[f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

[f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

[Chao Yu]

Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together.
So we read pages as contiguous as possible for better mount performance.

v1-->v2:
 o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng suggested.
 o add mark_page_accessed () before release page to delay VM reclaiming them.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
 fs/f2fs/segment.c |  108 ++++++++++++++++++++++++++++++++++++++++-------------
 fs/f2fs/segment.h |    2 +
 2 files changed, 84 insertions(+), 26 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fa284d3..656fe40 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -14,6 +14,7 @@
 #include <linux/blkdev.h>
 #include <linux/prefetch.h>
 #include <linux/vmalloc.h>
+#include <linux/swap.h>
 
 #include "f2fs.h"
 #include "segment.h"
@@ -1480,41 +1481,96 @@ static int build_curseg(struct f2fs_sb_info *sbi)
 	return restore_curseg_summaries(sbi);
 }
 
+static int ra_sit_pages(struct f2fs_sb_info *sbi, int start,
+					int nrpages, bool *is_order)
+{
+	struct address_space *mapping = sbi->meta_inode->i_mapping;
+	struct sit_info *sit_i = SIT_I(sbi);
+	struct page *page;
+	block_t blk_addr;
+	int blkno = start, readcnt = 0;
+	int sit_blk_cnt = SIT_BLK_CNT(sbi);
+
+	for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
+
+		if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
+			*is_order = !*is_order;
+			break;
+		}
+
+		blk_addr = sit_i->sit_base_addr + blkno;
+		if (*is_order)
+			blk_addr += sit_i->sit_blocks;
+repeat:
+		page = grab_cache_page(mapping, blk_addr);
+		if (!page) {
+			cond_resched();
+			goto repeat;
+		}
+		if (PageUptodate(page)) {
+			mark_page_accessed(page);
+			f2fs_put_page(page, 1);
+			readcnt++;
+			continue;
+		}
+
+		submit_read_page(sbi, page, blk_addr, READ_SYNC);
+
+		mark_page_accessed(page);
+		f2fs_put_page(page, 0);
+		readcnt++;
+	}
+
+	f2fs_submit_read_bio(sbi, READ_SYNC);
+	return readcnt;
+}
+
 static void build_sit_entries(struct f2fs_sb_info *sbi)
 {
 	struct sit_info *sit_i = SIT_I(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
 	struct f2fs_summary_block *sum = curseg->sum_blk;
-	unsigned int start;
-
-	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
-		struct seg_entry *se = &sit_i->sentries[start];
-		struct f2fs_sit_block *sit_blk;
-		struct f2fs_sit_entry sit;
-		struct page *page;
-		int i;
+	bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
+	int sit_blk_cnt = SIT_BLK_CNT(sbi);
+	unsigned int i, start, end;
+	unsigned int readed, start_blk = 0;
 
-		mutex_lock(&curseg->curseg_mutex);
-		for (i = 0; i < sits_in_cursum(sum); i++) {
-			if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
-				sit = sit_in_journal(sum, i);
-				mutex_unlock(&curseg->curseg_mutex);
-				goto got_it;
+	do {
+		readed = ra_sit_pages(sbi, start_blk, sit_blk_cnt, &is_order);
+
+		start = start_blk * sit_i->sents_per_block;
+		end = (start_blk + readed) * sit_i->sents_per_block;
+
+		for (; start < end && start < TOTAL_SEGS(sbi); start++) {
+			struct seg_entry *se = &sit_i->sentries[start];
+			struct f2fs_sit_block *sit_blk;
+			struct f2fs_sit_entry sit;
+			struct page *page;
+
+			mutex_lock(&curseg->curseg_mutex);
+			for (i = 0; i < sits_in_cursum(sum); i++) {
+				if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
+					sit = sit_in_journal(sum, i);
+					mutex_unlock(&curseg->curseg_mutex);
+					goto got_it;
+				}
 			}
-		}
-		mutex_unlock(&curseg->curseg_mutex);
-		page = get_current_sit_page(sbi, start);
-		sit_blk = (struct f2fs_sit_block *)page_address(page);
-		sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
-		f2fs_put_page(page, 1);
+			mutex_unlock(&curseg->curseg_mutex);
+
+			page = get_current_sit_page(sbi, start);
+			sit_blk = (struct f2fs_sit_block *)page_address(page);
+			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
+			f2fs_put_page(page, 1);
 got_it:
-		check_block_count(sbi, start, &sit);
-		seg_info_from_raw_sit(se, &sit);
-		if (sbi->segs_per_sec > 1) {
-			struct sec_entry *e = get_sec_entry(sbi, start);
-			e->valid_blocks += se->valid_blocks;
+			check_block_count(sbi, start, &sit);
+			seg_info_from_raw_sit(se, &sit);
+			if (sbi->segs_per_sec > 1) {
+				struct sec_entry *e = get_sec_entry(sbi, start);
+				e->valid_blocks += se->valid_blocks;
+			}
 		}
-	}
+		start_blk += readed;
+	} while (start_blk < sit_blk_cnt);
 }
 
 static void init_free_segmap(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 269f690..ad5b9f1 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -83,6 +83,8 @@
 	(segno / SIT_ENTRY_PER_BLOCK)
 #define	START_SEGNO(sit_i, segno)		\
 	(SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
+#define SIT_BLK_CNT(sbi)			\
+	((TOTAL_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
 #define f2fs_bitmap_size(nr)			\
 	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
 #define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)
-- 
1.7.9.5

Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

[Gu Zheng]

Hi Yu,
One more comment, please refer to inline.
On 11/16/2013 02:15 PM, Chao Yu wrote:

> Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together.
> So we read pages as contiguous as possible for better mount performance.
> 
> v1-->v2:
>  o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng suggested.
>  o add mark_page_accessed () before release page to delay VM reclaiming them.
> 
> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> ---
>  fs/f2fs/segment.c |  108 ++++++++++++++++++++++++++++++++++++++++-------------
>  fs/f2fs/segment.h |    2 +
>  2 files changed, 84 insertions(+), 26 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index fa284d3..656fe40 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -14,6 +14,7 @@
>  #include <linux/blkdev.h>
>  #include <linux/prefetch.h>
>  #include <linux/vmalloc.h>
> +#include <linux/swap.h>
>  
>  #include "f2fs.h"
>  #include "segment.h"
> @@ -1480,41 +1481,96 @@ static int build_curseg(struct f2fs_sb_info *sbi)
>  	return restore_curseg_summaries(sbi);
>  }
>  
> +static int ra_sit_pages(struct f2fs_sb_info *sbi, int start,
> +					int nrpages, bool *is_order)
> +{
> +	struct address_space *mapping = sbi->meta_inode->i_mapping;
> +	struct sit_info *sit_i = SIT_I(sbi);
> +	struct page *page;
> +	block_t blk_addr;
> +	int blkno = start, readcnt = 0;
> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
> +
> +	for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
> +
> +		if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
> +			*is_order = !*is_order;
> +			break;
> +		}
> +
> +		blk_addr = sit_i->sit_base_addr + blkno;
> +		if (*is_order)
> +			blk_addr += sit_i->sit_blocks;
> +repeat:
> +		page = grab_cache_page(mapping, blk_addr);
> +		if (!page) {
> +			cond_resched();
> +			goto repeat;
> +		}
> +		if (PageUptodate(page)) {
> +			mark_page_accessed(page);
> +			f2fs_put_page(page, 1);
> +			readcnt++;
> +			continue;
> +		}
> +
> +		submit_read_page(sbi, page, blk_addr, READ_SYNC);
> +
> +		mark_page_accessed(page);
> +		f2fs_put_page(page, 0);
> +		readcnt++;
> +	}
> +
> +	f2fs_submit_read_bio(sbi, READ_SYNC);
> +	return readcnt;
> +}
> +
>  static void build_sit_entries(struct f2fs_sb_info *sbi)
>  {
>  	struct sit_info *sit_i = SIT_I(sbi);
>  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
>  	struct f2fs_summary_block *sum = curseg->sum_blk;
> -	unsigned int start;
> -
> -	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
> -		struct seg_entry *se = &sit_i->sentries[start];
> -		struct f2fs_sit_block *sit_blk;
> -		struct f2fs_sit_entry sit;
> -		struct page *page;
> -		int i;
> +	bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
> +	unsigned int i, start, end;
> +	unsigned int readed, start_blk = 0;
>  
> -		mutex_lock(&curseg->curseg_mutex);
> -		for (i = 0; i < sits_in_cursum(sum); i++) {
> -			if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> -				sit = sit_in_journal(sum, i);
> -				mutex_unlock(&curseg->curseg_mutex);
> -				goto got_it;
> +	do {

How about using find_next_bit to get the suitable start_blk if the next blk
is not ordered here? And it also can simplify the logic of ra_sit_pages().

Thanks,
Gu

> +		readed = ra_sit_pages(sbi, start_blk, sit_blk_cnt, &is_order);
> +
> +		start = start_blk * sit_i->sents_per_block;
> +		end = (start_blk + readed) * sit_i->sents_per_block;
> +
> +		for (; start < end && start < TOTAL_SEGS(sbi); start++) {
> +			struct seg_entry *se = &sit_i->sentries[start];
> +			struct f2fs_sit_block *sit_blk;
> +			struct f2fs_sit_entry sit;
> +			struct page *page;
> +
> +			mutex_lock(&curseg->curseg_mutex);
> +			for (i = 0; i < sits_in_cursum(sum); i++) {
> +				if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> +					sit = sit_in_journal(sum, i);
> +					mutex_unlock(&curseg->curseg_mutex);
> +					goto got_it;
> +				}
>  			}
> -		}
> -		mutex_unlock(&curseg->curseg_mutex);
> -		page = get_current_sit_page(sbi, start);
> -		sit_blk = (struct f2fs_sit_block *)page_address(page);
> -		sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> -		f2fs_put_page(page, 1);
> +			mutex_unlock(&curseg->curseg_mutex);
> +
> +			page = get_current_sit_page(sbi, start);
> +			sit_blk = (struct f2fs_sit_block *)page_address(page);
> +			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> +			f2fs_put_page(page, 1);
>  got_it:
> -		check_block_count(sbi, start, &sit);
> -		seg_info_from_raw_sit(se, &sit);
> -		if (sbi->segs_per_sec > 1) {
> -			struct sec_entry *e = get_sec_entry(sbi, start);
> -			e->valid_blocks += se->valid_blocks;
> +			check_block_count(sbi, start, &sit);
> +			seg_info_from_raw_sit(se, &sit);
> +			if (sbi->segs_per_sec > 1) {
> +				struct sec_entry *e = get_sec_entry(sbi, start);
> +				e->valid_blocks += se->valid_blocks;
> +			}
>  		}
> -	}
> +		start_blk += readed;




> +	} while (start_blk < sit_blk_cnt);
>  }
>  
>  static void init_free_segmap(struct f2fs_sb_info *sbi)
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 269f690..ad5b9f1 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -83,6 +83,8 @@
>  	(segno / SIT_ENTRY_PER_BLOCK)
>  #define	START_SEGNO(sit_i, segno)		\
>  	(SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
> +#define SIT_BLK_CNT(sbi)			\
> +	((TOTAL_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
>  #define f2fs_bitmap_size(nr)			\
>  	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
>  #define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)

