[PATCH 5.10.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: replaced cifs_invalidate_cache() with fscache_invalidate() guarded by CONFIG_CIFS_FSCACHE ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/smb2ops.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 5d07e1400015b..0e95065ae0767 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -8,6 +8,7 @@
 #include <linux/pagemap.h>
 #include <linux/vfs.h>
 #include <linux/falloc.h>
+#include <linux/fscache.h>
 #include <linux/scatterlist.h>
 #include <linux/uuid.h>
 #include <linux/sort.h>
@@ -2045,7 +2046,7 @@ 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;
@@ -2070,6 +2071,13 @@ 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 */
+#ifdef CONFIG_CIFS_FSCACHE
+		fscache_invalidate(CIFS_I(inode)->fscache);
+#endif
+	}
+
 duplicate_extents_out:
 	return rc;
 }
-- 
2.53.0