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Message-Id: <20210614102700.522177219@linuxfoundation.org>
Date: Mon, 14 Jun 2021 12:26:43 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Alexander Ullrich <ealex1979@...il.com>,
Diego Ercolani <diego.ercolani@...il.com>,
Jan Szubiak <jan.szubiak@...uxpolska.pl>,
Marco Rebhan <me@...saiko.net>,
Matthias Ferdinand <bcache@...dv.net>,
Victor Westerhuis <victor@...terhu.is>,
Vojtech Pavlik <vojtech@...e.cz>, Coly Li <colyli@...e.de>,
Christoph Hellwig <hch@....de>,
Kent Overstreet <kent.overstreet@...il.com>,
Nix <nix@...eri.org.uk>, Takashi Iwai <tiwai@...e.com>,
Jens Axboe <axboe@...nel.dk>,
Rolf Fokkens <rolf@...ffokkens.nl>,
Thorsten Knabe <linux@...rsten-knabe.de>
Subject: [PATCH 5.12 071/173] bcache: remove bcache device self-defined readahead
From: Coly Li <colyli@...e.de>
commit 1616a4c2ab1a80893b6890ae93da40a2b1d0c691 upstream.
For read cache missing, bcache defines a readahead size for the read I/O
request to the backing device for the missing data. This readahead size
is initialized to 0, and almost no one uses it to avoid unnecessary read
amplifying onto backing device and write amplifying onto cache device.
Considering upper layer file system code has readahead logic allready
and works fine with readahead_cache_policy sysfile interface, we don't
have to keep bcache self-defined readahead anymore.
This patch removes the bcache self-defined readahead for cache missing
request for backing device, and the readahead sysfs file interfaces are
removed as well.
This is the preparation for next patch to fix potential kernel panic due
to oversized request in a simpler method.
Reported-by: Alexander Ullrich <ealex1979@...il.com>
Reported-by: Diego Ercolani <diego.ercolani@...il.com>
Reported-by: Jan Szubiak <jan.szubiak@...uxpolska.pl>
Reported-by: Marco Rebhan <me@...saiko.net>
Reported-by: Matthias Ferdinand <bcache@...dv.net>
Reported-by: Victor Westerhuis <victor@...terhu.is>
Reported-by: Vojtech Pavlik <vojtech@...e.cz>
Reported-and-tested-by: Rolf Fokkens <rolf@...ffokkens.nl>
Reported-and-tested-by: Thorsten Knabe <linux@...rsten-knabe.de>
Signed-off-by: Coly Li <colyli@...e.de>
Reviewed-by: Christoph Hellwig <hch@....de>
Cc: stable@...r.kernel.org
Cc: Kent Overstreet <kent.overstreet@...il.com>
Cc: Nix <nix@...eri.org.uk>
Cc: Takashi Iwai <tiwai@...e.com>
Link: https://lore.kernel.org/r/20210607125052.21277-2-colyli@suse.de
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/md/bcache/bcache.h | 1 -
drivers/md/bcache/request.c | 13 +------------
drivers/md/bcache/stats.c | 14 --------------
drivers/md/bcache/stats.h | 1 -
drivers/md/bcache/sysfs.c | 4 ----
5 files changed, 1 insertion(+), 32 deletions(-)
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -364,7 +364,6 @@ struct cached_dev {
/* The rest of this all shows up in sysfs */
unsigned int sequential_cutoff;
- unsigned int readahead;
unsigned int io_disable:1;
unsigned int verify:1;
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -880,7 +880,6 @@ static int cached_dev_cache_miss(struct
struct bio *bio, unsigned int sectors)
{
int ret = MAP_CONTINUE;
- unsigned int reada = 0;
struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
struct bio *miss, *cache_bio;
@@ -892,14 +891,7 @@ static int cached_dev_cache_miss(struct
goto out_submit;
}
- if (!(bio->bi_opf & REQ_RAHEAD) &&
- !(bio->bi_opf & (REQ_META|REQ_PRIO)) &&
- s->iop.c->gc_stats.in_use < CUTOFF_CACHE_READA)
- reada = min_t(sector_t, dc->readahead >> 9,
- get_capacity(bio->bi_bdev->bd_disk) -
- bio_end_sector(bio));
-
- s->insert_bio_sectors = min(sectors, bio_sectors(bio) + reada);
+ s->insert_bio_sectors = min(sectors, bio_sectors(bio));
