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Re: [dm-devel] [PATCH 11/15] dm: use new hashtable implementation



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On Mon, Dec 17, 2012 at 10:01 AM, Sasha Levin <sasha levin oracle com> wrote:
> Switch dm to use the new hashtable implementation. This reduces the amount of
> generic unrelated code in the dm.
>
> This patch depends on d9b482c ("hashtable: introduce a small and naive
> hashtable") which was merged in v3.6.
>
> Signed-off-by: Sasha Levin <sasha levin oracle com>
> ---
>  drivers/md/dm-snap.c                               | 24 +++++------------
>  drivers/md/persistent-data/dm-block-manager.c      |  1 -
>  .../persistent-data/dm-persistent-data-internal.h  | 19 --------------
>  .../md/persistent-data/dm-transaction-manager.c    | 30 +++++++---------------
>  4 files changed, 16 insertions(+), 58 deletions(-)
>  delete mode 100644 drivers/md/persistent-data/dm-persistent-data-internal.h
>
> diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
> index 223e7eb..4b19fa0 100644
> --- a/drivers/md/dm-snap.c
> +++ b/drivers/md/dm-snap.c
> @@ -34,9 +34,7 @@ static const char dm_snapshot_merge_target_name[] = "snapshot-merge";
>   */
>  #define MIN_IOS 256
>
> -#define DM_TRACKED_CHUNK_HASH_SIZE     16
> -#define DM_TRACKED_CHUNK_HASH(x)       ((unsigned long)(x) & \
> -                                        (DM_TRACKED_CHUNK_HASH_SIZE - 1))
> +#define DM_TRACKED_CHUNK_HASH_BITS     4
>
>  struct dm_exception_table {
>         uint32_t hash_mask;
> @@ -80,7 +78,7 @@ struct dm_snapshot {
>         /* Chunks with outstanding reads */
>         spinlock_t tracked_chunk_lock;
>         mempool_t *tracked_chunk_pool;
> -       struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
> +       DECLARE_HASHTABLE(tracked_chunk_hash, DM_TRACKED_CHUNK_HASH_BITS);
>
>         /* The on disk metadata handler */
>         struct dm_exception_store *store;
> @@ -202,8 +200,7 @@ static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,
>         c->chunk = chunk;
>
>         spin_lock_irq(&s->tracked_chunk_lock);
> -       hlist_add_head(&c->node,
> -                      &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);
> +       hash_add(s->tracked_chunk_hash, &c->node, chunk);
>         spin_unlock_irq(&s->tracked_chunk_lock);
>
>         return c;
> @@ -215,7 +212,7 @@ static void stop_tracking_chunk(struct dm_snapshot *s,
>         unsigned long flags;
>
>         spin_lock_irqsave(&s->tracked_chunk_lock, flags);
> -       hlist_del(&c->node);
> +       hash_del(&c->node);
>         spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
>
>         mempool_free(c, s->tracked_chunk_pool);
> @@ -229,8 +226,7 @@ static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk)
>
>         spin_lock_irq(&s->tracked_chunk_lock);
>
> -       hlist_for_each_entry(c, hn,
> -           &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) {
> +       hash_for_each_possible(s->tracked_chunk_hash, c, hn, node, chunk) {
>                 if (c->chunk == chunk) {
>                         found = 1;
>                         break;
> @@ -1032,7 +1028,6 @@ static void stop_merge(struct dm_snapshot *s)
>  static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>  {
>         struct dm_snapshot *s;
> -       int i;
>         int r = -EINVAL;
>         char *origin_path, *cow_path;
>         unsigned args_used, num_flush_requests = 1;
> @@ -1127,8 +1122,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>                 goto bad_tracked_chunk_pool;
>         }
>
> -       for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
> -               INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]);
> +       hash_init(s->tracked_chunk_hash);
>
>         spin_lock_init(&s->tracked_chunk_lock);
>
> @@ -1252,9 +1246,6 @@ static void __handover_exceptions(struct dm_snapshot *snap_src,
>
>  static void snapshot_dtr(struct dm_target *ti)
>  {
> -#ifdef CONFIG_DM_DEBUG
> -       int i;
> -#endif
>         struct dm_snapshot *s = ti->private;
>         struct dm_snapshot *snap_src = NULL, *snap_dest = NULL;
>
> @@ -1285,8 +1276,7 @@ static void snapshot_dtr(struct dm_target *ti)
>         smp_mb();
>
>  #ifdef CONFIG_DM_DEBUG
> -       for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
> -               BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i]));
> +       BUG_ON(!hash_empty(s->tracked_chunk_hash));
>  #endif
>
>         mempool_destroy(s->tracked_chunk_pool);
> diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
> index 28c3ed0..083a133 100644
> --- a/drivers/md/persistent-data/dm-block-manager.c
> +++ b/drivers/md/persistent-data/dm-block-manager.c
> @@ -4,7 +4,6 @@
>   * This file is released under the GPL.
