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dm writecache: flush origin device when writing and cache is full

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Commit d53f1fafec ("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: d53f1fafec ("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>
This commit is contained in:
Mikulas Patocka 2021-06-15 13:45:55 -04:00 committed by Mike Snitzer
parent 293128b1ef
commit ee55b92a73
1 changed files with 6 additions and 2 deletions
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8
drivers/md/dm-writecache.c
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@ -1297,8 +1297,12 @@ static int writecache_map(struct dm_target *ti, struct bio *bio)
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) {
@ -2484,7 +2488,7 @@ 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;