| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <f037ec6c-1290-4caa-a790-1d65d9f7c985@vivo.com>
Date: Mon, 25 Aug 2025 11:42:28 +0800
From: Liao Yuanhong <liaoyuanhong@...o.com>
To: Chao Yu <chao@...nel.org>, Jaegeuk Kim <jaegeuk@...nel.org>,
"open list:F2FS FILE SYSTEM" <linux-f2fs-devel@...ts.sourceforge.net>,
open list <linux-kernel@...r.kernel.org>
Cc: liaoyuanhong@...o.com
Subject: Re: [PATCH v2] f2fs: Use allocate_section_policy to control write
priority in multi-devices setups
On 8/25/2025 11:10 AM, Chao Yu wrote:
> Yuanhong,
>
> On 8/20/25 16:21, Liao Yuanhong wrote:
>> Introduces two new sys nodes: allocate_section_hint and
>> allocate_section_policy. The allocate_section_hint identifies the boundary
>> between devices, measured in sections; it defaults to the end of the device
>> for single storage setups, and the end of the first device for multiple
>> storage setups. The allocate_section_policy determines the write strategy,
>> with a default value of 0 for normal sequential write strategy. A value of
>> 1 prioritizes writes before the allocate_section_hint, while a value of 2
>> prioritizes writes after it.
>>
>> This strategy addresses the issue where, despite F2FS supporting multiple
>> devices, SOC vendors lack multi-devices support (currently only supporting
>> zoned devices). As a workaround, multiple storage devices are mapped to a
>> single dm device. Both this workaround and the F2FS multi-devices solution
>> may require prioritizing writing to certain devices, such as a device with
>> better performance or when switching is needed due to performance
>> degradation near a device's end. For scenarios with more than two devices,
>> sort them at mount time to utilize this feature.
>>
>> When using this feature with a single storage device, it has almost no
>> impact. However, for configurations where multiple storage devices are
>> mapped to the same dm device using F2FS, utilizing this feature can provide
>> some optimization benefits. Therefore, I believe it should not be limited
>> to just multi-devices usage.
>>
>> Signed-off-by: Liao Yuanhong <liaoyuanhong@...o.com>
>> ---
>> Changes in v2:
>> - Updated the feature naming to better reflect its actual functionality.
>> - Appended patch description to clarify whether the usage should be
>> limited to multi-devices.
>> - Improved the code style.
>> - Fixed typo.
>> ---
>> Documentation/ABI/testing/sysfs-fs-f2fs | 22 ++++++++++++++++++++++
>> fs/f2fs/f2fs.h | 8 ++++++++
>> fs/f2fs/gc.c | 5 +++++
>> fs/f2fs/segment.c | 18 +++++++++++++++++-
>> fs/f2fs/super.c | 4 ++++
>> fs/f2fs/sysfs.c | 18 ++++++++++++++++++
>> 6 files changed, 74 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
>> index ee3acc8c2cb8..b590809869ca 100644
>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
>> @@ -911,3 +911,25 @@ Description: Used to adjust the BG_GC priority when pending IO, with a default v
>> bggc_io_aware = 1 skip background GC if there is pending read IO
>> bggc_io_aware = 2 don't aware IO for background GC
>> ================== ======================================================
>> +
>> +What: /sys/fs/f2fs/<disk>/allocate_section_hint
>> +Date: August 2025
>> +Contact: "Liao Yuanhong" <liaoyuanhong@...o.com>
>> +Description: Indicates the hint section between the first device and others in multi-devices
>> + setup. It defaults to the end of the first device in sections. For a single storage
>> + device, it defaults to the total number of sections. It can be manually set to match
>> + scenarios where multi-devices are mapped to the same dm device.
>> +
>> +What: /sys/fs/f2fs/<disk>/allocate_section_policy
>> +Date: August 2025
>> +Contact: "Liao Yuanhong" <liaoyuanhong@...o.com>
>> +Description: Controls write priority in multi-devices setups. A value of 0 means normal writing.
>> + A value of 1 prioritizes writing to devices before the allocate_section_hint. A value of 2
>> + prioritizes writing to devices after the allocate_section_hint. The default is 0.
