From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2618A15A85A for ; Tue, 25 Aug 2026 03:16:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787627799; cv=none; b=GPMLGbaLMJH5ZTneNA0r3QHfhWb5syjyDVjOvSPh8yEdrd0ArjzyF5MWM+0uwh/1adLVAKwIVXLIWvE/oe1AXHYo2dVmXijeHQjVDoTJBP6KOd1CJlviu7BmPkZKG/i5e4gEIfbFX0vElZlvNFoOEgiC8Lb9CYEgfmvlR6sq2VM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787627799; c=relaxed/simple; bh=hWuBs1F5UttXb59Ym7tl23nQg+T0db3ax3EyAuWY4oo=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=P4cwEtAYKik+yYCMs6/mSv++tBSDHjp3In5ybEr42O/4rVdIVPw9UgpsaLhBo9P9vkMVg5n/eneqj9N1YBcZFwJQ5hYvPHX6Li9fUc5HTa0WHcHqkch/7j1Et59OY7t/QG+Qk+poQSxoGB3BgVsVBazJk1iORW6SFQrV9+6dXeA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ivnRmAlD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ivnRmAlD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FE861F000E9; Tue, 25 Aug 2026 03:16:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787627797; bh=usZ8o5e5NemINIdTPZwsdtrFOrvwemEKPupJ65Ao44M=; h=Date:Cc:Subject:To:References:From:In-Reply-To; b=ivnRmAlDPRw3ZeUfb+CKw4t51FbzASdaT8jqL7Q09ZzjMHldNLxl9Mq+pqfBa6cZf sL+opwjcVTueYXf+1sLK1QINZFnvKZ3Fwt2LCEHU2TGoReUGWS1oquteEXPVzY20q2 J79QTgAuyb6+dAXZAWexiXaU9zMcMQDRxs2bpmURg1A++W1c1oa3nqOhKd+NukfeRK 8InB4E4FvTwuYpCr941XXPew+GizyIMSDEp0oNZ12JNf1GisNT1Ybex4JLw+bWFOwz n8/YGY/WyFvaiXptAJZ7tcTcCq1JkRazHp2bmj5EN6dTVUiDEs3X99MKd1/5A/69uB 8ND8RaarXgWGg== Message-ID: <093eae1e-f533-404c-b8da-f5025d4e3db2@kernel.org> Date: Tue, 25 Aug 2026 11:16:34 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, Daeho Jeong Subject: Re: [f2fs-dev] [PATCH] f2fs: support resizable tail section and unify pinned allocation To: Daeho Jeong , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com References: <20260824191404.2558269-1-daeho43@gmail.com> Content-Language: en-US From: Chao Yu In-Reply-To: <20260824191404.2558269-1-daeho43@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/25/26 03:14, Daeho Jeong wrote: > From: Daeho Jeong > > Currently, zoned block devices restrict pinned file allocations to > conventional zones at the beginning of the storage (before > first_seq_zone_segno), triggering range GC when conventional space is > exhausted. > > On regular block devices, when preparing for future online filesystem > resizing (e.g. partition shrinking), pinned files must not be allocated > in the tail area that will be truncated, as pinned files cannot be > relocated by GC. Specifying the resizable tail area size (in sections) > allows uniform mount configuration across devices of different storage > capacities. > > To support this, introduce a unified `pinned_area_max_secno` boundary > abstraction in `f2fs_sb_info`: > 1. Add `-o resizable_tail_secno=%u` mount option to specify the number > of sections at the tail of the filesystem reserved for resizing. > 2. In `f2fs_fill_super()`, initialize `sbi->pinned_area_max_secno` as: > min(MAIN_SECS(sbi) - resizable_tail_sec, zoned_max_sec). > 3. In `get_new_segment()`, restrict segment allocation for pinned files > (`pinning == true`) to `0 .. sbi->pinned_area_max_secno - 1`. If no > free section is available in the pinned area, return -EAGAIN. > 4. In `f2fs_allocate_pinning_section()`, unify the range GC trigger to > run `f2fs_gc_range()` up to `sbi->pinned_area_max_secno` whenever > `sbi->pinned_area_max_secno < MAIN_SECS(sbi)` and allocation > returns -EAGAIN. > 5. Expose `/sys/fs/f2fs//pinned_area_max_secno` as a read-only > sysfs node. > > Signed-off-by: Daeho Jeong > Signed-off-by: Sunmin Jeong > --- > Documentation/ABI/testing/sysfs-fs-f2fs | 7 +++++ > Documentation/filesystems/f2fs.rst | 8 +++++- > fs/f2fs/f2fs.h | 2 ++ > fs/f2fs/segment.c | 33 ++++++++++++----------- > fs/f2fs/segment.h | 1 + > fs/f2fs/super.c | 36 +++++++++++++++++++++++++ > fs/f2fs/sysfs.c | 2 ++ > 7 files changed, 72 insertions(+), 17 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs > index 85194e4c7f01..0cebc89799dd 100644 > --- a/Documentation/ABI/testing/sysfs-fs-f2fs > +++ b/Documentation/ABI/testing/sysfs-fs-f2fs > @@ -1013,3 +1013,10 @@ Description: Every time a write operation completes f2fs_write_end_io() is > the maximum size of a write bio that is completed in atomic > (atc) context. The default value for this attribute is UINT_MAX > which means that this functionality is disabled by default. > + > +What: /sys/fs/f2fs//pinned_area_max_secno > +Date: August 2026 > +Contact: "Daeho Jeong" > +Description: This is a read-only entry to show the upper bound section number > + for pinned files. Pinned files will only be allocated within > + sections 0 to pinned_area_max_secno - 1. > diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst > index 1a5fd4afe609..a3c3b6948734 100644 > --- a/Documentation/filesystems/f2fs.rst > +++ b/Documentation/filesystems/f2fs.rst > @@ -417,7 +417,13 @@ lookup_mode=%s Control the directory lookup behavior for casefolded > auto F2FS determines the mode based on the > on-disk `SB_ENC_NO_COMPAT_FALLBACK_FL` > flag. > - ================== ======================================== > +resizable_tail_secno=%u Control the number of sections at the tail of the > + filesystem reserved for online resizing. Pinned files > + will only be allocated within sections 0 to > + (MAIN_SECS - resizable_tail_secno) - 1. If set to 0 > + (default), there is no tail restriction unless running > + on a zoned block device where conventional zones are > + used. > ======================== ============================================================ > > Debugfs Entries > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index b0a9c14de595..16720f1f0a9c 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -255,6 +255,7 @@ struct f2fs_mount_info { > block_t unusable_cap; /* Amount of space allowed to be > * unusable when disabling checkpoint > */ > + unsigned int resizable_tail_secno; /* number of resizable tail sections */ > > /* For compression */ > unsigned char compress_algorithm; /* algorithm type */ > @@ -2005,6 +2006,7 @@ struct f2fs_sb_info { > spinlock_t dev_lock; /* protect dirty_device */ > bool aligned_blksize; /* all devices has the same logical blksize */ > unsigned int first_seq_zone_segno; /* first segno in sequential zone */ > + unsigned int pinned_area_max_secno; /* upper bound section for pinned files */ > unsigned int bggc_io_aware; /* For adjust the BG_GC priority when pending IO */ > unsigned int allocate_section_hint; /* the boundary position between devices */ > unsigned int allocate_section_policy; /* determine the section writing priority */ > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 56decf9c691c..ed6f2947210b 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -2877,6 +2877,7 @@ static int get_new_segment(struct f2fs_sb_info *sbi, > unsigned int old_zoneno = GET_ZONE_FROM_SEG(sbi, *newseg); > unsigned int alloc_policy = sbi->allocate_section_policy; > unsigned int alloc_hint = sbi->allocate_section_hint; > + unsigned int max_secno = MAIN_SECS(sbi); > bool init = true; > bool looped = false; > int i, devi; > @@ -2908,7 +2909,7 @@ static int get_new_segment(struct f2fs_sb_info *sbi, > */ > if (f2fs_sb_has_blkzoned(sbi)) { > /* Prioritize writing to conventional zones */ > - if (sbi->blkzone_alloc_policy == BLKZONE_ALLOC_PRIOR_CONV || pinning) > + if (sbi->blkzone_alloc_policy == BLKZONE_ALLOC_PRIOR_CONV) > segno = 0; > else > segno = max(sbi->first_seq_zone_segno, *newseg); > @@ -2924,19 +2925,24 @@ static int get_new_segment(struct f2fs_sb_info *sbi, > alloc_hint > MAIN_SECS(sbi)) > alloc_hint = MAIN_SECS(sbi); > > - if (alloc_policy == ALLOCATE_FORWARD_FROM_HINT && > - hint < alloc_hint) > + if (pinning) { > + max_secno = sbi->pinned_area_max_secno; > + hint = 0; > + } else if (alloc_policy == ALLOCATE_FORWARD_FROM_HINT && > + hint < alloc_hint) { > hint = alloc_hint; > - else if (alloc_policy == ALLOCATE_FORWARD_WITHIN_HINT && > - hint >= alloc_hint) > + } else if (alloc_policy == ALLOCATE_FORWARD_WITHIN_HINT && > + hint >= alloc_hint) { > hint = 0; > + } > > find_other_zone: > - secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint); > + secno = find_next_zero_bit(free_i->free_secmap, max_secno, hint); > > - if (secno >= MAIN_SECS(sbi)) { > + if (secno >= max_secno) { > if (looped) { > - ret = -ENOSPC; > + ret = (pinning && has_pinned_area(sbi)) ? > + -EAGAIN : -ENOSPC; > f2fs_bug_on(sbi, !pinning); > goto out_unlock; > } > @@ -3001,12 +3007,6 @@ static int get_new_segment(struct f2fs_sb_info *sbi, > goto out_unlock; > } > > - /* no free section in conventional device or conventional zone */ > - if (new_sec && pinning && > - f2fs_is_sequential_zone_area(sbi, START_BLOCK(sbi, segno))) { > - ret = -EAGAIN; > - goto out_unlock; > - } > __set_inuse(sbi, segno); > *newseg = segno; > out_unlock: > @@ -3472,8 +3472,9 @@ int f2fs_allocate_pinning_section(struct f2fs_sb_info *sbi) > err = f2fs_allocate_new_section(sbi, CURSEG_COLD_DATA_PINNED, false); > f2fs_unlock_op(sbi, &lc); > > - if (f2fs_sb_has_blkzoned(sbi) && err == -EAGAIN && gc_required) { > - err = f2fs_gc_range(sbi, 0, sbi->first_seq_zone_segno - 1, > + if (has_pinned_area(sbi) && err == -EAGAIN && gc_required) { > + err = f2fs_gc_range(sbi, 0, > + sbi->pinned_area_max_secno * SEGS_PER_SEC(sbi) - 1, > true, ZONED_PIN_SEC_REQUIRED_COUNT, true); > if (err) > return err; > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h > index db1079169a23..1dd8a2fa929d 100644 > --- a/fs/f2fs/segment.h > +++ b/fs/f2fs/segment.h > @@ -43,6 +43,7 @@ static inline void sanity_check_seg_type(struct f2fs_sb_info *sbi, > > #define MAIN_SEGS(sbi) (SM_I(sbi)->main_segments) > #define MAIN_SECS(sbi) ((sbi)->total_sections) > +#define has_pinned_area(sbi) ((sbi)->pinned_area_max_secno < MAIN_SECS(sbi)) Looks more like has_unpinned_area(sbi), since we assign pinned_area_max_secno w/ MAIN_SECS(sbi) by default, and will decrease it only if there is conv sections or valid resizable_tail_secno. > > #define TOTAL_SEGS(sbi) \ > (SM_I(sbi) ? SM_I(sbi)->segment_count : \ > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > index 3bdb0f891c35..c1e315282ec6 100644 > --- a/fs/f2fs/super.c > +++ b/fs/f2fs/super.c > @@ -235,6 +235,7 @@ enum { > Opt_jqfmt, > Opt_checkpoint, > Opt_lookup_mode, > + Opt_resizable_tail_secno, > Opt_err, > }; > > @@ -366,6 +367,7 @@ static const struct fs_parameter_spec f2fs_param_specs[] = { > fsparam_flag("age_extent_cache", Opt_age_extent_cache), > fsparam_enum("errors", Opt_errors, f2fs_param_errors), > fsparam_enum("lookup_mode", Opt_lookup_mode, f2fs_param_lookup_mode), > + fsparam_u32("resizable_tail_secno", Opt_resizable_tail_secno), > {} > }; > > @@ -551,6 +553,17 @@ static inline void adjust_unusable_cap_perc(struct f2fs_sb_info *sbi) > F2FS_OPTION(sbi).unusable_cap_perc); > } > > +static inline void adjust_pinned_area_boundary(struct f2fs_sb_info *sbi) > +{ > + sbi->pinned_area_max_secno = MAIN_SECS(sbi); > + if (f2fs_sb_has_blkzoned(sbi) && sbi->first_seq_zone_segno != NULL_SEGNO) > + sbi->pinned_area_max_secno = min(sbi->pinned_area_max_secno, > + GET_SEC_FROM_SEG(sbi, sbi->first_seq_zone_segno)); > + if (F2FS_OPTION(sbi).resizable_tail_secno) > + sbi->pinned_area_max_secno = min(sbi->pinned_area_max_secno, > + MAIN_SECS(sbi) - F2FS_OPTION(sbi).resizable_tail_secno); > +} > + > static void init_once(void *foo) > { > struct f2fs_inode_info *fi = (struct f2fs_inode_info *) foo; > @@ -1235,6 +1248,9 @@ static int f2fs_parse_param(struct fs_context *fc, struct fs_parameter *param) > F2FS_CTX_INFO(ctx).lookup_mode = result.uint_32; > ctx->spec_mask |= F2FS_SPEC_lookup_mode; > break; > + case Opt_resizable_tail_secno: > + F2FS_CTX_INFO(ctx).resizable_tail_secno = result.uint_32; > + break; > } > return 0; > } > @@ -1771,6 +1787,12 @@ static void f2fs_apply_options(struct fs_context *fc, struct super_block *sb) > > static int f2fs_sanity_check_options(struct f2fs_sb_info *sbi, bool remount) > { > + if (remount && > + F2FS_OPTION(sbi).resizable_tail_secno >= MAIN_SECS(sbi)) { > + f2fs_err(sbi, "Option resizable_tail_secno is larger than or equal to total sections (%u >= %u)", > + F2FS_OPTION(sbi).resizable_tail_secno, MAIN_SECS(sbi)); > + return -EINVAL; > + } > if (f2fs_sb_has_device_alias(sbi) && > !test_opt(sbi, READ_EXTENT_CACHE)) { > f2fs_err(sbi, "device aliasing requires extent cache"); > @@ -2544,6 +2566,10 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root) > else if (F2FS_OPTION(sbi).lookup_mode == LOOKUP_AUTO) > seq_show_option(seq, "lookup_mode", "auto"); > > + if (F2FS_OPTION(sbi).resizable_tail_secno) > + seq_printf(seq, ",resizable_tail_secno=%u", > + F2FS_OPTION(sbi).resizable_tail_secno); > + > return 0; > } > > @@ -2586,6 +2612,7 @@ static void default_options(struct f2fs_sb_info *sbi, bool remount) > F2FS_OPTION(sbi).bggc_mode = BGGC_MODE_ON; > F2FS_OPTION(sbi).memory_mode = MEMORY_MODE_NORMAL; > F2FS_OPTION(sbi).errors = MOUNT_ERRORS_CONTINUE; > + F2FS_OPTION(sbi).resizable_tail_secno = 0; > > set_opt(sbi, INLINE_XATTR); > set_opt(sbi, INLINE_DATA); > @@ -3045,6 +3072,7 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb) > sb->s_flags = (sb->s_flags & ~SB_POSIXACL) | > (test_opt(sbi, POSIX_ACL) ? SB_POSIXACL : 0); > > + adjust_pinned_area_boundary(sbi); > limit_reserve_root(sbi); > fc->sb_flags = (flags & ~SB_LAZYTIME) | (sb->s_flags & SB_LAZYTIME); > > @@ -5287,6 +5315,14 @@ 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); > > + if (F2FS_OPTION(sbi).resizable_tail_secno >= MAIN_SECS(sbi)) { > + f2fs_err(sbi, "Option resizable_tail_secno is larger than or equal to total sections (%u >= %u)", > + F2FS_OPTION(sbi).resizable_tail_secno, MAIN_SECS(sbi)); > + err = -EINVAL; > + goto free_nm; > + } How about merging this check into the one in f2fs_sanity_check_options()? Thanks, > + adjust_pinned_area_boundary(sbi); > + > sbi->reserved_pin_section = f2fs_sb_has_blkzoned(sbi) ? > ZONED_PIN_SEC_REQUIRED_COUNT : > GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)); > diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c > index 3201e2185fea..811e350a1430 100644 > --- a/fs/f2fs/sysfs.c > +++ b/fs/f2fs/sysfs.c > @@ -1313,6 +1313,7 @@ F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy); > #endif > F2FS_SBI_GENERAL_RW_ATTR(carve_out); > F2FS_SBI_GENERAL_RW_ATTR(reserved_pin_section); > +F2FS_SBI_GENERAL_RO_ATTR(pinned_area_max_secno); > F2FS_SBI_GENERAL_RW_ATTR(bggc_io_aware); > F2FS_SBI_GENERAL_RW_ATTR(max_lock_elapsed_time); > F2FS_SBI_GENERAL_RW_ATTR(lock_duration_priority); > @@ -1525,6 +1526,7 @@ static struct attribute *f2fs_attrs[] = { > ATTR_LIST(max_read_extent_count), > ATTR_LIST(carve_out), > ATTR_LIST(reserved_pin_section), > + ATTR_LIST(pinned_area_max_secno), > ATTR_LIST(allocate_section_hint), > ATTR_LIST(allocate_section_policy), > ATTR_LIST(max_lock_elapsed_time),