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Date: Fri, 13 Jul 2018 11:26:27 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Yunlong Song <yunlong.song@...wei.com>, <jaegeuk@...nel.org>,
<chao@...nel.org>, <yunlong.song@...oud.com>
CC: <miaoxie@...wei.com>, <bintian.wang@...wei.com>,
<shengyong1@...wei.com>, <heyunlei@...wei.com>,
<linux-f2fs-devel@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/5] f2fs: do not __punch_discard_cmd in lfs mode
On 2018/7/12 23:09, Yunlong Song wrote:
> In lfs mode, it is better to submit and wait for discard of the
> new_blkaddr's overall section, rather than punch it which makes
> more small discards and is not friendly with flash alignment. And
> f2fs does not have to wait discard of each new_blkaddr except for the
> start_block of each section with this patch.
For non-zoned block device, unaligned discard can be allowed; and if synchronous
discard is very slow, it will block block allocator here, rather than that, I
prefer just punch 4k lba of discard entry for performance.
If you don't want to encounter this condition, I suggest issue large size
discard more quickly.
Thanks,
>
> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
> ---
> fs/f2fs/segment.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
> fs/f2fs/segment.h | 7 ++++-
> 2 files changed, 75 insertions(+), 8 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index f6c20e0..bce321a 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -893,7 +893,19 @@ static void __remove_discard_cmd(struct f2fs_sb_info *sbi,
> static void f2fs_submit_discard_endio(struct bio *bio)
> {
> struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private;
> + struct f2fs_sb_info *sbi = F2FS_SB(dc->bdev->bd_super);
>
> + if (test_opt(sbi, LFS)) {
> + unsigned int segno = GET_SEGNO(sbi, dc->lstart);
> + unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
> + int cnt = (dc->len >> sbi->log_blocks_per_seg) /
> + sbi->segs_per_sec;
> +
> + while (cnt--) {
> + set_bit(secno, FREE_I(sbi)->discard_secmap);
> + secno++;
> + }
> + }
> dc->error = blk_status_to_errno(bio->bi_status);
> dc->state = D_DONE;
> complete_all(&dc->wait);
> @@ -1349,8 +1361,15 @@ static void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
> dc = (struct discard_cmd *)f2fs_lookup_rb_tree(&dcc->root,
> NULL, blkaddr);
> if (dc) {
> - if (dc->state == D_PREP) {
> + if (dc->state == D_PREP && !test_opt(sbi, LFS))
> __punch_discard_cmd(sbi, dc, blkaddr);
> + else if (dc->state == D_PREP && test_opt(sbi, LFS)) {
> + struct discard_policy dpolicy;
> +
> + __init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);
> + __submit_discard_cmd(sbi, &dpolicy, dc);
> + dc->ref++;
> + need_wait = true;
> } else {
> dc->ref++;
> need_wait = true;
> @@ -2071,9 +2090,10 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> unsigned int hint = GET_SEC_FROM_SEG(sbi, *newseg);
> unsigned int old_zoneno = GET_ZONE_FROM_SEG(sbi, *newseg);
> unsigned int left_start = hint;
> - bool init = true;
> + bool init = true, check_discard = test_opt(sbi, LFS) ? true : false;
> int go_left = 0;
> int i;
> + unsigned long *free_secmap;
>
> spin_lock(&free_i->segmap_lock);
>
> @@ -2084,11 +2104,25 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> goto got_it;
> }
> find_other_zone:
> - secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
> + if (check_discard) {
> + int entries = f2fs_bitmap_size(MAIN_SECS(sbi)) / sizeof(unsigned long);
> +
> + free_secmap = free_i->tmp_secmap;
> + for (i = 0; i < entries; i++)
> + free_secmap[i] = (!(free_i->free_secmap[i] ^
> + free_i->discard_secmap[i])) | free_i->free_secmap[i];
> + } else
> + free_secmap = free_i->free_secmap;
> +
> + secno = find_next_zero_bit(free_secmap, MAIN_SECS(sbi), hint);
