From: Mikulas Patocka mpatocka@redhat.com
commit ee55b92a7391bf871939330f662651b54be51b73 upstream.
Commit d53f1fafec9d086f1c5166436abefdaef30e0363 ("dm writecache: do direct write if the cache is full") changed dm-writecache, so that it writes directly to the origin device if the cache is full. Unfortunately, it doesn't forward flush requests to the origin device, so that there is a bug where flushes are being ignored.
Fix this by adding missing flush forwarding.
For PMEM mode, we fix this bug by disabling direct writes to the origin device, because it performs better.
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Fixes: d53f1fafec9d ("dm writecache: do direct write if the cache is full") Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/dm-writecache.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -1297,8 +1297,12 @@ static int writecache_map(struct dm_targ writecache_flush(wc); if (writecache_has_error(wc)) goto unlock_error; + if (unlikely(wc->cleaner)) + goto unlock_remap_origin; goto unlock_submit; } else { + if (dm_bio_get_target_bio_nr(bio)) + goto unlock_remap_origin; writecache_offload_bio(wc, bio); goto unlock_return; } @@ -1377,7 +1381,7 @@ read_next_block: } e = writecache_pop_from_freelist(wc, (sector_t)-1); if (unlikely(!e)) { - if (!found_entry) { + if (!WC_MODE_PMEM(wc) && !found_entry) { direct_write: e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING); if (e) { @@ -2481,7 +2485,7 @@ overflow: goto bad; }
- ti->num_flush_bios = 1; + ti->num_flush_bios = WC_MODE_PMEM(wc) ? 1 : 2; ti->flush_supported = true; ti->num_discard_bios = 1;