linux-kernel - Re: [PATCH] fs/ceph/mds_client: use cap_wait

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Date: Tue, 11 Jun 2024 15:58:17 +0800
From: Xiubo Li <xiubli@...hat.com>
To: Max Kellermann <max.kellermann@...os.com>, idryomov@...il.com,
 ceph-devel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fs/ceph/mds_client: use cap_wait_list only if debugfs is
 enabled


On 6/11/24 10:11, Xiubo Li wrote:
>
> On 6/7/24 00:41, Max Kellermann wrote:
>> Only debugfs uses this list.  By omitting it, we save some memory and
>> reduce lock contention on `caps_list_lock`.
>>
>> Signed-off-by: Max Kellermann <max.kellermann@...os.com>
>> ---
>>   fs/ceph/caps.c       | 6 ++++++
>>   fs/ceph/mds_client.c | 2 ++
>>   fs/ceph/mds_client.h | 6 ++++++
>>   3 files changed, 14 insertions(+)
>>
>> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
>> index c4941ba245ac..772879aa26ee 100644
>> --- a/fs/ceph/caps.c
>> +++ b/fs/ceph/caps.c
>> @@ -3067,10 +3067,13 @@ int __ceph_get_caps(struct inode *inode, 
>> struct ceph_file_info *fi, int need,
>>                          flags, &_got);
>>           WARN_ON_ONCE(ret == -EAGAIN);
>>           if (!ret) {
>> +#ifdef CONFIG_DEBUG_FS
>>               struct ceph_mds_client *mdsc = fsc->mdsc;
>>               struct cap_wait cw;
>> +#endif
>>               DEFINE_WAIT_FUNC(wait, woken_wake_function);
>>   +#ifdef CONFIG_DEBUG_FS
>>               cw.ino = ceph_ino(inode);
>>               cw.tgid = current->tgid;
>>               cw.need = need;
>> @@ -3079,6 +3082,7 @@ int __ceph_get_caps(struct inode *inode, struct 
>> ceph_file_info *fi, int need,
>>               spin_lock(&mdsc->caps_list_lock);
>>               list_add(&cw.list, &mdsc->cap_wait_list);
>>               spin_unlock(&mdsc->caps_list_lock);
>> +#endif // CONFIG_DEBUG_FS
>>                 /* make sure used fmode not timeout */
>>               ceph_get_fmode(ci, flags, FMODE_WAIT_BIAS);
>> @@ -3097,9 +3101,11 @@ int __ceph_get_caps(struct inode *inode, 
>> struct ceph_file_info *fi, int need,
>>               remove_wait_queue(&ci->i_cap_wq, &wait);
>>               ceph_put_fmode(ci, flags, FMODE_WAIT_BIAS);
>>   +#ifdef CONFIG_DEBUG_FS
>>               spin_lock(&mdsc->caps_list_lock);
>>               list_del(&cw.list);
>>               spin_unlock(&mdsc->caps_list_lock);
>> +#endif
>>                 if (ret == -EAGAIN)
>>                   continue;
>> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
>> index c2157f6e0c69..62238f3e6e19 100644
>> --- a/fs/ceph/mds_client.c
>> +++ b/fs/ceph/mds_client.c
>> @@ -5505,7 +5505,9 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
>>       INIT_DELAYED_WORK(&mdsc->delayed_work, delayed_work);
>>       mdsc->last_renew_caps = jiffies;
>>       INIT_LIST_HEAD(&mdsc->cap_delay_list);
>> +#ifdef CONFIG_DEBUG_FS
>>       INIT_LIST_HEAD(&mdsc->cap_wait_list);
>> +#endif
>>       spin_lock_init(&mdsc->cap_delay_lock);
>>       INIT_LIST_HEAD(&mdsc->cap_unlink_delay_list);
>>       INIT_LIST_HEAD(&mdsc->snap_flush_list);
>> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
>> index cfa18cf915a0..13dd83f783ec 100644
>> --- a/fs/ceph/mds_client.h
>> +++ b/fs/ceph/mds_client.h
>> @@ -416,6 +416,8 @@ struct ceph_quotarealm_inode {
>>       struct inode *inode;
>>   };
>>   +#ifdef CONFIG_DEBUG_FS
>> +
>>   struct cap_wait {
>>       struct list_head    list;
>>       u64            ino;
>> @@ -424,6 +426,8 @@ struct cap_wait {
>>       int            want;
>>   };
>>   +#endif // CONFIG_DEBUG_FS
>> +
>>   enum {
>>       CEPH_MDSC_STOPPING_BEGIN = 1,
>>       CEPH_MDSC_STOPPING_FLUSHING = 2,
>> @@ -512,7 +516,9 @@ struct ceph_mds_client {
>>       spinlock_t    caps_list_lock;
>>       struct        list_head caps_list; /* unused (reserved or
>>                           unreserved) */
>> +#ifdef CONFIG_DEBUG_FS
>>       struct        list_head cap_wait_list;
>> +#endif
>>       int        caps_total_count;    /* total caps allocated */
>>       int        caps_use_count;      /* in use */
>>       int        caps_use_max;         /* max used caps */
> Reviewed-by: Xiubo Li <xiubli@...hat.com>

Applied to the 'testing' branch and renamed the title to "ceph: use 
cap_wait_list only if debugfs is enabled"

Thanks

- Xiubo