bcache: Track dirty data by stripe

To make background writeback aware of raid5/6 stripes, we first need to
track the amount of dirty data within each stripe - we do this by
breaking up the existing sectors_dirty into per stripe atomic_ts

Signed-off-by: Kent Overstreet <koverstreet@google.com>

7 files changed, 105 insertions, 26 deletions

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index d099d8894c2f..dbddef0cdb59 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -437,7 +437,10 @@ struct bcache_device {
         /* If nonzero, we're detaching/unregistering from cache set */
         atomic_t                detaching;
 
-        atomic_long_t           sectors_dirty;
+        uint64_t                nr_stripes;
+        unsigned                stripe_size_bits;
+        atomic_t                *stripe_sectors_dirty;
+
         unsigned long           sectors_dirty_last;
         long                    sectors_dirty_derivative;
 
@@ -1159,9 +1162,6 @@ static inline void wake_up_allocators(struct cache_set *c)
 
 /* Forward declarations */
 
-void bch_writeback_queue(struct cached_dev *);
-void bch_writeback_add(struct cached_dev *, unsigned);
-
 void bch_count_io_errors(struct cache *, int, const char *);
 void bch_bbio_count_io_errors(struct cache_set *, struct bio *,
                               int, const char *);
@@ -1224,8 +1224,6 @@ void bch_cache_set_stop(struct cache_set *);
 struct cache_set *bch_cache_set_alloc(struct cache_sb *);
 void bch_btree_cache_free(struct cache_set *);
 int bch_btree_cache_alloc(struct cache_set *);
-void bch_sectors_dirty_init(struct cached_dev *);
-void bch_cached_dev_writeback_init(struct cached_dev *);
 void bch_moving_init_cache_set(struct cache_set *);
 
 int bch_cache_allocator_start(struct cache *ca);
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 230c3a6d9be2..b93cf56260a4 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -24,6 +24,7 @@
 #include "btree.h"
 #include "debug.h"
 #include "request.h"
+#include "writeback.h"
 
 #include <linux/slab.h>
 #include <linux/bitops.h>
@@ -1599,14 +1600,14 @@ static bool fix_overlapping_extents(struct btree *b,
                                     struct btree_iter *iter,
                                     struct btree_op *op)
 {
-        void subtract_dirty(struct bkey *k, int sectors)
+        void subtract_dirty(struct bkey *k, uint64_t offset, int sectors)
         {
-                struct bcache_device *d = b->c->devices[KEY_INODE(k)];
-
-                if (KEY_DIRTY(k) && d)
-                        atomic_long_sub(sectors, &d->sectors_dirty);
+                if (KEY_DIRTY(k))
+                        bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k),
+                                                     offset, -sectors);
         }
 
+        uint64_t old_offset;
         unsigned old_size, sectors_found = 0;
 
         while (1) {
@@ -1618,6 +1619,7 @@ static bool fix_overlapping_extents(struct btree *b,
                 if (bkey_cmp(k, &START_KEY(insert)) <= 0)
                         continue;
 
+                old_offset = KEY_START(k);
                 old_size = KEY_SIZE(k);
 
                 /*
@@ -1673,7 +1675,7 @@ static bool fix_overlapping_extents(struct btree *b,
 
                         struct bkey *top;
 
-                        subtract_dirty(k, KEY_SIZE(insert));
+                        subtract_dirty(k, KEY_START(insert), KEY_SIZE(insert));
 
                         if (bkey_written(b, k)) {
                                 /*
@@ -1720,7 +1722,7 @@ static bool fix_overlapping_extents(struct btree *b,
                         }
                 }
 
-                subtract_dirty(k, old_size - KEY_SIZE(k));
+                subtract_dirty(k, old_offset, old_size - KEY_SIZE(k));
         }
 
 check_failed:
@@ -1796,6 +1798,10 @@ static bool btree_insert_key(struct btree *b, struct btree_op *op,
 insert: shift_keys(b, m, k);
 copy:   bkey_copy(m, k);
 merged:
+        if (KEY_DIRTY(k))
+                bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k),
+                                             KEY_START(k), KEY_SIZE(k));
+
         bch_check_keys(b, "%u for %s", status, op_type(op));
 
         if (b->level && !KEY_OFFSET(k))
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 695469958c1e..017c95fced8e 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -10,6 +10,7 @@
 #include "btree.h"
 #include "debug.h"
 #include "request.h"
+#include "writeback.h"
 
