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From:   Yangtao Li <frank.li@vivo.com>
To:     jaegeuk@kernel.org, chao@kernel.org
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, Yangtao Li <frank.li@vivo.com>
Subject: [PATCH v3] f2fs: add proc entry to show discard_plist info
Date:   Fri, 11 Nov 2022 23:39:21 +0800
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This patch adds a new proc entry to show discard_plist
information in more detail, which is very helpful to
know the discard pend list count clearly.

Such as:

Discard pending list(Show diacrd command count on each entry):
0                4943         138          66          29          21           9           8          12
8                   4           7           4           6           3           2           0           1
16                  1           2           2           0           0           1           0           0
24                  0           1           1           0           0           1           1           0
32                  0           1           0           0           0           0           0           0
......

Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
 fs/f2fs/f2fs.h    |  1 +
 fs/f2fs/segment.c | 22 ++++++++++++++++------
 fs/f2fs/sysfs.c   | 29 +++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 04ef4cce3d7f..a0226c970cbc 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -405,6 +405,7 @@ struct discard_cmd_control {
 	wait_queue_head_t discard_wait_queue;	/* waiting queue for wake-up */
 	unsigned int discard_wake;		/* to wake up discard thread */
 	struct mutex cmd_lock;
+	unsigned int nr_pending[MAX_PLIST_NUM];	/* # of pending discards */
 	unsigned int nr_discards;		/* # of discards in the list */
 	unsigned int max_discards;		/* max. discards to be issued */
 	unsigned int max_discard_request;	/* max. discard request per round */
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index aa4be7f25963..72e60d5ee70f 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -921,6 +921,7 @@ static struct discard_cmd *__create_discard_cmd(struct f2fs_sb_info *sbi,
 	dc->bio_ref = 0;
 	atomic_inc(&dcc->discard_cmd_cnt);
 	dcc->undiscard_blks += len;
+	dcc->nr_pending[plist_idx(len)]++;
 
 	return dc;
 }
@@ -1169,6 +1170,7 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
 		submit_bio(bio);
 
 		atomic_inc(&dcc->issued_discard);
+		dcc->nr_pending[plist_idx(len)]--;
 
 		f2fs_update_iostat(sbi, NULL, FS_DISCARD, 1);
 
@@ -1210,9 +1212,11 @@ static void __insert_discard_tree(struct f2fs_sb_info *sbi,
 }
 
 static void __relocate_discard_cmd(struct discard_cmd_control *dcc,
-						struct discard_cmd *dc)
+						struct discard_cmd *dc, unsigned int index)
 {
 	list_move_tail(&dc->list, &dcc->pend_list[plist_idx(dc->len)]);
+	dcc->nr_pending[plist_idx(dc->len)]++;
+	dcc->nr_pending[index]--;
 }
 
 static void __punch_discard_cmd(struct f2fs_sb_info *sbi,
@@ -1230,9 +1234,10 @@ static void __punch_discard_cmd(struct f2fs_sb_info *sbi,
 	dcc->undiscard_blks -= di.len;
 
 	if (blkaddr > di.lstart) {
+		block_t old_len = dc->len;
 		dc->len = blkaddr - dc->lstart;
 		dcc->undiscard_blks += dc->len;
-		__relocate_discard_cmd(dcc, dc);
+		__relocate_discard_cmd(dcc, dc, plist_idx(old_len));
 		modified = true;
 	}
 
@@ -1243,11 +1248,12 @@ static void __punch_discard_cmd(struct f2fs_sb_info *sbi,
 					di.lstart + di.len - 1 - blkaddr,
 					NULL, NULL);
 		} else {
+			block_t old_len = dc->len;
 			dc->lstart++;
 			dc->len--;
 			dc->start++;
 			dcc->undiscard_blks += dc->len;
-			__relocate_discard_cmd(dcc, dc);
+			__relocate_discard_cmd(dcc, dc, plist_idx(old_len));
 		}
 	}
 }
@@ -1306,9 +1312,10 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
 			prev_dc->bdev == bdev &&
 			__is_discard_back_mergeable(&di, &prev_dc->di,
 							max_discard_blocks)) {
+			block_t old_len = prev_dc->di.len;
 			prev_dc->di.len += di.len;
 			dcc->undiscard_blks += di.len;
-			__relocate_discard_cmd(dcc, prev_dc);
+			__relocate_discard_cmd(dcc, prev_dc, plist_idx(old_len));
 			di = prev_dc->di;
 			tdc = prev_dc;
 			merged = true;
@@ -1318,13 +1325,16 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
 			next_dc->bdev == bdev &&
 			__is_discard_front_mergeable(&di, &next_dc->di,
 							max_discard_blocks)) {
+			block_t old_len = next_dc->di.len;
 			next_dc->di.lstart = di.lstart;
 			next_dc->di.len += di.len;
 			next_dc->di.start = di.start;
 			dcc->undiscard_blks += di.len;
-			__relocate_discard_cmd(dcc, next_dc);
-			if (tdc)
+			__relocate_discard_cmd(dcc, next_dc, plist_idx(old_len));
+			if (tdc) {
+				dcc->nr_pending[plist_idx(tdc->len)]--;
 				__remove_discard_cmd(sbi, tdc);
+			}
 			merged = true;
 		}
 
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 032c03e09580..2176553f97c9 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -1252,6 +1252,32 @@ static int __maybe_unused victim_bits_seq_show(struct seq_file *seq,
 	return 0;
 }
 
+static int __maybe_unused discard_plist_seq_show(struct seq_file *seq,
+						void *offset)
+{
+	struct super_block *sb = seq->private;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
+	int i;
+
+	seq_puts(seq, "Discard pending list(Show diacrd command count on each entry):\n");
+	if (!f2fs_realtime_discard_enable(sbi))
+		return 0;
+
+	for (i = 0; i < MAX_PLIST_NUM; i++) {
+		if (i % 8 == 0)
+			seq_printf(seq, "%-10d", i);
+		seq_printf(seq, " %10d", dcc->nr_pending[i]);
+		if (i % 8 == 7)
+			seq_putc(seq, '\n');
+		else
+			seq_putc(seq, ' ');
+	}
+	seq_putc(seq, '\n');
+
+	return 0;
+}
+
 int __init f2fs_init_sysfs(void)
 {
 	int ret;
@@ -1322,6 +1348,8 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
 #endif
 		proc_create_single_data("victim_bits", 0444, sbi->s_proc,
 				victim_bits_seq_show, sb);
+		proc_create_single_data("discard_plist", 0444, sbi->s_proc,
+				discard_plist_seq_show, sb);
 	}
 	return 0;
 put_feature_list_kobj:
@@ -1345,6 +1373,7 @@ void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi)
 		remove_proc_entry("segment_info", sbi->s_proc);
 		remove_proc_entry("segment_bits", sbi->s_proc);
 		remove_proc_entry("victim_bits", sbi->s_proc);
+		remove_proc_entry("discard_plist", sbi->s_proc);
 		remove_proc_entry(sbi->sb->s_id, f2fs_proc_root);
 	}
 
-- 
2.25.1