Hi Stephen,
On Jun 19, 2013, at 3:27 PM, Stephen Rothwell <s...@canb.auug.org.au> wrote:
> Hi Andrew,
>
> Today's linux-next merge of the akpm tree got a conflict in
> fs/ext4/extents_status.c between commit 6480bad916be ("ext4: improve
> extent cache shrink mechanism to avoid to burn CPU time") from the ext
> tree and commit 1f42d0934b4e ("fs: convert fs shrinkers to new scan/count
> API") from the akpm tree.
>
> I fixed it up (I am not sure if the result makes complete sense - see
> below) and can carry the fix as necessary (no action is required).
The patch looks good to me. Thanks for fixing it.
Regards,
- Zheng
>
> --
> Cheers,
> Stephen Rothwell s...@canb.auug.org.au
>
> diff --cc fs/ext4/extents_status.c
> index 80dcc59,4bce4f0..0000000
> --- a/fs/ext4/extents_status.c
> +++ b/fs/ext4/extents_status.c
> @@@ -876,58 -878,32 +876,63 @@@ int ext4_es_zeroout(struct inode *inode
> EXTENT_STATUS_WRITTEN);
> }
>
> +static int ext4_inode_touch_time_cmp(void *priv, struct list_head *a,
> + struct list_head *b)
> +{
> + struct ext4_inode_info *eia, *eib;
> + unsigned long diff;
> +
> + eia = list_entry(a, struct ext4_inode_info, i_es_lru);
> + eib = list_entry(b, struct ext4_inode_info, i_es_lru);
> +
> + diff = eia->i_touch_when - eib->i_touch_when;
> + if (diff < 0)
> + return -1;
> + if (diff > 0)
> + return 1;
> + return 0;
> +}
>
> - static int ext4_es_shrink(struct shrinker *shrink, struct shrink_control
> *sc)
> + static long ext4_es_count(struct shrinker *shrink, struct shrink_control
> *sc)
> + {
> + long nr;
> + struct ext4_sb_info *sbi = container_of(shrink,
> + struct ext4_sb_info, s_es_shrinker);
> +
> + nr = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
> + trace_ext4_es_shrink_enter(sbi->s_sb, sc->nr_to_scan, nr);
> + return nr;
> + }
> +
> + static long ext4_es_scan(struct shrinker *shrink, struct shrink_control *sc)
> {
> struct ext4_sb_info *sbi = container_of(shrink,
> struct ext4_sb_info, s_es_shrinker);
> struct ext4_inode_info *ei;
> - struct list_head *cur, *tmp, scanned;
> + struct list_head *cur, *tmp;
> + LIST_HEAD(skiped);
> int nr_to_scan = sc->nr_to_scan;
> - int ret, nr_shrunk = 0;
> -
> - ret = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
> - trace_ext4_es_shrink_enter(sbi->s_sb, nr_to_scan, ret);
> -
> - if (!nr_to_scan)
> - return ret;
> + int ret = 0, nr_shrunk = 0;
>
> - INIT_LIST_HEAD(&scanned);
> -
> spin_lock(&sbi->s_es_lru_lock);
> +
> + /*
> + * If the inode that is at the head of LRU list is newer than
> + * last_sorted time, that means that we need to sort this list.
> + */
> + ei = list_first_entry(&sbi->s_es_lru, struct ext4_inode_info, i_es_lru);
> + if (sbi->s_es_last_sorted < ei->i_touch_when) {
> + list_sort(NULL, &sbi->s_es_lru, ext4_inode_touch_time_cmp);
> + sbi->s_es_last_sorted = jiffies;
> + }
> +
> list_for_each_safe(cur, tmp, &sbi->s_es_lru) {
> - list_move_tail(cur, &scanned);
> + /*
> + * If we have already reclaimed all extents from extent
> + * status tree, just stop the loop immediately.
> + */
> + if (percpu_counter_read_positive(&sbi->s_extent_cache_cnt) == 0)
> + break;
>
> ei = list_entry(cur, struct ext4_inode_info, i_es_lru);
>
> @@@ -951,22 -923,22 +956,22 @@@
> if (nr_to_scan == 0)
> break;
> }
> - list_splice_tail(&scanned, &sbi->s_es_lru);
> +
> + /* Move the newer inodes into the tail of the LRU list. */
> + list_splice_tail(&skiped, &sbi->s_es_lru);
> spin_unlock(&sbi->s_es_lru_lock);
>
> - ret = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
> trace_ext4_es_shrink_exit(sbi->s_sb, nr_shrunk, ret);
> - return ret;
> + return nr_shrunk;
> }
>
> -void ext4_es_register_shrinker(struct super_block *sb)
> +void ext4_es_register_shrinker(struct ext4_sb_info *sbi)
> {
> - struct ext4_sb_info *sbi;
> -
> - sbi = EXT4_SB(sb);
> INIT_LIST_HEAD(&sbi->s_es_lru);
> spin_lock_init(&sbi->s_es_lru_lock);
> + sbi->s_es_last_sorted = 0;
> - sbi->s_es_shrinker.shrink = ext4_es_shrink;
> + sbi->s_es_shrinker.scan_objects = ext4_es_scan;
> + sbi->s_es_shrinker.count_objects = ext4_es_count;
> sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
> register_shrinker(&sbi->s_es_shrinker);
> }
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