 #include <linux/cgroup.h>
 #include <linux/module.h>
@@ -1044,7 +1045,7 @@ static void request_write(struct cached_dev *dc, struct search *s)
                 closure_bio_submit(bio, cl, s->d);
         } else {
                 s->op.cache_bio = bio;
-                bch_writeback_add(dc, bio_sectors(bio));
+                bch_writeback_add(dc);
         }
 out:
         closure_call(&s->op.cl, bch_insert_data, NULL, cl);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index dbfa1c38e85e..8c73f0c7f28a 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -10,6 +10,7 @@
 #include "btree.h"
 #include "debug.h"
 #include "request.h"
+#include "writeback.h"
 
 #include <linux/blkdev.h>
 #include <linux/buffer_head.h>
@@ -744,13 +745,35 @@ static void bcache_device_free(struct bcache_device *d)
                 mempool_destroy(d->unaligned_bvec);
         if (d->bio_split)
                 bioset_free(d->bio_split);
+        if (is_vmalloc_addr(d->stripe_sectors_dirty))
+                vfree(d->stripe_sectors_dirty);
+        else
+                kfree(d->stripe_sectors_dirty);
 
         closure_debug_destroy(&d->cl);
 }
 
-static int bcache_device_init(struct bcache_device *d, unsigned block_size)
+static int bcache_device_init(struct bcache_device *d, unsigned block_size,
+                              sector_t sectors)
 {
         struct request_queue *q;
+        size_t n;
+
+        if (!d->stripe_size_bits)
+                d->stripe_size_bits = 31;
+
+        d->nr_stripes = round_up(sectors, 1 << d->stripe_size_bits) >>
+                d->stripe_size_bits;
+
+        if (!d->nr_stripes || d->nr_stripes > SIZE_MAX / sizeof(atomic_t))
+                return -ENOMEM;
+
+        n = d->nr_stripes * sizeof(atomic_t);
+        d->stripe_sectors_dirty = n < PAGE_SIZE << 6
+                ? kzalloc(n, GFP_KERNEL)
+                : vzalloc(n);
+        if (!d->stripe_sectors_dirty)
+                return -ENOMEM;
 
         if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||
             !(d->unaligned_bvec = mempool_create_kmalloc_pool(1,
@@ -760,6 +783,7 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size)
             !(q = blk_alloc_queue(GFP_KERNEL)))
                 return -ENOMEM;
 
+        set_capacity(d->disk, sectors);
         snprintf(d->disk->disk_name, DISK_NAME_LEN, "bcache%i", bcache_minor);
 
         d->disk->major          = bcache_major;
@@ -1047,7 +1071,8 @@ static int cached_dev_init(struct cached_dev *dc, unsigned block_size)
                 hlist_add_head(&io->hash, dc->io_hash + RECENT_IO);
         }
 
-        ret = bcache_device_init(&dc->disk, block_size);
+        ret = bcache_device_init(&dc->disk, block_size,
+                         dc->bdev->bd_part->nr_sects - dc->sb.data_offset);
         if (ret)
                 return ret;
 
@@ -1146,11 +1171,10 @@ static int flash_dev_run(struct cache_set *c, struct uuid_entry *u)
 
         kobject_init(&d->kobj, &bch_flash_dev_ktype);
 
-        if (bcache_device_init(d, block_bytes(c)))
+        if (bcache_device_init(d, block_bytes(c), u->sectors))
                 goto err;
 
         bcache_device_attach(d, c, u - c->uuids);
-        set_capacity(d->disk, u->sectors);
         bch_flash_dev_request_init(d);
         add_disk(d->disk);
 
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index f5c2d8695230..cf8d91ec3238 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -9,6 +9,7 @@
 #include "sysfs.h"
 #include "btree.h"
 #include "request.h"
+#include "writeback.h"
 
 #include <linux/blkdev.h>
 #include <linux/sort.h>
@@ -128,7 +129,7 @@ SHOW(__bch_cached_dev)
                 char derivative[20];
                 char target[20];
                 bch_hprint(dirty,
-                       atomic_long_read(&dc->disk.sectors_dirty) << 9);
+                           bcache_dev_sectors_dirty(&dc->disk) << 9);
                 bch_hprint(derivative,  dc->writeback_rate_derivative << 9);
                 bch_hprint(target,      dc->writeback_rate_target << 9);
 
