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SubjectRe: [Ocfs2-devel] [PATCH] ocfs2: fix the application IO timeout when fstrim is running
Hello ChangWei,

>>> On 2019/1/15 at 16:00, in message
<63ADC13FD55D6546B7DECE290D39E37301278265F3@H3CMLB12-EX.srv.huawei-3com.com>,
Changwei Ge <ge.changwei@h3c.com> wrote:
> On 2019/1/15 13:49, Gang He wrote:
>> Hello Changewei,
>>
>>>>> On 2019/1/15 at 11:50, in message
>> <63ADC13FD55D6546B7DECE290D39E3730127825EFD@H3CMLB12-EX.srv.huawei-3com.com>,
>> Changwei Ge <ge.changwei@h3c.com> wrote:
>>> Hi Gang,
>>>
>>> Most parts of this patch look sane to me, just a tiny question...
>>>
>>> On 2019/1/11 17:01, Gang He wrote:
>>>> The user reported this problem, the upper application IO was
>>>> timeout when fstrim was running on this ocfs2 partition. the
>>>> application monitoring resource agent considered that this
>>>> application did not work, then this node was fenced by the cluster
>>>> brain (e.g. pacemaker).
>>>> The root cause is that fstrim thread always holds main_bm meta-file
>>>> related locks until all the cluster groups are trimmed.
>>>> This patch will make fstrim thread release main_bm meta-file
>>>> related locks when each cluster group is trimmed, this will let
>>>> the current application IO has a chance to claim the clusters from
>>>> main_bm meta-file.
>>>>
>>>> Signed-off-by: Gang He <ghe@suse.com>
>>>> ---
>>>> fs/ocfs2/alloc.c | 159 +++++++++++++++++++++++++----------------
>>>> fs/ocfs2/dlmglue.c | 5 ++
>>>> fs/ocfs2/ocfs2.h | 1 +
>>>> fs/ocfs2/ocfs2_trace.h | 2 +
>>>> fs/ocfs2/super.c | 2 +
>>>> 5 files changed, 106 insertions(+), 63 deletions(-)
>>>>
>>>> diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
>>>> index d1cbb27808e2..6f0999015a44 100644
>>>> --- a/fs/ocfs2/alloc.c
>>>> +++ b/fs/ocfs2/alloc.c
>>>> @@ -7532,10 +7532,11 @@ static int ocfs2_trim_group(struct super_block *sb,
>>>> return count;
>>>> }
>>>>
>>>> -int ocfs2_trim_fs(struct super_block *sb, struct fstrim_range *range)
>>>> +static
>>>> +int ocfs2_trim_mainbm(struct super_block *sb, struct fstrim_range *range)
>>>> {
>>>> struct ocfs2_super *osb = OCFS2_SB(sb);
>>>> - u64 start, len, trimmed, first_group, last_group, group;
>>>> + u64 start, len, trimmed = 0, first_group, last_group = 0, group = 0;
>>>> int ret, cnt;
>>>> u32 first_bit, last_bit, minlen;
>>>> struct buffer_head *main_bm_bh = NULL;
>>>> @@ -7543,7 +7544,6 @@ int ocfs2_trim_fs(struct super_block *sb, struct
>>> fstrim_range *range)
>>>> struct buffer_head *gd_bh = NULL;
>>>> struct ocfs2_dinode *main_bm;
>>>> struct ocfs2_group_desc *gd = NULL;
>>>> - struct ocfs2_trim_fs_info info, *pinfo = NULL;
>>>>
>>>> start = range->start >> osb->s_clustersize_bits;
>>>> len = range->len >> osb->s_clustersize_bits;
>>>> @@ -7552,6 +7552,9 @@ int ocfs2_trim_fs(struct super_block *sb, struct
>>> fstrim_range *range)
>>>> if (minlen >= osb->bitmap_cpg || range->len < sb->s_blocksize)
>>>> return -EINVAL;
>>>>
>>>> + trace_ocfs2_trim_mainbm(start, len, minlen);
>>>> +
>>>> +next_group:
>>>> main_bm_inode = ocfs2_get_system_file_inode(osb,
>>>> GLOBAL_BITMAP_SYSTEM_INODE,
>>>> OCFS2_INVALID_SLOT);
>>>> @@ -7570,64 +7573,34 @@ int ocfs2_trim_fs(struct super_block *sb, struct
>>> fstrim_range *range)
>>>> }
>>>> main_bm = (struct ocfs2_dinode *)main_bm_bh->b_data;
>>>>
>>>> - if (start >= le32_to_cpu(main_bm->i_clusters)) {
>>>> - ret = -EINVAL;
>>>> - goto out_unlock;
>>>> - }
>>>> -
>>>> - len = range->len >> osb->s_clustersize_bits;
>>>> - if (start + len > le32_to_cpu(main_bm->i_clusters))
>>>> - len = le32_to_cpu(main_bm->i_clusters) - start;
>>>> -
>>>> - trace_ocfs2_trim_fs(start, len, minlen);
>>>> -
>>>> - ocfs2_trim_fs_lock_res_init(osb);
>>>> - ret = ocfs2_trim_fs_lock(osb, NULL, 1);
>>>> - if (ret < 0) {
>>>> - if (ret != -EAGAIN) {
>>>> - mlog_errno(ret);
>>>> - ocfs2_trim_fs_lock_res_uninit(osb);
>>>> + /*
>>>> + * Do some check before trim the first group.
