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rxrpc: Fix afs large storage transmission performance drop 

[ Upstream commit 02c28dffb13abbaaedece1e4a6493b48ad3f913a ]

Commit 2ad6691d988c, which moved the modification of the status annotation
for a packet in the Tx buffer prior to the retransmission moved the state
clearance, but managed to lose the bit that set it to UNACK.

Consequently, if a retransmission occurs, the packet is accidentally
changed to the ACK state (ie. 0) by masking it off, which means that the
packet isn't counted towards the tally of newly-ACK'd packets if it gets
hard-ACK'd.  This then prevents the congestion control algorithm from
recovering properly.

Fix by reinstating the change of state to UNACK.

Spotted by the generic/460 xfstest.

Fixes: 2ad6691d988c ("rxrpc: Fix race between incoming ACK parser and retransmitter")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
David Howells 2020-06-17 15:46:33 +01:00 committed by Greg Kroah-Hartman
parent 60d7de28e0
commit 53e9b62672
1 changed files with 1 additions and 1 deletions
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2
net/rxrpc/call_event.c
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@ -253,7 +253,7 @@ static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
* confuse things
*/
annotation &= ~RXRPC_TX_ANNO_MASK;
annotation |= RXRPC_TX_ANNO_RESENT;
annotation |= RXRPC_TX_ANNO_UNACK | RXRPC_TX_ANNO_RESENT;
call->rxtx_annotations[ix] = annotation;
skb = call->rxtx_buffer[ix];