[PATCH 6.1.y] cifs: add revalidation on FSCTL failure in smb2_duplicate_extents()

[Sasha Levin <sashal@kernel.org>]

From: Frank Sorenson <sorenson@redhat.com>

[ Upstream commit 53676a5e28231186c9f56d87b7998b640699bc15 ]

smb2_duplicate_extents() has no handling for
FSCTL_DUPLICATE_EXTENTS_TO_FILE failure: when the FSCTL fails, local
inode metadata may be stale from the pre-extension or from concurrent
remote writes, but is never refreshed.

Force revalidation on FSCTL failure and use i_size_read() for the
pre-extension check.

Fixes: cfc63fc8126a ("smb3: fix cached file size problems in duplicate extents (reflink)")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Sorenson <sorenson@redhat.com>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
[ sashal: adapted the if/else block to a standalone failure check because the success-path metadata query is absent ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/client/smb2ops.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index ecc5f27ff1413..5a07d411a00a6 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -2027,7 +2027,7 @@ smb2_duplicate_extents(const unsigned int xid,
 		src_off, dest_off, len);
 
 	inode = d_inode(trgtfile->dentry);
-	if (inode->i_size < dest_off + len) {
+	if (i_size_read(inode) < dest_off + len) {
 		rc = smb2_set_file_size(xid, tcon, trgtfile, dest_off + len, false);
 		if (rc)
 			goto duplicate_extents_out;
@@ -2052,6 +2052,11 @@ smb2_duplicate_extents(const unsigned int xid,
 	if (ret_data_len > 0)
 		cifs_dbg(FYI, "Non-zero response length in duplicate extents\n");
 
+	if (rc) {
+		CIFS_I(inode)->time = 0; /* force reval */
+		cifs_invalidate_cache(inode, 0);
+	}
+
 duplicate_extents_out:
 	return rc;
 }
-- 
2.53.0