linux-kernel - Re: [PATCH v6 12/22] erofs: add cookie context helper functions

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Message-ID: <f1455f47-dbeb-46cb-69bd-5edf193f69fe@linux.alibaba.com>
Date:   Mon, 28 Mar 2022 11:11:43 +0800
From:   JeffleXu <jefflexu@...ux.alibaba.com>
To:     dhowells@...hat.com, linux-cachefs@...hat.com, xiang@...nel.org,
        chao@...nel.org, linux-erofs@...ts.ozlabs.org,
        torvalds@...ux-foundation.org, gregkh@...uxfoundation.org,
        willy@...radead.org, linux-fsdevel@...r.kernel.org,
        joseph.qi@...ux.alibaba.com, bo.liu@...ux.alibaba.com,
        tao.peng@...ux.alibaba.com, gerry@...ux.alibaba.com,
        eguan@...ux.alibaba.com, linux-kernel@...r.kernel.org,
        luodaowen.backend@...edance.com, tianzichen@...ishou.com,
        fannaihao@...du.com
Subject: Re: [PATCH v6 12/22] erofs: add cookie context helper functions



On 3/25/22 9:41 PM, Gao Xiang wrote:
> Hi Jeffle,
> 
> On Fri, Mar 25, 2022 at 08:22:13PM +0800, Jeffle Xu wrote:
>> Introduce "struct erofs_fscache" for managing cookie for backinig file,
>> and helper functions for initializing and cleaning up this context
>> structure.
>>
>> Signed-off-by: Jeffle Xu <jefflexu@...ux.alibaba.com>
>> ---
>>  fs/erofs/fscache.c  | 61 +++++++++++++++++++++++++++++++++++++++++++++
>>  fs/erofs/internal.h | 14 +++++++++++
>>  2 files changed, 75 insertions(+)
>>
>> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
>> index 08cf570a0810..73235fd43bf6 100644
>> --- a/fs/erofs/fscache.c
>> +++ b/fs/erofs/fscache.c
>> @@ -7,6 +7,67 @@
>>  
>>  static struct fscache_volume *volume;
>>  
>> +static int erofs_fscache_init_cookie(struct erofs_fscache *ctx, char *path)
>> +{
>> +	struct fscache_cookie *cookie;
>> +
>> +	cookie = fscache_acquire_cookie(volume, FSCACHE_ADV_WANT_CACHE_SIZE,
>> +					path, strlen(path),
>> +					NULL, 0, 0);
> 
> It'd be better to rearrange in one line?

Sure.

> 
> 					path, strlen(path), NULL, 0, 0);
> 
>> +	if (!cookie)
>> +		return -EINVAL;
>> +
>> +	fscache_use_cookie(cookie, false);
>> +	ctx->cookie = cookie;
>> +	return 0;
>> +}
>> +
>> +static inline void erofs_fscache_cleanup_cookie(struct erofs_fscache *ctx)
>> +{
>> +	struct fscache_cookie *cookie = ctx->cookie;
>> +
>> +	fscache_unuse_cookie(cookie, NULL, NULL);
>> +	fscache_relinquish_cookie(cookie, false);
>> +	ctx->cookie = NULL;
>> +}
>> +
>> +/*
>> + * erofs_fscache_get - create an fscache context for blob file
>> + * @sb:		superblock
>> + * @path:	name of blob file
>> + *
>> + * Return: fscache context on success, ERR_PTR() on failure.
>> + */
>> +struct erofs_fscache *erofs_fscache_get(struct super_block *sb, char *path)
> 
> erofs_fscache_register?

OK.


> 
>> +{
>> +	struct erofs_fscache *ctx;
>> +	int ret;
>> +
>> +	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
>> +	if (!ctx)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	ret = erofs_fscache_init_cookie(ctx, path);
> 
> Can we fold it here? No need to introduce such simple wrapper..
> 
>> +	if (ret) {
>> +		erofs_err(sb, "failed to init cookie");
> 
> It would be better to print the path?

OK.

> 
>> +		goto err;
> 
> 		kfree(ctx);
> 		return ERR_PTR(ret);
> 
> At least for now.

Yeah, it's better.

> 
>> +	}
>> +
>> +	return ctx;
>> +err:
>> +	kfree(ctx);
>> +	return ERR_PTR(ret);
>> +}
>> +
>> +void erofs_fscache_put(struct erofs_fscache *ctx)
> 
> erofs_fscache_unregister?

OK.

> 
>> +{
>> +	if (!ctx)
>> +		return;
>> +
>> +	erofs_fscache_cleanup_cookie(ctx);
> 
> Fold it too, since such helper doesn't simplify code a lot but need
> to take one more time to redirect..

OK.

-- 
Thanks,
Jeffle