From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1B0A426B751 for ; Fri, 13 Jun 2025 08:49:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749804542; cv=none; b=Z3oSkDw2oMGXanCzhZBMhAxPS9EV8ZaAFBz1nA8hfrkdRVgOvlTX381Ho9d5WLurG9zadAyw9eT+QgNvxVcYma9J8OnYiluWCFIcbZ16yM4ib9sBfEECtlrlYygm2K7JR9ZRpbtohqa01VqxhnVF8i9Vqe64wtjSHgbRT/JzVpM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749804542; c=relaxed/simple; bh=u7x16W5kMhuO8mP73I83fX0Qfs/D8SHE0KX4Q48Oks4=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=CtLwRz57fFHbBQWBGPVoo+ONjdCFUvw5gX/nrsOd6LkfVY56xOCDya/98KNX5GZF3xoXSJuV2cx1tIZcvKrFRBgDXmGoiX2cwloAEAO1qiqygWV60ZTOtrFBqLLRKVavFzwwvBO2IUMJ7Z17BWxj5UYGoVudHmLepOOVqbIqRxE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u9KNX1ky; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u9KNX1ky" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2679BC4CEE3; Fri, 13 Jun 2025 08:48:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749804541; bh=u7x16W5kMhuO8mP73I83fX0Qfs/D8SHE0KX4Q48Oks4=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=u9KNX1kyhxLrcRKV+BaqoAHpw8g08yiQNw6sCBxBOcU/6FRYDtY1+vAzEE7lwOSnt 12MYGMa17cjhZNQX+0Qr1FzeSN0rxo3/5Mv8S94RLxnbDQaA9vBG/EOsJEsTYbYM2P V9pRionuNZtVbZQql/dAuhVJ+acNjYSXQRoX18vu3U+nds1vJ4mtRIet490xhi2Z52 jIBcgNOWg23HQBXj4zBw0sqnYo/VvPJaKH5W3eEo1KyZM9pkgSpBVJNZxwhBRPI+lQ 3+9dsV/i0988EswF8HbtjH1nfqQDqnJ8LAD2BdnZmhTjlIbGX/a2ZoD2gJQ3QNBY7f NitUwarcD28/Q== Message-ID: <12dc51f7-a765-4995-bf6d-8abe973f4ea1@kernel.org> Date: Fri, 13 Jun 2025 16:49:07 +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, jaegeuk@kernel.org, bo.wu@vivo.com, linux-kernel@vger.kernel.org, feng.han@honor.com, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: continue to allocate pinned section when gc happens EAGAIN To: Zhiguo Niu , wangzijie References: <20250612123444.1779509-1-wangzijie1@honor.com> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2025/6/13 16:25, Zhiguo Niu wrote: > wangzijie 于2025年6月12日周四 20:38写道： >> >>> On 6/12/25 11:27, wangzijie wrote: >>>> Wu Bo once mentioned a fallocate fail scenario in this link[1]. >>>> After commit 3fdd89b452c2("f2fs: prevent writing without fallocate() >>>> for pinned files"), we cannot directly generate 4K size file and >>>> pin it, but we can still generate non-segment aligned pinned file: >>>> >>>> touch test_file >>>> ./f2fs_io pinfile set test_file >>>> ./f2fs_io fallocate 0 0 8192 test_file >>>> truncate -s 4096 test_file >>> >>> Well, shouldn't we avoid such case by adding check condition in setattr? >> >> Maybe like this? >> >> --- >> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >> index 6bd3de64f..2f6537d9c 100644 >> --- a/fs/f2fs/file.c >> +++ b/fs/f2fs/file.c >> @@ -1027,6 +1027,8 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, >> struct inode *inode = d_inode(dentry); >> struct f2fs_inode_info *fi = F2FS_I(inode); >> int err; >> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode); >> + block_t sec_blks = CAP_BLKS_PER_SEC(sbi); >> >> if (unlikely(f2fs_cp_error(F2FS_I_SB(inode)))) >> return -EIO; >> @@ -1047,6 +1049,11 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, >> !IS_ALIGNED(attr->ia_size, >> F2FS_BLK_TO_BYTES(fi->i_cluster_size))) >> return -EINVAL; >> + if (f2fs_is_pinned_file(inode) && >> + attr->ia_size < i_size_read(inode) && >> + !IS_ALIGNED(attr->ia_size, >> + F2FS_BLK_TO_BYTES(sec_blks))); >> + return -EINVAL; > Hi Chao and zijie, > Excuse me ,I'm a bit confused about this: > when a pin file size is not alinged with size of "section", it can not > be truncated? IMO, the pinned file can only be truncated to section-aligned size. Thanks > thanks！ >> } >> >> err = setattr_prepare(idmap, dentry, attr); >> --- >> >>>> >>>> By doing this, pin+fallocate failure(gc happens EAGAIN but f2fs shows >>>> enough spare space) may occurs. >>>> >>>> From message in commit 2e42b7f817ac("f2fs: stop allocating pinned sections >>>> if EAGAIN happens"), gc EAGAIN doesn't guarantee a free section, so we stop >>>> allocating. But after commit 48ea8b200414 ("f2fs: fix to avoid panic once >>>> fallocation fails for pinfile"), we have a way to avoid panic caused by >>>> concurrent pinfile allocation run out of free section, so I think that we >>>> can continue to allocate pinned section when gc happens EAGAIN. Even if we >>>> don't have free section, f2fs_allocate_pinning_section() can fail with ENOSPC. >>> >>> What do you think of introduce /sys/fs/f2fs//reserved_pin_section to >>> tune @needed parameter of has_not_enough_free_secs()? If we configure it >>> w/ zero, it can avoid f2fs_gc() before preallocation. >>> >>> --- >>> fs/f2fs/f2fs.h | 3 +++ >>> fs/f2fs/file.c | 5 ++--- >>> fs/f2fs/super.c | 3 +++ >>> fs/f2fs/sysfs.c | 9 +++++++++ >>> 4 files changed, 17 insertions(+), 3 deletions(-) >>> >>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >>> index 785537576aa8..ffb15da570d7 100644 >>> --- a/fs/f2fs/f2fs.h >>> +++ b/fs/f2fs/f2fs.h >>> @@ -1731,6 +1731,9 @@ 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..48b97a95fd63 100644 >>> --- a/fs/f2fs/super.c >>> +++ b/fs/f2fs/super.c >>> @@ -4975,6 +4975,9 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc) >>> sbi->last_valid_block_count = sbi->total_valid_block_count; >>> sbi->reserved_blocks = 0; >>> sbi->current_reserved_blocks = 0; >>> + sbi->reserved_pin_section = f2fs_sb_has_blkzoned(sbi) ? >>> + ZONED_PIN_SEC_REQUIRED_COUNT : >>> + GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)); >>> limit_reserve_root(sbi); >>> adjust_unusable_cap_perc(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); >>> -- >>> 2.49.0 >> >> I think it's a good way to solve this problem. Thank you! >> >> >>>> >>>> [1] https://lore.kernel.org/linux-f2fs-devel/20231030094024.263707-1-bo.wu@vivo.com/t/#u >>>> >>>> Signed-off-by: wangzijie >>>> --- >>>> fs/f2fs/file.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >>>> index 6bd3de64f..05c80d2b5 100644 >>>> --- a/fs/f2fs/file.c >>>> +++ b/fs/f2fs/file.c >>>> @@ -1859,7 +1859,7 @@ static int f2fs_expand_inode_data(struct inode *inode, loff_t offset, >>>> f2fs_down_write(&sbi->gc_lock); >>>> stat_inc_gc_call_count(sbi, FOREGROUND); >>>> err = f2fs_gc(sbi, &gc_control); >>>> - if (err && err != -ENODATA) { >>>> + if (err && err != -ENODATA && err != -EAGAIN) { >>>> f2fs_up_write(&sbi->pin_sem); >>>> goto out_err; >>>> } >>> >>> >>> >>> _______________________________________________ >>> Linux-f2fs-devel mailing list >>> Linux-f2fs-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >> >> >> >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel