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 <mpatocka@xxxxxxxxxx>
---
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;
--
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