cifs: Set zero_point in the copy_file_range() and remap_file_range()

Set zero_point in the copy_file_range() and remap_file_range()
implementations so that we don't skip reading data modified on a
server-side copy.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org

diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
index 847df5152835f3d38c26241c7cba42e8333b3e8c..9d656a08f617298fcedb31ad0116d3e180e2aa7f 100644 (file)
--- a/fs/smb/client/cifsfs.c
+++ b/fs/smb/client/cifsfs.c
@@ -1287,6 +1287,8 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
        rc = cifs_flush_folio(target_inode, destend, &fstart, &fend, false);
        if (rc)
                goto unlock;
+       if (fend > target_cifsi->netfs.zero_point)
+               target_cifsi->netfs.zero_point = fend + 1;
 
        /* Discard all the folios that overlap the destination region. */
        cifs_dbg(FYI, "about to discard pages %llx-%llx\n", fstart, fend);
@@ -1305,6 +1307,8 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
                        fscache_resize_cookie(cifs_inode_cookie(target_inode),
                                              new_size);
                }
+               if (rc == 0 && new_size > target_cifsi->netfs.zero_point)
+                       target_cifsi->netfs.zero_point = new_size;
        }
 
        /* force revalidate of size and timestamps of target file now
@@ -1396,6 +1400,8 @@ ssize_t cifs_file_copychunk_range(unsigned int xid,
        rc = cifs_flush_folio(target_inode, destend, &fstart, &fend, false);
        if (rc)
                goto unlock;
+       if (fend > target_cifsi->netfs.zero_point)
+               target_cifsi->netfs.zero_point = fend + 1;
 
        /* Discard all the folios that overlap the destination region. */
        truncate_inode_pages_range(&target_inode->i_data, fstart, fend);