From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit 133a48abf6ecc535d7eddc6da1c3e4c972445882 ]

If O_DIRECT bumps the commit_info rpcs_out field, then that could lead
to fsync() hangs. The fix is to ensure that O_DIRECT calls
nfs_commit_end().

Cc: stable@vger.kernel.org # 5.4
Fixes: 723c921e7dfc ("sched/wait, fs/nfs: Convert wait_on_atomic_t() usage to the new wait_var_event() API")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
[ chanho: Backports to v5.4.y ]
Signed-off-by: Chanho Min <chanho.min@lge.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfs/direct.c        | 2 +-
 fs/nfs/write.c         | 9 ++++++---
 include/linux/nfs_fs.h | 1 +
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 0682037f972be..32dc176ea1aba 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -700,7 +700,7 @@ static void nfs_direct_commit_complete(struct nfs_commit_data *data)
 		nfs_unlock_and_release_request(req);
 	}
 
-	if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
+	if (nfs_commit_end(cinfo.mds))
 		nfs_direct_write_complete(dreq);
 }
 
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 10ce264a64567..c9895316fc070 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1658,10 +1658,13 @@ static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
 	atomic_inc(&cinfo->rpcs_out);
 }
 
-static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
+bool nfs_commit_end(struct nfs_mds_commit_info *cinfo)
 {
-	if (atomic_dec_and_test(&cinfo->rpcs_out))
+	if (atomic_dec_and_test(&cinfo->rpcs_out)) {
 		wake_up_var(&cinfo->rpcs_out);
+		return true;
+	}
+	return false;
 }
 
 void nfs_commitdata_release(struct nfs_commit_data *data)
@@ -1756,6 +1759,7 @@ void nfs_init_commit(struct nfs_commit_data *data,
 	data->res.fattr   = &data->fattr;
 	data->res.verf    = &data->verf;
 	nfs_fattr_init(&data->fattr);
+	nfs_commit_begin(cinfo->mds);
 }
 EXPORT_SYMBOL_GPL(nfs_init_commit);
 
@@ -1801,7 +1805,6 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how,
 
 	/* Set up the argument struct */
 	nfs_init_commit(data, head, NULL, cinfo);
-	atomic_inc(&cinfo->mds->rpcs_out);
 	return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
 				   data->mds_ops, how, 0);
 }
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 49cf5c855cbe5..a96b116cc9224 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -549,6 +549,7 @@ extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
 extern int  nfs_commit_inode(struct inode *, int);
 extern struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail);
 extern void nfs_commit_free(struct nfs_commit_data *data);
+bool nfs_commit_end(struct nfs_mds_commit_info *cinfo);
 
 static inline int
 nfs_have_writebacks(struct inode *inode)