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Date: Sat, 25 Feb 2017 10:34:19 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/3] f2fs: add bitmaps for empty or full NAT
blocks
On 02/25, Chao Yu wrote:
> On 2017/2/24 6:54, Jaegeuk Kim wrote:
> > On 02/23, Chao Yu wrote:
> >> On 2017/2/14 10:06, Jaegeuk Kim wrote:
...
> >
> >>> +static int scan_nat_bits(struct f2fs_sb_info *sbi)
> >>> +{
> >>> + struct f2fs_nm_info *nm_i = NM_I(sbi);
> >>> + struct page *page;
> >>> + unsigned int i = 0;
> >>> + nid_t target = FREE_NID_PAGES * NAT_ENTRY_PER_BLOCK;
> >>> + nid_t nid;
> >>> +
> >>> + if (!is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG))
> >>> + return -EAGAIN;
> >>> +
> >>> + down_read(&nm_i->nat_tree_lock);
> >>> +check_empty:
> >>> + i = find_next_bit_le(nm_i->empty_nat_bits, nm_i->nat_blocks, i);
> >>> + if (i >= nm_i->nat_blocks) {
> >>> + i = 0;
> >>> + goto check_partial;
> >>> + }
> >>> +
> >>> + for (nid = i * NAT_ENTRY_PER_BLOCK; nid < (i + 1) * NAT_ENTRY_PER_BLOCK;
> >>> + nid++) {
> >>> + if (unlikely(nid >= nm_i->max_nid))
> >>> + break;
> >>> + add_free_nid(sbi, nid, true);
> >>> + }
> >>> +
> >>> + if (nm_i->nid_cnt[FREE_NID_LIST] >= target)
> >>> + goto out;
> >>> + i++;
> >>> + goto check_empty;
> >>> +
> >>> +check_partial:
> >>> + i = find_next_zero_bit_le(nm_i->full_nat_bits, nm_i->nat_blocks, i);
> >>> + if (i >= nm_i->nat_blocks) {
> >>> + disable_nat_bits(sbi, true);
> >>
> >> Can this happen in real world? Should be a bug in somewhere?
> >
> > It happens, since current design handles full_nat_bits optionally in order
> > to avoid scanning a whole NAT page to set it back as 1 from 0.
>
> All 0 value in full_nat_bits means the NAT block has at least one free nid,
> right? so if we traverse all such NAT blocks, and still haven't collect enough
> *target* number of free nids, we don't have to disable nat bit cache, we can
> just break out here.
No, I'm seeing this case:
1. mount with full=0, empty=0, which indicates some free nids.
2. allocate all there-in free nids, but still full=0, empty=0.
3. allocate more free nids.
...
... checkpoint makes full=1, empty=0
If there is no checkpoint and it consumes all the free nids, we can see all 0
value in full_nat_bits which is quite impossible. In that case, I'd prefer
to stop nat_bits and give fsck.f2fs to revive it back.
Thanks,
>
> Thanks,
>
> >
> >>
> >>> + return -EINVAL;
> >>> + }
> >>> +
> >>> + nid = i * NAT_ENTRY_PER_BLOCK;
> >>> + page = get_current_nat_page(sbi, nid);
> >>> + scan_nat_page(sbi, page, nid);
> >>> + f2fs_put_page(page, 1);
> >>> +
> >>> + if (nm_i->nid_cnt[FREE_NID_LIST] < target) {
> >>> + i++;
> >>> + goto check_partial;
> >>> + }
> >>> +out:
> >>> + up_read(&nm_i->nat_tree_lock);
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void __build_free_nids(struct f2fs_sb_info *sbi, bool sync, bool mount)
> >>> {
> >>> struct f2fs_nm_info *nm_i = NM_I(sbi);
> >>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> >>> @@ -1854,6 +1911,20 @@ static void __build_free_nids(struct f2fs_sb_info *sbi, bool sync)
> >>> if (!sync && !available_free_memory(sbi, FREE_NIDS))
> >>> return;
> >>>
> >>> + /* try to find free nids with nat_bits */
> >>> + if (!mount && !scan_nat_bits(sbi) && nm_i->nid_cnt[FREE_NID_LIST])
> >>> + return;
> >>> +
> >>> + /* find next valid candidate */
> >>
> >> This is just for mount case?
> >
> > Yup, it reuses free nids in dirty NAT blocks, so that we can make them as full
> > NAT pages.