>> +
>> + =========================== ==========================================================
>> + value description
>> + allocate_section_policy = 0 Normal writing
>> + allocate_section_policy = 1 Prioritize writing to section before allocate_section_hint
>> + allocate_section_policy = 2 Prioritize writing to section after allocate_section_hint
>> + =========================== ==========================================================
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index d6a49de1b7e9..5ce9bf6be462 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -162,6 +162,12 @@ enum bggc_io_aware_policy {
>> AWARE_NONE, /* don't aware IO for background GC */
>> };
>>
>> +enum device_allocation_policy {
>> + ALLOCATE_FORWARD_NOHINT,
>> + ALLOCATE_FORWARD_WITHIN_HINT,
>> + ALLOCATE_FORWARD_FROM_HINT,
>> +};
>> +
>> /*
>> * An implementation of an rwsem that is explicitly unfair to readers. This
>> * prevents priority inversion when a low-priority reader acquires the read lock
>> @@ -1850,6 +1856,8 @@ struct f2fs_sb_info {
>> bool aligned_blksize; /* all devices has the same logical blksize */
>> unsigned int first_seq_zone_segno; /* first segno in sequential zone */
>> 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 */
>>
>> /* For write statistics */
>> u64 sectors_written_start;
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 098e9f71421e..b57b8fd64747 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -2182,6 +2182,8 @@ static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs)
>> SM_I(sbi)->segment_count = (int)SM_I(sbi)->segment_count + segs;
>> MAIN_SEGS(sbi) = (int)MAIN_SEGS(sbi) + segs;
>> MAIN_SECS(sbi) += secs;
>> + if (sbi->allocate_section_hint > MAIN_SECS(sbi))
>> + sbi->allocate_section_hint = MAIN_SECS(sbi);
>> FREE_I(sbi)->free_sections = (int)FREE_I(sbi)->free_sections + secs;
>> FREE_I(sbi)->free_segments = (int)FREE_I(sbi)->free_segments + segs;
>> F2FS_CKPT(sbi)->user_block_count = cpu_to_le64(user_block_count + blks);
>> @@ -2189,6 +2191,9 @@ static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs)
>> if (f2fs_is_multi_device(sbi)) {
>> int last_dev = sbi->s_ndevs - 1;
>>
>> + sbi->allocate_section_hint = FDEV(0).total_segments /
>> + SEGS_PER_SEC(sbi);
>> +
>> FDEV(last_dev).total_segments =
>> (int)FDEV(last_dev).total_segments + segs;
>> FDEV(last_dev).end_blk =
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 04b0a3c1804d..e0f6589c6a1c 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -2807,6 +2807,10 @@ static int get_new_segment(struct f2fs_sb_info *sbi,
>> }
>> #endif
>>
>> + if (sbi->allocate_section_policy == ALLOCATE_FORWARD_FROM_HINT &&
>> + hint < sbi->allocate_section_hint)
>> + hint = sbi->allocate_section_hint;
>> +
>> find_other_zone:
>> secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
>>
>> @@ -2828,13 +2832,25 @@ static int get_new_segment(struct f2fs_sb_info *sbi,
>> #endif
>>
>> if (secno >= MAIN_SECS(sbi)) {
>> - secno = find_first_zero_bit(free_i->free_secmap,
>> + if (sbi->allocate_section_policy == ALLOCATE_FORWARD_FROM_HINT) {
>> + secno = find_next_zero_bit(free_i->free_secmap,
>> + MAIN_SECS(sbi), sbi->allocate_section_hint);
>> + if (secno >= MAIN_SECS(sbi))
>> + secno = find_first_zero_bit(free_i->free_secmap,
>> + MAIN_SECS(sbi));
>> + } else {
>> + secno = find_first_zero_bit(free_i->free_secmap,
>> MAIN_SECS(sbi));
>> + }
>> if (secno >= MAIN_SECS(sbi)) {
>> ret = -ENOSPC;
>> f2fs_bug_on(sbi, !pinning);
>> goto out_unlock;
>> }
>> + } else if (sbi->allocate_section_policy == ALLOCATE_FORWARD_WITHIN_HINT &&
>> + secno >= sbi->allocate_section_hint) {
>> + secno = find_first_zero_bit(free_i->free_secmap,
>> + MAIN_SECS(sbi));
> Will we hit "secno >= MAIN_SECS(sbi)" case here?
Yes, there may be hit 'secno>=MAIN_SECS (sbi)' case, and I will fix this
issue in
the new version patch.
