Re: [PATCH 3/8] staging: erofs: add error handling for xattr submodule

[Chao Yu]

Hi Xiang,

On 2018/8/13 10:36, Gao Xiang wrote:
> Hi Chao,
> 
> On 2018/8/13 10:00, Chao Yu wrote:
>> On 2018/8/12 22:01, Chao Yu wrote:
>>> From: Gao Xiang <gaoxiang25@xxxxxxxxxx>
>>>
>>> This patch enhances the missing error handling code for
>>> xattr submodule, which improves the stability for the rare cases.
>>>
>>> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
>>> Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
>>> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
>>> ---
>>>  drivers/staging/erofs/internal.h |   6 +-
>>>  drivers/staging/erofs/xattr.c    | 120 ++++++++++++++++++++-----------
>>>  2 files changed, 83 insertions(+), 43 deletions(-)
>>>
>>> diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
>>> index a756abeff7e9..8951e01216e3 100644
>>> --- a/drivers/staging/erofs/internal.h
>>> +++ b/drivers/staging/erofs/internal.h
>>> @@ -485,10 +485,10 @@ struct erofs_map_blocks_iter {
>>>  
>>>  
>>>  static inline struct page *
>>> -erofs_get_inline_page_nofail(struct inode *inode,
>>> -			     erofs_blk_t blkaddr)
>>> +erofs_get_inline_page(struct inode *inode,
>>> +		      erofs_blk_t blkaddr)
>>>  {
>>> -	return erofs_get_meta_page_nofail(inode->i_sb,
>>> +	return erofs_get_meta_page(inode->i_sb,
>>>  		blkaddr, S_ISDIR(inode->i_mode));
>>>  }
>>>  
>>> diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
>>> index 2593c856b079..1b5815fc70db 100644
>>> --- a/drivers/staging/erofs/xattr.c
>>> +++ b/drivers/staging/erofs/xattr.c
>>> @@ -24,16 +24,25 @@ struct xattr_iter {
>>>  
>>>  static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
>>>  {
>>> -	/* only init_inode_xattrs use non-atomic once */
>>> +	/* the only user of kunmap() is 'init_inode_xattrs' */
>>>  	if (unlikely(!atomic))
>>>  		kunmap(it->page);
>>>  	else
>>>  		kunmap_atomic(it->kaddr);
>>> +
>>>  	unlock_page(it->page);
>>>  	put_page(it->page);
>>>  }
>>>  
>>> -static void init_inode_xattrs(struct inode *inode)
>>> +static inline void xattr_iter_end_final(struct xattr_iter *it)
>>> +{
>>> +	if (unlikely(it->page == NULL))
>>> +		return;
>>> +
>>> +	xattr_iter_end(it, true);
>>> +}
>>> +
>>> +static int init_inode_xattrs(struct inode *inode)
>>>  {
>>>  	struct xattr_iter it;
>>>  	unsigned i;
>>> @@ -44,7 +53,7 @@ static void init_inode_xattrs(struct inode *inode)
>>>  	bool atomic_map;
>>>  
>>>  	if (likely(inode_has_inited_xattr(inode)))
>>> -		return;
>>> +		return 0;
>>>  
>>>  	vi = EROFS_V(inode);
>>>  	BUG_ON(!vi->xattr_isize);
>>> @@ -54,8 +63,9 @@ static void init_inode_xattrs(struct inode *inode)
>>>  	it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
>>>  	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
>>>  
>>> -	it.page = erofs_get_inline_page_nofail(inode, it.blkaddr);
>>> -	BUG_ON(IS_ERR(it.page));
>>> +	it.page = erofs_get_inline_page(inode, it.blkaddr);
>>> +	if (IS_ERR(it.page))
>>> +		return PTR_ERR(it.page);
>>>  
>>>  	/* read in shared xattr array (non-atomic, see kmalloc below) */
>>>  	it.kaddr = kmap(it.page);
>>> @@ -64,9 +74,12 @@ static void init_inode_xattrs(struct inode *inode)
>>>  	ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
>>>  
>>>  	vi->xattr_shared_count = ih->h_shared_count;
>>> -	vi->xattr_shared_xattrs = (unsigned *)kmalloc_array(
>>> -		vi->xattr_shared_count, sizeof(unsigned),
>>> -		GFP_KERNEL | __GFP_NOFAIL);
>>> +	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
>>> +						sizeof(unsigned), GFP_KERNEL);
>>> +	if (unlikely(vi->xattr_shared_xattrs == NULL)) {
>>> +		xattr_iter_end(&it, atomic_map);
>>> +		return -ENOMEM;
>>> +	}
>>>  
>>>  	/* let's skip ibody header */
>>>  	it.ofs += sizeof(struct erofs_xattr_ibody_header);
>>> @@ -77,9 +90,10 @@ static void init_inode_xattrs(struct inode *inode)
>>>  			BUG_ON(it.ofs != EROFS_BLKSIZ);
>>>  			xattr_iter_end(&it, atomic_map);
>>>  
>>> -			it.page = erofs_get_meta_page_nofail(sb,
>>> +			it.page = erofs_get_meta_page(sb,
>>>  				++it.blkaddr, S_ISDIR(inode->i_mode));
>>> -			BUG_ON(IS_ERR(it.page));
>>> +			if (IS_ERR(it.page))
>>> +				return PTR_ERR(it.page);
>>>  
>>>  			it.kaddr = kmap_atomic(it.page);
>>>  			atomic_map = true;
>>> @@ -92,6 +106,7 @@ static void init_inode_xattrs(struct inode *inode)
>>>  	xattr_iter_end(&it, atomic_map);
>>>  
>>>  	inode_set_inited_xattr(inode);
>>> +	return 0;
>>>  }
>>>  
>>>  struct xattr_iter_handlers {
>>> @@ -101,19 +116,24 @@ struct xattr_iter_handlers {
>>>  	void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
>>>  };
>>>  
>>> -static void xattr_iter_fixup(struct xattr_iter *it)
>>> +static inline int xattr_iter_fixup(struct xattr_iter *it)
>>>  {
>>> -	if (unlikely(it->ofs >= EROFS_BLKSIZ)) {
>>> -		xattr_iter_end(it, true);
>>> +	if (likely(it->ofs < EROFS_BLKSIZ))
>>> +		return 0;
>>>  
>>> -		it->blkaddr += erofs_blknr(it->ofs);
>>> -		it->page = erofs_get_meta_page_nofail(it->sb,
>>> -			it->blkaddr, false);
>>> -		BUG_ON(IS_ERR(it->page));
>>> +	xattr_iter_end(it, true);
>>>  
>>> -		it->kaddr = kmap_atomic(it->page);
>>> -		it->ofs = erofs_blkoff(it->ofs);
>>> +	it->blkaddr += erofs_blknr(it->ofs);
>>> +
>>> +	it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
>>> +	if (IS_ERR(it->page)) {
>>> +		it->page = NULL;
>>> +		return PTR_ERR(it->page);
>> As LKP reported, we need to fix this as below:
>>
>> err = PTR_ERR(it->page);
>> it->page = NULL;
>> return err;
>>
>> Thanks,
>>
> 
> I have seen this at
> https://lists.01.org/pipermail/kbuild-all/2018-August/051187.html
> 
> I will fix it soon. Thanks for report.

I checked v2 patch, it looks good to me now. I will send v2 patchset later.

Thanks,

> 
> Thanks,
> Gao Xiang
> 
> .
>