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

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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