>>>> + */
>>>> + if (!group) {
>>>> + if (start >= le32_to_cpu(main_bm->i_clusters)) {
>>>> + ret = -EINVAL;
>>>> goto out_unlock;
>>>> }
>>>>
>>>> - mlog(ML_NOTICE, "Wait for trim on device (%s) to "
>>>> - "finish, which is running from another node.\n",
>>>> - osb->dev_str);
>>>> - ret = ocfs2_trim_fs_lock(osb, &info, 0);
>>>> - if (ret < 0) {
>>>> - mlog_errno(ret);
>>>> - ocfs2_trim_fs_lock_res_uninit(osb);
>>>> - goto out_unlock;
>>>> - }
>>>> + if (start + len > le32_to_cpu(main_bm->i_clusters))
>>>> + len = le32_to_cpu(main_bm->i_clusters) - start;
>>>>
>>>> - if (info.tf_valid && info.tf_success &&
>>>> - info.tf_start == start && info.tf_len == len &&
>>>> - info.tf_minlen == minlen) {
>>>> - /* Avoid sending duplicated trim to a shared device */
>>>> - mlog(ML_NOTICE, "The same trim on device (%s) was "
>>>> - "just done from node (%u), return.\n",
>>>> - osb->dev_str, info.tf_nodenum);
>>>> - range->len = info.tf_trimlen;
>>>> - goto out_trimunlock;
>>>> - }
>>>> + /*
>>>> + * Determine first and last group to examine based on
>>>> + * start and len
>>>> + */
>>>> + first_group = ocfs2_which_cluster_group(main_bm_inode, start);
>>>> + if (first_group == osb->first_cluster_group_blkno)
>>>> + first_bit = start;
>>>> + else
>>>> + first_bit = start - ocfs2_blocks_to_clusters(sb,
>>>> + first_group);
>>>> + last_group = ocfs2_which_cluster_group(main_bm_inode,
>>>> + start + len - 1);
>>>> + group = first_group;
>>>> }
>>>>
>>>> - info.tf_nodenum = osb->node_num;
>>>> - info.tf_start = start;
>>>> - info.tf_len = len;
>>>> - info.tf_minlen = minlen;
>>>> -
>>>> - /* Determine first and last group to examine based on start and len */
>>>> - first_group = ocfs2_which_cluster_group(main_bm_inode, start);
>>>> - if (first_group == osb->first_cluster_group_blkno)
>>>> - first_bit = start;
>>>> - else
>>>> - first_bit = start - ocfs2_blocks_to_clusters(sb, first_group);
>>>> - last_group = ocfs2_which_cluster_group(main_bm_inode, start + len - 1);
>>>> - last_bit = osb->bitmap_cpg;
>>>> -
>>>> - trimmed = 0;
>>>> - for (group = first_group; group <= last_group;) {
>>>> + do {
>>>> if (first_bit + len >= osb->bitmap_cpg)
>>>> last_bit = osb->bitmap_cpg;
>>>> else
>>>> @@ -7659,21 +7632,81 @@ int ocfs2_trim_fs(struct super_block *sb, struct
>>> fstrim_range *range)
>>>> group = ocfs2_clusters_to_blocks(sb, osb->bitmap_cpg);
>>>> else
>>>> group += ocfs2_clusters_to_blocks(sb, osb->bitmap_cpg);
>>>> - }
>>>> - range->len = trimmed * sb->s_blocksize;
>>>> + } while (0);
>>>>
>>>> - info.tf_trimlen = range->len;
>>>> - info.tf_success = (ret ? 0 : 1);
>>>> - pinfo = &info;
>>>> -out_trimunlock:
>>>> - ocfs2_trim_fs_unlock(osb, pinfo);
>>>> - ocfs2_trim_fs_lock_res_uninit(osb);
>>>> out_unlock:
>>>> ocfs2_inode_unlock(main_bm_inode, 0);
