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From:   Daeho Jeong <daeho43@gmail.com>
To:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com
Cc:     Daeho Jeong <daehojeong@google.com>
Subject: [PATCH] f2fs: add GC_URGENT_LOW mode in gc_urgent
Date:   Tue, 30 Jun 2020 09:54:22 +0900
Message-Id: <20200630005422.2389686-1-daeho43@gmail.com>
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From: Daeho Jeong <daehojeong@google.com>

Added a new gc_urgent mode, GC_URGENT_LOW, in which mode
F2FS will lower the bar of checking idle in order to
process outstanding discard commands and GC a little bit
aggressively.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
 Documentation/ABI/testing/sysfs-fs-f2fs |  4 +++-
 fs/f2fs/f2fs.h                          | 10 ++++++++--
 fs/f2fs/gc.c                            |  6 +++---
 fs/f2fs/segment.c                       |  4 ++--
 fs/f2fs/sysfs.c                         |  6 ++++--
 5 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 4bb93a06d8ab..7f730c4c8df2 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -229,7 +229,9 @@ Date:		August 2017
 Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
 Description:	Do background GC agressively when set. When gc_urgent = 1,
 		background thread starts to do GC by given gc_urgent_sleep_time
-		interval. It is set to 0 by default.
+		interval. When gc_urgent = 2, F2FS will lower the bar of
+		checking idle in order to process outstanding discard commands
+		and GC a little bit aggressively. It is set to 0 by default.
 
 What:		/sys/fs/f2fs/<disk>/gc_urgent_sleep_time
 Date:		August 2017
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e6e47618a357..4b28fd42fdbc 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1283,7 +1283,8 @@ enum {
 	GC_NORMAL,
 	GC_IDLE_CB,
 	GC_IDLE_GREEDY,
-	GC_URGENT,
+	GC_URGENT_HIGH,
+	GC_URGENT_LOW,
 };
 
 enum {
@@ -1540,6 +1541,7 @@ struct f2fs_sb_info {
 	unsigned int cur_victim_sec;		/* current victim section num */
 	unsigned int gc_mode;			/* current GC state */
 	unsigned int next_victim_seg[2];	/* next segment in victim section */
+
 	/* for skip statistic */
 	unsigned int atomic_files;              /* # of opened atomic file */
 	unsigned long long skipped_atomic_files[2];	/* FG_GC and BG_GC */
@@ -2480,7 +2482,7 @@ static inline void *f2fs_kmem_cache_alloc(struct kmem_cache *cachep,
 
 static inline bool is_idle(struct f2fs_sb_info *sbi, int type)
 {
-	if (sbi->gc_mode == GC_URGENT)
+	if (sbi->gc_mode == GC_URGENT_HIGH)
 		return true;
 
 	if (get_pages(sbi, F2FS_RD_DATA) || get_pages(sbi, F2FS_RD_NODE) ||
@@ -2498,6 +2500,10 @@ static inline bool is_idle(struct f2fs_sb_info *sbi, int type)
 			atomic_read(&SM_I(sbi)->fcc_info->queued_flush))
 		return false;
 
+	if (sbi->gc_mode == GC_URGENT_LOW &&
+			(type == DISCARD_TIME || type == GC_TIME))
+		return true;
+
 	return f2fs_time_over(sbi, type);
 }
 
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 6eec3b2d606d..3b718da69910 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -82,7 +82,7 @@ static int gc_thread_func(void *data)
 		 * invalidated soon after by user update or deletion.
 		 * So, I'd like to wait some time to collect dirty segments.
 		 */
-		if (sbi->gc_mode == GC_URGENT) {
+		if (sbi->gc_mode == GC_URGENT_HIGH) {
 			wait_ms = gc_th->urgent_sleep_time;
 			down_write(&sbi->gc_lock);
 			goto do_gc;
@@ -176,7 +176,7 @@ static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
 		gc_mode = GC_CB;
 		break;
 	case GC_IDLE_GREEDY:
-	case GC_URGENT:
+	case GC_URGENT_HIGH:
 		gc_mode = GC_GREEDY;
 		break;
 	}
@@ -211,7 +211,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
 	 * foreground GC and urgent GC cases.
 	 */
 	if (gc_type != FG_GC &&
-			(sbi->gc_mode != GC_URGENT) &&
+			(sbi->gc_mode != GC_URGENT_HIGH) &&
 			p->max_search > sbi->max_victim_search)
 		p->max_search = sbi->max_victim_search;
 
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index b45e473508a9..5924b3965ae4 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -174,7 +174,7 @@ bool f2fs_need_SSR(struct f2fs_sb_info *sbi)
 
 	if (f2fs_lfs_mode(sbi))
 		return false;
-	if (sbi->gc_mode == GC_URGENT)
+	if (sbi->gc_mode == GC_URGENT_HIGH)
 		return true;
 	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
 		return true;
@@ -1759,7 +1759,7 @@ static int issue_discard_thread(void *data)
 			continue;
 		}
 
-		if (sbi->gc_mode == GC_URGENT)
+		if (sbi->gc_mode == GC_URGENT_HIGH)
 			__init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);
 
 		sb_start_intwrite(sbi->sb);
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index e877c59b9fdb..ab40e1f89f23 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -350,14 +350,16 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return -EINVAL;
 
 	if (!strcmp(a->attr.name, "gc_urgent")) {
-		if (t >= 1) {
-			sbi->gc_mode = GC_URGENT;
+		if (t == 1) {
+			sbi->gc_mode = GC_URGENT_HIGH;
 			if (sbi->gc_thread) {
 				sbi->gc_thread->gc_wake = 1;
 				wake_up_interruptible_all(
 					&sbi->gc_thread->gc_wait_queue_head);
 				wake_up_discard_thread(sbi, true);
 			}
+		} else if (t == 2) {
+			sbi->gc_mode = GC_URGENT_LOW;
 		} else {
 			sbi->gc_mode = GC_NORMAL;
 		}
-- 
2.27.0.212.ge8ba1cc988-goog