@@ -144,7 +145,7 @@ SHOW(__bch_cached_dev)
         }
 
         sysfs_hprint(dirty_data,
-                     atomic_long_read(&dc->disk.sectors_dirty) << 9);
+                     bcache_dev_sectors_dirty(&dc->disk) << 9);
 
         var_printf(sequential_merge,    "%i");
         var_hprint(sequential_cutoff);
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 553949eefd51..dd815475c524 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -9,6 +9,7 @@
 #include "bcache.h"
 #include "btree.h"
 #include "debug.h"
+#include "writeback.h"
 
 #include <trace/events/bcache.h>
 
@@ -38,7 +39,7 @@ static void __update_writeback_rate(struct cached_dev *dc)
 
         int change = 0;
         int64_t error;
-        int64_t dirty = atomic_long_read(&dc->disk.sectors_dirty);
+        int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
         int64_t derivative = dirty - dc->disk.sectors_dirty_last;
 
         dc->disk.sectors_dirty_last = dirty;
@@ -183,10 +184,8 @@ void bch_writeback_queue(struct cached_dev *dc)
         }
 }
 
-void bch_writeback_add(struct cached_dev *dc, unsigned sectors)
+void bch_writeback_add(struct cached_dev *dc)
 {
-        atomic_long_add(sectors, &dc->disk.sectors_dirty);
-
         if (!atomic_read(&dc->has_dirty) &&
             !atomic_xchg(&dc->has_dirty, 1)) {
                 atomic_inc(&dc->count);
@@ -205,6 +204,34 @@ void bch_writeback_add(struct cached_dev *dc, unsigned sectors)
         }
 }
 
+void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode,
+                                  uint64_t offset, int nr_sectors)
+{
+        struct bcache_device *d = c->devices[inode];
+        unsigned stripe_size, stripe_offset;
+        uint64_t stripe;
+
+        if (!d)
+                return;
+
+        stripe_size = 1 << d->stripe_size_bits;
+        stripe = offset >> d->stripe_size_bits;
+        stripe_offset = offset & (stripe_size - 1);
+
+        while (nr_sectors) {
+                int s = min_t(unsigned, abs(nr_sectors),
+                              stripe_size - stripe_offset);
+
+                if (nr_sectors < 0)
+                        s = -s;
+
+                atomic_add(s, d->stripe_sectors_dirty + stripe);
+                nr_sectors -= s;
+                stripe_offset = 0;
+                stripe++;
+        }
+}
+
 /* Background writeback - IO loop */
 
 static void dirty_io_destructor(struct closure *cl)
@@ -392,8 +419,9 @@ static int bch_btree_sectors_dirty_init(struct btree *b, struct btree_op *op,
                                 break;
 
                         if (KEY_DIRTY(k))
-                                atomic_long_add(KEY_SIZE(k),
-                                                &dc->disk.sectors_dirty);
+                                bcache_dev_sectors_dirty_add(b->c, dc->disk.id,
+                                                             KEY_START(k),
+                                                             KEY_SIZE(k));
                 } else {
                         btree(sectors_dirty_init, k, b, op, dc);
                         if (KEY_INODE(k) > dc->disk.id)
diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
new file mode 100644
index 000000000000..5ce9771df047
--- /dev/null
+++ b/drivers/md/bcache/writeback.h
@@ -0,0 +1,21 @@
+#ifndef _BCACHE_WRITEBACK_H
+#define _BCACHE_WRITEBACK_H
+
+static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
+{
+        uint64_t i, ret = 0;
+
+        for (i = 0; i < d->nr_stripes; i++)
+                ret += atomic_read(d->stripe_sectors_dirty + i);
+
+        return ret;
+}
+
+void bcache_dev_sectors_dirty_add(struct cache_set *, unsigned, uint64_t, int);
+void bch_writeback_queue(struct cached_dev *);
+void bch_writeback_add(struct cached_dev *);
+
+void bch_sectors_dirty_init(struct cached_dev *dc);
+void bch_cached_dev_writeback_init(struct cached_dev *);
+
+#endif