f2fs: use sbi->write_mutex for write bios

This patch removes an unnecessary semaphore (i.e., sbi->bio_sem).
There is no reason to use the semaphore when f2fs submits read and write IOs.
Instead, let's use a write mutex and cover the sbi->bio[] by the lock.

Change log from v1:
 o split write_mutex suggested by Chao Yu

Chao described,
"All DATA/NODE/META bio buffers in superblock is protected by
'sbi->write_mutex', but each bio buffer area is independent, So we
should split write_mutex to three for DATA/NODE/META."

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

1 files changed, 9 insertions, 4 deletions

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index d5043bd..68b8a2b 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -869,9 +869,14 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
 
 void f2fs_submit_bio(struct f2fs_sb_info *sbi, enum page_type type, bool sync)
 {
-	down_write(&sbi->bio_sem);
+	enum page_type btype = PAGE_TYPE_OF_BIO(type);
+
+	if (!sbi->bio[btype])
+		return;
+
+	mutex_lock(&sbi->write_mutex[btype]);
 	do_submit_bio(sbi, type, sync);
-	up_write(&sbi->bio_sem);
+	mutex_unlock(&sbi->write_mutex[btype]);
 }
 
 static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
@@ -882,7 +887,7 @@ static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
 
 	verify_block_addr(sbi, blk_addr);
 
-	down_write(&sbi->bio_sem);
+	mutex_lock(&sbi->write_mutex[type]);
 
 	inc_page_count(sbi, F2FS_WRITEBACK);
 
@@ -917,7 +922,7 @@ retry:
 
 	sbi->last_block_in_bio[type] = blk_addr;
 
-	up_write(&sbi->bio_sem);
+	mutex_unlock(&sbi->write_mutex[type]);
 	trace_f2fs_submit_write_page(page, blk_addr, type);
 }