RE: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

[Chao Yu]

Hi Gu,

> -----Original Message-----
> From: Gu Zheng [mailto:guz.fnst@cn.fujitsu.com]
> Sent: Monday, November 18, 2013 7:16 PM
> To: Chao Yu
> Cc: '???'; linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; 谭姝
> Subject: Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance
> 
> Hi Yu,
> One more comment, please refer to inline.
> On 11/16/2013 02:15 PM, Chao Yu wrote:
> 
> > Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together.
> > So we read pages as contiguous as possible for better mount performance.
> >
> > v1-->v2:
> >  o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng suggested.
> >  o add mark_page_accessed () before release page to delay VM reclaiming them.
> >
> > Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> > ---
> >  fs/f2fs/segment.c |  108 ++++++++++++++++++++++++++++++++++++++++-------------
> >  fs/f2fs/segment.h |    2 +
> >  2 files changed, 84 insertions(+), 26 deletions(-)
> >
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index fa284d3..656fe40 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/blkdev.h>
> >  #include <linux/prefetch.h>
> >  #include <linux/vmalloc.h>
> > +#include <linux/swap.h>
> >
> >  #include "f2fs.h"
> >  #include "segment.h"
> > @@ -1480,41 +1481,96 @@ static int build_curseg(struct f2fs_sb_info *sbi)
> >  	return restore_curseg_summaries(sbi);
> >  }
> >
> > +static int ra_sit_pages(struct f2fs_sb_info *sbi, int start,
> > +					int nrpages, bool *is_order)
> > +{
> > +	struct address_space *mapping = sbi->meta_inode->i_mapping;
> > +	struct sit_info *sit_i = SIT_I(sbi);
> > +	struct page *page;
> > +	block_t blk_addr;
> > +	int blkno = start, readcnt = 0;
> > +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
> > +
> > +	for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
> > +
> > +		if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
> > +			*is_order = !*is_order;
> > +			break;
> > +		}
> > +
> > +		blk_addr = sit_i->sit_base_addr + blkno;
> > +		if (*is_order)
> > +			blk_addr += sit_i->sit_blocks;
> > +repeat:
> > +		page = grab_cache_page(mapping, blk_addr);
> > +		if (!page) {
> > +			cond_resched();
> > +			goto repeat;
> > +		}
> > +		if (PageUptodate(page)) {
> > +			mark_page_accessed(page);
> > +			f2fs_put_page(page, 1);
> > +			readcnt++;
> > +			continue;
> > +		}
> > +
> > +		submit_read_page(sbi, page, blk_addr, READ_SYNC);
> > +
> > +		mark_page_accessed(page);
> > +		f2fs_put_page(page, 0);
> > +		readcnt++;
> > +	}
> > +
> > +	f2fs_submit_read_bio(sbi, READ_SYNC);
> > +	return readcnt;
> > +}
> > +
> >  static void build_sit_entries(struct f2fs_sb_info *sbi)
> >  {
> >  	struct sit_info *sit_i = SIT_I(sbi);
> >  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
> >  	struct f2fs_summary_block *sum = curseg->sum_blk;
> > -	unsigned int start;
> > -
> > -	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
> > -		struct seg_entry *se = &sit_i->sentries[start];
> > -		struct f2fs_sit_block *sit_blk;
> > -		struct f2fs_sit_entry sit;
> > -		struct page *page;
> > -		int i;
> > +	bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
> > +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
> > +	unsigned int i, start, end;
> > +	unsigned int readed, start_blk = 0;
> >
> > -		mutex_lock(&curseg->curseg_mutex);
> > -		for (i = 0; i < sits_in_cursum(sum); i++) {
> > -			if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> > -				sit = sit_in_journal(sum, i);
> > -				mutex_unlock(&curseg->curseg_mutex);
> > -				goto got_it;
> > +	do {
> 
> How about using find_next_bit to get the suitable start_blk if the next blk
> is not ordered here? And it also can simplify the logic of ra_sit_pages().

That's a good idea.
But I thought there maybe endianness problem between test_bit and 
f2fs_test_bit, so find_next_bit may get wrong result. Am I right?

Thanks,
Yu
> 
> Thanks,
> Gu
> 
> > +		readed = ra_sit_pages(sbi, start_blk, sit_blk_cnt, &is_order);
> > +
> > +		start = start_blk * sit_i->sents_per_block;
> > +		end = (start_blk + readed) * sit_i->sents_per_block;
> > +
> > +		for (; start < end && start < TOTAL_SEGS(sbi); start++) {
> > +			struct seg_entry *se = &sit_i->sentries[start];
> > +			struct f2fs_sit_block *sit_blk;
> > +			struct f2fs_sit_entry sit;
> > +			struct page *page;
> > +
> > +			mutex_lock(&curseg->curseg_mutex);
> > +			for (i = 0; i < sits_in_cursum(sum); i++) {
> > +				if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> > +					sit = sit_in_journal(sum, i);
> > +					mutex_unlock(&curseg->curseg_mutex);
> > +					goto got_it;
> > +				}
> >  			}
> > -		}
> > -		mutex_unlock(&curseg->curseg_mutex);
> > -		page = get_current_sit_page(sbi, start);
> > -		sit_blk = (struct f2fs_sit_block *)page_address(page);
> > -		sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> > -		f2fs_put_page(page, 1);
> > +			mutex_unlock(&curseg->curseg_mutex);
> > +
> > +			page = get_current_sit_page(sbi, start);
> > +			sit_blk = (struct f2fs_sit_block *)page_address(page);
> > +			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> > +			f2fs_put_page(page, 1);
> >  got_it:
> > -		check_block_count(sbi, start, &sit);
> > -		seg_info_from_raw_sit(se, &sit);
> > -		if (sbi->segs_per_sec > 1) {
> > -			struct sec_entry *e = get_sec_entry(sbi, start);
> > -			e->valid_blocks += se->valid_blocks;
> > +			check_block_count(sbi, start, &sit);
> > +			seg_info_from_raw_sit(se, &sit);
> > +			if (sbi->segs_per_sec > 1) {
> > +				struct sec_entry *e = get_sec_entry(sbi, start);
> > +				e->valid_blocks += se->valid_blocks;
> > +			}
> >  		}
> > -	}
> > +		start_blk += readed;
> 
> 
> 
> 
> > +	} while (start_blk < sit_blk_cnt);
> >  }
> >
> >  static void init_free_segmap(struct f2fs_sb_info *sbi)
> > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> > index 269f690..ad5b9f1 100644
> > --- a/fs/f2fs/segment.h
> > +++ b/fs/f2fs/segment.h
> > @@ -83,6 +83,8 @@
> >  	(segno / SIT_ENTRY_PER_BLOCK)
> >  #define	START_SEGNO(sit_i, segno)		\
> >  	(SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
> > +#define SIT_BLK_CNT(sbi)			\
> > +	((TOTAL_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
> >  #define f2fs_bitmap_size(nr)			\
> >  	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
> >  #define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)

Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

[Gu Zheng]

Hi Yu,
On 11/20/2013 01:37 PM, Chao Yu wrote:

> Hi Gu,
> 
>> -----Original Message-----
>> From: Gu Zheng [mailto:guz.fnst@cn.fujitsu.com]
>> Sent: Monday, November 18, 2013 7:16 PM
>> To: Chao Yu
>> Cc: '???'; linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; 谭姝
>> Subject: Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance
>>
>> Hi Yu,
>> One more comment, please refer to inline.
>> On 11/16/2013 02:15 PM, Chao Yu wrote:
>>
>>> Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together.
>>> So we read pages as contiguous as possible for better mount performance.
>>>
>>> v1-->v2:
>>>  o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng suggested.
>>>  o add mark_page_accessed () before release page to delay VM reclaiming them.
>>>
>>> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
>>> ---
>>>  fs/f2fs/segment.c |  108 ++++++++++++++++++++++++++++++++++++++++-------------
>>>  fs/f2fs/segment.h |    2 +
>>>  2 files changed, 84 insertions(+), 26 deletions(-)
>>>
>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>> index fa284d3..656fe40 100644
>>> --- a/fs/f2fs/segment.c
>>> +++ b/fs/f2fs/segment.c
>>> @@ -14,6 +14,7 @@
>>>  #include <linux/blkdev.h>
>>>  #include <linux/prefetch.h>
>>>  #include <linux/vmalloc.h>
>>> +#include <linux/swap.h>
>>>
>>>  #include "f2fs.h"
>>>  #include "segment.h"
>>> @@ -1480,41 +1481,96 @@ static int build_curseg(struct f2fs_sb_info *sbi)
>>>  	return restore_curseg_summaries(sbi);
>>>  }
>>>
>>> +static int ra_sit_pages(struct f2fs_sb_info *sbi, int start,
>>> +					int nrpages, bool *is_order)
>>> +{
>>> +	struct address_space *mapping = sbi->meta_inode->i_mapping;
>>> +	struct sit_info *sit_i = SIT_I(sbi);
>>> +	struct page *page;
>>> +	block_t blk_addr;
>>> +	int blkno = start, readcnt = 0;
>>> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
>>> +
>>> +	for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
>>> +
>>> +		if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
>>> +			*is_order = !*is_order;
>>> +			break;
>>> +		}
>>> +
>>> +		blk_addr = sit_i->sit_base_addr + blkno;
>>> +		if (*is_order)
>>> +			blk_addr += sit_i->sit_blocks;
>>> +repeat:
>>> +		page = grab_cache_page(mapping, blk_addr);
>>> +		if (!page) {
>>> +			cond_resched();
>>> +			goto repeat;
>>> +		}
>>> +		if (PageUptodate(page)) {
>>> +			mark_page_accessed(page);
>>> +			f2fs_put_page(page, 1);
>>> +			readcnt++;
>>> +			continue;
>>> +		}
>>> +
>>> +		submit_read_page(sbi, page, blk_addr, READ_SYNC);
>>> +
>>> +		mark_page_accessed(page);
>>> +		f2fs_put_page(page, 0);
>>> +		readcnt++;
>>> +	}
>>> +
>>> +	f2fs_submit_read_bio(sbi, READ_SYNC);
>>> +	return readcnt;
>>> +}
>>> +
>>>  static void build_sit_entries(struct f2fs_sb_info *sbi)
>>>  {
>>>  	struct sit_info *sit_i = SIT_I(sbi);
>>>  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
>>>  	struct f2fs_summary_block *sum = curseg->sum_blk;
>>> -	unsigned int start;
>>> -
>>> -	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
>>> -		struct seg_entry *se = &sit_i->sentries[start];
>>> -		struct f2fs_sit_block *sit_blk;
>>> -		struct f2fs_sit_entry sit;
>>> -		struct page *page;
>>> -		int i;
>>> +	bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
>>> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
>>> +	unsigned int i, start, end;
>>> +	unsigned int readed, start_blk = 0;
>>>
>>> -		mutex_lock(&curseg->curseg_mutex);
>>> -		for (i = 0; i < sits_in_cursum(sum); i++) {
>>> -			if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
>>> -				sit = sit_in_journal(sum, i);
>>> -				mutex_unlock(&curseg->curseg_mutex);
>>> -				goto got_it;
>>> +	do {
>>
>> How about using find_next_bit to get the suitable start_blk if the next blk
>> is not ordered here? And it also can simplify the logic of ra_sit_pages().
> 
> That's a good idea.
> But I thought there maybe endianness problem between test_bit and 
> f2fs_test_bit, so find_next_bit may get wrong result. Am I right?

