Re: [PATCH 2/3 v2] f2fs: add bitmaps for empty or full NAT blocks

From: Jaegeuk Kim
Date: Thu Feb 23 2017 - 18:06:18 EST

Change log from v1:
- modified some condition checks suggested by Chao

This patches adds bitmaps to represent empty or full NAT blocks containing
free nid entries.

If we can find valid crc|cp_ver in the last block of checkpoint pack, we'll
use these bitmaps when building free nids. In order to avoid checkpointing
burden, up-to-date bitmaps will be flushed only during umount time. So,
normally we can get this gain, but when power-cut happens, we rely on fsck.f2fs
which recovers this bitmap again.

After this patch, we build free nids from nid #0 at mount time to make more
full NAT blocks, but in runtime, we check empty NAT blocks to load free nids
without loading any NAT pages from disk.

Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
fs/f2fs/checkpoint.c | 28 +++++++-
fs/f2fs/debug.c | 1 +
fs/f2fs/f2fs.h | 31 +++++++-
fs/f2fs/node.c | 188 +++++++++++++++++++++++++++++++++++++++++++-----
fs/f2fs/segment.c | 2 +-
include/linux/f2fs_fs.h | 1 +
6 files changed, 231 insertions(+), 20 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 042f8d9afe44..cd7132121573 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1024,6 +1024,10 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)

spin_lock(&sbi->cp_lock);

+ if (cpc->reason == CP_UMOUNT && ckpt->cp_pack_total_block_count >
+ sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks)
+ disable_nat_bits(sbi, false);
+
if (cpc->reason == CP_UMOUNT)
__set_ckpt_flags(ckpt, CP_UMOUNT_FLAG);
else
@@ -1136,6 +1140,28 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)

start_blk = __start_cp_next_addr(sbi);

+ /* write nat bits */
+ if (enabled_nat_bits(sbi, cpc)) {
+ __u64 cp_ver = cur_cp_version(ckpt);
+ unsigned int i;
+ block_t blk;
+
+ cp_ver |= ((__u64)crc32 << 32);
+ *(__le64 *)nm_i->nat_bits = cpu_to_le64(cp_ver);
+
+ blk = start_blk + sbi->blocks_per_seg - nm_i->nat_bits_blocks;
+ for (i = 0; i < nm_i->nat_bits_blocks; i++)
+ update_meta_page(sbi, nm_i->nat_bits +
+ (i << F2FS_BLKSIZE_BITS), blk + i);
+
+ /* Flush all the NAT BITS pages */
+ while (get_pages(sbi, F2FS_DIRTY_META)) {
+ sync_meta_pages(sbi, META, LONG_MAX);
+ if (unlikely(f2fs_cp_error(sbi)))
+ return -EIO;
+ }
+ }
+
/* need to wait for end_io results */
wait_on_all_pages_writeback(sbi);
if (unlikely(f2fs_cp_error(sbi)))
@@ -1272,7 +1298,7 @@ int write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
ckpt->checkpoint_ver = cpu_to_le64(++ckpt_ver);

/* write cached NAT/SIT entries to NAT/SIT area */
- flush_nat_entries(sbi);
+ flush_nat_entries(sbi, cpc);
flush_sit_entries(sbi, cpc);

/* unlock all the fs_lock[] in do_checkpoint() */
diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index de8da9fc5c99..015ad2b73a92 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -193,6 +193,7 @@ static void update_mem_info(struct f2fs_sb_info *sbi)
/* build nm */
si->base_mem += sizeof(struct f2fs_nm_info);
si->base_mem += __bitmap_size(sbi, NAT_BITMAP);
+ si->base_mem += (NM_I(sbi)->nat_bits_blocks << F2FS_BLKSIZE_BITS);

get_cache:
si->cache_mem = 0;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e26cc6909a54..d1156cdd211e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -554,6 +554,7 @@ struct f2fs_nm_info {
struct list_head nat_entries; /* cached nat entry list (clean) */
unsigned int nat_cnt; /* the # of cached nat entries */
unsigned int dirty_nat_cnt; /* total num of nat entries in set */
+ unsigned int nat_blocks; /* # of nat blocks */

/* free node ids management */
struct radix_tree_root free_nid_root;/* root of the free_nid cache */
@@ -564,6 +565,11 @@ struct f2fs_nm_info {

/* for checkpoint */
char *nat_bitmap; /* NAT bitmap pointer */
+
+ unsigned int nat_bits_blocks; /* # of nat bits blocks */
+ unsigned char *nat_bits; /* NAT bits blocks */
+ unsigned char *full_nat_bits; /* full NAT pages */
+ unsigned char *empty_nat_bits; /* empty NAT pages */
#ifdef CONFIG_F2FS_CHECK_FS
char *nat_bitmap_mir; /* NAT bitmap mirror */
#endif
@@ -1171,6 +1177,27 @@ static inline void clear_ckpt_flags(struct f2fs_sb_info *sbi, unsigned int f)
spin_unlock(&sbi->cp_lock);
}

