linux-kernel - [PATCH 8/9] f2fs: avoid race for summary information

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Date:	Mon, 01 Apr 2013 15:55:59 +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 8/9] f2fs: avoid race for summary information

In order to do GC more reliably, I'd like to lock the vicitm summary page
until its GC is completed, and also prevent any checkpoint process.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
---
 fs/f2fs/gc.c    | 8 +-------
 fs/f2fs/node.c  | 2 +-
 fs/f2fs/super.c | 7 +++++--
 3 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 54aceb2..54ac13d 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -641,12 +641,6 @@ static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
 	if (IS_ERR(sum_page))
 		return;
 
-	/*
-	 * CP needs to lock sum_page. In this time, we don't need
-	 * to lock this page, because this summary page is not gone anywhere.
-	 * Also, this page is not gonna be updated before GC is done.
-	 */
-	unlock_page(sum_page);
 	sum = page_address(sum_page);
 
 	switch (GET_SUM_TYPE((&sum->footer))) {
@@ -660,7 +654,7 @@ static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
 	stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
 	stat_inc_call_count(sbi->stat_info);
 
-	f2fs_put_page(sum_page, 0);
+	f2fs_put_page(sum_page, 1);
 }
 
 int f2fs_gc(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index c5360b7..7555fb7 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1148,7 +1148,7 @@ static int f2fs_write_node_pages(struct address_space *mapping,
 
 	/* First check balancing cached NAT entries */
 	if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) {
-		write_checkpoint(sbi, false);
+		f2fs_sync_fs(sbi->sb, true);
 		return 0;
 	}
 
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index ea325c8..161e6c6 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -137,10 +137,13 @@ int f2fs_sync_fs(struct super_block *sb, int sync)
 	if (!sbi->s_dirty && !get_pages(sbi, F2FS_DIRTY_NODES))
 		return 0;
 
-	if (sync)
+	if (sync) {
+		mutex_lock(&sbi->gc_mutex);
 		write_checkpoint(sbi, false);
-	else
+		mutex_unlock(&sbi->gc_mutex);
+	} else {
 		f2fs_balance_fs(sbi);
+	}
 
 	return 0;
 }
-- 
1.8.1.3.566.gaa39828

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