[PATCH 5.10 292/770] NFSD add vfs_fsync after async copy is done

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Olga Kornievskaia <kolga@xxxxxxxxxx>

[ Upstream commit eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d ]

Currently, the server does all copies as NFS_UNSTABLE. For synchronous
copies linux client will append a COMMIT to the COPY compound but for
async copies it does not (because COMMIT needs to be done after all
bytes are copied and not as a reply to the COPY operation).

However, in order to save the client doing a COMMIT as a separate
rpc, the server can reply back with NFS_FILE_SYNC copy. This patch
proposed to add vfs_fsync() call at the end of the async copy.

Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
[ cel: adjusted to apply to v5.10.y ]
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/nfsd/nfs4proc.c | 15 ++++++++++++++-
 fs/nfsd/xdr4.h     |  1 +
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index dfce9c432a5ee..aa0da0737a3ff 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1366,7 +1366,8 @@ static const struct nfsd4_callback_ops nfsd4_cb_offload_ops = {
 
 static void nfsd4_init_copy_res(struct nfsd4_copy *copy, bool sync)
 {
-	copy->cp_res.wr_stable_how = NFS_UNSTABLE;
+	copy->cp_res.wr_stable_how =
+		copy->committed ? NFS_FILE_SYNC : NFS_UNSTABLE;
 	copy->cp_synchronous = sync;
 	gen_boot_verifier(&copy->cp_res.wr_verifier, copy->cp_clp->net);
 }
@@ -1375,10 +1376,12 @@ static ssize_t _nfsd_copy_file_range(struct nfsd4_copy *copy)
 {
 	struct file *dst = copy->nf_dst->nf_file;
 	struct file *src = copy->nf_src->nf_file;
+	errseq_t since;
 	ssize_t bytes_copied = 0;
 	u64 bytes_total = copy->cp_count;
 	u64 src_pos = copy->cp_src_pos;
 	u64 dst_pos = copy->cp_dst_pos;
+	__be32 status;
 
 	/* See RFC 7862 p.67: */
 	if (bytes_total == 0)
@@ -1395,6 +1398,16 @@ static ssize_t _nfsd_copy_file_range(struct nfsd4_copy *copy)
 		src_pos += bytes_copied;
 		dst_pos += bytes_copied;
 	} while (bytes_total > 0 && !copy->cp_synchronous);
+	/* for a non-zero asynchronous copy do a commit of data */
+	if (!copy->cp_synchronous && copy->cp_res.wr_bytes_written > 0) {
+		since = READ_ONCE(dst->f_wb_err);
+		status = vfs_fsync_range(dst, copy->cp_dst_pos,
+					 copy->cp_res.wr_bytes_written, 0);
+		if (!status)
+			status = filemap_check_wb_err(dst->f_mapping, since);
+		if (!status)
+			copy->committed = true;
+	}
 	return bytes_copied;
 }
 
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index fe540a3415c6a..37af86e370cb3 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -567,6 +567,7 @@ struct nfsd4_copy {
 	struct vfsmount		*ss_mnt;
 	struct nfs_fh		c_fh;
 	nfs4_stateid		stateid;
+	bool			committed;
 };
 
 struct nfsd4_seek {
-- 
2.43.0