[PATCH 1/2] f2fs: clean up the do_submit_bio flow

[PATCH 1/2] f2fs: clean up the do_submit_bio flow

[Jaegeuk Kim]

This patch introduces PAGE_TYPE_OF_BIO() and cleans up do_submit_bio() with it.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
---
 fs/f2fs/f2fs.h    |  1 +
 fs/f2fs/segment.c | 39 +++++++++++++++++++++------------------
 2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index fe5c2fc..1c783fd 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -351,6 +351,7 @@ enum count_type {
  *			with waiting the bio's completion
  * ...			Only can be used with META.
  */
+#define PAGE_TYPE_OF_BIO(type)	(type) > META ? META : (type)
 enum page_type {
 	DATA,
 	NODE,
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 1f83999..dad5f1a 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -837,32 +837,35 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
 				enum page_type type, bool sync)
 {
 	int rw = sync ? WRITE_SYNC : WRITE;
-	enum page_type btype = type > META ? META : type;
+	enum page_type btype = PAGE_TYPE_OF_BIO(type);
+	struct bio *bio = sbi->bio[btype];
+	struct bio_private *p;
+
+	if (!bio)
+		return;
+
+	sbi->bio[btype] = NULL;
 
 	if (type >= META_FLUSH)
 		rw = WRITE_FLUSH_FUA;
-
 	if (btype == META)
 		rw |= REQ_META;
 
-	if (sbi->bio[btype]) {
-		struct bio_private *p = sbi->bio[btype]->bi_private;
-		p->sbi = sbi;
-		sbi->bio[btype]->bi_end_io = f2fs_end_io_write;
+	p = bio->bi_private;
+	p->sbi = sbi;
+	bio->bi_end_io = f2fs_end_io_write;
 
-		trace_f2fs_do_submit_bio(sbi->sb, btype, sync, sbi->bio[btype]);
+	trace_f2fs_do_submit_bio(sbi->sb, btype, sync, bio);
 
-		if (type == META_FLUSH) {
-			DECLARE_COMPLETION_ONSTACK(wait);
-			p->is_sync = true;
-			p->wait = &wait;
-			submit_bio(rw, sbi->bio[btype]);
-			wait_for_completion(&wait);
-		} else {
-			p->is_sync = false;
-			submit_bio(rw, sbi->bio[btype]);
-		}
-		sbi->bio[btype] = NULL;
+	if (type == META_FLUSH) {
+		DECLARE_COMPLETION_ONSTACK(wait);
+		p->is_sync = true;
+		p->wait = &wait;
+		submit_bio(rw, bio);
+		wait_for_completion(&wait);
+	} else {
+		p->is_sync = false;
+		submit_bio(rw, bio);
 	}
 }
 
-- 
1.8.4.474.g128a96c

[PATCH 2/2] f2fs: use sbi->wr_mutex for write bios

[Jaegeuk Kim]

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.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
---
 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);
-- 
1.8.4.474.g128a96c

Re: [PATCH 2/2] f2fs: use sbi->wr_mutex for write bios

[Gu Zheng]

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@samsung.com>
> ---
>  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);

Re: [PATCH 2/2] f2fs: use sbi->wr_mutex for write bios

[Jaegeuk Kim]

Hi Gu,

2013-11-18 (월), 17:21 +0800, Gu Zheng:
> 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?:)

Wow, it seems so. :)

-- 
Jaegeuk Kim
Samsung

RE: [f2fs-dev] [PATCH 1/2] f2fs: clean up the do_submit_bio flow

[Chao Yu]

Hi

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@samsung.com]
> Sent: Monday, November 18, 2013 5:12 PM
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Subject: [f2fs-dev] [PATCH 1/2] f2fs: clean up the do_submit_bio flow
> 
> This patch introduces PAGE_TYPE_OF_BIO() and cleans up do_submit_bio() with
it.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> ---
>  fs/f2fs/f2fs.h    |  1 +
>  fs/f2fs/segment.c | 39 +++++++++++++++++++++------------------
>  2 files changed, 22 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index fe5c2fc..1c783fd 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -351,6 +351,7 @@ enum count_type {
>   *			with waiting the bio's completion
>   * ...			Only can be used with META.
>   */
> +#define PAGE_TYPE_OF_BIO(type)	(type) > META ? META : (type)

