[Patch v2 1/2] CIFS: Fix an issue with re-sending wdata when transport returning -EAGAIN

Long Li
2019-03-15T07:56:17Z

From: Long Li <longli@microsoft.com>

When sending a wdata, 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 | 77 ++++++++++++++++++++++++++++++++++------------------------
1 file changed, 45 insertions(+), 32 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 9b53f33137b3..321df1d27422 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2620,43 +2620,56 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
struct TCP_Server_Info *server =
tlink_tcon(wdata->cfile->tlink)->ses->server;

- /*
- * Wait for credits to resend this wdata.
- * Note: we are attempting to resend the whole wdata not in segments
- */
do {
- rc = server->ops->wait_mtu_credits(server, wdata->bytes, &wsize,
- &credits);
+ if (wdata->cfile->invalidHandle) {
+ rc = cifs_reopen_file(wdata->cfile, false);
+ if (rc == -EAGAIN)
+ continue;
+ else if (rc)
+ break;
+ }

- if (rc)
- goto out;

- if (wsize < wdata->bytes) {
- add_credits_and_wake_if(server, &credits, 0);
- msleep(1000);
- }
- } while (wsize < wdata->bytes);
+ /*
+ * Wait for credits to resend this wdata.
+ * Note: we are attempting to resend the whole wdata not in
+ * segments
+ */
+ do {
+ rc = server->ops->wait_mtu_credits(server, wdata->bytes,
+ &wsize, &credits);
+ if (rc)
+ goto fail;
+
+ if (wsize < wdata->bytes) {
+ add_credits_and_wake_if(server, &credits, 0);
+ msleep(1000);
+ }
+ } while (wsize < wdata->bytes);
+ wdata->credits = credits;

- wdata->credits = credits;
- rc = -EAGAIN;
- while (rc == -EAGAIN) {
- rc = 0;
- if (wdata->cfile->invalidHandle)
- rc = cifs_reopen_file(wdata->cfile, false);
- if (!rc)
- rc = server->ops->async_writev(wdata,
+ rc = adjust_credits(server, &wdata->credits, wdata->bytes);
+
+ if (!rc) {
+ if (wdata->cfile->invalidHandle)
+ rc = -EAGAIN;
+ else
+ rc = server->ops->async_writev(wdata,
cifs_uncached_writedata_release);
- }
+ }

- if (!rc) {
- list_add_tail(&wdata->list, wdata_list);
- return 0;
- }
+ /* If the write was successfully sent, we are done */
+ if (!rc) {
+ list_add_tail(&wdata->list, wdata_list);
+ return 0;
+ }

- add_credits_and_wake_if(server, &wdata->credits, 0);
-out:
- kref_put(&wdata->refcount, cifs_uncached_writedata_release);
+ /* Roll back credits and retry if needed */
+ add_credits_and_wake_if(server, &wdata->credits, 0);
+ } while (rc == -EAGAIN);

+fail:
+ kref_put(&wdata->refcount, cifs_uncached_writedata_release);
return rc;
}

@@ -2884,12 +2897,12 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
wdata->bytes, &tmp_from,
ctx->cfile, cifs_sb, &tmp_list,
ctx);
+
+ kref_put(&wdata->refcount,
+ cifs_uncached_writedata_release);
}

list_splice(&tmp_list, &ctx->list);
-
- kref_put(&wdata->refcount,
- cifs_uncached_writedata_release);
goto restart_loop;
}
}
--
2.14.1