dec(struct nfs_io_counter *c)
+{
+ if (atomic_dec_and_test(&c->io_count)) {
+ clear_bit(NFS_IO_INPROGRESS, &c->flags);
+ smp_mb__after_clear_bit();
+ wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
+ }
+}
+
+static int
+__nfs_iocounter_wait(struct nfs_io_counter *c)
+{
+ wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
+ DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
+ int ret = 0;
+
+ do {
+ prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
+ set_bit(NFS_IO_INPROGRESS, &c->flags);
+ if (atomic_read(&c->io_count) == 0)
+ break;
+ ret = nfs_wait_bit_killable(&c->flags);
+ } while (atomic_read(&c->io_count) != 0);
+ finish_wait(wq, &q.wait);
+ return ret;
+}
+
+/**
+ * nfs_iocounter_wait - wait for i/o to complete
+ * @c: nfs_io_counter to use
+ *
+ * returns -ERESTARTSYS if interrupted by a fatal signal.
+ * Otherwise returns 0 once the io_count hits 0.
+ */
+int
+nfs_iocounter_wait(struct nfs_io_counter *c)
+{
+ if (atomic_read(&c->io_count) == 0)
+ return 0;
+ return __nfs_iocounter_wait(c);
+}
+
/**
* nfs_create_request - Create an NFS read/write request.
* @ctx: open context to use
@@ -118,6 +167,7 @@
return ERR_CAST(l_ctx);
}
req->wb_lock_context = l_ctx;
+ nfs_iocounter_inc(&l_ctx->io_count);
/* Initialize the request struct. Initially, we assume a
* long write-back delay. This will be adjusted in
@@ -177,6 +227,7 @@
req->wb_page = NULL;
}
if (l_ctx != NULL) {
+ nfs_iocounter_dec(&l_ctx->io_count);
nfs_put_lock_context(l_ctx);
req->wb_lock_context = NULL;
}