Fix a bug that low watermark was ignored and high watermark was used as both low and high.
The patch also verifies that high watermark is greater or equal than low watermark - if this condition is violated, the driver would consume too much CPU. Signed-off-by: Mikulas Patocka <[email protected]> --- drivers/md/dm-writecache.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) Index: linux-2.6/drivers/md/dm-writecache.c =================================================================== --- linux-2.6.orig/drivers/md/dm-writecache.c 2018-06-07 21:21:47.000000000 +0200 +++ linux-2.6/drivers/md/dm-writecache.c 2018-06-07 21:23:21.000000000 +0200 @@ -1590,7 +1590,7 @@ restart: wbl.size = 0; while (!list_empty(&wc->lru) && (wc->writeback_all || - wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark)) { + wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark)) { n_walked++; if (unlikely(n_walked > WRITEBACK_LATENCY) && @@ -2033,6 +2033,12 @@ invalid_optional: } } + if (high_wm_percent < low_wm_percent) { + r = -EINVAL; + ti->error = "High watermark must be greater or equal than low watermark"; + goto bad; + } + if (!WC_MODE_PMEM(wc)) { struct dm_io_region region; struct dm_io_request req; -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
