[PATCH 5.15 730/917] NFS: Fix up commit deadlocks

Greg Kroah-Hartman
2021-11-16T00:00:58Z

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().

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>
---
fs/nfs/direct.c | 2 +-
fs/nfs/pnfs_nfs.c | 2 --
fs/nfs/write.c | 9 ++++++---
include/linux/nfs_fs.h | 1 +
4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 2e894fec036b0..3c0335c15a730 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 02bd6e83961d9..316f68f96e573 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 735a054747752..7dce3e735fc53 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 b9a8b925db430..4d95cc999d121 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)
--
2.33.0