f2fs: split journal cache from curseg cache

In curseg cache, f2fs caches two different parts:
 - datas of current summay block, i.e. summary entries, footer info.
 - journal info, i.e. sparse nat/sit entries or io stat info.

With this approach, 1) it may cause higher lock contention when we access
or update both of the parts of cache since we use the same mutex lock
curseg_mutex to protect the cache. 2) current summary block with last
journal info will be writebacked into device as a normal summary block
when flushing, however, we treat journal info as valid one only in current
summary, so most normal summary blocks contain junk journal data, it wastes
remaining space of summary block.

So, in order to fix above issues, we split curseg cache into two parts:
a) current summary block, protected by original mutex lock curseg_mutex
b) journal cache, protected by newly introduced r/w semaphore journal_rwsem

When loading curseg cache during ->mount, we store summary info and
journal info into different caches; When doing checkpoint, we combine
datas of two cache into current summary block for persisting.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 13 insertions, 13 deletions

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 8230e35fc979..94b8016db04e 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -354,7 +354,7 @@ void get_node_info(struct f2fs_sb_info *sbi, nid_t nid, struct node_info *ni)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
-	struct f2fs_journal *journal = &curseg->sum_blk->journal;
+	struct f2fs_journal *journal = curseg->journal;
 	nid_t start_nid = START_NID(nid);
 	struct f2fs_nat_block *nat_blk;
 	struct page *page = NULL;
@@ -381,13 +381,13 @@ void get_node_info(struct f2fs_sb_info *sbi, nid_t nid, struct node_info *ni)
 	down_write(&nm_i->nat_tree_lock);
 
 	/* Check current segment summary */
-	mutex_lock(&curseg->curseg_mutex);
+	down_read(&curseg->journal_rwsem);
 	i = lookup_journal_in_cursum(journal, NAT_JOURNAL, nid, 0);
 	if (i >= 0) {
 		ne = nat_in_journal(journal, i);
 		node_info_from_raw_nat(ni, &ne);
 	}
-	mutex_unlock(&curseg->curseg_mutex);
+	up_read(&curseg->journal_rwsem);
 	if (i >= 0)
 		goto cache;
 
@@ -1613,7 +1613,7 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
-	struct f2fs_journal *journal = &curseg->sum_blk->journal;
+	struct f2fs_journal *journal = curseg->journal;
 	int i = 0;
 	nid_t nid = nm_i->next_scan_nid;
 
@@ -1645,7 +1645,7 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
 	nm_i->next_scan_nid = nid;
 
 	/* find free nids from current sum_pages */
-	mutex_lock(&curseg->curseg_mutex);
+	down_read(&curseg->journal_rwsem);
 	for (i = 0; i < nats_in_cursum(journal); i++) {
 		block_t addr;
 
@@ -1656,7 +1656,7 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
 		else
 			remove_free_nid(nm_i, nid);
 	}
-	mutex_unlock(&curseg->curseg_mutex);
+	up_read(&curseg->journal_rwsem);
 	up_read(&nm_i->nat_tree_lock);
 
 	ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nm_i->next_scan_nid),
@@ -1920,10 +1920,10 @@ static void remove_nats_in_journal(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
-	struct f2fs_journal *journal = &curseg->sum_blk->journal;
+	struct f2fs_journal *journal = curseg->journal;
 	int i;
 
-	mutex_lock(&curseg->curseg_mutex);
+	down_write(&curseg->journal_rwsem);
 	for (i = 0; i < nats_in_cursum(journal); i++) {
 		struct nat_entry *ne;
 		struct f2fs_nat_entry raw_ne;
@@ -1939,7 +1939,7 @@ static void remove_nats_in_journal(struct f2fs_sb_info *sbi)
 		__set_nat_cache_dirty(nm_i, ne);
 	}
 	update_nats_in_cursum(journal, -i);
-	mutex_unlock(&curseg->curseg_mutex);
+	up_write(&curseg->journal_rwsem);
 }
 
 static void __adjust_nat_entry_set(struct nat_entry_set *nes,
@@ -1964,7 +1964,7 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
 					struct nat_entry_set *set)
 {
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
-	struct f2fs_journal *journal = &curseg->sum_blk->journal;
+	struct f2fs_journal *journal = curseg->journal;
 	nid_t start_nid = set->set * NAT_ENTRY_PER_BLOCK;
 	bool to_journal = true;
 	struct f2fs_nat_block *nat_blk;
@@ -1980,7 +1980,7 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
 		to_journal = false;
 
 	if (to_journal) {
-		mutex_lock(&curseg->curseg_mutex);
+		down_write(&curseg->journal_rwsem);
 	} else {
 		page = get_next_nat_page(sbi, start_nid);
 		nat_blk = page_address(page);
@@ -2013,7 +2013,7 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
 	}
 
 	if (to_journal)
-		mutex_unlock(&curseg->curseg_mutex);
+		up_write(&curseg->journal_rwsem);
 	else
 		f2fs_put_page(page, 1);
 
@@ -2030,7 +2030,7 @@ void flush_nat_entries(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
-	struct f2fs_journal *journal = &curseg->sum_blk->journal;
+	struct f2fs_journal *journal = curseg->journal;
 	struct nat_entry_set *setvec[SETVEC_SIZE];
 	struct nat_entry_set *set, *tmp;
 	unsigned int found;