Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752109AbdHJLmy (ORCPT ); Thu, 10 Aug 2017 07:42:54 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:3492 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751373AbdHJLmw (ORCPT ); Thu, 10 Aug 2017 07:42:52 -0400 Subject: Re: [PATCH] f2fs: introduce cur_reserved_blocks in sysfs To: Chao Yu , , , CC: , , , , References: <1502199825-15218-1-git-send-email-yunlong.song@huawei.com> <5952a72c-9b42-6f5a-ce03-410b42ada799@huawei.com> <5bd696d4-a79d-5e58-e4a1-ce9ecbe979c7@huawei.com> From: Yunlong Song Message-ID: <8e96a71d-9b01-9fb4-d855-d08106ea2d60@huawei.com> Date: Thu, 10 Aug 2017 19:41:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <5bd696d4-a79d-5e58-e4a1-ce9ecbe979c7@huawei.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.111.220.140] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090206.598C46B0.00CF,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: d44bf8c295583ec8f5906668b27464a9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9701 Lines: 218 It may block the system in such case, but so does the hard version design. In the hard version, when reserve_blocks is set to the value = user_block_count - total_valid_block_count, then the user free space can also drop to zero and has the same problem. IMO, kernel does not need to take this responsibility, it's android's responsibility. On 2017/8/10 19:26, Chao Yu wrote: > On 2017/8/10 11:58, Yunlong Song wrote: >> I think the aim of reserved_blocks function is to leave space for f2fs >> and FTL, so I change it to a >> soft version so that it can be used to fit to the data image which does >> not satisfy the hard version, >> especially for backward compatibility when updated kernel with new >> default reserved_blocks set >> (currently it is initially set 0 as default, but can be set any value >> with my new patch). >> >> As for the uid/gid, does current f2fs space management design consider >> this issue? IMO, I think we > Upper layer application has considered this issue, as when free space touchs the > threshold, system will block any operation and give a hint to clean up user's > data. So w/o uid/gid reserved block, it will be OK. But for your requirement, > user free space will drop to zero, and before current reserved block number > touch soft reserved block limitation, user can only do deletion, so in this > time, if any system/service flow depends on file creation, could result in > blocking the system. > >> can just ensure the reserved space for file system no matter user/system >> type. Whether the value of >> reserved_blocks is OK or not, should not be filesystem's issue. >> Filesystem just provide this interface, >> and the upper layer, such as android vold should take care of the value >> of reserved_blocks and make >> sure its value is appropriate and will not block any activation of >> system user, if it really happens, android >> should change the value dynamically, it is fine, since we make >> reserved_blocks to a soft version. > We can not make sure in strategy changing flow, there is no file creation > dependence. Even if we can, if the reserved_blocks is not appropriate, why not > setting it correctly before? > > Thanks, > >> On 2017/8/10 11:15, Chao Yu wrote: >>> On 2017/8/8 21:43, Yunlong Song wrote: >>>> In this patch, we add a new sysfs interface, we can use it to gradually achieve >>>> the reserved_blocks finally, even when reserved_blocks is initially set over >>>> user_block_count - total_valid_block_count. This is very useful, especially when >>>> we upgrade kernel with new reserved_blocks value, but old disk image unluckily has >>>> user_block_count - total_valid_block_count smaller than the desired reserved_blocks. >>>> With this patch, f2fs can try its best to reserve space and get close to the >>>> reserved_blocks, and the current value of achieved reserved_blocks can be shown >>>> in real time. >>> Oh, this looks like a soft limitation in quota system, but original >>> reserved_blocks implementation likes a hard one, so this patch changes the >>> semantics of reserved_blocks. >>> >>> Actually, I doubt that it would be hard to reserve all left free space in real >>> user scenario now, since system user's activation may depend on free space of >>> data partition due to file creation requirement, so w/o supporting feature of >>> uid/gid reserved block, soft reservation will block any activation of system >>> user, such as android. >>> >>> Thanks, >>> >>>> Signed-off-by: Yunlong Song >>>> --- >>>> Documentation/ABI/testing/sysfs-fs-f2fs | 6 ++++++ >>>> fs/f2fs/f2fs.h | 9 +++++++-- >>>> fs/f2fs/super.c | 4 +++- >>>> fs/f2fs/sysfs.c | 15 ++++++++++----- >>>> 4 files changed, 26 insertions(+), 8 deletions(-) >>>> >>>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs >>>> index 11b7f4e..bdbb9f3 100644 >>>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs >>>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs >>>> @@ -151,3 +151,9 @@ Date: August 2017 >>>> Contact: "Jaegeuk Kim" >>>> Description: >>>> Controls sleep time of GC urgent mode >>>> + >>>> +What: /sys/fs/f2fs//cur_reserved_blocks >>>> +Date: August 2017 >>>> +Contact: "Yunlong Song" >>>> +Description: >>>> + Shows current reserved blocks in system. >>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >>>> index cea329f..3b7056f 100644 >>>> --- a/fs/f2fs/f2fs.h >>>> +++ b/fs/f2fs/f2fs.h >>>> @@ -1040,6 +1040,7 @@ struct f2fs_sb_info { >>>> block_t discard_blks; /* discard command candidats */ >>>> block_t last_valid_block_count; /* for recovery */ >>>> block_t reserved_blocks; /* configurable reserved blocks */ >>>> + block_t cur_reserved_blocks; /* current reserved blocks */ >>>> >>>> u32 s_next_generation; /* for NFS support */ >>>> >>>> @@ -1514,7 +1515,7 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi, >>>> >>>> spin_lock(&sbi->stat_lock); >>>> sbi->total_valid_block_count += (block_t)(*count); >>>> - avail_user_block_count = sbi->user_block_count - sbi->reserved_blocks; >>>> + avail_user_block_count = sbi->user_block_count - sbi->cur_reserved_blocks; >>>> if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) { >>>> diff = sbi->total_valid_block_count - avail_user_block_count; >>>> *count -= diff; >>>> @@ -1548,6 +1549,8 @@ static inline void dec_valid_block_count(struct f2fs_sb_info *sbi, >>>> f2fs_bug_on(sbi, sbi->total_valid_block_count < (block_t) count); >>>> f2fs_bug_on(sbi, inode->i_blocks < sectors); >>>> sbi->total_valid_block_count -= (block_t)count; >>>> + sbi->cur_reserved_blocks = min(sbi->reserved_blocks, >>>> + sbi->cur_reserved_blocks + count); >>>> spin_unlock(&sbi->stat_lock); >>>> f2fs_i_blocks_write(inode, count, false, true); >>>> } >>>> @@ -1694,7 +1697,7 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi, >>>> spin_lock(&sbi->stat_lock); >>>> >>>> valid_block_count = sbi->total_valid_block_count + 1; >>>> - if (unlikely(valid_block_count + sbi->reserved_blocks > >>>> + if (unlikely(valid_block_count + sbi->cur_reserved_blocks > >>>> sbi->user_block_count)) { >>>> spin_unlock(&sbi->stat_lock); >>>> goto enospc; >>>> @@ -1737,6 +1740,8 @@ static inline void dec_valid_node_count(struct f2fs_sb_info *sbi, >>>> >>>> sbi->total_valid_node_count--; >>>> sbi->total_valid_block_count--; >>>> + sbi->cur_reserved_blocks = min(sbi->reserved_blocks, >>>> + sbi->cur_reserved_blocks + 1); >>>> >>>> spin_unlock(&sbi->stat_lock); >>>> >>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c >>>> index 4c1bdcb..2934aa2 100644 >>>> --- a/fs/f2fs/super.c >>>> +++ b/fs/f2fs/super.c >>>> @@ -957,7 +957,7 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf) >>>> buf->f_blocks = total_count - start_count; >>>> buf->f_bfree = user_block_count - valid_user_blocks(sbi) + ovp_count; >>>> buf->f_bavail = user_block_count - valid_user_blocks(sbi) - >>>> - sbi->reserved_blocks; >>>> + sbi->cur_reserved_blocks; >>>> >>>> avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM; >>>> >>>> @@ -2411,6 +2411,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) >>>> le64_to_cpu(sbi->ckpt->valid_block_count); >>>> sbi->last_valid_block_count = sbi->total_valid_block_count; >>>> sbi->reserved_blocks = 0; >>>> + sbi->cur_reserved_blocks = min(sbi->reserved_blocks, >>>> + sbi->user_block_count - sbi->total_valid_block_count); >>>> >>>> for (i = 0; i < NR_INODE_TYPE; i++) { >>>> INIT_LIST_HEAD(&sbi->inode_list[i]); >>>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c >>>> index b769a3d..405c13f 100644 >>>> --- a/fs/f2fs/sysfs.c >>>> +++ b/fs/f2fs/sysfs.c >>>> @@ -76,6 +76,12 @@ static ssize_t lifetime_write_kbytes_show(struct f2fs_attr *a, >>>> BD_PART_WRITTEN(sbi))); >>>> } >>>> >>>> +static ssize_t cur_reserved_blocks_show(struct f2fs_attr *a, >>>> + struct f2fs_sb_info *sbi, char *buf) >>>> +{ >>>> + return snprintf(buf, PAGE_SIZE, "%u\n", sbi->cur_reserved_blocks); >>>> +} >>>> + >>>> static ssize_t features_show(struct f2fs_attr *a, >>>> struct f2fs_sb_info *sbi, char *buf) >>>> { >>>> @@ -143,12 +149,9 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a, >>>> #endif >>>> if (a->struct_type == RESERVED_BLOCKS) { >>>> spin_lock(&sbi->stat_lock); >>>> - if ((unsigned long)sbi->total_valid_block_count + t > >>>> - (unsigned long)sbi->user_block_count) { >>>> - spin_unlock(&sbi->stat_lock); >>>> - return -EINVAL; >>>> - } >>>> *ui = t; >>>> + sbi->cur_reserved_blocks = min(t, sbi->user_block_count - >>>> + sbi->total_valid_block_count); >>>> spin_unlock(&sbi->stat_lock); >>>> return count; >>>> } >>>> @@ -274,6 +277,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a, >>>> #endif >>>> F2FS_GENERAL_RO_ATTR(lifetime_write_kbytes); >>>> F2FS_GENERAL_RO_ATTR(features); >>>> +F2FS_GENERAL_RO_ATTR(cur_reserved_blocks); >>>> >>>> #ifdef CONFIG_F2FS_FS_ENCRYPTION >>>> F2FS_FEATURE_RO_ATTR(encryption, FEAT_CRYPTO); >>>> @@ -317,6 +321,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a, >>>> ATTR_LIST(lifetime_write_kbytes), >>>> ATTR_LIST(features), >>>> ATTR_LIST(reserved_blocks), >>>> + ATTR_LIST(cur_reserved_blocks), >>>> NULL, >>>> }; >>>> >>>> >>> . >>> > > . > -- Thanks, Yunlong Song