> >
> > Thanks,
> >
> >>
> >>> + if (is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG)) {
> >>> + int idx = find_next_zero_bit_le(nm_i->full_nat_bits,
> >>> + nm_i->nat_blocks, 0);
> >>> + if (idx >= nm_i->nat_blocks)
> >>> + set_sbi_flag(sbi, SBI_NEED_FSCK);
> >>> + else
> >>> + nid = idx * NAT_ENTRY_PER_BLOCK;
> >>> + }
> >>> +
> >>> /* readahead nat pages to be scanned */
> >>> ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), FREE_NID_PAGES,
> >>> META_NAT, true);
> >>> @@ -1896,10 +1967,10 @@ static void __build_free_nids(struct f2fs_sb_info *sbi, bool sync)
> >>> nm_i->ra_nid_pages, META_NAT, false);
> >>> }
> >>>
> >>> -void build_free_nids(struct f2fs_sb_info *sbi, bool sync)
> >>> +void build_free_nids(struct f2fs_sb_info *sbi, bool sync, bool mount)
> >>> {
> >>> mutex_lock(&NM_I(sbi)->build_lock);
> >>> - __build_free_nids(sbi, sync);
> >>> + __build_free_nids(sbi, sync, mount);
> >>> mutex_unlock(&NM_I(sbi)->build_lock);
> >>> }
> >>>
> >>> @@ -1941,7 +2012,7 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid)
> >>> spin_unlock(&nm_i->nid_list_lock);
> >>>
> >>> /* Let's scan nat pages and its caches to get free nids */
> >>> - build_free_nids(sbi, true);
> >>> + build_free_nids(sbi, true, false);
> >>> goto retry;
> >>> }
> >>>
> >>> @@ -2233,8 +2304,39 @@ static void __adjust_nat_entry_set(struct nat_entry_set *nes,
> >>> list_add_tail(&nes->set_list, head);
> >>> }
> >>>
> >>> +void __update_nat_bits(struct f2fs_sb_info *sbi, nid_t start_nid,
> >>> + struct page *page)
> >>> +{
> >>> + struct f2fs_nm_info *nm_i = NM_I(sbi);
> >>> + unsigned int nat_index = start_nid / NAT_ENTRY_PER_BLOCK;
> >>> + struct f2fs_nat_block *nat_blk = page_address(page);
> >>> + int valid = 0;
> >>> + int i;
> >>> +
> >>> + if (!is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG))
> >>> + return;
> >>> +
> >>> + for (i = 0; i < NAT_ENTRY_PER_BLOCK; i++) {
> >>> + if (start_nid == 0 && i == 0)
> >>> + valid++;
> >>> + if (nat_blk->entries[i].block_addr)
> >>> + valid++;
> >>> + }
> >>> + if (valid == 0) {
> >>> + test_and_set_bit_le(nat_index, nm_i->empty_nat_bits);
> >>> + test_and_clear_bit_le(nat_index, nm_i->full_nat_bits);
> >>
> >> set_bit_le/clear_bit_le
> >>
> >>> + return;
> >>> + }
> >>> +
> >>> + test_and_clear_bit_le(nat_index, nm_i->empty_nat_bits);
> >>
> >> ditto
> >>
> >>> + if (valid == NAT_ENTRY_PER_BLOCK)
> >>> + test_and_set_bit_le(nat_index, nm_i->full_nat_bits);
> >>> + else
> >>> + test_and_clear_bit_le(nat_index, nm_i->full_nat_bits);
> >>
> >> ditto
> >>
> >>> +}
> >>> +
> >>> static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>> - struct nat_entry_set *set)
> >>> + struct nat_entry_set *set, struct cp_control *cpc)
> >>> {
> >>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> >>> struct f2fs_journal *journal = curseg->journal;
> >>> @@ -2249,7 +2351,8 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>> * #1, flush nat entries to journal in current hot data summary block.
> >>> * #2, flush nat entries to nat page.