IMO, find_next_bit can do well with endianness issue internally, if
it's not so, that may be a weakness.
On the other side, why not introduce a 'f2fs_find_next_bit' if it's
seriously needed?:)

Regards,
Gu

> 
> Thanks,
> Yu
>>
>> Thanks,
>> Gu
>>
>>> +		readed = ra_sit_pages(sbi, start_blk, sit_blk_cnt, &is_order);
>>> +
>>> +		start = start_blk * sit_i->sents_per_block;
>>> +		end = (start_blk + readed) * sit_i->sents_per_block;
>>> +
>>> +		for (; start < end && start < TOTAL_SEGS(sbi); start++) {
>>> +			struct seg_entry *se = &sit_i->sentries[start];
>>> +			struct f2fs_sit_block *sit_blk;
>>> +			struct f2fs_sit_entry sit;
>>> +			struct page *page;
>>> +
>>> +			mutex_lock(&curseg->curseg_mutex);
>>> +			for (i = 0; i < sits_in_cursum(sum); i++) {
>>> +				if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
>>> +					sit = sit_in_journal(sum, i);
>>> +					mutex_unlock(&curseg->curseg_mutex);
>>> +					goto got_it;
>>> +				}
>>>  			}
>>> -		}
>>> -		mutex_unlock(&curseg->curseg_mutex);
>>> -		page = get_current_sit_page(sbi, start);
>>> -		sit_blk = (struct f2fs_sit_block *)page_address(page);
>>> -		sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
>>> -		f2fs_put_page(page, 1);
>>> +			mutex_unlock(&curseg->curseg_mutex);
>>> +
>>> +			page = get_current_sit_page(sbi, start);
>>> +			sit_blk = (struct f2fs_sit_block *)page_address(page);
>>> +			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
>>> +			f2fs_put_page(page, 1);
>>>  got_it:
>>> -		check_block_count(sbi, start, &sit);
>>> -		seg_info_from_raw_sit(se, &sit);
>>> -		if (sbi->segs_per_sec > 1) {
>>> -			struct sec_entry *e = get_sec_entry(sbi, start);
>>> -			e->valid_blocks += se->valid_blocks;
>>> +			check_block_count(sbi, start, &sit);
>>> +			seg_info_from_raw_sit(se, &sit);
>>> +			if (sbi->segs_per_sec > 1) {
>>> +				struct sec_entry *e = get_sec_entry(sbi, start);
>>> +				e->valid_blocks += se->valid_blocks;
>>> +			}
>>>  		}
>>> -	}
>>> +		start_blk += readed;
>>
>>
>>
>>
>>> +	} while (start_blk < sit_blk_cnt);
>>>  }
>>>
>>>  static void init_free_segmap(struct f2fs_sb_info *sbi)
>>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>>> index 269f690..ad5b9f1 100644
>>> --- a/fs/f2fs/segment.h
>>> +++ b/fs/f2fs/segment.h
>>> @@ -83,6 +83,8 @@
>>>  	(segno / SIT_ENTRY_PER_BLOCK)
>>>  #define	START_SEGNO(sit_i, segno)		\
>>>  	(SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
>>> +#define SIT_BLK_CNT(sbi)			\
>>> +	((TOTAL_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
>>>  #define f2fs_bitmap_size(nr)			\
>>>  	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
>>>  #define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)
> 
> 
> 

RE: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

[Chao Yu]

