From: Lars Ellenberg Date: Tue, 22 Apr 2014 14:37:16 +0000 (+0200) Subject: drbd: drbd_rs_number_requests: fix unit mismatch in comparison X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=7f34f61490ee87a470cf229069d59b0987f42a59;p=linux-beck.git drbd: drbd_rs_number_requests: fix unit mismatch in comparison We try to limit the number of "in-flight" resync requests. One condition for that is the amount of requested data should not exceed half of what can be covered by our "max-buffers" setting. However we compared number of 4k pages with number of in-flight 512 Byte sectors, and this extra throttle triggered much earlier than intended. Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c index 0b5e4294acf9..9f0acb011f30 100644 --- a/drivers/block/drbd/drbd_worker.c +++ b/drivers/block/drbd/drbd_worker.c @@ -504,9 +504,9 @@ struct fifo_buffer *fifo_alloc(int fifo_size) static int drbd_rs_controller(struct drbd_device *device, unsigned int sect_in) { struct disk_conf *dc; - unsigned int want; /* The number of sectors we want in the proxy */ + unsigned int want; /* The number of sectors we want in-flight */ int req_sect; /* Number of sectors to request in this turn */ - int correction; /* Number of sectors more we need in the proxy*/ + int correction; /* Number of sectors more we need in-flight */ int cps; /* correction per invocation of drbd_rs_controller() */ int steps; /* Number of time steps to plan ahead */ int curr_corr; @@ -577,8 +577,13 @@ static int drbd_rs_number_requests(struct drbd_device *device) * potentially causing a distributed deadlock on congestion during * online-verify or (checksum-based) resync, if max-buffers, * socket buffer sizes and resync rate settings are mis-configured. */ - if (mxb - device->rs_in_flight < number) - number = mxb - device->rs_in_flight; + + /* note that "number" is in units of "BM_BLOCK_SIZE" (which is 4k), + * mxb (as used here, and in drbd_alloc_pages on the peer) is + * "number of pages" (typically also 4k), + * but "rs_in_flight" is in "sectors" (512 Byte). */ + if (mxb - device->rs_in_flight/8 < number) + number = mxb - device->rs_in_flight/8; return number; }