[PATCH 2/2] CIFS: Fix a bug with re-sending rdata when transport returning -EAGAIN

[Long Li]

From: Long Li <lon...@microsoft.com>

When sending a rdata, transport may return -EAGAIN. In this case
we should re-obtain credits because the session may have been
reconnected.

Signed-off-by: Long Li <lon...@microsoft.com>
---
 fs/cifs/file.c | 51 +++++++++++++++++++++++++-------------------------
 1 file changed, 26 insertions(+), 25 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 08e73759d6ec..c83ca96f883b 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3335,44 +3335,45 @@ static int cifs_resend_rdata(struct cifs_readdata 
*rdata,
        struct TCP_Server_Info *server =
                tlink_tcon(rdata->cfile->tlink)->ses->server;
 
-       /*
-        * Wait for credits to resend this rdata.
-        * Note: we are attempting to resend the whole rdata not in segments
-        */
        do {
-               rc = server->ops->wait_mtu_credits(server, rdata->bytes,
+               /*
+                * Wait for credits to resend this rdata.
+                * Note: we are attempting to resend the whole rdata not in
+                * segments
+                */
+               do {
+                       rc = server->ops->wait_mtu_credits(server, rdata->bytes,
                                                &rsize, &credits);
 
-               if (rc)
-                       goto out;
+                       if (rc)
+                               goto fail;
 
-               if (rsize < rdata->bytes) {
-                       add_credits_and_wake_if(server, &credits, 0);
-                       msleep(1000);
-               }
-       } while (rsize < rdata->bytes);
+                       if (rsize < rdata->bytes) {
+                               add_credits_and_wake_if(server, &credits, 0);
+                               msleep(1000);
+                       }
+               } while (rsize < rdata->bytes);
 
-       rdata->credits = credits;
-       rc = -EAGAIN;
-       while (rc == -EAGAIN) {
+               rdata->credits = credits;
                rc = 0;
                if (rdata->cfile->invalidHandle)
                        rc = cifs_reopen_file(rdata->cfile, true);
                if (!rc)
                        rc = server->ops->async_readv(rdata);
-       }
 
-       if (!rc) {
-               /* Add to aio pending list */
-               list_add_tail(&rdata->list, rdata_list);
-               return 0;
-       }
+               /* If the read was successfully sent, we are done */
+               if (!rc) {
+                       /* Add to aio pending list */
+                       list_add_tail(&rdata->list, rdata_list);
+                       return 0;
+               }
 
-       add_credits_and_wake_if(server, &rdata->credits, 0);
-out:
-       kref_put(&rdata->refcount,
-               cifs_uncached_readdata_release);
+               /* Roll back credits and retry if needed */
+               add_credits_and_wake_if(server, &rdata->credits, 0);
+       } while (rc == -EAGAIN);
 
+fail:
+       kref_put(&rdata->refcount, cifs_uncached_readdata_release);
        return rc;
 }
 
-- 
2.17.1