Re: [PATCH v3 0/3] add support for drop_caches for individual filesystem

["yebin (H)" <yebin10@huawei.com>]

On 2026/2/27 11:31, Muchun Song wrote:
>
>
>> On Feb 27, 2026, at 10:55, Ye Bin <yebin@huaweicloud.com> wrote:
>>
>> From: Ye Bin <yebin10@huawei.com>
>>
>> In order to better analyze the issue of file system uninstallation caused
>> by kernel module opening files, it is necessary to perform dentry recycling
>> on a single file system. But now, apart from global dentry recycling, it is
>> not supported to do dentry recycling on a single file system separately.
>
> Would shrinker-debugfs satisfy your needs (See Documentation/admin-guide/mm/shrinker_debugfs.rst)?
>
> Thanks,
> Muchun
>
Thank you for the reminder. The reclamation of dentries and nodes can 
meet my needs. However, the reclamation of the page cache alone does not 
satisfy my requirements. I have reviewed the code of 
shrinker_debugfs_scan_write() and found that it does not support batch 
deletion of all dentries/inode for all nodes/memcgs,instead, users need 
to traverse through them one by one, which is not very convenient. Based 
on my previous experience, I have always performed dentry/inode 
reclamation at the file system level.

Thanks,
Ye Bin
>> This feature has usage scenarios in problem localization scenarios.At the
>> same time, it also provides users with a slightly fine-grained
>> pagecache/entry recycling mechanism.
>> This patchset supports the recycling of pagecache/entry for individual file
>> systems.
>>
>> Diff v3 vs v2
>> 1. Introduce introduce drop_sb_dentry_inode() helper instead of
>> reclaim_dcache_sb()/reclaim_icache_sb() helper for reclaim dentry/inode.
>> 2. Fixing compilation issues in specific architectures and configurations.
>>
>> Diff v2 vs v1:
>> 1. Fix possible live lock for shrink_icache_sb().
>> 2. Introduce reclaim_dcache_sb() for reclaim dentry.
>> 3. Fix potential deadlocks as follows:
>> https://lore.kernel.org/linux-fsdevel/00000000000098f75506153551a1@google.com/
>> After some consideration, it was decided that this feature would primarily
>> be used for debugging purposes. Instead of adding a new IOCTL command, the
>> task_work mechanism was employed to address potential deadlock issues.
>>
>> Ye Bin (3):
>>   mm/vmscan: introduce drop_sb_dentry_inode() helper
>>   sysctl: add support for drop_caches for individual filesystem
>>   Documentation: add instructions for using 'drop_fs_caches sysctl'
>>     sysctl
>>
>> Documentation/admin-guide/sysctl/vm.rst |  44 +++++++++
>> fs/drop_caches.c                        | 125 ++++++++++++++++++++++++
>> include/linux/mm.h                      |   1 +
>> mm/internal.h                           |   3 +
>> mm/shrinker.c                           |   4 +-
>> mm/vmscan.c                             |  50 ++++++++++
>> 6 files changed, 225 insertions(+), 2 deletions(-)
>>
>> --
>> 2.34.1
>>
>
> .
>