Revert "bcache: provide a switch to bypass all IO requests"

euleros/rtos inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4LOJ6
CVE: NA

--------------------------------

This patch set introduce many conflicts while backporting mainline
bcache patches, revert it temporarily.

This reverts commit 30dc9d9c.
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

Documentation/admin-guide/bcache.rst

@@ -441,10 +441,6 @@ sequential_cutoff
   most recent 128 IOs are tracked so sequential IO can be detected even when
   it isn't all done at once.
 
-read_bypass
-  If enbale, all IO will bypass the cache. This option could be useful when we
-  enable userspace prefetch and the cache device is low capacity.
-
 sequential_merge
   If non zero, bcache keeps a list of the last 128 requests submitted to compare
   against all new requests to determine which new requests are sequential

drivers/md/bcache/bcache.h

@@ -376,8 +376,6 @@ struct cached_dev {
 	unsigned char		writeback_percent;
 	unsigned int		writeback_delay;
 
-	unsigned int		read_bypass;
-
 	uint64_t		writeback_rate_target;
 	int64_t			writeback_rate_proportional;
 	int64_t			writeback_rate_integral;

drivers/md/bcache/request.c

@@ -852,7 +852,7 @@ static void cached_dev_read_done(struct closure *cl)
 	if (!s->prefetch)
 		bio_complete(s);
 
-	if (s->iop.bio && (!dc->read_bypass || s->prefetch) &&
+	if (s->iop.bio &&
 	    !test_bit(CACHE_SET_STOPPING, &s->iop.c->flags)) {
 		BUG_ON(!s->iop.replace);
 		closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
@@ -897,14 +897,12 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
 
 	s->cache_missed = 1;
 
-	if (s->cache_miss || s->iop.bypass ||
-	    (dc->read_bypass && !s->prefetch)) {
+	if (s->cache_miss || s->iop.bypass) {
 		miss = bio_next_split(bio, sectors, GFP_NOIO, &s->d->bio_split);
 		ret = miss == bio ? MAP_DONE : MAP_CONTINUE;
 		goto out_submit;
 	}
 
-	/* if called form do_readahead, no need to do this */
 	if (!(bio->bi_opf & REQ_RAHEAD) &&
 	    !(bio->bi_opf & (REQ_META|REQ_PRIO) ) &&
 	    s->iop.c->gc_stats.in_use < CUTOFF_CACHE_READA &&

drivers/md/bcache/super.c

@@ -1439,7 +1439,6 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
 	bch_cache_accounting_init(&dc->accounting, &dc->disk.cl);
 
 	dc->sequential_cutoff		= 4 << 20;
-	dc->read_bypass			= 0;
 
 	for (io = dc->io; io < dc->io + RECENT_IO; io++) {
 		list_add(&io->lru, &dc->io_lru);

drivers/md/bcache/sysfs.c

@@ -108,7 +108,6 @@ rw_attribute(congested_read_threshold_us);
 rw_attribute(congested_write_threshold_us);
 
 rw_attribute(sequential_cutoff);
-rw_attribute(read_bypass);
 rw_attribute(data_csum);
 rw_attribute(cache_mode);
 rw_attribute(readahead_cache_policy);
@@ -253,7 +252,6 @@ SHOW(__bch_cached_dev)
 	var_printf(partial_stripes_expensive,	"%u");
 
 	var_hprint(sequential_cutoff);
-	var_print(read_bypass);
 	var_hprint(readahead);
 
 	sysfs_print(running,		atomic_read(&dc->running));
@@ -348,9 +346,6 @@ STORE(__cached_dev)
 	sysfs_strtoul_clamp(sequential_cutoff,
 			    dc->sequential_cutoff,
 			    0, UINT_MAX);
-	sysfs_strtoul_clamp(read_bypass,
-			    dc->read_bypass,
-			    0, 1);
 	d_strtoi_h(readahead);
 
 	if (attr == &sysfs_clear_stats)
@@ -516,7 +511,6 @@ static struct attribute *bch_cached_dev_files[] = {
 	&sysfs_stripe_size,
 	&sysfs_partial_stripes_expensive,
 	&sysfs_sequential_cutoff,
-	&sysfs_read_bypass,
 	&sysfs_clear_stats,
 	&sysfs_running,
 	&sysfs_state,