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Message-ID: <4ac60332-bc04-f398-3746-4ff5dbe53887@gmail.com>
Date: Fri, 10 Mar 2017 11:23:57 +0800
From: Kinglong Mee <kinglongmee@...il.com>
To: Chao Yu <yuchao0@...wei.com>, jaegeuk@...nel.org
Cc: chao@...nel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net,
Kinglong Mee <kinglongmee@...il.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs: skip scanning free nid bitmap of full
NAT blocks
On 3/1/2017 17:09, Chao Yu wrote:
> This patch adds to account free nids for each NAT blocks, and while
> scanning all free nid bitmap, do check count and skip lookuping in
> full NAT block.
>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> fs/f2fs/debug.c | 1 +
> fs/f2fs/f2fs.h | 2 ++
> fs/f2fs/node.c | 34 ++++++++++++++++++++++++++++------
> 3 files changed, 31 insertions(+), 6 deletions(-)
>
> diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
> index a77df377e2e8..ee2d0a485fc3 100644
> --- a/fs/f2fs/debug.c
> +++ b/fs/f2fs/debug.c
> @@ -196,6 +196,7 @@ static void update_mem_info(struct f2fs_sb_info *sbi)
> si->base_mem += (NM_I(sbi)->nat_bits_blocks << F2FS_BLKSIZE_BITS);
> si->base_mem += NM_I(sbi)->nat_blocks * NAT_ENTRY_BITMAP_SIZE;
> si->base_mem += NM_I(sbi)->nat_blocks / 8;
> + si->base_mem += NM_I(sbi)->nat_blocks * sizeof(unsigned short);
>
> get_cache:
> si->cache_mem = 0;
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 7e2924981eeb..c0b33719dfa9 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -557,6 +557,8 @@ struct f2fs_nm_info {
> struct mutex build_lock; /* lock for build free nids */
> unsigned char (*free_nid_bitmap)[NAT_ENTRY_BITMAP_SIZE];
> unsigned char *nat_block_bitmap;
> + unsigned short *free_nid_count; /* free nid count of NAT block */
> + spinlock_t free_nid_lock; /* protect updating of nid count */
>
Sorry for my reply so late.
Is the free_nid_lock needed here?
The free_nid_count should be protected as free_nid_bitmap,
but there isn't any lock for free_nid_bitmap.
How about atomic?
The free node ids management seems a little complex now.
thanks,
Kinglong Mee
> /* for checkpoint */
> char *nat_bitmap; /* NAT bitmap pointer */
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 94967171dee8..1a759d45b7e4 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1823,7 +1823,8 @@ static void remove_free_nid(struct f2fs_sb_info *sbi, nid_t nid)
> kmem_cache_free(free_nid_slab, i);
> }
>
> -void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid, bool set)
> +void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid,
> + bool set, bool build)
> {
> struct f2fs_nm_info *nm_i = NM_I(sbi);
> unsigned int nat_ofs = NAT_BLOCK_OFFSET(nid);
> @@ -1836,6 +1837,13 @@ void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid, bool set)
> set_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
> else
> clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
> +
> + spin_lock(&nm_i->free_nid_lock);
> + if (set)
> + nm_i->free_nid_count[nat_ofs]++;
> + else if (!build)
> + nm_i->free_nid_count[nat_ofs]--;
> + spin_unlock(&nm_i->free_nid_lock);
> }
>
> static void scan_nat_page(struct f2fs_sb_info *sbi,
> @@ -1847,6 +1855,9 @@ static void scan_nat_page(struct f2fs_sb_info *sbi,
> unsigned int nat_ofs = NAT_BLOCK_OFFSET(start_nid);
> int i;
>
> + if (test_bit_le(nat_ofs, nm_i->nat_block_bitmap))
> + return;
> +
> set_bit_le(nat_ofs, nm_i->nat_block_bitmap);
>
> i = start_nid % NAT_ENTRY_PER_BLOCK;
> @@ -1861,7 +1872,7 @@ static void scan_nat_page(struct f2fs_sb_info *sbi,
> f2fs_bug_on(sbi, blk_addr == NEW_ADDR);
> if (blk_addr == NULL_ADDR)
> freed = add_free_nid(sbi, start_nid, true);
> - update_free_nid_bitmap(sbi, start_nid, freed);
> + update_free_nid_bitmap(sbi, start_nid, freed, true);
> }
> }
>
> @@ -1877,6 +1888,8 @@ static void scan_free_nid_bits(struct f2fs_sb_info *sbi)
> for (i = 0; i < nm_i->nat_blocks; i++) {
> if (!test_bit_le(i, nm_i->nat_block_bitmap))
> continue;
> + if (!nm_i->free_nid_count[i])
> + continue;
> for (idx = 0; idx < NAT_ENTRY_PER_BLOCK; idx++) {
> nid_t nid;
>
> @@ -2081,7 +2094,7 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid)
> __insert_nid_to_list(sbi, i, ALLOC_NID_LIST, false);
> nm_i->available_nids--;
>
> - update_free_nid_bitmap(sbi, *nid, false);
> + update_free_nid_bitmap(sbi, *nid, false, false);
>
> spin_unlock(&nm_i->nid_list_lock);
> return true;
> @@ -2137,7 +2150,7 @@ void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
>
> nm_i->available_nids++;
>
> - update_free_nid_bitmap(sbi, nid, true);
> + update_free_nid_bitmap(sbi, nid, true, false);
>
> spin_unlock(&nm_i->nid_list_lock);
>
> @@ -2467,11 +2480,11 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> add_free_nid(sbi, nid, false);
> spin_lock(&NM_I(sbi)->nid_list_lock);
> NM_I(sbi)->available_nids++;
> - update_free_nid_bitmap(sbi, nid, true);
> + update_free_nid_bitmap(sbi, nid, true, false);
> spin_unlock(&NM_I(sbi)->nid_list_lock);
> } else {
> spin_lock(&NM_I(sbi)->nid_list_lock);
> - update_free_nid_bitmap(sbi, nid, false);
> + update_free_nid_bitmap(sbi, nid, false, false);
> spin_unlock(&NM_I(sbi)->nid_list_lock);
> }
> }
> @@ -2651,6 +2664,14 @@ int init_free_nid_cache(struct f2fs_sb_info *sbi)
> GFP_KERNEL);
> if (!nm_i->nat_block_bitmap)
> return -ENOMEM;
> +
> + nm_i->free_nid_count = f2fs_kvzalloc(nm_i->nat_blocks *
> + sizeof(unsigned short), GFP_KERNEL);
> + if (!nm_i->free_nid_count)
> + return -ENOMEM;
> +
> + spin_lock_init(&nm_i->free_nid_lock);
> +
> return 0;
> }
>
> @@ -2730,6 +2751,7 @@ void destroy_node_manager(struct f2fs_sb_info *sbi)
>
> kvfree(nm_i->nat_block_bitmap);
> kvfree(nm_i->free_nid_bitmap);
> + kvfree(nm_i->free_nid_count);
>
> kfree(nm_i->nat_bitmap);
> kfree(nm_i->nat_bits);
>
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