Received-SPF: pass (google.com: domain of linux-ext4+bounces-385-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Subject: Re: [PATCH RFC v2 for-6.8/block 15/18] buffer: add a new helper to
 read sb block
To: Jan Kara <jack@suse.cz>, Yu Kuai <yukuai1@huaweicloud.com>
Cc: axboe@kernel.dk, roger.pau@citrix.com, colyli@suse.de,
 kent.overstreet@gmail.com, joern@lazybastard.org, miquel.raynal@bootlin.com,
 richard@nod.at, vigneshr@ti.com, sth@linux.ibm.com, hoeppner@linux.ibm.com,
 hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com,
 jejb@linux.ibm.com, martin.petersen@oracle.com, clm@fb.com,
 josef@toxicpanda.com, dsterba@suse.com, viro@zeniv.linux.org.uk,
 brauner@kernel.org, nico@fluxnic.net, xiang@kernel.org, chao@kernel.org,
 tytso@mit.edu, adilger.kernel@dilger.ca, agruenba@redhat.com, jack@suse.com,
 konishi.ryusuke@gmail.com, willy@infradead.org, akpm@linux-foundation.org,
 p.raghav@samsung.com, hare@suse.de, linux-block@vger.kernel.org,
 linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
 linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org,
 linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org,
 linux-bcachefs@vger.kernel.org, linux-btrfs@vger.kernel.org,
 linux-fsdevel@vger.kernel.org, linux-erofs@lists.ozlabs.org,
 linux-ext4@vger.kernel.org, gfs2@lists.linux.dev,
 linux-nilfs@vger.kernel.org, yi.zhang@huawei.com,
 "yangerkun@huawei.com" <yangerkun@huawei.com>,
 "yukuai (C)" <yukuai3@huawei.com>
References: <20231211140552.973290-1-yukuai1@huaweicloud.com>
 <20231211140753.975297-1-yukuai1@huaweicloud.com>
 <20231211172708.qpuk4rkwq4u2zbmj@quack3>
From: Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <be459c50-5179-2748-2636-7965b9e1cb7a@huaweicloud.com>
Date: Tue, 12 Dec 2023 09:32:10 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
Precedence: bulk
MIME-Version: 1.0
In-Reply-To: <20231211172708.qpuk4rkwq4u2zbmj@quack3>
Content-Type: text/plain; charset=gbk; format=flowed
Content-Transfer-Encoding: 8bit

Hi,

?? 2023/12/12 1:27, Jan Kara д??:
> On Mon 11-12-23 22:07:53, Yu Kuai wrote:
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> Unlike __bread_gfp(), ext4 has special handing while reading sb block:
>>
>> 1) __GFP_NOFAIL is not set, and memory allocation can fail;
>> 2) If buffer write failed before, set buffer uptodate and don't read
>>     block from disk;
>> 3) REQ_META is set for all IO, and REQ_PRIO is set for reading xattr;
>> 4) If failed, return error ptr instead of NULL;
>>
>> This patch add a new helper __bread_gfp2() that will match above 2 and 3(
>> 1 will be used, and 4 will still be encapsulated by ext4), and prepare to
>> prevent calling mapping_gfp_constraint() directly on bd_inode->i_mapping
>> in ext4.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ...
>> +/*
>> + * This works like __bread_gfp() except:
>> + * 1) If buffer write failed before, set buffer uptodate and don't read
>> + * block from disk;
>> + * 2) Caller can pass in additional op_flags like REQ_META;
>> + */
>> +struct buffer_head *
>> +__bread_gfp2(struct block_device *bdev, sector_t block, unsigned int size,
>> +	     blk_opf_t op_flags, gfp_t gfp)
>> +{
>> +	return bread_gfp(bdev, block, size, op_flags, gfp, true);
>> +}
>> +EXPORT_SYMBOL(__bread_gfp2);
> 
> __bread_gfp2() is not a great name, why not just using bread_gfp()
> directly? I'm not a huge fan of boolean arguments but three different flags
> arguments would be too much for my taste ;) so I guess I can live with
> that.

I agree that __bread_gfp2 is not a greate name, if possible, I'll try to
figure out a better name for v3.

Thanks for reviewing this patchset!
Kuai
> 
> 								Honza
>