dm cache: remove remainder of distinct discard block size

Discard block size not being equal to cache block size causes data
corruption by erroneously avoiding migrations in issue_copy() because
the discard state is being cleared for a group of cache blocks when it
should not.

Completely remove all code that enabled a distinction between the
cache block size and discard block size.

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 26 insertions, 46 deletions

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index bccb7ae34e61..8534679918f4 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -237,9 +237,8 @@ struct cache {
         /*
          * origin_blocks entries, discarded if set.
          */
-        dm_dblock_t discard_nr_blocks;
+        dm_oblock_t discard_nr_blocks;
         unsigned long *discard_bitset;
-        uint32_t discard_block_size;
 
         /*
          * Rather than reconstructing the table line for the status we just
@@ -526,48 +525,33 @@ static dm_block_t block_div(dm_block_t b, uint32_t n)
         return b;
 }
 
-static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
-{
-        uint32_t discard_blocks = cache->discard_block_size;
-        dm_block_t b = from_oblock(oblock);
-
-        if (!block_size_is_power_of_two(cache))
-                discard_blocks = discard_blocks / cache->sectors_per_block;
-        else
-                discard_blocks >>= cache->sectors_per_block_shift;
-
-        b = block_div(b, discard_blocks);
-
-        return to_dblock(b);
-}
-
-static void set_discard(struct cache *cache, dm_dblock_t b)
+static void set_discard(struct cache *cache, dm_oblock_t b)
 {
         unsigned long flags;
 
         atomic_inc(&cache->stats.discard_count);
 
         spin_lock_irqsave(&cache->lock, flags);
-        set_bit(from_dblock(b), cache->discard_bitset);
+        set_bit(from_oblock(b), cache->discard_bitset);
         spin_unlock_irqrestore(&cache->lock, flags);
 }
 
-static void clear_discard(struct cache *cache, dm_dblock_t b)
+static void clear_discard(struct cache *cache, dm_oblock_t b)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&cache->lock, flags);
-        clear_bit(from_dblock(b), cache->discard_bitset);
+        clear_bit(from_oblock(b), cache->discard_bitset);
         spin_unlock_irqrestore(&cache->lock, flags);
 }
 
-static bool is_discarded(struct cache *cache, dm_dblock_t b)
+static bool is_discarded(struct cache *cache, dm_oblock_t b)
 {
         int r;
         unsigned long flags;
 
         spin_lock_irqsave(&cache->lock, flags);
-        r = test_bit(from_dblock(b), cache->discard_bitset);
+        r = test_bit(from_oblock(b), cache->discard_bitset);
         spin_unlock_irqrestore(&cache->lock, flags);
 
         return r;
@@ -579,8 +563,7 @@ static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
         unsigned long flags;
 
         spin_lock_irqsave(&cache->lock, flags);
-        r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
-                     cache->discard_bitset);
+        r = test_bit(from_oblock(b), cache->discard_bitset);
         spin_unlock_irqrestore(&cache->lock, flags);
 
         return r;
@@ -705,7 +688,7 @@ static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
         check_if_tick_bio_needed(cache, bio);
         remap_to_origin(cache, bio);
         if (bio_data_dir(bio) == WRITE)
-                clear_discard(cache, oblock_to_dblock(cache, oblock));
+                clear_discard(cache, oblock);
 }
 
 static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
@@ -715,7 +698,7 @@ static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
         remap_to_cache(cache, bio, cblock);
         if (bio_data_dir(bio) == WRITE) {
                 set_dirty(cache, oblock, cblock);
-                clear_discard(cache, oblock_to_dblock(cache, oblock));
+                clear_discard(cache, oblock);
         }
 }
 
@@ -1288,14 +1271,14 @@ static void process_flush_bio(struct cache *cache, struct bio *bio)
 static void process_discard_bio(struct cache *cache, struct bio *bio)
 {
         dm_block_t start_block = dm_sector_div_up(bio->bi_iter.bi_sector,
-                                                  cache->discard_block_size);
+                                                  cache->sectors_per_block);
         dm_block_t end_block = bio_end_sector(bio);
         dm_block_t b;
 
-        end_block = block_div(end_block, cache->discard_block_size);
+        end_block = block_div(end_block, cache->sectors_per_block);
 
         for (b = start_block; b < end_block; b++)
-                set_discard(cache, to_dblock(b));
+                set_discard(cache, to_oblock(b));
 
         bio_endio(bio, 0);
 }
@@ -2292,14 +2275,13 @@ static int cache_create(struct cache_args *ca, struct cache **result)
         }
         clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
 
-        cache->discard_block_size = cache->sectors_per_block;
-        cache->discard_nr_blocks = oblock_to_dblock(cache, cache->origin_blocks);
-        cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
+        cache->discard_nr_blocks = cache->origin_blocks;
+        cache->discard_bitset = alloc_bitset(from_oblock(cache->discard_nr_blocks));
         if (!cache->discard_bitset) {
                 *error = "could not allocate discard bitset";
                 goto bad;
         }
-        clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
+        clear_bitset(cache->discard_bitset, from_oblock(cache->discard_nr_blocks));
 
         cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
         if (IS_ERR(cache->copier)) {
@@ -2583,16 +2565,16 @@ static int write_discard_bitset(struct cache *cache)
 {
         unsigned i, r;
 
-        r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
-                                           cache->discard_nr_blocks);
+        r = dm_cache_discard_bitset_resize(cache->cmd, cache->sectors_per_block,
+                                           cache->origin_blocks);
         if (r) {
                 DMERR("could not resize on-disk discard bitset");
                 return r;
         }
 
-        for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
-                r = dm_cache_set_discard(cache->cmd, to_dblock(i),
-                                         is_discarded(cache, to_dblock(i)));
+        for (i = 0; i < from_oblock(cache->discard_nr_blocks); i++) {
+                r = dm_cache_set_discard(cache->cmd, to_oblock(i),
+                                         is_discarded(cache, to_oblock(i)));
                 if (r)
                         return r;
         }
@@ -2689,16 +2671,14 @@ static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
 }
 
 static int load_discard(void *context, sector_t discard_block_size,
-                        dm_dblock_t dblock, bool discard)
+                        dm_oblock_t oblock, bool discard)
 {
         struct cache *cache = context;
 
-        /* FIXME: handle mis-matched block size */
-
         if (discard)
-                set_discard(cache, dblock);
+                set_discard(cache, oblock);
         else
-                clear_discard(cache, dblock);
+                clear_discard(cache, oblock);
 
         return 0;
 }
@@ -3089,8 +3069,8 @@ static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
         /*
          * FIXME: these limits may be incompatible with the cache device
          */
-        limits->max_discard_sectors = cache->discard_block_size;
-        limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
+        limits->max_discard_sectors = cache->sectors_per_block;
+        limits->discard_granularity = cache->sectors_per_block << SECTOR_SHIFT;
 }
 
 static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)