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Date: Thu, 31 Oct 2019 10:27:23 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Jaegeuk Kim <jaegeuk@...nel.org>
CC: <linux-kernel@...r.kernel.org>,
<linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: support aligned pinned file
On 2019/10/31 0:09, Jaegeuk Kim wrote:
> On 10/26, Chao Yu wrote:
>> On 2019/10/26 2:18, Jaegeuk Kim wrote:
>>> On 10/24, Chao Yu wrote:
>>>> Hi Jaegeuk,
>>>>
>>>> On 2019/10/23 1:16, Jaegeuk Kim wrote:
>>>>> This patch supports 2MB-aligned pinned file, which can guarantee no GC at all
>>>>> by allocating fully valid 2MB segment.
>>>>>
>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>>>> ---
>>>>> fs/f2fs/f2fs.h | 4 +++-
>>>>> fs/f2fs/file.c | 39 ++++++++++++++++++++++++++++++++++-----
>>>>> fs/f2fs/recovery.c | 2 +-
>>>>> fs/f2fs/segment.c | 21 ++++++++++++++++++++-
>>>>> fs/f2fs/segment.h | 2 ++
>>>>> fs/f2fs/super.c | 1 +
>>>>> fs/f2fs/sysfs.c | 2 ++
>>>>> 7 files changed, 63 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>> index ca342f4c7db1..c681f51e351b 100644
>>>>> --- a/fs/f2fs/f2fs.h
>>>>> +++ b/fs/f2fs/f2fs.h
>>>>> @@ -890,6 +890,7 @@ enum {
>>>>> CURSEG_WARM_NODE, /* direct node blocks of normal files */
>>>>> CURSEG_COLD_NODE, /* indirect node blocks */
>>>>> NO_CHECK_TYPE,
>>>>> + CURSEG_COLD_DATA_PINNED,/* cold data for pinned file */
>>>>> };
>>>>>
>>>>> struct flush_cmd {
>>>>> @@ -1301,6 +1302,7 @@ struct f2fs_sb_info {
>>>>>
>>>>> /* threshold for gc trials on pinned files */
>>>>> u64 gc_pin_file_threshold;
>>>>> + struct rw_semaphore pin_sem;
>>>>>
>>>>> /* maximum # of trials to find a victim segment for SSR and GC */
>>>>> unsigned int max_victim_search;
>>>>> @@ -3116,7 +3118,7 @@ void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
>>>>> int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
>>>>> void allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,
>>>>> unsigned int start, unsigned int end);
>>>>> -void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi);
>>>>> +void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi, int type);
>>>>> int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range);
>>>>> bool f2fs_exist_trim_candidates(struct f2fs_sb_info *sbi,
>>>>> struct cp_control *cpc);
>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>> index 29bc0a542759..f6c038e8a6a7 100644
>>>>> --- a/fs/f2fs/file.c
>>>>> +++ b/fs/f2fs/file.c
>>>>> @@ -1545,12 +1545,41 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
>>>>> if (off_end)
>>>>> map.m_len++;
>>>>>
>>>>> - if (f2fs_is_pinned_file(inode))
>>>>> - map.m_seg_type = CURSEG_COLD_DATA;
>>>>> + if (!map.m_len)
>>>>> + return 0;
>>>>> +
>>>>> + if (f2fs_is_pinned_file(inode)) {
>>>>> + block_t len = (map.m_len >> sbi->log_blocks_per_seg) <<
>>>>> + sbi->log_blocks_per_seg;
>>>>> + block_t done = 0;
>>>>> +
>>>>> + if (map.m_len % sbi->blocks_per_seg)
>>>>> + len += sbi->blocks_per_seg;
>>>>>
>>>>> - err = f2fs_map_blocks(inode, &map, 1, (f2fs_is_pinned_file(inode) ?
