Re: [Virtio-fs] [PATCH v4 6/8] fuse: mark inode DONT_CACHE when per-file DAX indication changes

[JeffleXu <jefflexu@linux.alibaba.com>]

On 8/17/21 6:26 PM, Dr. David Alan Gilbert wrote:
> * Jeffle Xu (jefflexu@linux.alibaba.com) wrote:
>> When the per-file DAX indication changes while the file is still
>> *opened*, it is quite complicated and maybe fragile to dynamically
>> change the DAX state.
>>
>> Hence mark the inode and corresponding dentries as DONE_CACHE once the
> 
>                                                      ^^^^^^^^^^
> typo as DONT ?
> 

Thanks. I will fix it.

> 
>> per-file DAX indication changes, so that the inode instance will be
>> evicted and freed as soon as possible once the file is closed and the
>> last reference to the inode is put. And then when the file gets reopened
>> next time, the inode will reflect the new DAX state.
>>
>> In summary, when the per-file DAX indication changes for an *opened*
>> file, the state of the file won't be updated until this file is closed
>> and reopened later.
>>
>> Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
>> ---
>>  fs/fuse/dax.c    | 9 +++++++++
>>  fs/fuse/fuse_i.h | 1 +
>>  fs/fuse/inode.c  | 3 +++
>>  3 files changed, 13 insertions(+)
>>
>> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
>> index 30833f8d37dd..f7ede0be4e00 100644
>> --- a/fs/fuse/dax.c
>> +++ b/fs/fuse/dax.c
>> @@ -1364,6 +1364,15 @@ void fuse_dax_inode_init(struct inode *inode, unsigned int flags)
>>  	inode->i_data.a_ops = &fuse_dax_file_aops;
>>  }
>>  
>> +void fuse_dax_dontcache(struct inode *inode, bool newdax)
>> +{
>> +	struct fuse_conn *fc = get_fuse_conn(inode);
>> +
>> +	if (fc->dax_mode == FUSE_DAX_INODE &&
>> +	    fc->perfile_dax && (!!IS_DAX(inode) != newdax))
>> +		d_mark_dontcache(inode);
>> +}
>> +
>>  bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment)
>>  {
>>  	if (fc->dax && (map_alignment > FUSE_DAX_SHIFT)) {
>> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
>> index 7b7b4c208af2..56fe1c4d2136 100644
>> --- a/fs/fuse/fuse_i.h
>> +++ b/fs/fuse/fuse_i.h
>> @@ -1260,6 +1260,7 @@ void fuse_dax_conn_free(struct fuse_conn *fc);
>>  bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi);
>>  void fuse_dax_inode_init(struct inode *inode, unsigned int flags);
>>  void fuse_dax_inode_cleanup(struct inode *inode);
>> +void fuse_dax_dontcache(struct inode *inode, bool newdax);
>>  bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment);
>>  void fuse_dax_cancel_work(struct fuse_conn *fc);
>>  
>> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
>> index 8080f78befed..8c9774c6a210 100644
>> --- a/fs/fuse/inode.c
>> +++ b/fs/fuse/inode.c
>> @@ -269,6 +269,9 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
>>  		if (inval)
>>  			invalidate_inode_pages2(inode->i_mapping);
>>  	}
>> +
>> +	if (IS_ENABLED(CONFIG_FUSE_DAX))
>> +		fuse_dax_dontcache(inode, attr->flags & FUSE_ATTR_DAX);
>>  }
>>  
>>  static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
>> -- 
>> 2.27.0
>>
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>>

-- 
Thanks,
Jeffle