Re: [PATCH] f2fs: introduce cur_reserved_blocks in sysfs
From: Chao Yu
Date: Fri Aug 11 2017 - 06:18:46 EST
On 2017/8/10 19:41, Yunlong Song wrote:
> It may block the system in such case, but so does the hard version
> design. In the hard version,
We'd better not let soft/hard reserved_blocks to eat all left free space, at
least needs to leave enough space for supporting system's activation.
Thanks,
> 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 <yunlong.song@xxxxxxxxxx>
>>>>> ---
>>>>> 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" <jaegeuk@xxxxxxxxxx>
>>>>> Description:
>>>>> Controls sleep time of GC urgent mode
>>>>> +
>>>>> +What: /sys/fs/f2fs/<disk>/cur_reserved_blocks
>>>>> +Date: August 2017
>>>>> +Contact: "Yunlong Song" <yunlong.song@xxxxxxxxxx>
>>>>> +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,
>>>>> };
>>>>>
>>>>>
>>>> .
>>>>
>>
>> .
>>
>