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Date:   Mon, 8 Jun 2020 10:44:17 +0200
From:   Jan Kara <jack@...e.cz>
To:     "zhangyi (F)" <yi.zhang@...wei.com>
Cc:     linux-ext4@...r.kernel.org, jack@...e.cz
Subject: Re: [PATCH v3 1/2] ext2: propagate errors up to ext2_find_entry()'s
 callers

On Mon 08-06-20 11:40:42, zhangyi (F) wrote:
> The same to commit <36de928641ee4> (ext4: propagate errors up to
> ext4_find_entry()'s callers') in ext4, also return error instead of NULL
> pointer in case of some error happens in ext2_find_entry() (e.g. -ENOMEM
> or -EIO). This could avoid a negative dentry cache entry installed even
> it failed to read directory block due to IO error.
> 
> Signed-off-by: zhangyi (F) <yi.zhang@...wei.com>

Thanks for the patches! I've applied them both to my tree.

								Honza

> ---
> v1 -> v2:
>  - Remove ret parameter in ext2_find_entry().
> 
>  fs/ext2/dir.c   | 53 ++++++++++++++++++++++++-------------------------
>  fs/ext2/ext2.h  |  3 ++-
>  fs/ext2/namei.c | 32 +++++++++++++++++++++++------
>  3 files changed, 54 insertions(+), 34 deletions(-)
> 
> diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
> index 13318e255ebf..95e4f0bd55a3 100644
> --- a/fs/ext2/dir.c
> +++ b/fs/ext2/dir.c
> @@ -348,7 +348,6 @@ struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
>  	struct page *page = NULL;
>  	struct ext2_inode_info *ei = EXT2_I(dir);
>  	ext2_dirent * de;
> -	int dir_has_error = 0;
>  
>  	if (npages == 0)
>  		goto out;
> @@ -362,25 +361,25 @@ struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
>  	n = start;
>  	do {
>  		char *kaddr;
> -		page = ext2_get_page(dir, n, dir_has_error);
> -		if (!IS_ERR(page)) {
> -			kaddr = page_address(page);
> -			de = (ext2_dirent *) kaddr;
> -			kaddr += ext2_last_byte(dir, n) - reclen;
> -			while ((char *) de <= kaddr) {
> -				if (de->rec_len == 0) {
> -					ext2_error(dir->i_sb, __func__,
> -						"zero-length directory entry");
> -					ext2_put_page(page);
> -					goto out;
> -				}
> -				if (ext2_match (namelen, name, de))
> -					goto found;
> -				de = ext2_next_entry(de);
> +		page = ext2_get_page(dir, n, 0);
> +		if (IS_ERR(page))
> +			return ERR_CAST(page);
> +
> +		kaddr = page_address(page);
> +		de = (ext2_dirent *) kaddr;
> +		kaddr += ext2_last_byte(dir, n) - reclen;
> +		while ((char *) de <= kaddr) {
> +			if (de->rec_len == 0) {
> +				ext2_error(dir->i_sb, __func__,
> +					"zero-length directory entry");
> +				ext2_put_page(page);
> +				goto out;
>  			}
> -			ext2_put_page(page);
> -		} else
> -			dir_has_error = 1;
> +			if (ext2_match(namelen, name, de))
> +				goto found;
> +			de = ext2_next_entry(de);
> +		}
> +		ext2_put_page(page);
>  
>  		if (++n >= npages)
>  			n = 0;
> @@ -414,18 +413,18 @@ struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
>  	return de;
>  }
>  
> -ino_t ext2_inode_by_name(struct inode *dir, const struct qstr *child)
> +int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
>  {
> -	ino_t res = 0;
>  	struct ext2_dir_entry_2 *de;
>  	struct page *page;
>  	
> -	de = ext2_find_entry (dir, child, &page);
> -	if (de) {
> -		res = le32_to_cpu(de->inode);
> -		ext2_put_page(page);
> -	}
> -	return res;
> +	de = ext2_find_entry(dir, child, &page);
> +	if (IS_ERR_OR_NULL(de))
> +		return PTR_ERR(de);
> +
> +	*ino = le32_to_cpu(de->inode);
> +	ext2_put_page(page);
> +	return 0;
>  }
>  
>  static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
> diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
> index 8178bd38a9d6..a321ff9bf1b4 100644
> --- a/fs/ext2/ext2.h
> +++ b/fs/ext2/ext2.h
> @@ -738,7 +738,8 @@ extern void ext2_rsv_window_add(struct super_block *sb, struct ext2_reserve_wind
>  
>  /* dir.c */
>  extern int ext2_add_link (struct dentry *, struct inode *);
> -extern ino_t ext2_inode_by_name(struct inode *, const struct qstr *);
> +extern int ext2_inode_by_name(struct inode *dir,
> +			      const struct qstr *child, ino_t *ino);
>  extern int ext2_make_empty(struct inode *, struct inode *);
>  extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,const struct qstr *, struct page **);
>  extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);
> diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
> index ccfbbf59e2fc..4b38e558d477 100644
> --- a/fs/ext2/namei.c
> +++ b/fs/ext2/namei.c
> @@ -56,12 +56,15 @@ static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
>  static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
>  {
>  	struct inode * inode;
> -	ino_t ino;
> +	ino_t ino = 0;
> +	int res;
>  	
>  	if (dentry->d_name.len > EXT2_NAME_LEN)
>  		return ERR_PTR(-ENAMETOOLONG);
>  
> -	ino = ext2_inode_by_name(dir, &dentry->d_name);
> +	res = ext2_inode_by_name(dir, &dentry->d_name, &ino);
> +	if (res)
> +		return ERR_PTR(res);
>  	inode = NULL;
>  	if (ino) {
>  		inode = ext2_iget(dir->i_sb, ino);
> @@ -78,7 +81,12 @@ static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, uns
>  struct dentry *ext2_get_parent(struct dentry *child)
>  {
>  	struct qstr dotdot = QSTR_INIT("..", 2);
> -	unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
> +	ino_t ino = 0;
> +	int res;
> +
> +	res = ext2_inode_by_name(d_inode(child), &dotdot, &ino);
> +	if (res)
> +		return ERR_PTR(res);
>  	if (!ino)
>  		return ERR_PTR(-ENOENT);
>  	return d_obtain_alias(ext2_iget(child->d_sb, ino));
> @@ -276,7 +284,11 @@ static int ext2_unlink(struct inode * dir, struct dentry *dentry)
>  	if (err)
>  		goto out;
>  
> -	de = ext2_find_entry (dir, &dentry->d_name, &page);
> +	de = ext2_find_entry(dir, &dentry->d_name, &page);
> +	if (IS_ERR(de)) {
> +		err = PTR_ERR(de);
> +		goto out;
> +	}
>  	if (!de) {
>  		err = -ENOENT;
>  		goto out;
> @@ -332,7 +344,11 @@ static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
>  	if (err)
>  		goto out;
>  
> -	old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
> +	old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_page);
> +	if (IS_ERR(old_de)) {
> +		err = PTR_ERR(old_de);
> +		goto out;
> +	}
>  	if (!old_de) {
>  		err = -ENOENT;
>  		goto out;
> @@ -354,7 +370,11 @@ static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
>  			goto out_dir;
>  
>  		err = -ENOENT;
> -		new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
> +		new_de = ext2_find_entry(new_dir, &new_dentry->d_name, &new_page);
> +		if (IS_ERR(new_de)) {
> +			err = PTR_ERR(new_de);
> +			goto out_dir;
> +		}
>  		if (!new_de)
>  			goto out_dir;
>  		ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
> -- 
> 2.21.3
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR

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