When doing MTU i/o we need to leave some credits for
possible reopen requests and other operations happening
in parallel. Currently we leave 1 credit which is not
enough even for reopen only: we need at least 2 credits
if durable handle reconnect fails. Also there may be
other operations at the same time including compounding
ones which require 3 credits at a time each. Fix this
by leaving 8 credits which is big enough to cover most
scenarios.
The proper fix would be to reconnect a file handle first
and then obtain credits for an MTU request but this leads
to bigger code changes and should happen in other patches.
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
---
fs/cifs/smb2ops.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 238b16d..82967f6 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -165,14 +165,14 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
scredits = server->credits;
/* can deadlock with reopen */
- if (scredits == 1) {
+ if (scredits <= 8) {
*num = SMB2_MAX_BUFFER_SIZE;
*credits = 0;
break;
}
- /* leave one credit for a possible reopen */
- scredits--;
+ /* leave some credits for reopen and other ops */
+ scredits -= 8;
*num = min_t(unsigned int, size,
scredits * SMB2_MAX_BUFFER_SIZE);
--
2.7.4
