CIFS: Optimize cifs_user_read() in a short read case on reconnects
by filling the output buffer with a data got from a partially received
response and requesting the remaining data from the server. This is
suitable for non-signed connections.
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index e170128..5d2501d 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3030,13 +3030,30 @@
else if (rdata->result == -EAGAIN) {
/* resend call if it's a retryable error */
struct list_head tmp_list;
+ unsigned int got_bytes = rdata->got_bytes;
list_del_init(&rdata->list);
INIT_LIST_HEAD(&tmp_list);
- rc = cifs_send_async_read(rdata->offset,
- rdata->bytes, rdata->cfile,
- cifs_sb, &tmp_list);
+ /*
+ * Got a part of data and then reconnect has
+ * happened -- fill the buffer and continue
+ * reading.
+ */
+ if (got_bytes && got_bytes < rdata->bytes) {
+ rc = cifs_readdata_to_iov(rdata, to);
+ if (rc) {
+ kref_put(&rdata->refcount,
+ cifs_uncached_readdata_release);
+ continue;
+ }
+ }
+
+ rc = cifs_send_async_read(
+ rdata->offset + got_bytes,
+ rdata->bytes - got_bytes,
+ rdata->cfile, cifs_sb,
+ &tmp_list);
list_splice(&tmp_list, &rdata_list);