>>>> brelse(main_bm_bh);
>>>> + main_bm_bh = NULL;
>>>> out_mutex:
>>>> inode_unlock(main_bm_inode);
>>>> iput(main_bm_inode);
>>>> +
>>>> + /*
>>>> + * If all the groups trim are not done or failed, but we should release
>>>> + * main_bm related locks for avoiding the current IO starve, then go to
>>>> + * trim the next group
>>>> + */
>>>> + if (ret >= 0 && group <= last_group)
>>>> + goto next_group;
>>>> out:
>>>> + range->len = trimmed * sb->s_blocksize;
>>>> + return ret;
>>>> +}
>>>> +
>>>> +int ocfs2_trim_fs(struct super_block *sb, struct fstrim_range *range)
>>>> +{
>>>> + int ret;
>>>> + struct ocfs2_super *osb = OCFS2_SB(sb);
>>>> + struct ocfs2_trim_fs_info info, *pinfo = NULL;
>>>> +
>>>> + ocfs2_trim_fs_lock_res_init(osb);
>>>> +
>>>> + trace_ocfs2_trim_fs(range->start, range->len, range->minlen);
>>>> +
>>>> + ret = ocfs2_trim_fs_lock(osb, NULL, 1);
>>>> + if (ret < 0) {
>>>> + if (ret != -EAGAIN) {
>>>> + mlog_errno(ret);
>>>> + ocfs2_trim_fs_lock_res_uninit(osb);
>>>> + return ret;
>>>> + }
>>>> +
>>>> + mlog(ML_NOTICE, "Wait for trim on device (%s) to "
>>>> + "finish, which is running from another node.\n",
>>>> + osb->dev_str);
>>>> + ret = ocfs2_trim_fs_lock(osb, &info, 0);
>>>> + if (ret < 0) {
>>>> + mlog_errno(ret);
>>>> + ocfs2_trim_fs_lock_res_uninit(osb);
>>>> + return ret;
>>>> + }
>>>> +
>>>> + if (info.tf_valid && info.tf_success &&
>>>> + info.tf_start == range->start &&
>>>> + info.tf_len == range->len &&
>>>> + info.tf_minlen == range->minlen) {
>>>> + /* Avoid sending duplicated trim to a shared device */
>>>> + mlog(ML_NOTICE, "The same trim on device (%s) was "
>>>> + "just done from node (%u), return.\n",
>>>> + osb->dev_str, info.tf_nodenum);
>>>> + range->len = info.tf_trimlen;
>>>> + goto out;
>>>> + }
>>>> + }
>>>> +
>>>> + info.tf_nodenum = osb->node_num;
>>>> + info.tf_start = range->start;
>>>> + info.tf_len = range->len;
>>>> + info.tf_minlen = range->minlen;
>>>> +
>>>> + ret = ocfs2_trim_mainbm(sb, range);
>>>> +
>>>> + info.tf_trimlen = range->len;
>>>> + info.tf_success = (ret < 0 ? 0 : 1);
>>>> + pinfo = &info;
>>>> +out:
>>>> + ocfs2_trim_fs_unlock(osb, pinfo);
>>>> + ocfs2_trim_fs_lock_res_uninit(osb);
>>>> return ret;
>>>> }
>>>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>>>> index 7c835824247e..af405586c5b1 100644
>>>> --- a/fs/ocfs2/dlmglue.c
>>>> +++ b/fs/ocfs2/dlmglue.c
>>>> @@ -686,6 +686,9 @@ void ocfs2_trim_fs_lock_res_init(struct ocfs2_super *osb)
>>>> {
>>>> struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
>>>>
>>>> + /* Only one trimfs thread are allowed to work at the same time. */
>>>> + mutex_lock(&osb->obs_trim_fs_mutex);
>>>> +
>>>
>>> Cluster lock of fstrim have a trylock behavior, will it be better if we
>>> trylock here?
