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drbd: No longer answer P_RS_DATA_REQUEST packets when in C_AHEAD mode 

When the sync source node replies to a P_RS_DATA_REQUEST packet
when it is already in ahead mode. I.e. those two packets
crossed each other on the wire, that may lead to diverging
bitmaps.

  This never happens in a well-tuned-system. In a well-tuned-
  system the resync controller has reduced the resync speed
  to zero long before we got into ahead-mode.

But we have to be prepared for the not-well-tuned-system
of course as well.
Because -> diverging bitmaps = non terminating resync.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Philipp Reisner 2010-12-27 10:53:28 +01:00
parent 617049aa7d
commit d612d309e4
3 changed files with 16 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/block/drbd/drbd_int.h
View File

@ -205,8 +205,9 @@ enum drbd_packets {
/* P_CKPT_DISABLE_REQ = 0x26, * currently reserved for protocol D */
P_DELAY_PROBE = 0x27, /* is used on BOTH sockets */
P_OUT_OF_SYNC = 0x28, /* Mark as out of sync (Outrunning), data socket */
P_RS_CANCEL = 0x29, /* meta: Used to cancel RS_DATA_REQUEST packet by SyncSource */
P_MAX_CMD = 0x28,
P_MAX_CMD = 0x2A,
P_MAY_IGNORE = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
P_MAX_OPT_CMD = 0x101,

12
drivers/block/drbd/drbd_receiver.c
View File

@ -4361,7 +4361,16 @@ static int got_NegRSDReply(struct drbd_conf *mdev, struct p_header80 *h)
if (get_ldev_if_state(mdev, D_FAILED)) {
drbd_rs_complete_io(mdev, sector);
drbd_rs_failed_io(mdev, sector, size);
switch (be16_to_cpu(h->command)) {
case P_NEG_RS_DREPLY:
drbd_rs_failed_io(mdev, sector, size);
case P_RS_CANCEL:
break;
default:
D_ASSERT(0);
put_ldev(mdev);
return false;
}
put_ldev(mdev);
}
@ -4459,6 +4468,7 @@ static struct asender_cmd *get_asender_cmd(int cmd)
[P_STATE_CHG_REPLY] = { sizeof(struct p_req_state_reply), got_RqSReply },
[P_RS_IS_IN_SYNC] = { sizeof(struct p_block_ack), got_IsInSync },
[P_DELAY_PROBE] = { sizeof(struct p_delay_probe93), got_skip },
[P_RS_CANCEL] = { sizeof(struct p_block_ack), got_NegRSDReply},
[P_MAX_CMD] = { 0, NULL },
};
if (cmd > P_MAX_CMD || asender_tbl[cmd].process == NULL)

4
drivers/block/drbd/drbd_worker.c
View File

@ -988,7 +988,9 @@ int w_e_end_rsdata_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
put_ldev(mdev);
}
if (likely((e->flags & EE_WAS_ERROR) == 0)) {
if (mdev->state.conn == C_AHEAD) {
ok = drbd_send_ack(mdev, P_RS_CANCEL, e);
} else if (likely((e->flags & EE_WAS_ERROR) == 0)) {
if (likely(mdev->state.pdsk >= D_INCONSISTENT)) {
inc_rs_pending(mdev);
ok = drbd_send_block(mdev, P_RS_DATA_REPLY, e);