Re: [PATCH 08/10] f2fs: relax async discard commands more

[Jaegeuk Kim <jaegeuk@kernel.org>]

Hi Chao,

On 01/06, Chao Yu wrote:
> On 2017/1/6 3:46, Jaegeuk Kim wrote:
> > On 01/05, Chao Yu wrote:
> >> On 2017/1/4 17:29, Chao Yu wrote:
> >>> On 2016/12/31 2:51, Jaegeuk Kim wrote:
> >>>> This patch relaxes async discard commands to avoid waiting its end_io during
> >>>> checkpoint.
> >>>> Instead of waiting them during checkpoint, it will be done when actually reusing
> >>>> them.
> >>>>
> >>>> Test on initial partition of nvme drive.
> >>>>
> >>>>  # time fstrim /mnt/test
> >>>>
> >>>> Before : 6.158s
> >>>> After : 4.822s
> >>>>
> >>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> >>>
> >>> Reviewed-by: Chao Yu <yuchao0@huawei.com>
> >>>
> >>> One comment below,
> >>
> >> I still have a comment on this patch.
> >>
> >>>> -void f2fs_wait_all_discard_bio(struct f2fs_sb_info *sbi)
> >>>> +/* This should be covered by global mutex, &sit_i->sentry_lock */
> >>>> +void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, unsigned int segno)
> >>>>  {
> >>>>  	struct list_head *wait_list = &(SM_I(sbi)->wait_list);
> >>>>  	struct bio_entry *be, *tmp;
> >>>> @@ -646,7 +650,15 @@ void f2fs_wait_all_discard_bio(struct f2fs_sb_info *sbi)
> >>>>  		struct bio *bio = be->bio;
> >>>>  		int err;
> >>>>  
> >>>> -		wait_for_completion_io(&be->event);
> >>>> +		if (!completion_done(&be->event)) {
> >>>> +			if ((be->start_segno >= segno &&
> >>>> +					be->end_segno <= segno) ||
> >>>
> >>> segno >= be->start_segno && segno < be->end_segno ?
> 
> Still can not understand this judgment condition, we should wait completion of
> discard command only when segno is locate in range of [start_segno, end_segno]?
> 
> But now, this condition can be true only when segno, start_segno, end_segno have
> equal value.
> 
> Please correct me if I'm wrong.

Urg. I rewrote it to use block addresses.

How about this?

>From fe24461eedd62815e0c56317f010a3a6e3004434 Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk@kernel.org>
Date: Thu, 29 Dec 2016 14:07:53 -0800
Subject: [PATCH] f2fs: relax async discard commands more

This patch relaxes async discard commands to avoid waiting its end_io during
checkpoint.
Instead of waiting them during checkpoint, it will be done when actually reusing
them.

Test on initial partition of nvme drive.

 # time fstrim /mnt/test

Before : 6.158s
After : 4.822s

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/checkpoint.c |  7 ++-----
 fs/f2fs/f2fs.h       |  4 +++-
 fs/f2fs/segment.c    | 23 +++++++++++++++++++----
 fs/f2fs/super.c      |  3 +++
 4 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index f73ee9534d83..1a9ba69a22ba 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1254,7 +1254,6 @@ int write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 		f2fs_bug_on(sbi, prefree_segments(sbi));
 		flush_sit_entries(sbi, cpc);
 		clear_prefree_segments(sbi, cpc);
-		f2fs_wait_all_discard_bio(sbi);
 		unblock_operations(sbi);
 		goto out;
 	}
@@ -1273,12 +1272,10 @@ int write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 
 	/* unlock all the fs_lock[] in do_checkpoint() */
 	err = do_checkpoint(sbi, cpc);
-	if (err) {
+	if (err)
 		release_discard_addrs(sbi);
-	} else {
+	else
 		clear_prefree_segments(sbi, cpc);
-		f2fs_wait_all_discard_bio(sbi);
-	}
 
 	unblock_operations(sbi);
 	stat_inc_cp_count(sbi->stat_info);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index bdcfe2a9b532..e0db895fd84c 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -183,6 +183,8 @@ struct discard_entry {
 
