This is a note to let you know that I've just added the patch titled
NFS: Fix deadlocks in nfs_scan_commit_list()
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfs-fix-deadlocks-in-nfs_scan_commit_list.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1a55c315230255ca9adbc315a11fa7b4fc2e3f39
Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date: Mon Oct 4 15:44:16 2021 -0400
NFS: Fix deadlocks in nfs_scan_commit_list()
[ Upstream commit 64a93dbf25d3a1368bb58ddf0f61d0a92d7479e3 ]
Partially revert commit 2ce209c42c01 ("NFS: Wait for requests that are
locked on the commit list"), since it can lead to deadlocks between
commit requests and nfs_join_page_group().
For now we should assume that any locked requests on the commit list are
either about to be removed and committed by another task, or the writes
they describe are about to be retransmitted. In either case, we should
not need to worry.
Fixes: 2ce209c42c01 ("NFS: Wait for requests that are locked on the commit list")
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 767e46c09074b..010733c8bdcd3 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1037,25 +1037,11 @@ nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
struct nfs_page *req, *tmp;
int ret = 0;
-restart:
list_for_each_entry_safe(req, tmp, src, wb_list) {
kref_get(&req->wb_kref);
if (!nfs_lock_request(req)) {
- int status;
-
- /* Prevent deadlock with nfs_lock_and_join_requests */
- if (!list_empty(dst)) {
- nfs_release_request(req);
- continue;
- }
- /* Ensure we make progress to prevent livelock */
- mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
- status = nfs_wait_on_request(req);
nfs_release_request(req);
- mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
- if (status < 0)
- break;
- goto restart;
+ continue;
}
nfs_request_remove_commit_list(req, cinfo);
clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
@@ -1904,6 +1890,7 @@ static int __nfs_commit_inode(struct inode *inode, int how,
int may_wait = how & FLUSH_SYNC;
int ret, nscan;
+ how &= ~FLUSH_SYNC;
nfs_init_cinfo_from_inode(&cinfo, inode);
nfs_commit_begin(cinfo.mds);
for (;;) {