>>>>> - F2FS_GET_BLOCK_PRE_DIO :
>>>>> - F2FS_GET_BLOCK_PRE_AIO));
>>>>> + map.m_len = sbi->blocks_per_seg;
>>>>> +next_alloc:
>>>>> + mutex_lock(&sbi->gc_mutex);
>>>>> + err = f2fs_gc(sbi, true, false, NULL_SEGNO);
>>>>> + if (err && err != -ENODATA && err != -EAGAIN)
>>>>> + goto out_err;
>>>>
>>>> To grab enough free space?
>>>>
>>>> Shouldn't we call
>>>>
>>>> if (has_not_enough_free_secs(sbi, 0, 0)) {
>>>> mutex_lock(&sbi->gc_mutex);
>>>> f2fs_gc(sbi, false, false, NULL_SEGNO);
>>>> }
>>>
>>> The above calls gc all the time. Do we need this?
>>
>> Hmmm... my concern is why we need to run foreground GC even if there is enough
>> free space..
>
> In order to get the free segment easily?
However, I doubt arbitrary foreground GC with greedy algorithm will ruin
hot/cold data separation, actually, for sufficient free segment case, it's
unnecessary to call FGGC.
Thanks,
>
>>
>>>
>>>>
>>>>> +
>>>>> + down_write(&sbi->pin_sem);
>>>>> + map.m_seg_type = CURSEG_COLD_DATA_PINNED;
>>>>> + f2fs_allocate_new_segments(sbi, CURSEG_COLD_DATA);
>>>>> + err = f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_DIO);
>>>>> + up_write(&sbi->pin_sem);
>>>>> +
>>>>> + done += map.m_len;
>>>>> + len -= map.m_len;
>>>>> + map.m_lblk += map.m_len;
>>>>> + if (!err && len)
>>>>> + goto next_alloc;
>>>>> +
>>>>> + map.m_len = done;
>>>>> + } else {
>>>>> + err = f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_AIO);
>>>>> + }
>>>>> +out_err:
>>>>> if (err) {
>>>>> pgoff_t last_off;
>>>>>
>>>>> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
>>>>> index 783773e4560d..76477f71d4ee 100644
>>>>> --- a/fs/f2fs/recovery.c
>>>>> +++ b/fs/f2fs/recovery.c
>>>>> @@ -711,7 +711,7 @@ static int recover_data(struct f2fs_sb_info *sbi, struct list_head *inode_list,
>>>>> f2fs_put_page(page, 1);
>>>>> }
>>>>> if (!err)
>>>>> - f2fs_allocate_new_segments(sbi);
>>>>> + f2fs_allocate_new_segments(sbi, NO_CHECK_TYPE);
>>>>> return err;
>>>>> }
>>>>>
>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>>> index 25c750cd0272..253d72c2663c 100644
>>>>> --- a/fs/f2fs/segment.c
>>>>> +++ b/fs/f2fs/segment.c
>>>>> @@ -2690,7 +2690,7 @@ void allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,
>>>>> up_read(&SM_I(sbi)->curseg_lock);
>>>>> }
>>>>>
>>>>> -void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi)
>>>>> +void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi, int type)
>>>>> {
>>>>> struct curseg_info *curseg;
>>>>> unsigned int old_segno;
>>>>> @@ -2699,6 +2699,9 @@ void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi)
>>>>> down_write(&SIT_I(sbi)->sentry_lock);
>>>>>
>>>>> for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
>>>>> + if (type != NO_CHECK_TYPE && i != type)
>>>>> + continue;
>>>>> +
>>>>> curseg = CURSEG_I(sbi, i);
>>>>> old_segno = curseg->segno;
>>>>> SIT_I(sbi)->s_ops->allocate_segment(sbi, i, true);
>>>>> @@ -3068,6 +3071,19 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
>>>>> {
>>>>> struct sit_info *sit_i = SIT_I(sbi);
>>>>> struct curseg_info *curseg = CURSEG_I(sbi, type);
>>>>> + bool put_pin_sem = false;
>>>>> +
>>>>> + if (type == CURSEG_COLD_DATA) {
>>>>> + /* GC during CURSEG_COLD_DATA_PINNED allocation */
>>>>> + if (down_read_trylock(&sbi->pin_sem)) {
>>>>> + put_pin_sem = true;
>>>>> + } else {
>>>>> + type = CURSEG_WARM_DATA;
>>>>> + curseg = CURSEG_I(sbi, type);
>>>>
>>>> It will mix pending cold data into warm area... rather than recovering curseg to
>>>> write pointer of last cold segment?
