The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 56517ab958b7c11030e626250c00b9b1a24b41eb Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date: Tue, 25 May 2021 10:23:05 -0400
Subject: [PATCH] NFS: Fix an Oopsable condition in __nfs_pageio_add_request()
Ensure that nfs_pageio_error_cleanup() resets the mirror array contents,
so that the structure reflects the fact that it is now empty.
Also change the test in nfs_pageio_do_add_request() to be more robust by
checking whether or not the list is empty rather than relying on the
value of pg_count.
Fixes: a7d42ddb3099 ("nfs: add mirroring support to pgio layer")
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 6c20b28d9d7c..d35c84af44e0 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -1094,15 +1094,16 @@ nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *prev = NULL;
unsigned int size;
- if (mirror->pg_count != 0) {
- prev = nfs_list_entry(mirror->pg_list.prev);
- } else {
+ if (list_empty(&mirror->pg_list)) {
if (desc->pg_ops->pg_init)
desc->pg_ops->pg_init(desc, req);
if (desc->pg_error < 0)
return 0;
mirror->pg_base = req->wb_pgbase;
- }
+ mirror->pg_count = 0;
+ mirror->pg_recoalesce = 0;
+ } else
+ prev = nfs_list_entry(mirror->pg_list.prev);
if (desc->pg_maxretrans && req->wb_nio > desc->pg_maxretrans) {
if (NFS_SERVER(desc->pg_inode)->flags & NFS_MOUNT_SOFTERR)
