Re: [PATCH v3 0/5] fs/dcache: Limit # of negative dentries

[Waiman Long]

On 08/18/2017 05:59 AM, Wangkai (Kevin,C) wrote:
>
>>> In my patch the DCACHE_FILE_REMOVED flag was to distinguish the
>>> removed file and The closed file, I found there was no difference of a
>>> dentry between the removed file and the closed File, they all on the lru list.
>> There is a difference between removed file and closed file. The type field of
>> d_flags will be empty for a removed file which indicate a negative dentry.
>> Anything else is a positive dentry. Look at the inline function d_is_negative()
>> [d_is_miss()] and you will see how it is done.
> After the file was removed, the dentry flag was not MISS, the flag was:
> DCACHE_REFERENCED | DCACHE_RCUACCESS | DCACHE_LRU_LIST | DCACHE_REGULAR_TYPE
> So, the dentry never be freed, until the kernel reclaim the slab memory.

The dentry_unlink_inode() function will clear DCACHE_REGULAR_TYPE.

Cheers,
Longman