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)