How about change test_opt(sbi, LFS) to f2fs_sb_has_blkzoned(sbi->sb) in this patch, which can
avoid punch discard (creating small discard) in zoned block device.

On 2018/7/13 11:26, Chao Yu wrote:
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.s...@huawei.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:


.


--
Thanks,
Yunlong Song



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