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Subject: Re: [PATCH v2 2/2] erofs: support reading chunk-based uncompressed
 files
To:     Gao Xiang <hsiangkao@linux.alibaba.com>
Cc:     linux-erofs@lists.ozlabs.org, Liu Bo <bo.liu@linux.alibaba.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Peng Tao <tao.peng@linux.alibaba.com>,
        Eryu Guan <eguan@linux.alibaba.com>,
        Liu Jiang <gerry@linux.alibaba.com>,
        Joseph Qi <joseph.qi@linux.alibaba.com>,
        Tao Ma <boyu.mt@taobao.com>
References: <20210818070713.4437-1-hsiangkao@linux.alibaba.com>
 <20210819063310.177035-1-hsiangkao@linux.alibaba.com>
 <20210819063310.177035-2-hsiangkao@linux.alibaba.com>
 <aaf64137-02f9-db98-10d4-4757bc6f25ec@kernel.org>
 <YR9x7W4wObWdZdrx@B-P7TQMD6M-0146.local>
From:   Chao Yu <chao@kernel.org>
Message-ID: <f501144f-f7fc-1150-0c41-4c1981bd0594@kernel.org>
Date:   Fri, 20 Aug 2021 17:29:36 +0800
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On 2021/8/20 17:12, Gao Xiang wrote:
> Hi Chao,
> 
> On Fri, Aug 20, 2021 at 05:04:13PM +0800, Chao Yu wrote:
>> On 2021/8/19 14:33, Gao Xiang wrote:
> 
> ...
> 
>>>    }
>>> +static int erofs_map_blocks(struct inode *inode,
>>> +			    struct erofs_map_blocks *map, int flags)
>>> +{
>>> +	struct super_block *sb = inode->i_sb;
>>> +	struct erofs_inode *vi = EROFS_I(inode);
>>> +	struct erofs_inode_chunk_index *idx;
>>> +	struct page *page;
>>> +	u64 chunknr;
>>> +	unsigned int unit;
>>> +	erofs_off_t pos;
>>> +	int err = 0;
>>> +
>>> +	if (map->m_la >= inode->i_size) {
>>> +		/* leave out-of-bound access unmapped */
>>> +		map->m_flags = 0;
>>> +		map->m_plen = 0;
>>> +		goto out;
>>> +	}
>>> +
>>> +	if (vi->datalayout != EROFS_INODE_CHUNK_BASED)
>>> +		return erofs_map_blocks_flatmode(inode, map, flags);
>>> +
>>> +	if (vi->chunkformat & EROFS_CHUNK_FORMAT_INDEXES)
>>> +		unit = sizeof(*idx);	/* chunk index */
>>> +	else
>>> +		unit = 4;		/* block map */
>>
>> You mean sizeof(__le32)?
> 
> Yeah, sizeof(__le32) == 4, either way works for me.
> 
> If some tendency about this, I will update when applying.

Xiang,

Yeah, I preper:

#define EROFS_BLOCK_MAP_ENTRY_SIZE	sizeof(__le32)

	unit = EROFS_BLOCK_MAP_ENTRY_SIZE;

to improve readablity, but unit = sizeof(__le32) is fine as well.