>> Here, I prefer to just serialize fstrim threads on the local node to
> simplify the code logic,
>> maybe the user want to do like that, although this behavior is not
> recommended.
>> You know, on one node, ideally, the user should call fstrim command once
> regularly.
>> If he calls fstrim command more times in a very short time,
>> the code will not make each fstrim command return to failure, just do the
> fstrim task one by one.
>
> I have a thought having nothing to do with your patch.
> Do you think it's possible for us to implement *discard on unlink file* like
> ext4 does.
> So the application doesn't have to invoke fstrim periodically.
Yes, we can do some investigation for adding a mount option "discard" to support discard a file when it is deleted.
This can be considered as another feature, since its discard occasion and granularity is different with fstrim.
The scheduled fstrim command can considered as a traditional file system level trim.
If the file system supports the on-demand discard when some blocks were released, that's better.
Of course. these two features can coexist.

Thanks
Gang

>
> Thanks,
> Changwei
>
>>
>> Thanks
>> Gang
>>
>>>
>>> Thanks,
>>> Changwei
>>>
>>>> ocfs2_lock_res_init_once(lockres);
>>>> ocfs2_build_lock_name(OCFS2_LOCK_TYPE_TRIM_FS, 0, 0, lockres->l_name);
>>>> ocfs2_lock_res_init_common(osb, lockres, OCFS2_LOCK_TYPE_TRIM_FS,
>>>> @@ -698,6 +701,8 @@ void ocfs2_trim_fs_lock_res_uninit(struct ocfs2_super
>>> *osb)
>>>>
>>>> ocfs2_simple_drop_lockres(osb, lockres);
>>>> ocfs2_lock_res_free(lockres);
>>>> +
>>>> + mutex_unlock(&osb->obs_trim_fs_mutex);
>>>> }
>>>>
>>>> static void ocfs2_orphan_scan_lock_res_init(struct ocfs2_lock_res *res,
>>>> diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
>>>> index 4f86ac0027b5..1f029fbe8b8d 100644
>>>> --- a/fs/ocfs2/ocfs2.h
>>>> +++ b/fs/ocfs2/ocfs2.h
>>>> @@ -407,6 +407,7 @@ struct ocfs2_super
>>>> struct ocfs2_lock_res osb_rename_lockres;
>>>> struct ocfs2_lock_res osb_nfs_sync_lockres;
>>>> struct ocfs2_lock_res osb_trim_fs_lockres;
>>>> + struct mutex obs_trim_fs_mutex;
>>>> struct ocfs2_dlm_debug *osb_dlm_debug;
>>>>
>>>> struct dentry *osb_debug_root;
>>>> diff --git a/fs/ocfs2/ocfs2_trace.h b/fs/ocfs2/ocfs2_trace.h
>>>> index 2ee76a90ba8f..dc4bce1649c1 100644
>>>> --- a/fs/ocfs2/ocfs2_trace.h
>>>> +++ b/fs/ocfs2/ocfs2_trace.h
>>>> @@ -712,6 +712,8 @@ TRACE_EVENT(ocfs2_trim_extent,
>>>>
>>>> DEFINE_OCFS2_ULL_UINT_UINT_UINT_EVENT(ocfs2_trim_group);
>>>>
>>>> +DEFINE_OCFS2_ULL_ULL_ULL_EVENT(ocfs2_trim_mainbm);
>>>> +
>>>> DEFINE_OCFS2_ULL_ULL_ULL_EVENT(ocfs2_trim_fs);
>>>>
>>>> /* End of trace events for fs/ocfs2/alloc.c. */
>>>> diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
>>>> index 3415e0b09398..96ae7cedd487 100644
>>>> --- a/fs/ocfs2/super.c
>>>> +++ b/fs/ocfs2/super.c
>>>> @@ -1847,6 +1847,8 @@ static int ocfs2_mount_volume(struct super_block *sb)
>>>> if (ocfs2_is_hard_readonly(osb))
>>>> goto leave;
>>>>
>>>> + mutex_init(&osb->obs_trim_fs_mutex);
>>>> +
>>>> status = ocfs2_dlm_init(osb);
>>>> if (status < 0) {
>>>> mlog_errno(status);
>>>>
>>

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