linux-kernel - [PATCH 9/9] f2fs: fix the bitmap consistency of dirty segments

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Date:	Mon, 01 Apr 2013 15:56:00 +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 9/9] f2fs: fix the bitmap consistency of dirty segments

Like below, there are 8 segment bitmaps for SSR victim candidates.

enum dirty_type {
	DIRTY_HOT_DATA,		/* dirty segments assigned as hot data logs */
	DIRTY_WARM_DATA,	/* dirty segments assigned as warm data logs */
	DIRTY_COLD_DATA,	/* dirty segments assigned as cold data logs */
	DIRTY_HOT_NODE,		/* dirty segments assigned as hot node logs */
	DIRTY_WARM_NODE,	/* dirty segments assigned as warm node logs */
	DIRTY_COLD_NODE,	/* dirty segments assigned as cold node logs */
	DIRTY,			/* to count # of dirty segments */
	PRE,			/* to count # of entirely obsolete segments */
	NR_DIRTY_TYPE
};

The upper 6 bitmaps indicates segments dirtied by active log areas respectively.
And, the DIRTY bitmap integrates all the 6 bitmaps.

For example,
 o DIRTY_HOT_DATA : 1010000
 o DIRTY_WARM_DATA: 0100000
 o DIRTY_COLD_DATA: 0001000
 o DIRTY_HOT_NODE : 0000010
 o DIRTY_WARM_NODE: 0000001
 o DIRTY_COLD_NODE: 0000000
In this case,
 o DIRTY          : 1111011,

 which means that we should guarantee the consistency between DIRTY and other
 bitmaps concreately.

However, the SSR mode selects victims freely from any log types, which can set
multiple bits across the various bitmap types.

So, this patch eliminates this inconsistency.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
---
 fs/f2fs/segment.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fe520d3..7c67ec2 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -49,9 +49,20 @@ static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
 
 	if (dirty_type == DIRTY) {
 		struct seg_entry *sentry = get_seg_entry(sbi, segno);
+		enum dirty_type t = DIRTY_HOT_DATA;
+
 		dirty_type = sentry->type;
+
 		if (!test_and_set_bit(segno, dirty_i->dirty_segmap[dirty_type]))
 			dirty_i->nr_dirty[dirty_type]++;
+
+		/* Only one bitmap should be set */
+		for (; t <= DIRTY_COLD_NODE; t++) {
+			if (t == dirty_type)
+				continue;
+			if (test_and_clear_bit(segno, dirty_i->dirty_segmap[t]))
+				dirty_i->nr_dirty[t]--;
+		}
 	}
 }
 
@@ -64,11 +75,13 @@ static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
 		dirty_i->nr_dirty[dirty_type]--;
 
 	if (dirty_type == DIRTY) {
-		struct seg_entry *sentry = get_seg_entry(sbi, segno);
-		dirty_type = sentry->type;
-		if (test_and_clear_bit(segno,
-					dirty_i->dirty_segmap[dirty_type]))
-			dirty_i->nr_dirty[dirty_type]--;
+		enum dirty_type t = DIRTY_HOT_DATA;
+
+		/* clear all the bitmaps */
+		for (; t <= DIRTY_COLD_NODE; t++)
+			if (test_and_clear_bit(segno, dirty_i->dirty_segmap[t]))
+				dirty_i->nr_dirty[t]--;
+
 		if (get_valid_blocks(sbi, segno, sbi->segs_per_sec) == 0)
 			clear_bit(GET_SECNO(sbi, segno),
 						dirty_i->victim_secmap);
-- 
1.8.1.3.566.gaa39828

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