Re: [PATCH 2/5] erofs: use meta buffers for inode operations

[Yue Hu <zbestahu@gmail.com>]

On Wed, 29 Dec 2021 12:14:02 +0800
Gao Xiang <hsiangkao@linux.alibaba.com> wrote:

> Get rid of old erofs_get_meta_page() within inode operations by
> using on-stack meta buffers in order to prepare subpage and folio
> features.
> 
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
> ---
>  fs/erofs/inode.c    | 68 +++++++++++++++++++++------------------------
>  fs/erofs/internal.h |  3 ++
>  2 files changed, 35 insertions(+), 36 deletions(-)
> 
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index 2345f1de438e..ff62f84f47d3 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -13,8 +13,8 @@
>   * the inode payload page if it's an extended inode) in order to fill
>   * inline data if possible.
>   */
> -static struct page *erofs_read_inode(struct inode *inode,
> -				     unsigned int *ofs)
> +static void *erofs_read_inode(struct erofs_buf *buf,
> +			      struct inode *inode, unsigned int *ofs)
>  {
>  	struct super_block *sb = inode->i_sb;
>  	struct erofs_sb_info *sbi = EROFS_SB(sb);
> @@ -22,7 +22,7 @@ static struct page *erofs_read_inode(struct inode *inode,
>  	const erofs_off_t inode_loc = iloc(sbi, vi->nid);
>  
>  	erofs_blk_t blkaddr, nblks = 0;
> -	struct page *page;
> +	void *kaddr;
>  	struct erofs_inode_compact *dic;
>  	struct erofs_inode_extended *die, *copied = NULL;
>  	unsigned int ifmt;
> @@ -34,14 +34,14 @@ static struct page *erofs_read_inode(struct inode *inode,
>  	erofs_dbg("%s, reading inode nid %llu at %u of blkaddr %u",
>  		  __func__, vi->nid, *ofs, blkaddr);
>  
> -	page = erofs_get_meta_page(sb, blkaddr);
> -	if (IS_ERR(page)) {
> +	kaddr = erofs_read_metabuf(buf, sb, blkaddr, EROFS_KMAP);
> +	if (IS_ERR(kaddr)) {
>  		erofs_err(sb, "failed to get inode (nid: %llu) page, err %ld",
> -			  vi->nid, PTR_ERR(page));
> -		return page;
> +			  vi->nid, PTR_ERR(kaddr));
> +		return kaddr;
>  	}
>  
> -	dic = page_address(page) + *ofs;
> +	dic = kaddr + *ofs;
>  	ifmt = le16_to_cpu(dic->i_format);
>  
>  	if (ifmt & ~EROFS_I_ALL) {
> @@ -62,12 +62,12 @@ static struct page *erofs_read_inode(struct inode *inode,
>  	switch (erofs_inode_version(ifmt)) {
>  	case EROFS_INODE_LAYOUT_EXTENDED:
>  		vi->inode_isize = sizeof(struct erofs_inode_extended);
> -		/* check if the inode acrosses page boundary */
> -		if (*ofs + vi->inode_isize <= PAGE_SIZE) {
> +		/* check if the extended inode acrosses block boundary */
> +		if (*ofs + vi->inode_isize <= EROFS_BLKSIZ) {
>  			*ofs += vi->inode_isize;
>  			die = (struct erofs_inode_extended *)dic;
>  		} else {
> -			const unsigned int gotten = PAGE_SIZE - *ofs;
> +			const unsigned int gotten = EROFS_BLKSIZ - *ofs;
>  
>  			copied = kmalloc(vi->inode_isize, GFP_NOFS);
>  			if (!copied) {
> @@ -75,18 +75,16 @@ static struct page *erofs_read_inode(struct inode *inode,
>  				goto err_out;
>  			}
>  			memcpy(copied, dic, gotten);
> -			unlock_page(page);
> -			put_page(page);
> -
> -			page = erofs_get_meta_page(sb, blkaddr + 1);
> -			if (IS_ERR(page)) {
> -				erofs_err(sb, "failed to get inode payload page (nid: %llu), err %ld",
> -					  vi->nid, PTR_ERR(page));
> +			kaddr = erofs_read_metabuf(buf, sb, blkaddr + 1,
> +						   EROFS_KMAP);
> +			if (IS_ERR(kaddr)) {
> +				erofs_err(sb, "failed to get inode payload block (nid: %llu), err %ld",
> +					  vi->nid, PTR_ERR(kaddr));
>  				kfree(copied);
> -				return page;
> +				return kaddr;
>  			}
>  			*ofs = vi->inode_isize - gotten;
> -			memcpy((u8 *)copied + gotten, page_address(page), *ofs);
> +			memcpy((u8 *)copied + gotten, kaddr, *ofs);
>  			die = copied;
>  		}
>  		vi->xattr_isize = erofs_xattr_ibody_size(die->i_xattr_icount);
> @@ -200,7 +198,7 @@ static struct page *erofs_read_inode(struct inode *inode,
