[PATCH 3/9] bcache: drop discard sysfs interface

[colyli@fnnas.com]

From: Coly Li <colyli@fnnas.com>

Since discard code is removed, now the sysfs interface to enable discard
is useless. This patch removes the corresponding sysfs entry, and remove
bool variable 'discard' from struct cache as well.

Signed-off-by: Coly Li <colyli@fnnas.com>
---
 drivers/md/bcache/bcache.h    |  5 +----
 drivers/md/bcache/super.c     |  3 ---
 drivers/md/bcache/sysfs.c     | 15 ---------------
 drivers/md/bcache/writeback.c |  3 +--
 4 files changed, 2 insertions(+), 24 deletions(-)

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 1d33e40d26ea..b8bd6d4a4298 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -447,8 +447,7 @@ struct cache {
 	 * free_inc: Incoming buckets - these are buckets that currently have
 	 * cached data in them, and we can't reuse them until after we write
 	 * their new gen to disk. After prio_write() finishes writing the new
-	 * gens/prios, they'll be moved to the free list (and possibly discarded
-	 * in the process)
+	 * gens/prios, they'll be moved to the free list.
 	 */
 	DECLARE_FIFO(long, free)[RESERVE_NR];
 	DECLARE_FIFO(long, free_inc);
@@ -467,8 +466,6 @@ struct cache {
 	 */
 	unsigned int		invalidate_needs_gc;
 
-	bool			discard; /* Get rid of? */
-
 	struct journal_device	journal;
 
 	/* The rest of this all shows up in sysfs */
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 6d250e366412..91a98ebc3f80 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -2382,9 +2382,6 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 	ca->bdev = file_bdev(bdev_file);
 	ca->sb_disk = sb_disk;
 
-	if (bdev_max_discard_sectors(file_bdev(bdev_file)))
-		ca->discard = CACHE_DISCARD(&ca->sb);
-
 	ret = cache_alloc(ca);
 	if (ret != 0) {
 		if (ret == -ENOMEM)
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 826b14cae4e5..72f38e5b6f5c 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -134,7 +134,6 @@ read_attribute(partial_stripes_expensive);
 rw_attribute(synchronous);
 rw_attribute(journal_delay_ms);
 rw_attribute(io_disable);
-rw_attribute(discard);
 rw_attribute(running);
 rw_attribute(label);
 rw_attribute(errors);
@@ -1036,7 +1035,6 @@ SHOW(__bch_cache)
 	sysfs_hprint(bucket_size,	bucket_bytes(ca));
 	sysfs_hprint(block_size,	block_bytes(ca));
 	sysfs_print(nbuckets,		ca->sb.nbuckets);
-	sysfs_print(discard,		ca->discard);
 	sysfs_hprint(written, atomic_long_read(&ca->sectors_written) << 9);
 	sysfs_hprint(btree_written,
 		     atomic_long_read(&ca->btree_sectors_written) << 9);
@@ -1142,18 +1140,6 @@ STORE(__bch_cache)
 	if (bcache_is_reboot)
 		return -EBUSY;
 
-	if (attr == &sysfs_discard) {
-		bool v = strtoul_or_return(buf);
-
-		if (bdev_max_discard_sectors(ca->bdev))
-			ca->discard = v;
-
-		if (v != CACHE_DISCARD(&ca->sb)) {
-			SET_CACHE_DISCARD(&ca->sb, v);
-			bcache_write_super(ca->set);
-		}
-	}
-
 	if (attr == &sysfs_cache_replacement_policy) {
 		v = __sysfs_match_string(cache_replacement_policies, -1, buf);
 		if (v < 0)
@@ -1185,7 +1171,6 @@ static struct attribute *bch_cache_attrs[] = {
 	&sysfs_block_size,
 	&sysfs_nbuckets,
 	&sysfs_priority_stats,
-	&sysfs_discard,
 	&sysfs_written,
 	&sysfs_btree_written,
 	&sysfs_metadata_written,
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 6ba73dc1a3df..cffef33b4acf 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -805,8 +805,7 @@ static int bch_writeback_thread(void *arg)
 			 * may set BCH_ENABLE_AUTO_GC via sysfs, then when
 			 * BCH_DO_AUTO_GC is set, garbage collection thread
 			 * will be wake up here. After moving gc, the shrunk
-			 * btree and discarded free buckets SSD space may be
-			 * helpful for following write requests.
+			 * btree may be helpful for following write requests.
 			 */
 			if (c->gc_after_writeback ==
 			    (BCH_ENABLE_AUTO_GC|BCH_DO_AUTO_GC)) {
-- 
2.47.3