> This patch introduces /sys/fs/f2fs/<dev>/reserved_pin_section for tuning
> @needed parameter of has_not_enough_free_secs(), if we configure it w/
> zero, it can avoid f2fs_gc() as much as possible while fallocating on
> pinned file.
>
> Signed-off-by: Chao Yu <c...@kernel.org>
Thanks for helping to introduce this sysfs entry.
Reviewed-by: wangzijie <wangzij...@honor.com>
> ---
> v2:
> - assign SM_I(sbi)->ovp_segments after f2fs_build_segment_manager()
> Documentation/ABI/testing/sysfs-fs-f2fs | 9 +++++++++
> fs/f2fs/f2fs.h | 3 +++
> fs/f2fs/file.c | 5 ++---
> fs/f2fs/super.c | 4 ++++
> fs/f2fs/sysfs.c | 9 +++++++++
> 5 files changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs
> b/Documentation/ABI/testing/sysfs-fs-f2fs
> index bf03263b9f46..c2a233f2a085 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -861,3 +861,12 @@ Description: This is a read-only entry to show the
> value of sb.s_encoding_flags,
> SB_ENC_STRICT_MODE_FL 0x00000001
> SB_ENC_NO_COMPAT_FALLBACK_FL 0x00000002
> ============================ ==========
> +
> +What: /sys/fs/f2fs/<disk>/reserved_pin_section
> +Date: June 2025
> +Contact: "Chao Yu" <c...@kernel.org>
> +Description: This threshold is used to control triggering garbage collection
> while
> + fallocating on pinned file, so, it can guarantee there is
> enough free
> + reserved section before preallocating on pinned file.
> + By default, the value is ovp_sections, especially, for zoned
> ufs, the
> + value is 1.
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 9333a22b9a01..fa27498202a3 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1724,6 +1724,9 @@ struct f2fs_sb_info {
> /* for skip statistic */
> unsigned long long skipped_gc_rwsem; /* FG_GC only */
>
> + /* free sections reserved for pinned file */
> + unsigned int reserved_pin_section;
> +
> /* threshold for gc trials on pinned files */
> unsigned short gc_pin_file_threshold;
> struct f2fs_rwsem pin_sem;
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 696131e655ed..a909f79db178 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1887,9 +1887,8 @@ static int f2fs_expand_inode_data(struct inode *inode,
> loff_t offset,
> }
> }
>
> - if (has_not_enough_free_secs(sbi, 0, f2fs_sb_has_blkzoned(sbi) ?
> - ZONED_PIN_SEC_REQUIRED_COUNT :
> - GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) {
> + if (has_not_enough_free_secs(sbi, 0,
> + sbi->reserved_pin_section)) {
> f2fs_down_write(&sbi->gc_lock);
> stat_inc_gc_call_count(sbi, FOREGROUND);
> err = f2fs_gc(sbi, &gc_control);
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 57adeff5ef25..e0ecc341f1d3 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -5017,6 +5017,10 @@ static int f2fs_fill_super(struct super_block *sb,
> struct fs_context *fc)
> /* get segno of first zoned block device */
> sbi->first_seq_zone_segno = get_first_seq_zone_segno(sbi);
>
> + sbi->reserved_pin_section = f2fs_sb_has_blkzoned(sbi) ?
> + ZONED_PIN_SEC_REQUIRED_COUNT :
> + GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi));
> +
> /* Read accumulated write IO statistics if exists */
> seg_i = CURSEG_I(sbi, CURSEG_HOT_NODE);
> if (__exist_node_summaries(sbi))
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 75134d69a0bd..51be7ffb38c5 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -824,6 +824,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
> return count;
> }
>
> + if (!strcmp(a->attr.name, "reserved_pin_section")) {
> + if (t > GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))
> + return -EINVAL;
> + *ui = (unsigned int)t;
> + return count;
> + }
> +
> *ui = (unsigned int)t;
>
> return count;
> @@ -1130,6 +1137,7 @@ F2FS_SBI_GENERAL_RO_ATTR(unusable_blocks_per_sec);
> F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
> #endif
> F2FS_SBI_GENERAL_RW_ATTR(carve_out);
> +F2FS_SBI_GENERAL_RW_ATTR(reserved_pin_section);
>
> /* STAT_INFO ATTR */
> #ifdef CONFIG_F2FS_STAT_FS
> @@ -1323,6 +1331,7 @@ static struct attribute *f2fs_attrs[] = {
> ATTR_LIST(last_age_weight),
> ATTR_LIST(max_read_extent_count),
> ATTR_LIST(carve_out),
> + ATTR_LIST(reserved_pin_section),
> NULL,
> };
> ATTRIBUTE_GROUPS(f2fs);
> --
> 2.40.1
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