Re: [f2fs-dev] [PATCH v2] f2fs: rename checkpoint=merge mount option to checkpoint_merge

From: Chao Yu
Date: Tue Feb 02 2021 - 03:31:09 EST


On 2021/2/2 16:02, Daeho Jeong wrote:
I chose the same step with "flush_merge", because it doesn't have
"noflush_merge".

Oh, "noxxx" option was added only when we set the option by default in
default_options(), when user want to disable the default option, it
needs to use "noxxx" option, and then we will show this "noxxx" option
string to user via show_options() to indicate that "noxxx" option is
working now.

Anyway I think we should fix to show "noflush_merge" option because we
have set flush_merge by default.

Do you think we need that for both, "noflush_merge" and "nocheckpoint_merge"?

For "nocheckpoint_merge", we can introduce this option only when we want
to set "checkpoint_merge" by default.

Here is the example from noinline_data:

Commit 75342797988 ("f2fs: enable inline data by default")

Thanks,


I thought we needed to give some time to make this be turned on by
default. It might be a little radical. :)

What do you think?

2021년 2월 2일 (화) 오후 4:40, Chao Yu <yuchao0@xxxxxxxxxx>님이 작성:

On 2021/2/2 13:18, Daeho Jeong wrote:
From: Daeho Jeong <daehojeong@xxxxxxxxxx>

As checkpoint=merge comes in, mount option setting related to checkpoint
had been mixed up and it became hard to understand. So, I separated
this option from "checkpoint=" and made another mount option
"checkpoint_merge" for this.

Signed-off-by: Daeho Jeong <daehojeong@xxxxxxxxxx>
---
v2: renamed "checkpoint=merge" to "checkpoint_merge"
---
Documentation/filesystems/f2fs.rst | 6 +++---
fs/f2fs/super.c | 26 ++++++++++++++------------
2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
index d0ead45dc706..475994ed8b15 100644
--- a/Documentation/filesystems/f2fs.rst
+++ b/Documentation/filesystems/f2fs.rst
@@ -247,9 +247,9 @@ checkpoint=%s[:%u[%]] Set to "disable" to turn off checkpointing. Set to "enabl
hide up to all remaining free space. The actual space that
would be unusable can be viewed at /sys/fs/f2fs/<disk>/unusable
This space is reclaimed once checkpoint=enable.
- Here is another option "merge", which creates a kernel daemon
- and makes it to merge concurrent checkpoint requests as much
- as possible to eliminate redundant checkpoint issues. Plus,
+checkpoint_merge When checkpoint is enabled, this can be used to create a kernel
+ daemon and make it to merge concurrent checkpoint requests as
+ much as possible to eliminate redundant checkpoint issues. Plus,
we can eliminate the sluggish issue caused by slow checkpoint
operation when the checkpoint is done in a process context in
a cgroup having low i/o budget and cpu shares. To make this
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 56696f6cfa86..d8603e6c4916 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -145,6 +145,7 @@ enum {
Opt_checkpoint_disable_cap_perc,
Opt_checkpoint_enable,
Opt_checkpoint_merge,
+ Opt_nocheckpoint_merge,
Opt_compress_algorithm,
Opt_compress_log_size,
Opt_compress_extension,
@@ -215,7 +216,8 @@ static match_table_t f2fs_tokens = {
{Opt_checkpoint_disable_cap, "checkpoint=disable:%u"},
{Opt_checkpoint_disable_cap_perc, "checkpoint=disable:%u%%"},
{Opt_checkpoint_enable, "checkpoint=enable"},
- {Opt_checkpoint_merge, "checkpoint=merge"},
+ {Opt_checkpoint_merge, "checkpoint_merge"},
+ {Opt_nocheckpoint_merge, "nocheckpoint_merge"},
{Opt_compress_algorithm, "compress_algorithm=%s"},
{Opt_compress_log_size, "compress_log_size=%u"},
{Opt_compress_extension, "compress_extension=%s"},
@@ -946,6 +948,9 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
case Opt_checkpoint_merge:
set_opt(sbi, MERGE_CHECKPOINT);
break;
+ case Opt_nocheckpoint_merge:
+ clear_opt(sbi, MERGE_CHECKPOINT);
+ break;
#ifdef CONFIG_F2FS_FS_COMPRESSION
case Opt_compress_algorithm:
if (!f2fs_sb_has_compression(sbi)) {
@@ -1142,12 +1147,6 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
return -EINVAL;
}

- if (test_opt(sbi, DISABLE_CHECKPOINT) &&
- test_opt(sbi, MERGE_CHECKPOINT)) {
- f2fs_err(sbi, "checkpoint=merge cannot be used with checkpoint=disable\n");
- return -EINVAL;
- }
-
/* Not pass down write hints if the number of active logs is lesser
* than NR_CURSEG_PERSIST_TYPE.
*/
@@ -1782,7 +1781,7 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
seq_printf(seq, ",checkpoint=disable:%u",
F2FS_OPTION(sbi).unusable_cap);
if (test_opt(sbi, MERGE_CHECKPOINT))
- seq_puts(seq, ",checkpoint=merge");
+ seq_puts(seq, ",checkpoint_merge");

Other noxxx options will be shown in show_options(), how about following them?

if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_POSIX)
seq_printf(seq, ",fsync_mode=%s", "posix");
else if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_STRICT)
@@ -1827,6 +1826,7 @@ static void default_options(struct f2fs_sb_info *sbi)
sbi->sb->s_flags |= SB_LAZYTIME;
set_opt(sbi, FLUSH_MERGE);
set_opt(sbi, DISCARD);
+ clear_opt(sbi, MERGE_CHECKPOINT);

Why should we clear checkpoint_merge option in default_options()?

Thanks,

if (f2fs_sb_has_blkzoned(sbi))
F2FS_OPTION(sbi).fs_mode = FS_MODE_LFS;
else
@@ -2066,9 +2066,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
}
}

- if (!test_opt(sbi, MERGE_CHECKPOINT)) {
- f2fs_stop_ckpt_thread(sbi);
- } else {
+ if (!test_opt(sbi, DISABLE_CHECKPOINT) &&
+ test_opt(sbi, MERGE_CHECKPOINT)) {
err = f2fs_start_ckpt_thread(sbi);
if (err) {
f2fs_err(sbi,
@@ -2076,6 +2075,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
err);
goto restore_gc;
}
+ } else {
+ f2fs_stop_ckpt_thread(sbi);
}

/*
@@ -3831,7 +3832,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)

/* setup checkpoint request control and start checkpoint issue thread */
f2fs_init_ckpt_req_control(sbi);
- if (test_opt(sbi, MERGE_CHECKPOINT)) {
+ if (!test_opt(sbi, DISABLE_CHECKPOINT) &&
+ test_opt(sbi, MERGE_CHECKPOINT)) {
err = f2fs_start_ckpt_thread(sbi);
if (err) {
f2fs_err(sbi,

.