Hi Gu,

> -----Original Message-----
> From: Gu Zheng [mailto:guz.fnst@cn.fujitsu.com]
> Sent: Wednesday, November 20, 2013 5:38 PM
> To: Chao Yu
> Cc: '???'; linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; '谭姝'
> Subject: Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance
> 
> Hi Yu,
> On 11/20/2013 01:37 PM, Chao Yu wrote:
> 
> > Hi Gu,
> >
> >> -----Original Message-----
> >> From: Gu Zheng [mailto:guz.fnst@cn.fujitsu.com]
> >> Sent: Monday, November 18, 2013 7:16 PM
> >> To: Chao Yu
> >> Cc: '???'; linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; 谭
姝
> >> Subject: Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance
> >>
> >> Hi Yu,
> >> One more comment, please refer to inline.
> >> On 11/16/2013 02:15 PM, Chao Yu wrote:
> >>
> >>> Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together.
> >>> So we read pages as contiguous as possible for better mount performance.
> >>>
> >>> v1-->v2:
> >>>  o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng suggested.
> >>>  o add mark_page_accessed () before release page to delay VM reclaiming them.
> >>>
> >>> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> >>> ---
> >>>  fs/f2fs/segment.c |  108 ++++++++++++++++++++++++++++++++++++++++-------------
> >>>  fs/f2fs/segment.h |    2 +
> >>>  2 files changed, 84 insertions(+), 26 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >>> index fa284d3..656fe40 100644
> >>> --- a/fs/f2fs/segment.c
> >>> +++ b/fs/f2fs/segment.c
> >>> @@ -14,6 +14,7 @@
> >>>  #include <linux/blkdev.h>
> >>>  #include <linux/prefetch.h>
> >>>  #include <linux/vmalloc.h>
> >>> +#include <linux/swap.h>
> >>>
> >>>  #include "f2fs.h"
> >>>  #include "segment.h"
> >>> @@ -1480,41 +1481,96 @@ static int build_curseg(struct f2fs_sb_info *sbi)
> >>>  	return restore_curseg_summaries(sbi);
> >>>  }
> >>>
> >>> +static int ra_sit_pages(struct f2fs_sb_info *sbi, int start,
> >>> +					int nrpages, bool *is_order)
> >>> +{
> >>> +	struct address_space *mapping = sbi->meta_inode->i_mapping;
> >>> +	struct sit_info *sit_i = SIT_I(sbi);
> >>> +	struct page *page;
> >>> +	block_t blk_addr;
> >>> +	int blkno = start, readcnt = 0;
> >>> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
> >>> +
> >>> +	for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
> >>> +
> >>> +		if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
> >>> +			*is_order = !*is_order;
> >>> +			break;
> >>> +		}
> >>> +
> >>> +		blk_addr = sit_i->sit_base_addr + blkno;
> >>> +		if (*is_order)
> >>> +			blk_addr += sit_i->sit_blocks;
> >>> +repeat:
> >>> +		page = grab_cache_page(mapping, blk_addr);
> >>> +		if (!page) {
> >>> +			cond_resched();
> >>> +			goto repeat;
> >>> +		}
> >>> +		if (PageUptodate(page)) {
> >>> +			mark_page_accessed(page);
> >>> +			f2fs_put_page(page, 1);
> >>> +			readcnt++;
> >>> +			continue;
> >>> +		}
> >>> +
> >>> +		submit_read_page(sbi, page, blk_addr, READ_SYNC);
> >>> +
> >>> +		mark_page_accessed(page);
> >>> +		f2fs_put_page(page, 0);
> >>> +		readcnt++;
> >>> +	}
> >>> +
> >>> +	f2fs_submit_read_bio(sbi, READ_SYNC);
> >>> +	return readcnt;
> >>> +}
> >>> +
> >>>  static void build_sit_entries(struct f2fs_sb_info *sbi)
> >>>  {
> >>>  	struct sit_info *sit_i = SIT_I(sbi);
> >>>  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
> >>>  	struct f2fs_summary_block *sum = curseg->sum_blk;
> >>> -	unsigned int start;
> >>> -
> >>> -	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
> >>> -		struct seg_entry *se = &sit_i->sentries[start];
> >>> -		struct f2fs_sit_block *sit_blk;
> >>> -		struct f2fs_sit_entry sit;
> >>> -		struct page *page;
> >>> -		int i;
> >>> +	bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
> >>> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
> >>> +	unsigned int i, start, end;
> >>> +	unsigned int readed, start_blk = 0;
> >>>
> >>> -		mutex_lock(&curseg->curseg_mutex);
> >>> -		for (i = 0; i < sits_in_cursum(sum); i++) {
> >>> -			if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> >>> -				sit = sit_in_journal(sum, i);
> >>> -				mutex_unlock(&curseg->curseg_mutex);
> >>> -				goto got_it;
> >>> +	do {
> >>
> >> How about using find_next_bit to get the suitable start_blk if the next blk
> >> is not ordered here? And it also can simplify the logic of ra_sit_pages().
> >
> > That's a good idea.
> > But I thought there maybe endianness problem between test_bit and
> > f2fs_test_bit, so find_next_bit may get wrong result. Am I right?
> 
> IMO, find_next_bit can do well with endianness issue internally, if
> it's not so, that may be a weakness.

Right, I mean that if we want to set first position in bitmap, 
we cloud use f2fs_set_bit(0, bitmap) or set_bit(7, bitmap).
Two types of interface could not be used mixedly.

So could we use {set,test,clear}_bit intead of f2fs_{set,test,clear}_bit?

> On the other side, why not introduce a 'f2fs_find_next_bit' if it's
> seriously needed?:)

Agreed, that's a good point, they were really needed for
uniform style and readability.

> 
> Regards,
> Gu
> 
> >
> > Thanks,
> > Yu
> >>
> >> Thanks,
> >> Gu
> >>
> >>> +		readed = ra_sit_pages(sbi, start_blk, sit_blk_cnt, &is_order);
> >>> +
> >>> +		start = start_blk * sit_i->sents_per_block;
> >>> +		end = (start_blk + readed) * sit_i->sents_per_block;
> >>> +
> >>> +		for (; start < end && start < TOTAL_SEGS(sbi); start++) {
> >>> +			struct seg_entry *se = &sit_i->sentries[start];
> >>> +			struct f2fs_sit_block *sit_blk;
> >>> +			struct f2fs_sit_entry sit;
> >>> +			struct page *page;
> >>> +
> >>> +			mutex_lock(&curseg->curseg_mutex);
> >>> +			for (i = 0; i < sits_in_cursum(sum); i++) {
> >>> +				if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
> >>> +					sit = sit_in_journal(sum, i);
> >>> +					mutex_unlock(&curseg->curseg_mutex);
> >>> +					goto got_it;
> >>> +				}
> >>>  			}
> >>> -		}
> >>> -		mutex_unlock(&curseg->curseg_mutex);
> >>> -		page = get_current_sit_page(sbi, start);
> >>> -		sit_blk = (struct f2fs_sit_block *)page_address(page);
> >>> -		sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> >>> -		f2fs_put_page(page, 1);
> >>> +			mutex_unlock(&curseg->curseg_mutex);
> >>> +
> >>> +			page = get_current_sit_page(sbi, start);
> >>> +			sit_blk = (struct f2fs_sit_block *)page_address(page);
> >>> +			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> >>> +			f2fs_put_page(page, 1);
> >>>  got_it:
> >>> -		check_block_count(sbi, start, &sit);
> >>> -		seg_info_from_raw_sit(se, &sit);
> >>> -		if (sbi->segs_per_sec > 1) {
> >>> -			struct sec_entry *e = get_sec_entry(sbi, start);
> >>> -			e->valid_blocks += se->valid_blocks;
> >>> +			check_block_count(sbi, start, &sit);
> >>> +			seg_info_from_raw_sit(se, &sit);
> >>> +			if (sbi->segs_per_sec > 1) {
> >>> +				struct sec_entry *e = get_sec_entry(sbi, start);
> >>> +				e->valid_blocks += se->valid_blocks;
> >>> +			}
> >>>  		}
> >>> -	}
> >>> +		start_blk += readed;
> >>
> >>
> >>
> >>
> >>> +	} while (start_blk < sit_blk_cnt);
> >>>  }
> >>>
> >>>  static void init_free_segmap(struct f2fs_sb_info *sbi)
> >>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> >>> index 269f690..ad5b9f1 100644
> >>> --- a/fs/f2fs/segment.h
> >>> +++ b/fs/f2fs/segment.h
> >>> @@ -83,6 +83,8 @@
> >>>  	(segno / SIT_ENTRY_PER_BLOCK)
> >>>  #define	START_SEGNO(sit_i, segno)		\
> >>>  	(SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
> >>> +#define SIT_BLK_CNT(sbi)			\
> >>> +	((TOTAL_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
> >>>  #define f2fs_bitmap_size(nr)			\
> >>>  	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
> >>>  #define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)
> >
> >
> >
> 
> 
> =

Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

[Gu Zheng]

On 11/21/2013 01:46 PM, Chao Yu wrote:

> Hi Gu,
> 
>> -----Original Message-----
>> From: Gu Zheng [mailto:guz.fnst@cn.fujitsu.com]
>> Sent: Wednesday, November 20, 2013 5:38 PM
>> To: Chao Yu
>> Cc: '???'; linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; '谭姝'
>> Subject: Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance
>>
>> Hi Yu,
>> On 11/20/2013 01:37 PM, Chao Yu wrote:
>>
>>> Hi Gu,
>>>
>>>> -----Original Message-----
>>>> From: Gu Zheng [mailto:guz.fnst@cn.fujitsu.com]
>>>> Sent: Monday, November 18, 2013 7:16 PM
>>>> To: Chao Yu
>>>> Cc: '???'; linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; 谭
> 姝
>>>> Subject: Re: [f2fs-dev] [PATCH V2 2/2] f2fs: read contiguous sit entry pages by merging for mount performance
>>>>
>>>> Hi Yu,
>>>> One more comment, please refer to inline.
>>>> On 11/16/2013 02:15 PM, Chao Yu wrote:
>>>>
>>>>> Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together.
>>>>> So we read pages as contiguous as possible for better mount performance.
>>>>>
>>>>> v1-->v2:
>>>>>  o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng suggested.
>>>>>  o add mark_page_accessed () before release page to delay VM reclaiming them.
>>>>>
>>>>> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
>>>>> ---
>>>>>  fs/f2fs/segment.c |  108 ++++++++++++++++++++++++++++++++++++++++-------------
>>>>>  fs/f2fs/segment.h |    2 +
>>>>>  2 files changed, 84 insertions(+), 26 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>>> index fa284d3..656fe40 100644
>>>>> --- a/fs/f2fs/segment.c
>>>>> +++ b/fs/f2fs/segment.c
>>>>> @@ -14,6 +14,7 @@
>>>>>  #include <linux/blkdev.h>
>>>>>  #include <linux/prefetch.h>
>>>>>  #include <linux/vmalloc.h>
>>>>> +#include <linux/swap.h>
>>>>>
>>>>>  #include "f2fs.h"
>>>>>  #include "segment.h"
>>>>> @@ -1480,41 +1481,96 @@ static int build_curseg(struct f2fs_sb_info *sbi)
>>>>>  	return restore_curseg_summaries(sbi);
>>>>>  }
>>>>>
>>>>> +static int ra_sit_pages(struct f2fs_sb_info *sbi, int start,
>>>>> +					int nrpages, bool *is_order)
>>>>> +{
>>>>> +	struct address_space *mapping = sbi->meta_inode->i_mapping;
>>>>> +	struct sit_info *sit_i = SIT_I(sbi);
>>>>> +	struct page *page;
>>>>> +	block_t blk_addr;
>>>>> +	int blkno = start, readcnt = 0;
>>>>> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
>>>>> +
>>>>> +	for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
>>>>> +
>>>>> +		if ((!f2fs_test_bit(blkno, sit_i->sit_bitmap) ^ !*is_order)) {
>>>>> +			*is_order = !*is_order;
>>>>> +			break;
>>>>> +		}
>>>>> +
>>>>> +		blk_addr = sit_i->sit_base_addr + blkno;
>>>>> +		if (*is_order)
>>>>> +			blk_addr += sit_i->sit_blocks;
>>>>> +repeat:
>>>>> +		page = grab_cache_page(mapping, blk_addr);
>>>>> +		if (!page) {
>>>>> +			cond_resched();
>>>>> +			goto repeat;
>>>>> +		}
>>>>> +		if (PageUptodate(page)) {
>>>>> +			mark_page_accessed(page);
>>>>> +			f2fs_put_page(page, 1);
>>>>> +			readcnt++;
>>>>> +			continue;
>>>>> +		}
>>>>> +
>>>>> +		submit_read_page(sbi, page, blk_addr, READ_SYNC);
>>>>> +
>>>>> +		mark_page_accessed(page);
>>>>> +		f2fs_put_page(page, 0);
>>>>> +		readcnt++;
>>>>> +	}
>>>>> +
>>>>> +	f2fs_submit_read_bio(sbi, READ_SYNC);
>>>>> +	return readcnt;
>>>>> +}
>>>>> +
>>>>>  static void build_sit_entries(struct f2fs_sb_info *sbi)
>>>>>  {
>>>>>  	struct sit_info *sit_i = SIT_I(sbi);
>>>>>  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
>>>>>  	struct f2fs_summary_block *sum = curseg->sum_blk;
>>>>> -	unsigned int start;
>>>>> -
>>>>> -	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
>>>>> -		struct seg_entry *se = &sit_i->sentries[start];
>>>>> -		struct f2fs_sit_block *sit_blk;
>>>>> -		struct f2fs_sit_entry sit;
>>>>> -		struct page *page;
>>>>> -		int i;
>>>>> +	bool is_order = f2fs_test_bit(0, sit_i->sit_bitmap) ? true : false;
>>>>> +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
>>>>> +	unsigned int i, start, end;
>>>>> +	unsigned int readed, start_blk = 0;
>>>>>
>>>>> -		mutex_lock(&curseg->curseg_mutex);
>>>>> -		for (i = 0; i < sits_in_cursum(sum); i++) {
>>>>> -			if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
>>>>> -				sit = sit_in_journal(sum, i);
>>>>> -				mutex_unlock(&curseg->curseg_mutex);
>>>>> -				goto got_it;
>>>>> +	do {
>>>>
>>>> How about using find_next_bit to get the suitable start_blk if the next blk
>>>> is not ordered here? And it also can simplify the logic of ra_sit_pages().
>>>
>>> That's a good idea.
>>> But I thought there maybe endianness problem between test_bit and
>>> f2fs_test_bit, so find_next_bit may get wrong result. Am I right?
>>
>> IMO, find_next_bit can do well with endianness issue internally, if
>> it's not so, that may be a weakness.
> 
> Right, I mean that if we want to set first position in bitmap, 
> we cloud use f2fs_set_bit(0, bitmap) or set_bit(7, bitmap).
> Two types of interface could not be used mixedly.
> 
> So could we use {set,test,clear}_bit intead of f2fs_{set,test,clear}_bit?