>  		inode->i_blocks = roundup(inode->i_size, EROFS_BLKSIZ) >> 9;
>  	else
>  		inode->i_blocks = nblks << LOG_SECTORS_PER_BLOCK;
> -	return page;
> +	return kaddr;
>  
>  bogusimode:
>  	erofs_err(inode->i_sb, "bogus i_mode (%o) @ nid %llu",
> @@ -209,12 +207,11 @@ static struct page *erofs_read_inode(struct inode *inode,
>  err_out:
>  	DBG_BUGON(1);
>  	kfree(copied);
> -	unlock_page(page);
> -	put_page(page);
> +	erofs_put_metabuf(buf);
>  	return ERR_PTR(err);
>  }
>  
> -static int erofs_fill_symlink(struct inode *inode, void *data,
> +static int erofs_fill_symlink(struct inode *inode, void *kaddr,
>  			      unsigned int m_pofs)
>  {
>  	struct erofs_inode *vi = EROFS_I(inode);
> @@ -222,7 +219,7 @@ static int erofs_fill_symlink(struct inode *inode, void *data,
>  
>  	/* if it cannot be handled with fast symlink scheme */
>  	if (vi->datalayout != EROFS_INODE_FLAT_INLINE ||
> -	    inode->i_size >= PAGE_SIZE) {
> +	    inode->i_size >= EROFS_BLKSIZ) {
>  		inode->i_op = &erofs_symlink_iops;
>  		return 0;
>  	}
> @@ -232,8 +229,8 @@ static int erofs_fill_symlink(struct inode *inode, void *data,
>  		return -ENOMEM;
>  
>  	m_pofs += vi->xattr_isize;
> -	/* inline symlink data shouldn't cross page boundary as well */
> -	if (m_pofs + inode->i_size > PAGE_SIZE) {
> +	/* inline symlink data shouldn't cross block boundary */
> +	if (m_pofs + inode->i_size > EROFS_BLKSIZ) {
>  		kfree(lnk);
>  		erofs_err(inode->i_sb,
>  			  "inline data cross block boundary @ nid %llu",
> @@ -241,8 +238,7 @@ static int erofs_fill_symlink(struct inode *inode, void *data,
>  		DBG_BUGON(1);
>  		return -EFSCORRUPTED;
>  	}
> -
> -	memcpy(lnk, data + m_pofs, inode->i_size);
> +	memcpy(lnk, kaddr + m_pofs, inode->i_size);
>  	lnk[inode->i_size] = '\0';
>  
>  	inode->i_link = lnk;
> @@ -253,16 +249,17 @@ static int erofs_fill_symlink(struct inode *inode, void *data,
>  static int erofs_fill_inode(struct inode *inode, int isdir)
>  {
>  	struct erofs_inode *vi = EROFS_I(inode);
> -	struct page *page;
> +	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
> +	void *kaddr;
>  	unsigned int ofs;
>  	int err = 0;
>  
>  	trace_erofs_fill_inode(inode, isdir);
>  
>  	/* read inode base data from disk */
> -	page = erofs_read_inode(inode, &ofs);
> -	if (IS_ERR(page))
> -		return PTR_ERR(page);
> +	kaddr = erofs_read_inode(&buf, inode, &ofs);
> +	if (IS_ERR(kaddr))
> +		return PTR_ERR(kaddr);
>  
>  	/* setup the new inode */
>  	switch (inode->i_mode & S_IFMT) {
> @@ -278,7 +275,7 @@ static int erofs_fill_inode(struct inode *inode, int isdir)
>  		inode->i_fop = &erofs_dir_fops;
>  		break;
>  	case S_IFLNK:
> -		err = erofs_fill_symlink(inode, page_address(page), ofs);
> +		err = erofs_fill_symlink(inode, kaddr, ofs);
>  		if (err)
>  			goto out_unlock;
>  		inode_nohighmem(inode);
> @@ -302,8 +299,7 @@ static int erofs_fill_inode(struct inode *inode, int isdir)
>  	inode->i_mapping->a_ops = &erofs_raw_access_aops;
>  
>  out_unlock:
> -	unlock_page(page);
> -	put_page(page);
> +	erofs_put_metabuf(&buf);
>  	return err;
>  }
>  
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 7053f1c4171d..f1e4eb3025f6 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -475,6 +475,9 @@ struct erofs_map_dev {
>  /* data.c */
>  extern const struct file_operations erofs_file_fops;
>  struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr);
> +void erofs_put_metabuf(struct erofs_buf *buf);
> +void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
> +			 erofs_blk_t blkaddr, enum erofs_kmap_type type);
>  int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *dev);
>  int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>  		 u64 start, u64 len);

Reviewed-by: Yue Hu <huyue2@yulong.com>