+static inline void disable_nat_bits(struct f2fs_sb_info *sbi, bool lock)
+{
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+
+ if (lock)
+ spin_lock(&sbi->cp_lock);
+ __clear_ckpt_flags(F2FS_CKPT(sbi), CP_NAT_BITS_FLAG);
+ kfree(NM_I(sbi)->nat_bits);
+ NM_I(sbi)->nat_bits = NULL;
+ if (lock)
+ spin_unlock(&sbi->cp_lock);
+}
+
+static inline bool enabled_nat_bits(struct f2fs_sb_info *sbi,
+ struct cp_control *cpc)
+{
+ bool set = is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG);
+
+ return (cpc) ? (cpc->reason == CP_UMOUNT) && set : set;
+}
+
static inline void f2fs_lock_op(struct f2fs_sb_info *sbi)
{
down_read(&sbi->cp_rwsem);
@@ -2131,7 +2158,7 @@ void move_node_page(struct page *node_page, int gc_type);
int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
struct writeback_control *wbc, bool atomic);
int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc);
-void build_free_nids(struct f2fs_sb_info *sbi, bool sync);
+void build_free_nids(struct f2fs_sb_info *sbi, bool sync, bool mount);
bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid);
void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid);
void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid);
@@ -2142,7 +2169,7 @@ int recover_xattr_data(struct inode *inode, struct page *page,
int recover_inode_page(struct f2fs_sb_info *sbi, struct page *page);
int restore_node_summary(struct f2fs_sb_info *sbi,
unsigned int segno, struct f2fs_summary_block *sum);
-void flush_nat_entries(struct f2fs_sb_info *sbi);
+void flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc);
int build_node_manager(struct f2fs_sb_info *sbi);
void destroy_node_manager(struct f2fs_sb_info *sbi);
int __init create_node_manager_caches(void);
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 8ebc4c78e6a4..43d35ec11851 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -338,6 +338,9 @@ static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni,
set_nat_flag(e, IS_CHECKPOINTED, false);
__set_nat_cache_dirty(nm_i, e);

+ if (enabled_nat_bits(sbi, NULL) && new_blkaddr == NEW_ADDR)
+ clear_bit_le(NAT_BLOCK_OFFSET(ni->nid), nm_i->empty_nat_bits);
+
/* update fsync_mark if its inode nat entry is still alive */
if (ni->nid != ni->ino)
e = __lookup_nat_cache(nm_i, ni->ino);
@@ -1841,7 +1844,60 @@ static void scan_nat_page(struct f2fs_sb_info *sbi,
}
}

-static void __build_free_nids(struct f2fs_sb_info *sbi, bool sync)
+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 (!enabled_nat_bits(sbi, NULL))
+ 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);
+ up_read(&nm_i->nat_tree_lock);
+ 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);
@@ -1856,6 +1912,21 @@ 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 */
+ if (enabled_nat_bits(sbi, NULL)) {
+ 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);
@@ -1898,10 +1969,10 @@ 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);
}

@@ -1943,7 +2014,7 @@ 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;
}

@@ -2235,8 +2306,39 @@ 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 (!enabled_nat_bits(sbi, NULL))
+ 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) {
+ set_bit_le(nat_index, nm_i->empty_nat_bits);
+ clear_bit_le(nat_index, nm_i->full_nat_bits);
+ return;
+ }
+
+ clear_bit_le(nat_index, nm_i->empty_nat_bits);
+ if (valid == NAT_ENTRY_PER_BLOCK)
+ set_bit_le(nat_index, nm_i->full_nat_bits);
+ else
+ clear_bit_le(nat_index, nm_i->full_nat_bits);
+}
+
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;
@@ -2251,7 +2353,8 @@ 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 (enabled_nat_bits(sbi, cpc) ||
+ !__has_cursum_space(journal, set->entry_cnt, NAT_JOURNAL))
to_journal = false;

if (to_journal) {
@@ -2291,10 +2394,12 @@ 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);

@@ -2305,7 +2410,7 @@ 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);
@@ -2326,7 +2431,8 @@ 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 ||
+ !__has_cursum_space(journal, nm_i->dirty_nat_cnt, NAT_JOURNAL))
remove_nats_in_journal(sbi);

while ((found = __gang_lookup_nat_set(nm_i,
@@ -2340,27 +2446,72 @@ 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 = cur_cp_version(ckpt);
+ 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 (!enabled_nat_bits(sbi, NULL))
+ 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 -
@@ -2394,6 +2545,10 @@ 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);
@@ -2416,7 +2571,7 @@ 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;
}

@@ -2475,6 +2630,7 @@ 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 3e95db5375ed..9eb6d89bf9e2 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
--
2.11.0