We'd better to add parentheses for macro to avoid style problem.:)

#define PAGE_TYPE_OF_BIO(type)	((type) > META ? META : (type))

>  enum page_type {
>  	DATA,
>  	NODE,
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 1f83999..dad5f1a 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -837,32 +837,35 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
>  				enum page_type type, bool sync)
>  {
>  	int rw = sync ? WRITE_SYNC : WRITE;
> -	enum page_type btype = type > META ? META : type;
> +	enum page_type btype = PAGE_TYPE_OF_BIO(type);
> +	struct bio *bio = sbi->bio[btype];
> +	struct bio_private *p;
> +
> +	if (!bio)
> +		return;
> +
> +	sbi->bio[btype] = NULL;
> 
>  	if (type >= META_FLUSH)
>  		rw = WRITE_FLUSH_FUA;
> -
>  	if (btype == META)
>  		rw |= REQ_META;
> 
> -	if (sbi->bio[btype]) {
> -		struct bio_private *p = sbi->bio[btype]->bi_private;
> -		p->sbi = sbi;
> -		sbi->bio[btype]->bi_end_io = f2fs_end_io_write;
> +	p = bio->bi_private;
> +	p->sbi = sbi;
> +	bio->bi_end_io = f2fs_end_io_write;
> 
> -		trace_f2fs_do_submit_bio(sbi->sb, btype, sync, sbi->bio[btype]);
> +	trace_f2fs_do_submit_bio(sbi->sb, btype, sync, bio);
> 
> -		if (type == META_FLUSH) {
> -			DECLARE_COMPLETION_ONSTACK(wait);
> -			p->is_sync = true;
> -			p->wait = &wait;
> -			submit_bio(rw, sbi->bio[btype]);
> -			wait_for_completion(&wait);
> -		} else {
> -			p->is_sync = false;
> -			submit_bio(rw, sbi->bio[btype]);
> -		}
> -		sbi->bio[btype] = NULL;
> +	if (type == META_FLUSH) {
> +		DECLARE_COMPLETION_ONSTACK(wait);
> +		p->is_sync = true;
> +		p->wait = &wait;
> +		submit_bio(rw, bio);
> +		wait_for_completion(&wait);
> +	} else {
> +		p->is_sync = false;
> +		submit_bio(rw, bio);
>  	}
>  }
> 
> --
> 1.8.4.474.g128a96c
> 
> 
> ------------------------------------------------------------------------------
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RE: [f2fs-dev] [PATCH 1/2] f2fs: clean up the do_submit_bio flow

[Chao Yu]

Hi

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@samsung.com]
> Sent: Monday, November 18, 2013 5:12 PM
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net
> Subject: [f2fs-dev] [PATCH 1/2] f2fs: clean up the do_submit_bio flow
> 
> This patch introduces PAGE_TYPE_OF_BIO() and cleans up do_submit_bio() with it.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> ---
>  fs/f2fs/f2fs.h    |  1 +
>  fs/f2fs/segment.c | 39 +++++++++++++++++++++------------------
>  2 files changed, 22 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index fe5c2fc..1c783fd 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -351,6 +351,7 @@ enum count_type {
>   *			with waiting the bio's completion
>   * ...			Only can be used with META.
>   */
> +#define PAGE_TYPE_OF_BIO(type)	(type) > META ? META : (type)
>  enum page_type {
>  	DATA,
>  	NODE,
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 1f83999..dad5f1a 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -837,32 +837,35 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
>  				enum page_type type, bool sync)
>  {
>  	int rw = sync ? WRITE_SYNC : WRITE;
> -	enum page_type btype = type > META ? META : type;
> +	enum page_type btype = PAGE_TYPE_OF_BIO(type);

->f2fs_submit_bio()
	: enum page_type btype = PAGE_TYPE_OF_BIO(type);
	->do_submit_bio()
		: enum page_type btype = PAGE_TYPE_OF_BIO(type);

Could we remove PAGE_TYPE_OF_BIO or use f2fs_bug_on to instead
in do_submit_bio()? because it looks redundant , and also 
submit_write_page() will not pass the type which is larger than META.

