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Message-ID: <20191030160942.GA34056@jaegeuk-macbookpro.roam.corp.google.com>
Date: Wed, 30 Oct 2019 09:09:42 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
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 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?
>
> >
> >>
> >>> +
> >>> + 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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