[PATCH v3] f2fs: add proc entry to show discard_plist info

From: Yangtao Li
Date: Fri Nov 11 2022 - 10:39:50 EST

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@xxxxxxxx>
---
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