> +	struct bio *bio = sbi->bio[btype];
> +	struct bio_private *p;
> +
> +	if (!bio)
> +		return;
> +
> +	sbi->bio[btype] = NULL;
> 
>  	if (type >= META_FLUSH)
>  		rw = WRITE_FLUSH_FUA;
> -
>  	if (btype == META)
>  		rw |= REQ_META;
> 
> -	if (sbi->bio[btype]) {
> -		struct bio_private *p = sbi->bio[btype]->bi_private;
> -		p->sbi = sbi;
> -		sbi->bio[btype]->bi_end_io = f2fs_end_io_write;
> +	p = bio->bi_private;
> +	p->sbi = sbi;
> +	bio->bi_end_io = f2fs_end_io_write;
> 
> -		trace_f2fs_do_submit_bio(sbi->sb, btype, sync, sbi->bio[btype]);
> +	trace_f2fs_do_submit_bio(sbi->sb, btype, sync, bio);
> 
> -		if (type == META_FLUSH) {
> -			DECLARE_COMPLETION_ONSTACK(wait);
> -			p->is_sync = true;
> -			p->wait = &wait;
> -			submit_bio(rw, sbi->bio[btype]);
> -			wait_for_completion(&wait);
> -		} else {
> -			p->is_sync = false;
> -			submit_bio(rw, sbi->bio[btype]);
> -		}
> -		sbi->bio[btype] = NULL;
> +	if (type == META_FLUSH) {
> +		DECLARE_COMPLETION_ONSTACK(wait);
> +		p->is_sync = true;
> +		p->wait = &wait;
> +		submit_bio(rw, bio);
> +		wait_for_completion(&wait);
> +	} else {
> +		p->is_sync = false;
> +		submit_bio(rw, bio);
>  	}
>  }
> 
> --
> 1.8.4.474.g128a96c
> 
> 
> ------------------------------------------------------------------------------
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> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

RE: [f2fs-dev] [PATCH 1/2] f2fs: clean up the do_submit_bio flow

[Jaegeuk Kim]

Hi,

2013-11-19 (화), 13:25 +0800, Chao Yu:
> Hi
> 
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk.kim@samsung.com]
> > Sent: Monday, November 18, 2013 5:12 PM
> > Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net
> > Subject: [f2fs-dev] [PATCH 1/2] f2fs: clean up the do_submit_bio flow
> > 
> > This patch introduces PAGE_TYPE_OF_BIO() and cleans up do_submit_bio() with it.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> > ---
> >  fs/f2fs/f2fs.h    |  1 +
> >  fs/f2fs/segment.c | 39 +++++++++++++++++++++------------------
> >  2 files changed, 22 insertions(+), 18 deletions(-)
> > 
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index fe5c2fc..1c783fd 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -351,6 +351,7 @@ enum count_type {
> >   *			with waiting the bio's completion
> >   * ...			Only can be used with META.
> >   */
> > +#define PAGE_TYPE_OF_BIO(type)	(type) > META ? META : (type)


I'll add parenthesis as you suggested. Thanks.

> >  enum page_type {
> >  	DATA,
> >  	NODE,
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 1f83999..dad5f1a 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -837,32 +837,35 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
> >  				enum page_type type, bool sync)
> >  {
> >  	int rw = sync ? WRITE_SYNC : WRITE;
> > -	enum page_type btype = type > META ? META : type;
> > +	enum page_type btype = PAGE_TYPE_OF_BIO(type);
> 
> ->f2fs_submit_bio()
> 	: enum page_type btype = PAGE_TYPE_OF_BIO(type);
> 	->do_submit_bio()
> 		: enum page_type btype = PAGE_TYPE_OF_BIO(type);
> 
> Could we remove PAGE_TYPE_OF_BIO or use f2fs_bug_on to instead
> in do_submit_bio()? because it looks redundant , and also 
> submit_write_page() will not pass the type which is larger than META.

The f2fs_submit_bio(type) calls do_submit_bio(type) in which the type is
able to be META_FLUSH from sync_meta_pages().
So, we need to do this. :)

-- 
Jaegeuk Kim
Samsung