Thanks,

> 
>>
>> Otherwise it looks good to me.
>>
>> Reviewed-by: Chao Yu <chao@kernel.org>
>>
> 
> Thanks for the review!
> 
> Thanks,
> Gao Xiang
> 
>> Thanks,
>>
>>> +
>>> +	chunknr = map->m_la >> vi->chunkbits;
>>> +	pos = ALIGN(iloc(EROFS_SB(sb), vi->nid) + vi->inode_isize +
>>> +		    vi->xattr_isize, unit) + unit * chunknr;
>>> +
>>> +	page = erofs_get_meta_page(inode->i_sb, erofs_blknr(pos));
>>> +	if (IS_ERR(page))
>>> +		return PTR_ERR(page);
>>> +
>>> +	map->m_la = chunknr << vi->chunkbits;
>>> +	map->m_plen = min_t(erofs_off_t, 1UL << vi->chunkbits,
>>> +			    roundup(inode->i_size - map->m_la, EROFS_BLKSIZ));
>>> +
>>> +	/* handle block map */
>>> +	if (!(vi->chunkformat & EROFS_CHUNK_FORMAT_INDEXES)) {
>>> +		__le32 *blkaddr = page_address(page) + erofs_blkoff(pos);
>>> +
>>> +		if (le32_to_cpu(*blkaddr) == EROFS_NULL_ADDR) {
>>> +			map->m_flags = 0;
>>> +		} else {
>>> +			map->m_pa = blknr_to_addr(le32_to_cpu(*blkaddr));
>>> +			map->m_flags = EROFS_MAP_MAPPED;
>>> +		}
>>> +		goto out_unlock;
>>> +	}
>>> +	/* parse chunk indexes */
>>> +	idx = page_address(page) + erofs_blkoff(pos);
>>> +	switch (le32_to_cpu(idx->blkaddr)) {
>>> +	case EROFS_NULL_ADDR:
>>> +		map->m_flags = 0;
>>> +		break;
>>> +	default:
>>> +		/* only one device is supported for now */
>>> +		if (idx->device_id) {
>>> +			erofs_err(sb, "invalid device id %u @ %llu for nid %llu",
>>> +				  le32_to_cpu(idx->device_id),
>>> +				  chunknr, vi->nid);
>>> +			err = -EFSCORRUPTED;
>>> +			goto out_unlock;
>>> +		}
>>> +		map->m_pa = blknr_to_addr(le32_to_cpu(idx->blkaddr));
>>> +		map->m_flags = EROFS_MAP_MAPPED;
>>> +		break;
>>> +	}
>>> +out_unlock:
>>> +	unlock_page(page);
>>> +	put_page(page);
>>> +out:
>>> +	map->m_llen = map->m_plen;
>>> +	return err;
>>> +}
>>> +
>>>    static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>>>    		unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
>>>    {
>>> @@ -94,7 +164,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>>>    	map.m_la = offset;
>>>    	map.m_llen = length;
>>> -	ret = erofs_map_blocks_flatmode(inode, &map, EROFS_GET_BLOCKS_RAW);
>>> +	ret = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
>>>    	if (ret < 0)
>>>    		return ret;
>>> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
>>> index d13e0709599c..4408929bd6f5 100644
>>> --- a/fs/erofs/inode.c
>>> +++ b/fs/erofs/inode.c
>>> @@ -2,6 +2,7 @@
>>>    /*
>>>     * Copyright (C) 2017-2018 HUAWEI, Inc.
>>>     *             https://www.huawei.com/
>>> + * Copyright (C) 2021, Alibaba Cloud
>>>     */
>>>    #include "xattr.h"
>>> @@ -122,7 +123,9 @@ static struct page *erofs_read_inode(struct inode *inode,
>>>    		/* total blocks for compressed files */
>>>    		if (erofs_inode_is_data_compressed(vi->datalayout))
>>>    			nblks = le32_to_cpu(die->i_u.compressed_blocks);
>>> -
>>> +		else if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
>>> +			/* fill chunked inode summary info */
>>> +			vi->chunkformat = le16_to_cpu(die->i_u.c.format);
>>>    		kfree(copied);
>>>    		break;
>>>    	case EROFS_INODE_LAYOUT_COMPACT:
>>> @@ -160,6 +163,8 @@ static struct page *erofs_read_inode(struct inode *inode,
>>>    		inode->i_size = le32_to_cpu(dic->i_size);
>>>    		if (erofs_inode_is_data_compressed(vi->datalayout))
>>>    			nblks = le32_to_cpu(dic->i_u.compressed_blocks);
>>> +		else if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
>>> +			vi->chunkformat = le16_to_cpu(dic->i_u.c.format);
>>>    		break;
>>>    	default:
>>>    		erofs_err(inode->i_sb,
>>> @@ -169,6 +174,17 @@ static struct page *erofs_read_inode(struct inode *inode,
>>>    		goto err_out;
>>>    	}
>>> +	if (vi->datalayout == EROFS_INODE_CHUNK_BASED) {
>>> +		if (!(vi->chunkformat & EROFS_CHUNK_FORMAT_ALL)) {
>>> +			erofs_err(inode->i_sb,
>>> +				  "unsupported chunk format %x of nid %llu",
>>> +				  vi->chunkformat, vi->nid);
>>> +			err = -EOPNOTSUPP;
>>> +			goto err_out;
>>> +		}
>>> +		vi->chunkbits = LOG_BLOCK_SIZE +
>>> +			(vi->chunkformat & EROFS_CHUNK_FORMAT_BLKBITS_MASK);
>>> +	}
>>>    	inode->i_mtime.tv_sec = inode->i_ctime.tv_sec;
>>>    	inode->i_atime.tv_sec = inode->i_ctime.tv_sec;
>>>    	inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec;
>>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>>> index 91089ab8a816..9524e155b38f 100644
>>> --- a/fs/erofs/internal.h
>>> +++ b/fs/erofs/internal.h
>>> @@ -2,6 +2,7 @@
>>>    /*
>>>     * Copyright (C) 2017-2018 HUAWEI, Inc.
>>>     *             https://www.huawei.com/
>>> + * Copyright (C) 2021, Alibaba Cloud
>>>     */
>>>    #ifndef __EROFS_INTERNAL_H
>>>    #define __EROFS_INTERNAL_H
>>> @@ -261,6 +262,10 @@ struct erofs_inode {
>>>    	union {
>>>    		erofs_blk_t raw_blkaddr;
>>> +		struct {
>>> +			unsigned short	chunkformat;
>>> +			unsigned char	chunkbits;
>>> +		};
>>>    #ifdef CONFIG_EROFS_FS_ZIP
>>>    		struct {
>>>    			unsigned short z_advise;
>>>