> >>> */
> >>> - if (!__has_cursum_space(journal, set->entry_cnt, NAT_JOURNAL))
> >>> + if (cpc->reason == CP_UMOUNT ||
> >>
> >> if ((cpc->reason == CP_UMOUNT && is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG)) ||
> >>
> >>> + !__has_cursum_space(journal, set->entry_cnt, NAT_JOURNAL))
> >>> to_journal = false;
> >>>
> >>> if (to_journal) {
> >>> @@ -2289,10 +2392,12 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>> }
> >>> }
> >>>
> >>> - if (to_journal)
> >>> + if (to_journal) {
> >>> up_write(&curseg->journal_rwsem);
> >>> - else
> >>> + } else {
> >>> + __update_nat_bits(sbi, start_nid, page);
> >>> f2fs_put_page(page, 1);
> >>> + }
> >>>
> >>> f2fs_bug_on(sbi, set->entry_cnt);
> >>>
> >>> @@ -2303,7 +2408,7 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>> /*
> >>> * This function is called during the checkpointing process.
> >>> */
> >>> -void flush_nat_entries(struct f2fs_sb_info *sbi)
> >>> +void flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>> {
> >>> struct f2fs_nm_info *nm_i = NM_I(sbi);
> >>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> >>> @@ -2324,7 +2429,8 @@ void flush_nat_entries(struct f2fs_sb_info *sbi)
> >>> * entries, remove all entries from journal and merge them
> >>> * into nat entry set.
> >>> */
> >>> - if (!__has_cursum_space(journal, nm_i->dirty_nat_cnt, NAT_JOURNAL))
> >>> + if (cpc->reason == CP_UMOUNT ||
> >>
> >> if ((cpc->reason == CP_UMOUNT && is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG)) ||
> >>
> >>> + !__has_cursum_space(journal, nm_i->dirty_nat_cnt, NAT_JOURNAL))
> >>> remove_nats_in_journal(sbi);
> >>>
> >>> while ((found = __gang_lookup_nat_set(nm_i,
> >>> @@ -2338,27 +2444,72 @@ void flush_nat_entries(struct f2fs_sb_info *sbi)
> >>>
> >>> /* flush dirty nats in nat entry set */
> >>> list_for_each_entry_safe(set, tmp, &sets, set_list)
> >>> - __flush_nat_entry_set(sbi, set);
> >>> + __flush_nat_entry_set(sbi, set, cpc);
> >>>
> >>> up_write(&nm_i->nat_tree_lock);
> >>>
> >>> f2fs_bug_on(sbi, nm_i->dirty_nat_cnt);
> >>> }
> >>>
> >>> +static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
> >>> +{
> >>> + struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
> >>> + struct f2fs_nm_info *nm_i = NM_I(sbi);
> >>> + unsigned int nat_bits_bytes = nm_i->nat_blocks / BITS_PER_BYTE;
> >>> + unsigned int i;
> >>> + __u64 cp_ver = le64_to_cpu(ckpt->checkpoint_ver);
> >>
> >> __u64 cp_ver = cur_cp_version(ckpt);
> >>
> >> Thanks,
> >>
> >>> + size_t crc_offset = le32_to_cpu(ckpt->checksum_offset);
> >>> + __u64 crc = le32_to_cpu(*((__le32 *)
> >>> + ((unsigned char *)ckpt + crc_offset)));
> >>> + block_t nat_bits_addr;
> >>> +
> >>> + if (!is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG))
> >>> + return 0;
> >>> +
> >>> + nm_i->nat_bits_blocks = F2FS_BYTES_TO_BLK((nat_bits_bytes << 1) + 8 +
> >>> + F2FS_BLKSIZE - 1);
> >>> + nm_i->nat_bits = kzalloc(nm_i->nat_bits_blocks << F2FS_BLKSIZE_BITS,
> >>> + GFP_KERNEL);
> >>> + if (!nm_i->nat_bits)
> >>> + return -ENOMEM;
> >>> +
> >>> + nat_bits_addr = __start_cp_addr(sbi) + sbi->blocks_per_seg -
> >>> + nm_i->nat_bits_blocks;
> >>> + for (i = 0; i < nm_i->nat_bits_blocks; i++) {
> >>> + struct page *page = get_meta_page(sbi, nat_bits_addr++);
> >>> +
> >>> + memcpy(nm_i->nat_bits + (i << F2FS_BLKSIZE_BITS),
> >>> + page_address(page), F2FS_BLKSIZE);
> >>> + f2fs_put_page(page, 1);
> >>> + }
> >>> +
> >>> + cp_ver |= (crc << 32);
> >>> + if (cpu_to_le64(cp_ver) != *(__le64 *)nm_i->nat_bits) {
