[Patch v2 2/2] CIFS: Fix an issue with re-sending rdata when transport returning -EAGAIN

Long Li
2019-03-15T07:56:22Z

From: Long Li <longli@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.

Change in v2: adjust_credits before re-sending

Signed-off-by: Long Li <longli@microsoft.com>
---
fs/cifs/file.c | 71 +++++++++++++++++++++++++++++++++-------------------------
1 file changed, 41 insertions(+), 30 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 321df1d27422..9d90cc07e38b 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3347,44 +3347,55 @@ 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,
+ if (rdata->cfile->invalidHandle) {
+ rc = cifs_reopen_file(rdata->cfile, true);
+ if (rc == -EAGAIN)
+ continue;
+ else if (rc)
+ break;
+ }
+
+ /*
+ * 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;

- rdata->credits = credits;
- rc = -EAGAIN;
- while (rc == -EAGAIN) {
- rc = 0;
- if (rdata->cfile->invalidHandle)
- rc = cifs_reopen_file(rdata->cfile, true);
- if (!rc)
- rc = server->ops->async_readv(rdata);
- }
+ rc = adjust_credits(server, &rdata->credits, rdata->bytes);
+ if (!rc) {
+ if (rdata->cfile->invalidHandle)
+ rc = -EAGAIN;
+ else
+ 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;
}

--
2.14.1