>   */
>  #include "dm-block-manager.h"
> -#include "dm-persistent-data-internal.h"
>  #include "../dm-bufio.h"
>
>  #include <linux/crc32c.h>
> diff --git a/drivers/md/persistent-data/dm-persistent-data-internal.h b/drivers/md/persistent-data/dm-persistent-data-internal.h
> deleted file mode 100644
> index c49e26f..0000000
> --- a/drivers/md/persistent-data/dm-persistent-data-internal.h
> +++ /dev/null
> @@ -1,19 +0,0 @@
> -/*
> - * Copyright (C) 2011 Red Hat, Inc.
> - *
> - * This file is released under the GPL.
> - */
> -
> -#ifndef _DM_PERSISTENT_DATA_INTERNAL_H
> -#define _DM_PERSISTENT_DATA_INTERNAL_H
> -
> -#include "dm-block-manager.h"
> -
> -static inline unsigned dm_hash_block(dm_block_t b, unsigned hash_mask)
> -{
> -       const unsigned BIG_PRIME = 4294967291UL;
> -
> -       return (((unsigned) b) * BIG_PRIME) & hash_mask;
> -}
> -
> -#endif /* _PERSISTENT_DATA_INTERNAL_H */
> diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c
> index d247a35..9eb9417 100644
> --- a/drivers/md/persistent-data/dm-transaction-manager.c
> +++ b/drivers/md/persistent-data/dm-transaction-manager.c
> @@ -7,11 +7,11 @@
>  #include "dm-space-map.h"
>  #include "dm-space-map-disk.h"
>  #include "dm-space-map-metadata.h"
> -#include "dm-persistent-data-internal.h"
>
>  #include <linux/export.h>
>  #include <linux/slab.h>
>  #include <linux/device-mapper.h>
> +#include <linux/hashtable.h>
>
>  #define DM_MSG_PREFIX "transaction manager"
>
> @@ -25,8 +25,7 @@ struct shadow_info {
>  /*
>   * It would be nice if we scaled with the size of transaction.
>   */
> -#define HASH_SIZE 256
> -#define HASH_MASK (HASH_SIZE - 1)
> +#define DM_HASH_BITS 8
>
>  struct dm_transaction_manager {
>         int is_clone;
> @@ -36,7 +35,7 @@ struct dm_transaction_manager {
>         struct dm_space_map *sm;
>
>         spinlock_t lock;
> -       struct hlist_head buckets[HASH_SIZE];
> +       DECLARE_HASHTABLE(hash, DM_HASH_BITS);
>  };
>
>  /*----------------------------------------------------------------*/
> @@ -44,12 +43,11 @@ struct dm_transaction_manager {
>  static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
>  {
>         int r = 0;
> -       unsigned bucket = dm_hash_block(b, HASH_MASK);
>         struct shadow_info *si;
>         struct hlist_node *n;
>
>         spin_lock(&tm->lock);
> -       hlist_for_each_entry(si, n, tm->buckets + bucket, hlist)
> +       hash_for_each_possible(tm->hash, si, n, hlist, b)
>                 if (si->where == b) {
>                         r = 1;
>                         break;
> @@ -65,15 +63,13 @@ static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
>   */
>  static void insert_shadow(struct dm_transaction_manager *tm, dm_block_t b)
>  {
> -       unsigned bucket;
>         struct shadow_info *si;
>
>         si = kmalloc(sizeof(*si), GFP_NOIO);
>         if (si) {
>                 si->where = b;
> -               bucket = dm_hash_block(b, HASH_MASK);
>                 spin_lock(&tm->lock);
> -               hlist_add_head(&si->hlist, tm->buckets + bucket);
> +               hash_add(tm->hash, &si->hlist, b);
>                 spin_unlock(&tm->lock);
>         }
>  }
> @@ -82,18 +78,12 @@ static void wipe_shadow_table(struct dm_transaction_manager *tm)
>  {
>         struct shadow_info *si;
>         struct hlist_node *n, *tmp;
> -       struct hlist_head *bucket;
>         int i;
>
>         spin_lock(&tm->lock);
> -       for (i = 0; i < HASH_SIZE; i++) {
> -               bucket = tm->buckets + i;
> -               hlist_for_each_entry_safe(si, n, tmp, bucket, hlist)
> -                       kfree(si);
> -
> -               INIT_HLIST_HEAD(bucket);
> -       }
> -
> +       hash_for_each_safe(tm->hash, i, n, tmp, si, hlist)
> +               kfree(si);
> +       hash_init(tm->hash);
>         spin_unlock(&tm->lock);
>  }
>
> @@ -102,7 +92,6 @@ static void wipe_shadow_table(struct dm_transaction_manager *tm)
>  static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
>                                                    struct dm_space_map *sm)
>  {
> -       int i;
>         struct dm_transaction_manager *tm;
>
>         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
> @@ -115,8 +104,7 @@ static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
>         tm->sm = sm;
>
>         spin_lock_init(&tm->lock);
> -       for (i = 0; i < HASH_SIZE; i++)
> -               INIT_HLIST_HEAD(tm->buckets + i);
> +       hash_init(tm->hash);
>
>         return tm;
>  }
> --
> 1.8.0
>
> --
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