From fa10c64092c2e85b4763e815428ad12abb16b734 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Tue, 8 Jun 2021 21:22:52 +0800
Subject: [PATCH] NFS: Ensure NFS writeback allocations don't recurse back into
NFS.
mainline inclusion
from mainline-v5.0-rc1
commit 875bc3fbf2724134234ddb3069c8e9862b0b19b3
category: bugfix
bugzilla: NA
CVE: NA
--------------------------------
All the allocations that we can hit in the NFS layer and sunrpc layers
themselves are already marked as GFP_NOFS, but we need to ensure that
any calls to generic kernel functionality do the right thing as well.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
fs/nfs/write.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index d419d89b91f7..5ae98c0cde04 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -26,6 +26,7 @@
#include <linux/iversion.h>
#include <linux/uaccess.h>
+#include <linux/sched/mm.h>
#include "delegation.h"
#include "internal.h"
@@ -727,11 +728,13 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
struct inode *inode = mapping->host;
struct nfs_pageio_descriptor pgio;
- struct nfs_io_completion *ioc = nfs_io_completion_alloc(GFP_NOFS);
+ struct nfs_io_completion *ioc;
+ unsigned int pflags = memalloc_nofs_save();
int err;
nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
+ ioc = nfs_io_completion_alloc(GFP_NOFS);
if (ioc)
nfs_io_completion_init(ioc, nfs_io_completion_commit, inode);
@@ -742,6 +745,8 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
nfs_pageio_complete(&pgio);
nfs_io_completion_put(ioc);
+ memalloc_nofs_restore(pflags);
+
if (err < 0)
goto out_err;
err = pgio.pg_error;
--
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