>>>>
>>>> I know maybe that fallocate aligned address could be corner case, but I guess
>>>> there should be some better solutions can handle race case more effectively.
>>>>
>>>> One solution could be: allocating a virtual log header to select free segment as
>>>> 2m-aligned space target.
>>>
>>> I thought about that, but concluded to avoid too much changes.
>>
>> We have an unupstreamed feature which is based on virtual log header, I can
>> introduce that basic virtual log fwk, which can be used for aligned allocation
>> and later new features, would you like to check that?
>>
>> Thanks,
>>
>>>
>>>>
>>>> Thanks,
>>>>
>>>>> + }
>>>>> + } else if (type == CURSEG_COLD_DATA_PINNED) {
>>>>> + type = CURSEG_COLD_DATA;
>>>>> + }
>>>>>
>>>>> down_read(&SM_I(sbi)->curseg_lock);
>>>>>
>>>>> @@ -3133,6 +3149,9 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
>>>>> mutex_unlock(&curseg->curseg_mutex);
>>>>>
>>>>> up_read(&SM_I(sbi)->curseg_lock);
>>>>> +
>>>>> + if (put_pin_sem)
>>>>> + up_read(&sbi->pin_sem);
>>>>> }
>>>>>
>>>>> static void update_device_state(struct f2fs_io_info *fio)
>>>>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>>>>> index 325781a1ae4d..a95467b202ea 100644
>>>>> --- a/fs/f2fs/segment.h
>>>>> +++ b/fs/f2fs/segment.h
>>>>> @@ -313,6 +313,8 @@ struct sit_entry_set {
>>>>> */
>>>>> static inline struct curseg_info *CURSEG_I(struct f2fs_sb_info *sbi, int type)
>>>>> {
>>>>> + if (type == CURSEG_COLD_DATA_PINNED)
>>>>> + type = CURSEG_COLD_DATA;
>>>>> return (struct curseg_info *)(SM_I(sbi)->curseg_array + type);
>>>>> }
>>>>>
>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>>>> index f320fd11db48..c02a47ce551b 100644
>>>>> --- a/fs/f2fs/super.c
>>>>> +++ b/fs/f2fs/super.c
>>>>> @@ -2853,6 +2853,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
>>>>> spin_lock_init(&sbi->dev_lock);
>>>>>
>>>>> init_rwsem(&sbi->sb_lock);
>>>>> + init_rwsem(&sbi->pin_sem);
>>>>> }
>>>>>
>>>>> static int init_percpu_info(struct f2fs_sb_info *sbi)
>>>>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>>>>> index b558b64a4c9c..f164959e4224 100644
>>>>> --- a/fs/f2fs/sysfs.c
>>>>> +++ b/fs/f2fs/sysfs.c
>>>>> @@ -154,6 +154,8 @@ static ssize_t features_show(struct f2fs_attr *a,
>>>>> if (f2fs_sb_has_casefold(sbi))
>>>>> len += snprintf(buf + len, PAGE_SIZE - len, "%s%s",
>>>>> len ? ", " : "", "casefold");
>>>>> + len += snprintf(buf + len, PAGE_SIZE - len, "%s%s",
>>>>> + len ? ", " : "", "pin_file");
>>>>> len += snprintf(buf + len, PAGE_SIZE - len, "\n");
>>>>> return len;
>>>>> }
>>>>>
>>> .
>>>
> .
>
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