We can convert f2fs_{set,test,clear}_bit to a wrapper of {set,test,clear}_bit.

Thanks,
Gu

> 
>> On the other side, why not introduce a 'f2fs_find_next_bit' if it's
>> seriously needed?:)
> 
> Agreed, that's a good point, they were really needed for
> uniform style and readability.
> 
>>
>> Regards,
>> Gu
>>
>>>
>>> Thanks,
>>> Yu
>>>>
>>>> Thanks,
>>>> Gu
>>>>
>>>>> +		readed = ra_sit_pages(sbi, start_blk, sit_blk_cnt, &is_order);
>>>>> +
>>>>> +		start = start_blk * sit_i->sents_per_block;
>>>>> +		end = (start_blk + readed) * sit_i->sents_per_block;
>>>>> +
>>>>> +		for (; start < end && start < TOTAL_SEGS(sbi); start++) {
>>>>> +			struct seg_entry *se = &sit_i->sentries[start];
>>>>> +			struct f2fs_sit_block *sit_blk;
>>>>> +			struct f2fs_sit_entry sit;
>>>>> +			struct page *page;
>>>>> +
>>>>> +			mutex_lock(&curseg->curseg_mutex);
>>>>> +			for (i = 0; i < sits_in_cursum(sum); i++) {
>>>>> +				if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
>>>>> +					sit = sit_in_journal(sum, i);
>>>>> +					mutex_unlock(&curseg->curseg_mutex);
>>>>> +					goto got_it;
>>>>> +				}
>>>>>  			}
>>>>> -		}
>>>>> -		mutex_unlock(&curseg->curseg_mutex);
>>>>> -		page = get_current_sit_page(sbi, start);
>>>>> -		sit_blk = (struct f2fs_sit_block *)page_address(page);
>>>>> -		sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
>>>>> -		f2fs_put_page(page, 1);
>>>>> +			mutex_unlock(&curseg->curseg_mutex);
>>>>> +
>>>>> +			page = get_current_sit_page(sbi, start);
>>>>> +			sit_blk = (struct f2fs_sit_block *)page_address(page);
>>>>> +			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
>>>>> +			f2fs_put_page(page, 1);
>>>>>  got_it:
>>>>> -		check_block_count(sbi, start, &sit);
>>>>> -		seg_info_from_raw_sit(se, &sit);
>>>>> -		if (sbi->segs_per_sec > 1) {
>>>>> -			struct sec_entry *e = get_sec_entry(sbi, start);
>>>>> -			e->valid_blocks += se->valid_blocks;
>>>>> +			check_block_count(sbi, start, &sit);
>>>>> +			seg_info_from_raw_sit(se, &sit);
>>>>> +			if (sbi->segs_per_sec > 1) {
>>>>> +				struct sec_entry *e = get_sec_entry(sbi, start);
>>>>> +				e->valid_blocks += se->valid_blocks;
>>>>> +			}
>>>>>  		}
>>>>> -	}
>>>>> +		start_blk += readed;
>>>>
>>>>
>>>>
>>>>
>>>>> +	} while (start_blk < sit_blk_cnt);
>>>>>  }
>>>>>
>>>>>  static void init_free_segmap(struct f2fs_sb_info *sbi)
>>>>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>>>>> index 269f690..ad5b9f1 100644
>>>>> --- a/fs/f2fs/segment.h
>>>>> +++ b/fs/f2fs/segment.h
>>>>> @@ -83,6 +83,8 @@
>>>>>  	(segno / SIT_ENTRY_PER_BLOCK)
>>>>>  #define	START_SEGNO(sit_i, segno)		\
>>>>>  	(SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
>>>>> +#define SIT_BLK_CNT(sbi)			\
>>>>> +	((TOTAL_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
>>>>>  #define f2fs_bitmap_size(nr)			\
>>>>>  	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
>>>>>  #define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)
>>>
>>>
>>>
>>
>>
>> =
> 
>