ext4: fix bug for rename with RENAME_WHITEOUT

ext4_rename will create a special inode for whiteout and use this 'ino'
to replace the source file's dir entry 'ino'. Once error happens
latter(small ext4 img, and consume all space, so the rename with dst
path not exist will fail due to the ENOSPC return from ext4_add_entry in
ext4_rename), the cleanup do drop the nlink for whiteout, but forget to
restore 'ino' with source file. This will lead to "deleted inode
referenced".

Signed-off-by: yangerkun <yangerkun@huawei.com>
---
 fs/ext4/namei.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

在 2020/12/29 16:56, yangerkun 写道:
> ext4_rename will create a special inode for whiteout and use this 'ino'
> to replace the source file's dir entry 'ino'. Once error happens
> latter(small ext4 img, and consume all space, so the rename with dst
> path not exist will fail due to the ENOSPC return from ext4_add_entry in
> ext4_rename), the cleanup do drop the nlink for whiteout, but forget to
> restore 'ino' with source file. This will lead to "deleted inode
> referenced".
> 
> Signed-off-by: yangerkun <yangerkun@huawei.com>
> ---
>   fs/ext4/namei.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index b17a082b7db1..0e89e5a0c758 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -3593,9 +3593,6 @@ static int ext4_setent(handle_t *handle, struct ext4_renament *ent,
>   			return retval2;
>   		}
>   	}
> -	brelse(ent->bh);
> -	ent->bh = NULL;
> -
>   	return retval;
>   }
>   
> @@ -3794,6 +3791,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
>   		}
>   	}
>   
> +	old_file_type = old.de->file_type;
>   	if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
>   		ext4_handle_sync(handle);
>   
> @@ -3821,7 +3819,6 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
>   	force_reread = (new.dir->i_ino == old.dir->i_ino &&
>   			ext4_test_inode_flag(new.dir, EXT4_INODE_INLINE_DATA));
>   
> -	old_file_type = old.de->file_type;
>   	if (whiteout) {
>   		/*
>   		 * Do this before adding a new entry, so the old entry is sure
> @@ -3919,15 +3916,18 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
>   	retval = 0;
>   
>   end_rename:
> -	brelse(old.dir_bh);
> -	brelse(old.bh);
> -	brelse(new.bh);
>   	if (whiteout) {
> +		ext4_setent(handle, &old,
> +			    old.inode->i_ino, old_file_type);
>   		if (retval)
>   			drop_nlink(whiteout);
>   		unlock_new_inode(whiteout);
>   		iput(whiteout);
> +

This is a mistake... Will send v2.

>   	}
> +	brelse(old.dir_bh);
> +	brelse(old.bh);
> +	brelse(new.bh);
>   	if (handle)
>   		ext4_journal_stop(handle);
>   	return retval;
>