[ 053/123] NFS: Ensure that we free the rpc_task after read and write cleanups are done

Greg Kroah-Hartman
2013-01-09T21:18:36Z

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);