NFS: Ensure that we free the rpc_task after read and write cleanups a…

…re done 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 <[email protected]> Cc: Weston Andros Adamson <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Bruce Fields <[email protected]> Cc: [email protected] [>= 3.5]
TeohJayShen · Jan 4, 2013 · 6db6dd7 · 6db6dd7
1 parent c6567ed
commit 6db6dd7
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Showing 2 changed files with 14 additions and 6 deletions.
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
@@ -91,12 +91,16 @@ void nfs_readdata_release(struct nfs_read_data *rdata)
 	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);
 

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
@@ -126,12 +126,16 @@ void nfs_writedata_release(struct nfs_write_data *wdata)
 	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);