linux-kernel - [PATCH 2/2] f2fs: implement a lock-free stat

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Message-id: <1393226284-22447-2-git-send-email-jaegeuk.kim@samsung.com>
Date:	Mon, 24 Feb 2014 16:18:04 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	unlisted-recipients:; (no To-header on input)
Cc:	Jaegeuk Kim <jaegeuk.kim@...sung.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: [PATCH 2/2] f2fs: implement a lock-free stat_show

The stat_show is just to show the current status of f2fs.
So, we can remove all the there-in locks.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
---
 fs/f2fs/debug.c   |  3 ---
 fs/f2fs/f2fs.h    | 18 +++---------------
 fs/f2fs/segment.h | 27 +++------------------------
 3 files changed, 6 insertions(+), 42 deletions(-)

diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index 46a12e4..b7111c4 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -86,7 +86,6 @@ static void update_sit_info(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_stat_info *si = F2FS_STAT(sbi);
 	unsigned int blks_per_sec, hblks_per_sec, total_vblocks, bimodal, dist;
-	struct sit_info *sit_i = SIT_I(sbi);
 	unsigned int segno, vblocks;
 	int ndirty = 0;
 
@@ -94,7 +93,6 @@ static void update_sit_info(struct f2fs_sb_info *sbi)
 	total_vblocks = 0;
 	blks_per_sec = sbi->segs_per_sec * (1 << sbi->log_blocks_per_seg);
 	hblks_per_sec = blks_per_sec / 2;
-	mutex_lock(&sit_i->sentry_lock);
 	for (segno = 0; segno < TOTAL_SEGS(sbi); segno += sbi->segs_per_sec) {
 		vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);
 		dist = abs(vblocks - hblks_per_sec);
@@ -105,7 +103,6 @@ static void update_sit_info(struct f2fs_sb_info *sbi)
 			ndirty++;
 		}
 	}
-	mutex_unlock(&sit_i->sentry_lock);
 	dist = TOTAL_SECS(sbi) * hblks_per_sec * hblks_per_sec / 100;
 	si->bimodal = bimodal / dist;
 	if (si->dirty_count)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 11fd8be..4beedcc 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -704,11 +704,7 @@ static inline int get_blocktype_secs(struct f2fs_sb_info *sbi, int block_type)
 
 static inline block_t valid_user_blocks(struct f2fs_sb_info *sbi)
 {
-	block_t ret;
-	spin_lock(&sbi->stat_lock);
-	ret = sbi->total_valid_block_count;
-	spin_unlock(&sbi->stat_lock);
-	return ret;
+	return sbi->total_valid_block_count;
 }
 
 static inline unsigned long __bitmap_size(struct f2fs_sb_info *sbi, int flag)
@@ -804,11 +800,7 @@ static inline void dec_valid_node_count(struct f2fs_sb_info *sbi,
 
 static inline unsigned int valid_node_count(struct f2fs_sb_info *sbi)
 {
-	unsigned int ret;
-	spin_lock(&sbi->stat_lock);
-	ret = sbi->total_valid_node_count;
-	spin_unlock(&sbi->stat_lock);
-	return ret;
+	return sbi->total_valid_node_count;
 }
 
 static inline void inc_valid_inode_count(struct f2fs_sb_info *sbi)
@@ -829,11 +821,7 @@ static inline void dec_valid_inode_count(struct f2fs_sb_info *sbi)
 
 static inline unsigned int valid_inode_count(struct f2fs_sb_info *sbi)
 {
-	unsigned int ret;
-	spin_lock(&sbi->stat_lock);
-	ret = sbi->total_valid_inode_count;
-	spin_unlock(&sbi->stat_lock);
-	return ret;
+	return sbi->total_valid_inode_count;
 }
 
 static inline void f2fs_put_page(struct page *page, int unlock)
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 4024546..c3d5e36 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -380,26 +380,12 @@ static inline void get_sit_bitmap(struct f2fs_sb_info *sbi,
 
 static inline block_t written_block_count(struct f2fs_sb_info *sbi)
 {
-	struct sit_info *sit_i = SIT_I(sbi);
-	block_t vblocks;
-
-	mutex_lock(&sit_i->sentry_lock);
-	vblocks = sit_i->written_valid_blocks;
-	mutex_unlock(&sit_i->sentry_lock);
-
-	return vblocks;
+	return SIT_I(sbi)->written_valid_blocks;
 }
 
 static inline unsigned int free_segments(struct f2fs_sb_info *sbi)
 {
-	struct free_segmap_info *free_i = FREE_I(sbi);
-	unsigned int free_segs;
-
-	read_lock(&free_i->segmap_lock);
-	free_segs = free_i->free_segments;
-	read_unlock(&free_i->segmap_lock);
-
-	return free_segs;
+	return FREE_I(sbi)->free_segments;
 }
 
 static inline int reserved_segments(struct f2fs_sb_info *sbi)
@@ -409,14 +395,7 @@ static inline int reserved_segments(struct f2fs_sb_info *sbi)
 
 static inline unsigned int free_sections(struct f2fs_sb_info *sbi)
 {
-	struct free_segmap_info *free_i = FREE_I(sbi);
-	unsigned int free_secs;
-
-	read_lock(&free_i->segmap_lock);
-	free_secs = free_i->free_sections;
-	read_unlock(&free_i->segmap_lock);
-
-	return free_secs;
+	return FREE_I(sbi)->free_sections;
 }
 
 static inline unsigned int prefree_segments(struct f2fs_sb_info *sbi)
-- 
1.8.4.474.g128a96c

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