From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Mon, 4 Oct 2021 19:37:42 +0000 (-0400)
Subject: NFS: Fix up commit deadlocks
X-Git-Tag: accepted/tizen/unified/20230118.172025~5337
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9443fcc22a6cbe0caf1c83f756a0416e83ddb07f;p=platform%2Fkernel%2Flinux-rpi.git

NFS: Fix up commit deadlocks

[ 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().

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 2e894fe..3c0335c 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -620,7 +620,7 @@ 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/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c
index 02bd6e8..316f68f 100644
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -468,7 +468,6 @@ pnfs_bucket_alloc_ds_commits(struct list_head *list,
 				goto out_error;
 			data->ds_commit_index = i;
 			list_add_tail(&data->list, list);
-			atomic_inc(&cinfo->mds->rpcs_out);
 			nreq++;
 		}
 		mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
@@ -520,7 +519,6 @@ pnfs_generic_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
 		data->ds_commit_index = -1;
 		list_splice_init(mds_pages, &data->pages);
 		list_add_tail(&data->list, &list);
-		atomic_inc(&cinfo->mds->rpcs_out);
 		nreq++;
 	}
 
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 735a054..7dce3e7 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1657,10 +1657,13 @@ 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)
@@ -1760,6 +1763,7 @@ 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);
 
@@ -1806,7 +1810,6 @@ 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);
 	if (NFS_SERVER(inode)->nfs_client->cl_minorversion)
 		task_flags = RPC_TASK_MOVEABLE;
 	return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index b9a8b92..4d95cc9 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -569,6 +569,7 @@ 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)