Hi Kim,
On 11/18/2013 05:12 PM, Jaegeuk Kim wrote:
> 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.
My god, I just sent out an almost the same patch, do we have a telepathy?:)
Regard,
Gu
>
> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
> ---
> fs/f2fs/data.c | 4 ----
> fs/f2fs/f2fs.h | 2 +-
> fs/f2fs/segment.c | 13 +++++++++----
> fs/f2fs/super.c | 2 +-
> 4 files changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 84867dc..7550026 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -390,8 +390,6 @@ 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);
>
> @@ -401,13 +399,11 @@ 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 1c783fd..76f5586 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -375,7 +375,7 @@ 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 write_mutex; /* mutex for writing IOs */
>
> /* for checkpoint */
> struct f2fs_checkpoint *ckpt; /* raw checkpoint pointer */
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index dad5f1a..893d489 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -871,9 +871,14 @@ 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);
> do_submit_bio(sbi, type, sync);
> - up_write(&sbi->bio_sem);
> + mutex_unlock(&sbi->write_mutex);
> }
>
> static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
> @@ -884,7 +889,7 @@ 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);
>
> inc_page_count(sbi, F2FS_WRITEBACK);
>
> @@ -919,7 +924,7 @@ retry:
>
> sbi->last_block_in_bio[type] = blk_addr;
>
> - up_write(&sbi->bio_sem);
> + mutex_unlock(&sbi->write_mutex);
> trace_f2fs_submit_write_page(page, blk_addr, type);
> }
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 2c52527..c7b6300 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -882,7 +882,7 @@ 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->write_mutex);
> init_rwsem(&sbi->cp_rwsem);
> init_waitqueue_head(&sbi->cp_wait);
> init_sb_info(sbi);
--
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