If the cache device is full, we do a direct write to the origin device.
Note that we must not do it if the written block is already in the cache.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-writecache.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
Index: linux-2.6/drivers/md/dm-writecache.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-writecache.c 2020-02-23 18:15:56.000000000 +0100
+++ linux-2.6/drivers/md/dm-writecache.c 2020-02-23 18:15:56.000000000 +0100
@@ -1194,6 +1194,7 @@ read_next_block:
}
} else {
do {
+ bool found_entry = false;
if (writecache_has_error(wc))
goto unlock_error;
e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
@@ -1204,9 +1205,21 @@ read_next_block:
wc->overwrote_committed = true;
goto bio_copy;
}
+ found_entry = true;
}
e = writecache_pop_from_freelist(wc, (sector_t)-1);
if (unlikely(!e)) {
+ if (!found_entry) {
+ e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
+ if (e) {
+ sector_t next_boundary = read_original_sector(wc, e) - bio->bi_iter.bi_sector;
+ BUG_ON(!next_boundary);
+ if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {
+ dm_accept_partial_bio(bio, next_boundary);
+ }
+ }
+ goto unlock_remap_origin;
+ }
writecache_wait_on_freelist(wc);
continue;
}
--
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