 struct bio_entry {
 	struct list_head list;
+	block_t lstart;
+	block_t len;
 	struct bio *bio;
 	struct completion event;
 	int error;
@@ -2111,7 +2113,7 @@ void destroy_flush_cmd_control(struct f2fs_sb_info *, bool);
 void invalidate_blocks(struct f2fs_sb_info *, block_t);
 bool is_checkpointed_data(struct f2fs_sb_info *, block_t);
 void refresh_sit_entry(struct f2fs_sb_info *, block_t, block_t);
-void f2fs_wait_all_discard_bio(struct f2fs_sb_info *);
+void f2fs_wait_discard_bio(struct f2fs_sb_info *, block_t);
 void clear_prefree_segments(struct f2fs_sb_info *, struct cp_control *);
 void release_discard_addrs(struct f2fs_sb_info *);
 int npages_for_summary_flush(struct f2fs_sb_info *, bool);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 485b9118b418..672bcdefe836 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -625,20 +625,23 @@ static void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno)
 }
 
 static struct bio_entry *__add_bio_entry(struct f2fs_sb_info *sbi,
-							struct bio *bio)
+			struct bio *bio, block_t lstart, block_t len)
 {
 	struct list_head *wait_list = &(SM_I(sbi)->wait_list);
 	struct bio_entry *be = f2fs_kmem_cache_alloc(bio_entry_slab, GFP_NOFS);
 
 	INIT_LIST_HEAD(&be->list);
 	be->bio = bio;
+	be->lstart = lstart;
+	be->len = len;
 	init_completion(&be->event);
 	list_add_tail(&be->list, wait_list);
 
 	return be;
 }
 
-void f2fs_wait_all_discard_bio(struct f2fs_sb_info *sbi)
+/* This should be covered by global mutex, &sit_i->sentry_lock */
+void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
 {
 	struct list_head *wait_list = &(SM_I(sbi)->wait_list);
 	struct bio_entry *be, *tmp;
@@ -647,7 +650,15 @@ void f2fs_wait_all_discard_bio(struct f2fs_sb_info *sbi)
 		struct bio *bio = be->bio;
 		int err;
 
-		wait_for_completion_io(&be->event);
+		if (!completion_done(&be->event)) {
+			if ((be->lstart <= blkaddr &&
+					blkaddr < be->lstart + be->len) ||
+					blkaddr == NULL_ADDR)
+				wait_for_completion_io(&be->event);
+			else
+				continue;
+		}
+
 		err = be->error;
 		if (err == -EOPNOTSUPP)
 			err = 0;
@@ -675,6 +686,7 @@ static int __f2fs_issue_discard_async(struct f2fs_sb_info *sbi,
 		struct block_device *bdev, block_t blkstart, block_t blklen)
 {
 	struct bio *bio = NULL;
+	block_t lblkstart = blkstart;
 	int err;
 
 	trace_f2fs_issue_discard(sbi->sb, blkstart, blklen);
@@ -689,7 +701,8 @@ static int __f2fs_issue_discard_async(struct f2fs_sb_info *sbi,
 				SECTOR_FROM_BLOCK(blklen),
 				GFP_NOFS, 0, &bio);
 	if (!err && bio) {
-		struct bio_entry *be = __add_bio_entry(sbi, bio);
+		struct bio_entry *be = __add_bio_entry(sbi, bio,
+						lblkstart, blklen);
 
 		bio->bi_private = be;
 		bio->bi_end_io = f2fs_submit_bio_wait_endio;
@@ -1575,6 +1588,8 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
 
 	*new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
 
+	f2fs_wait_discard_bio(sbi, *new_blkaddr);
+
 	/*
 	 * __add_sum_entry should be resided under the curseg_mutex
 	 * because, this function updates a summary entry in the
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f3697f97e527..461c29043aec 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -770,6 +770,9 @@ static void f2fs_put_super(struct super_block *sb)
 		write_checkpoint(sbi, &cpc);
 	}
 
+	/* be sure to wait for any on-going discard commands */
+	f2fs_wait_discard_bio(sbi, NULL_ADDR);
+
 	/* write_checkpoint can update stat informaion */
 	f2fs_destroy_stats(sbi);
 
-- 
2.11.0


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