>> }
>> segno = GET_SEG_FROM_SEC(sbi, secno);
>> zoneno = GET_ZONE_FROM_SEC(sbi, secno);
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 5aa9d650512d..fa38a3e6b9cd 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -3942,6 +3942,7 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
>> segs_per_sec = le32_to_cpu(raw_super->segs_per_sec);
>> secs_per_zone = le32_to_cpu(raw_super->secs_per_zone);
>> total_sections = le32_to_cpu(raw_super->section_count);
>> + sbi->allocate_section_hint = total_sections;
> What about assigning sbi->allocate_section_hint in anywhere else rather than
> in sanity_check_raw_super()?
You're right, it's not suitable to initialize sbi->allocate_section_hint
here. I'll put it in
init_sb_info() or f2fs_scan_devices().
>>
>> /* blocks_per_seg should be 512, given the above check */
>> blocks_per_seg = BIT(le32_to_cpu(raw_super->log_blocks_per_seg));
>> @@ -4713,6 +4714,7 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>> logical_blksize = bdev_logical_block_size(sbi->sb->s_bdev);
>> sbi->aligned_blksize = true;
>> sbi->bggc_io_aware = AWARE_ALL_IO;
>> + sbi->allocate_section_policy = ALLOCATE_FORWARD_NOHINT;
>> #ifdef CONFIG_BLK_DEV_ZONED
>> sbi->max_open_zones = UINT_MAX;
>> sbi->blkzone_alloc_policy = BLKZONE_ALLOC_PRIOR_SEQ;
>> @@ -4744,6 +4746,8 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>> SEGS_TO_BLKS(sbi,
>> FDEV(i).total_segments) - 1 +
>> le32_to_cpu(raw_super->segment0_blkaddr);
>> + sbi->allocate_section_hint = FDEV(i).total_segments /
>> + SEGS_PER_SEC(sbi);
>> } else {
>> FDEV(i).start_blk = FDEV(i - 1).end_blk + 1;
>> FDEV(i).end_blk = FDEV(i).start_blk +
>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>> index 1ffaf9e74ce9..81b99c2a02a9 100644
>> --- a/fs/f2fs/sysfs.c
>> +++ b/fs/f2fs/sysfs.c
>> @@ -889,6 +889,20 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>> return count;
>> }
>>
>> + if (!strcmp(a->attr.name, "allocate_section_hint")) {
>> + if (t < 0 || t > MAIN_SECS(sbi))
>> + return -EINVAL;
>> + sbi->allocate_section_hint = t;
> Will it race w/ resize_fs ioctl?
>
> Thanks,
Does this mean that after executing resize_fs, the current
allocate_section_hint value will
not match the resized size? If so, I've handled the data update in
update_fs_metadata().
If not, what other areas might cause a conflict? Please let me know so I
can address the
issue immediately.
Thanks,
Liao
>> + return count;
>> + }
>> +
>> + if (!strcmp(a->attr.name, "allocate_section_policy")) {
>> + if (t < ALLOCATE_FORWARD_NOHINT || t > ALLOCATE_FORWARD_FROM_HINT)
>> + return -EINVAL;
>> + sbi->allocate_section_policy = t;
>> + return count;
>> + }
>> +
>> *ui = (unsigned int)t;
>>
>> return count;
>> @@ -1161,6 +1175,8 @@ F2FS_SBI_GENERAL_RW_ATTR(max_victim_search);
>> F2FS_SBI_GENERAL_RW_ATTR(migration_granularity);
>> F2FS_SBI_GENERAL_RW_ATTR(migration_window_granularity);
>> F2FS_SBI_GENERAL_RW_ATTR(dir_level);
>> +F2FS_SBI_GENERAL_RW_ATTR(allocate_section_hint);
>> +F2FS_SBI_GENERAL_RW_ATTR(allocate_section_policy);
>> #ifdef CONFIG_F2FS_IOSTAT
>> F2FS_SBI_GENERAL_RW_ATTR(iostat_enable);
>> F2FS_SBI_GENERAL_RW_ATTR(iostat_period_ms);
>> @@ -1398,6 +1414,8 @@ static struct attribute *f2fs_attrs[] = {
>> ATTR_LIST(max_read_extent_count),
>> ATTR_LIST(carve_out),
>> ATTR_LIST(reserved_pin_section),
>> + ATTR_LIST(allocate_section_hint),
>> + ATTR_LIST(allocate_section_policy),
>> NULL,
>> };
>> ATTRIBUTE_GROUPS(f2fs);
Powered by blists - more mailing lists