> if (secno >= MAIN_SECS(sbi)) {
> if (dir == ALLOC_RIGHT) {
> - secno = find_next_zero_bit(free_i->free_secmap,
> + secno = find_next_zero_bit(free_secmap,
> MAIN_SECS(sbi), 0);
> + if (secno >= MAIN_SECS(sbi) && check_discard) {
> + check_discard = false;
> + goto find_other_zone;
> + }
> f2fs_bug_on(sbi, secno >= MAIN_SECS(sbi));
> } else {
> go_left = 1;
> @@ -2098,13 +2132,17 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> if (go_left == 0)
> goto skip_left;
>
> - while (test_bit(left_start, free_i->free_secmap)) {
> + while (test_bit(left_start, free_secmap)) {
> if (left_start > 0) {
> left_start--;
> continue;
> }
> - left_start = find_next_zero_bit(free_i->free_secmap,
> + left_start = find_next_zero_bit(free_secmap,
> MAIN_SECS(sbi), 0);
> + if (left_start >= MAIN_SECS(sbi) && check_discard) {
> + check_discard = false;
> + goto find_other_zone;
> + }
> f2fs_bug_on(sbi, left_start >= MAIN_SECS(sbi));
> break;
> }
> @@ -2719,7 +2757,18 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
>
> *new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
>
> - f2fs_wait_discard_bio(sbi, *new_blkaddr);
> + if (test_opt(sbi, LFS)) {
> + unsigned int start_segno, secno;
> +
> + secno = GET_SEC_FROM_SEG(sbi, curseg->segno);
> + start_segno = secno * sbi->segs_per_sec;
> + if (*new_blkaddr == START_BLOCK(sbi, start_segno) &&
> + !test_bit(secno, FREE_I(sbi)->discard_secmap))
> + f2fs_wait_discard_bio(sbi, *new_blkaddr);
> + f2fs_bug_on(sbi, !test_bit(secno, FREE_I(sbi)->discard_secmap));
> + }
> + else
> + f2fs_wait_discard_bio(sbi, *new_blkaddr);
>
> /*
> * __add_sum_entry should be resided under the curseg_mutex
> @@ -3648,10 +3697,21 @@ static int build_free_segmap(struct f2fs_sb_info *sbi)
> if (!free_i->free_secmap)
> return -ENOMEM;
>
> + free_i->discard_secmap = f2fs_kvmalloc(sbi, sec_bitmap_size, GFP_KERNEL);
> + if (!free_i->discard_secmap)
> + return -ENOMEM;
> +
> + free_i->tmp_secmap = f2fs_kvmalloc(sbi, sec_bitmap_size, GFP_KERNEL);
> + if (!free_i->tmp_secmap)
> + return -ENOMEM;
> +
> /* set all segments as dirty temporarily */
> memset(free_i->free_segmap, 0xff, bitmap_size);
> memset(free_i->free_secmap, 0xff, sec_bitmap_size);
>
> + /* set all sections as discarded temporarily */
> + memset(free_i->discard_secmap, 0xff, sec_bitmap_size);
> +
> /* init free segmap information */
> free_i->start_segno = GET_SEGNO_FROM_SEG0(sbi, MAIN_BLKADDR(sbi));
> free_i->free_segments = 0;
> @@ -4047,6 +4107,8 @@ static void destroy_free_segmap(struct f2fs_sb_info *sbi)
> SM_I(sbi)->free_info = NULL;
> kvfree(free_i->free_segmap);
> kvfree(free_i->free_secmap);
> + kvfree(free_i->discard_secmap);
> + kvfree(free_i->tmp_secmap);
> kfree(free_i);
> }
>
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 5049551..b37a909 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -259,6 +259,8 @@ struct free_segmap_info {
> spinlock_t segmap_lock; /* free segmap lock */
> unsigned long *free_segmap; /* free segment bitmap */
> unsigned long *free_secmap; /* free section bitmap */
> + unsigned long *discard_secmap; /* discard section bitmap */
> + unsigned long *tmp_secmap; /* bitmap for temporal use */
> };
>
> /* Notice: The order of dirty type is same with CURSEG_XXX in f2fs.h */
> @@ -453,8 +455,11 @@ static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
> next = find_next_bit(free_i->free_segmap,
> start_segno + sbi->segs_per_sec, start_segno);
> if (next >= start_segno + sbi->segs_per_sec) {
> - if (test_and_clear_bit(secno, free_i->free_secmap))
> + if (test_and_clear_bit(secno, free_i->free_secmap)) {
> free_i->free_sections++;
> + if (test_opt(sbi, LFS))
> + clear_bit(secno, free_i->discard_secmap);
> + }
> }
> }
> skip_free:
>
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