> >>> + disable_nat_bits(sbi, true);
> >>> + return 0;
> >>> + }
> >>> +
> >>> + nm_i->full_nat_bits = nm_i->nat_bits + 8;
> >>> + nm_i->empty_nat_bits = nm_i->full_nat_bits + nat_bits_bytes;
> >>> +
> >>> + f2fs_msg(sbi->sb, KERN_NOTICE, "Found nat_bits in checkpoint");
> >>> + return 0;
> >>> +}
> >>> +
> >>> static int init_node_manager(struct f2fs_sb_info *sbi)
> >>> {
> >>> struct f2fs_super_block *sb_raw = F2FS_RAW_SUPER(sbi);
> >>> struct f2fs_nm_info *nm_i = NM_I(sbi);
> >>> unsigned char *version_bitmap;
> >>> - unsigned int nat_segs, nat_blocks;
> >>> + unsigned int nat_segs;
> >>> + int err;
> >>>
> >>> nm_i->nat_blkaddr = le32_to_cpu(sb_raw->nat_blkaddr);
> >>>
> >>> /* segment_count_nat includes pair segment so divide to 2. */
> >>> nat_segs = le32_to_cpu(sb_raw->segment_count_nat) >> 1;
> >>> - nat_blocks = nat_segs << le32_to_cpu(sb_raw->log_blocks_per_seg);
> >>> -
> >>> - nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks;
> >>> + nm_i->nat_blocks = nat_segs << le32_to_cpu(sb_raw->log_blocks_per_seg);
> >>> + nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nm_i->nat_blocks;
> >>>
> >>> /* not used nids: 0, node, meta, (and root counted as valid node) */
> >>> nm_i->available_nids = nm_i->max_nid - sbi->total_valid_node_count -
> >>> @@ -2392,6 +2543,10 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
> >>> if (!nm_i->nat_bitmap)
> >>> return -ENOMEM;
> >>>
> >>> + err = __get_nat_bitmaps(sbi);
> >>> + if (err)
> >>> + return err;
> >>> +
> >>> #ifdef CONFIG_F2FS_CHECK_FS
> >>> nm_i->nat_bitmap_mir = kmemdup(version_bitmap, nm_i->bitmap_size,
> >>> GFP_KERNEL);
> >>> @@ -2414,7 +2569,7 @@ int build_node_manager(struct f2fs_sb_info *sbi)
> >>> if (err)
> >>> return err;
> >>>
> >>> - build_free_nids(sbi, true);
> >>> + build_free_nids(sbi, true, true);
> >>> return 0;
> >>> }
> >>>
> >>> @@ -2473,6 +2628,7 @@ void destroy_node_manager(struct f2fs_sb_info *sbi)
> >>> up_write(&nm_i->nat_tree_lock);
> >>>
> >>> kfree(nm_i->nat_bitmap);
> >>> + kfree(nm_i->nat_bits);
> >>> #ifdef CONFIG_F2FS_CHECK_FS
> >>> kfree(nm_i->nat_bitmap_mir);
> >>> #endif
> >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >>> index df2ff5cfe8f4..8e1ec248c653 100644
> >>> --- a/fs/f2fs/segment.c
> >>> +++ b/fs/f2fs/segment.c
> >>> @@ -386,7 +386,7 @@ void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi)
> >>> if (!available_free_memory(sbi, FREE_NIDS))
> >>> try_to_free_nids(sbi, MAX_FREE_NIDS);
> >>> else
> >>> - build_free_nids(sbi, false);
> >>> + build_free_nids(sbi, false, false);
> >>>
> >>> if (!is_idle(sbi))
> >>> return;
> >>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> >>> index f0748524ca8c..1c92ace2e8f8 100644
> >>> --- a/include/linux/f2fs_fs.h
> >>> +++ b/include/linux/f2fs_fs.h
> >>> @@ -114,6 +114,7 @@ struct f2fs_super_block {
> >>> /*
> >>> * For checkpoint
> >>> */
> >>> +#define CP_NAT_BITS_FLAG 0x00000080
> >>> #define CP_CRC_RECOVERY_FLAG 0x00000040
> >>> #define CP_FASTBOOT_FLAG 0x00000020
> >>> #define CP_FSCK_FLAG 0x00000010
> >>>
> >>
> >>
> >> ------------------------------------------------------------------------------
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> >> _______________________________________________
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> >> Linux-f2fs-devel@...ts.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> >
> > .
> >
>
>
> ------------------------------------------------------------------------------
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