s->iop.replace_key = KEY(s->iop.inode,
bio->bi_iter.bi_sector + s->insert_bio_sectors,
@@ -933,9 +925,6 @@ static int cached_dev_cache_miss(struct
if (bch_bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO))
goto out_put;
- if (reada)
- bch_mark_cache_readahead(s->iop.c, s->d);
-
s->cache_miss = miss;
s->iop.bio = cache_bio;
bio_get(cache_bio);
--- a/drivers/md/bcache/stats.c
+++ b/drivers/md/bcache/stats.c
@@ -46,7 +46,6 @@ read_attribute(cache_misses);
read_attribute(cache_bypass_hits);
read_attribute(cache_bypass_misses);
read_attribute(cache_hit_ratio);
-read_attribute(cache_readaheads);
read_attribute(cache_miss_collisions);
read_attribute(bypassed);
@@ -64,7 +63,6 @@ SHOW(bch_stats)
DIV_SAFE(var(cache_hits) * 100,
var(cache_hits) + var(cache_misses)));
- var_print(cache_readaheads);
var_print(cache_miss_collisions);
sysfs_hprint(bypassed, var(sectors_bypassed) << 9);
#undef var
@@ -86,7 +84,6 @@ static struct attribute *bch_stats_files
&sysfs_cache_bypass_hits,
&sysfs_cache_bypass_misses,
&sysfs_cache_hit_ratio,
- &sysfs_cache_readaheads,
&sysfs_cache_miss_collisions,
&sysfs_bypassed,
NULL
@@ -113,7 +110,6 @@ void bch_cache_accounting_clear(struct c
acc->total.cache_misses = 0;
acc->total.cache_bypass_hits = 0;
acc->total.cache_bypass_misses = 0;
- acc->total.cache_readaheads = 0;
acc->total.cache_miss_collisions = 0;
acc->total.sectors_bypassed = 0;
}
@@ -145,7 +141,6 @@ static void scale_stats(struct cache_sta
scale_stat(&stats->cache_misses);
scale_stat(&stats->cache_bypass_hits);
scale_stat(&stats->cache_bypass_misses);
- scale_stat(&stats->cache_readaheads);
scale_stat(&stats->cache_miss_collisions);
scale_stat(&stats->sectors_bypassed);
}
@@ -168,7 +163,6 @@ static void scale_accounting(struct time
move_stat(cache_misses);
move_stat(cache_bypass_hits);
move_stat(cache_bypass_misses);
- move_stat(cache_readaheads);
move_stat(cache_miss_collisions);
move_stat(sectors_bypassed);
@@ -209,14 +203,6 @@ void bch_mark_cache_accounting(struct ca
mark_cache_stats(&c->accounting.collector, hit, bypass);
}
-void bch_mark_cache_readahead(struct cache_set *c, struct bcache_device *d)
-{
- struct cached_dev *dc = container_of(d, struct cached_dev, disk);
-
- atomic_inc(&dc->accounting.collector.cache_readaheads);
- atomic_inc(&c->accounting.collector.cache_readaheads);
-}
-
void bch_mark_cache_miss_collision(struct cache_set *c, struct bcache_device *d)
{
struct cached_dev *dc = container_of(d, struct cached_dev, disk);
--- a/drivers/md/bcache/stats.h
+++ b/drivers/md/bcache/stats.h
@@ -7,7 +7,6 @@ struct cache_stat_collector {
atomic_t cache_misses;
atomic_t cache_bypass_hits;
atomic_t cache_bypass_misses;
- atomic_t cache_readaheads;
atomic_t cache_miss_collisions;
atomic_t sectors_bypassed;
};
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -137,7 +137,6 @@ rw_attribute(io_disable);
rw_attribute(discard);
rw_attribute(running);
rw_attribute(label);
-rw_attribute(readahead);
rw_attribute(errors);
rw_attribute(io_error_limit);
rw_attribute(io_error_halflife);
@@ -260,7 +259,6 @@ SHOW(__bch_cached_dev)
var_printf(partial_stripes_expensive, "%u");
var_hprint(sequential_cutoff);
- var_hprint(readahead);
sysfs_print(running, atomic_read(&dc->running));
sysfs_print(state, states[BDEV_STATE(&dc->sb)]);
@@ -365,7 +363,6 @@ STORE(__cached_dev)
sysfs_strtoul_clamp(sequential_cutoff,
dc->sequential_cutoff,
0, UINT_MAX);
- d_strtoi_h(readahead);
if (attr == &sysfs_clear_stats)
bch_cache_accounting_clear(&dc->accounting);
@@ -538,7 +535,6 @@ static struct attribute *bch_cached_dev_
&sysfs_running,
&sysfs_state,
&sysfs_label,
- &sysfs_readahead,
#ifdef CONFIG_BCACHE_DEBUG
&sysfs_verify,
&sysfs_bypass_torture_test,
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