[PATCH] f2fs: use mutex rather than the rw_sem

From: Gu Zheng
Date: Mon Nov 18 2013 - 04:20:52 EST


Use mutex rather than the rw_sem to protect bio related fields,
because it's needless to take the read_sem in the read path.


Signed-off-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
---
fs/f2fs/data.c | 4 ----
fs/f2fs/f2fs.h | 2 +-
fs/f2fs/segment.c | 8 ++++----
fs/f2fs/super.c | 2 +-
4 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index aa3438c..b4e4c7e 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -383,8 +383,6 @@ int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,

trace_f2fs_readpage(page, blk_addr, type);

- down_read(&sbi->bio_sem);
-
/* Allocate a new bio */
bio = f2fs_bio_alloc(bdev, 1);

@@ -394,13 +392,11 @@ int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,

if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
bio_put(bio);
- up_read(&sbi->bio_sem);
f2fs_put_page(page, 1);
return -EFAULT;
}

submit_bio(type, bio);
- up_read(&sbi->bio_sem);
return 0;
}

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 89dc750..78a0054 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -361,7 +361,7 @@ struct f2fs_sb_info {
struct f2fs_sm_info *sm_info; /* segment manager */
struct bio *bio[NR_PAGE_TYPE]; /* bios to merge */
sector_t last_block_in_bio[NR_PAGE_TYPE]; /* last block number */
- struct rw_semaphore bio_sem; /* IO semaphore */
+ struct mutex bio_mutex; /* IO write mutex */

/* for checkpoint */
struct f2fs_checkpoint *ckpt; /* raw checkpoint pointer */
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fa284d3..e91f65c 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -653,9 +653,9 @@ 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);
+ mutex_lock(&sbi->bio_mutex);
do_submit_bio(sbi, type, sync);
- up_write(&sbi->bio_sem);
+ mutex_unlock(&sbi->bio_mutex);
}

static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
@@ -666,7 +666,7 @@ 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->bio_mutex);

inc_page_count(sbi, F2FS_WRITEBACK);

@@ -701,7 +701,7 @@ retry:

sbi->last_block_in_bio[type] = blk_addr;

- up_write(&sbi->bio_sem);
+ mutex_unlock(&sbi->bio_mutex);
trace_f2fs_submit_write_page(page, blk_addr, type);
}

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index bafff72..fab3550 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -874,7 +874,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
mutex_init(&sbi->node_write);
sbi->por_doing = false;
spin_lock_init(&sbi->stat_lock);
- init_rwsem(&sbi->bio_sem);
+ mutex_init(&sbi->bio_mutex);
init_rwsem(&sbi->cp_rwsem);
init_waitqueue_head(&sbi->cp_wait);
init_sb_info(sbi);
--
1.7.7

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