releases/3.7.2/nfs-ensure-that-we-free-the-rpc_task-after-read-and-write-cleanups-are-done.patch

From 6db6dd7d3fd8f7c765dabc376493d6791ab28bd6 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Fri, 4 Jan 2013 12:47:04 -0500
Subject: NFS: Ensure that we free the rpc_task after read and write cleanups are done

From: Trond Myklebust <Trond.Myklebust@netapp.com>

commit 6db6dd7d3fd8f7c765dabc376493d6791ab28bd6 upstream.

This patch ensures that we free the rpc_task after the cleanup callbacks
are done in order to avoid a deadlock problem that can be triggered if
the callback needs to wait for another workqueue item to complete.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Weston Andros Adamson <dros@netapp.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Bruce Fields <bfields@fieldses.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfs/read.c  |   10 +++++++---
 fs/nfs/write.c |   10 +++++++---
 2 files changed, 14 insertions(+), 6 deletions(-)

--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -91,12 +91,16 @@ void nfs_readdata_release(struct nfs_rea
 	put_nfs_open_context(rdata->args.context);
 	if (rdata->pages.pagevec != rdata->pages.page_array)
 		kfree(rdata->pages.pagevec);
-	if (rdata != &read_header->rpc_data)
-		kfree(rdata);
-	else
+	if (rdata == &read_header->rpc_data) {
 		rdata->header = NULL;
+		rdata = NULL;
+	}
 	if (atomic_dec_and_test(&hdr->refcnt))
 		hdr->completion_ops->completion(hdr);
+	/* Note: we only free the rpc_task after callbacks are done.
+	 * See the comment in rpc_free_task() for why
+	 */
+	kfree(rdata);
 }
 EXPORT_SYMBOL_GPL(nfs_readdata_release);
 
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -126,12 +126,16 @@ void nfs_writedata_release(struct nfs_wr
 	put_nfs_open_context(wdata->args.context);
 	if (wdata->pages.pagevec != wdata->pages.page_array)
 		kfree(wdata->pages.pagevec);
-	if (wdata != &write_header->rpc_data)
-		kfree(wdata);
-	else
+	if (wdata == &write_header->rpc_data) {
 		wdata->header = NULL;
+		wdata = NULL;
+	}
 	if (atomic_dec_and_test(&hdr->refcnt))
 		hdr->completion_ops->completion(hdr);
+	/* Note: we only free the rpc_task after callbacks are done.
+	 * See the comment in rpc_free_task() for why
+	 */
+	kfree(wdata);
 }
 EXPORT_SYMBOL_GPL(nfs_writedata_release);