Re: [PATCH v2 2/2] erofs: support reading chunk-based uncompressed files

[Gao Xiang]

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.

> 
> Otherwise it looks good to me.
> 
> Reviewed-by: Chao Yu <chao@xxxxxxxxxx>
> 

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;
> >