Re: [PATCH 1/3] staging: erofs: fix error handling when failed to read compresssed data

[Chao Yu <yuchao0@huawei.com>]

On 2019/3/22 11:25, Gao Xiang wrote:
> ping?
> 
> Hi Chao,
> could you take some time looking into this series?

Done, sorry for the delay.

Thanks,

> 
> Thanks,
> Gao Xiang
> 
> On 2019/3/19 21:54, Gao Xiang wrote:
>> Complete read error handling paths for all three kinds of
>> compressed pages:
>>
>>  1) For cache-managed pages, PG_uptodate will be checked since
>>     read_endio will unlock and SetPageUptodate for these pages;
>>
>>  2) For inplaced pages, read_endio cannot SetPageUptodate directly
>>     since it should be used to mark the final decompressed data,
>>     PG_error will be set with page locked for IO error instead;
>>
>>  3) For staging pages, PG_error is used, which is similar to
>>     what we do for inplaced pages.
>>
>> Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
>> Cc: <stable@vger.kernel.org> # 4.19+
>> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
>> ---
>>
>> This series focus on fixing error handling when failed to read
>> compresssed data due to previous incomplete paths.
>>
>> In addition, the last 2 patches add IO error fault injection
>> for reading paths, which I have used to test the first patch as well.
>>
>> Thanks,
>> Gao Xiang
>>
>>  drivers/staging/erofs/unzip_vle.c | 41 ++++++++++++++++++++++++++-------------
>>  1 file changed, 28 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
>> index 8715bc50e09c..3416d3f10324 100644
>> --- a/drivers/staging/erofs/unzip_vle.c
>> +++ b/drivers/staging/erofs/unzip_vle.c
>> @@ -972,6 +972,7 @@ static int z_erofs_vle_unzip(struct super_block *sb,
>>  	overlapped = false;
>>  	compressed_pages = grp->compressed_pages;
>>  
>> +	err = 0;
>>  	for (i = 0; i < clusterpages; ++i) {
>>  		unsigned int pagenr;
>>  
>> @@ -981,26 +982,39 @@ static int z_erofs_vle_unzip(struct super_block *sb,
>>  		DBG_BUGON(!page);
>>  		DBG_BUGON(!page->mapping);
>>  
>> -		if (z_erofs_is_stagingpage(page))
>> -			continue;
>> +		if (!z_erofs_is_stagingpage(page)) {
>>  #ifdef EROFS_FS_HAS_MANAGED_CACHE
>> -		if (page->mapping == MNGD_MAPPING(sbi)) {
>> -			DBG_BUGON(!PageUptodate(page));
>> -			continue;
>> -		}
>> +			if (page->mapping == MNGD_MAPPING(sbi)) {
>> +				if (unlikely(!PageUptodate(page)))
>> +					err = -EIO;
>> +				continue;
>> +			}
>>  #endif
>>  
>> -		/* only non-head page could be reused as a compressed page */
>> -		pagenr = z_erofs_onlinepage_index(page);
>> +			/*
>> +			 * only if non-head page can be selected
>> +			 * for inplace decompression
>> +			 */
>> +			pagenr = z_erofs_onlinepage_index(page);
>>  
>> -		DBG_BUGON(pagenr >= nr_pages);
>> -		DBG_BUGON(pages[pagenr]);
>> -		++sparsemem_pages;
>> -		pages[pagenr] = page;
>> +			DBG_BUGON(pagenr >= nr_pages);
>> +			DBG_BUGON(pages[pagenr]);
>> +			++sparsemem_pages;
>> +			pages[pagenr] = page;
>> +
>> +			overlapped = true;
>> +		}
>>  
>> -		overlapped = true;
>> +		/* PG_error needs checking for inplaced and staging pages */
>> +		if (unlikely(PageError(page))) {
>> +			DBG_BUGON(PageUptodate(page));
>> +			err = -EIO;
>> +		}
>>  	}
>>  
>> +	if (unlikely(err))
>> +		goto out;
>> +
>>  	llen = (nr_pages << PAGE_SHIFT) - work->pageofs;
>>  
>>  	if (z_erofs_vle_workgrp_fmt(grp) == Z_EROFS_VLE_WORKGRP_FMT_PLAIN) {
>> @@ -1194,6 +1208,7 @@ pickup_page_for_submission(struct z_erofs_vle_workgroup *grp,
>>  	if (page->mapping == mc) {
>>  		WRITE_ONCE(grp->compressed_pages[nr], page);
>>  
>> +		ClearPageError(page);
>>  		if (!PagePrivate(page)) {
>>  			/*
>>  			 * impossible to be !PagePrivate(page) for
>>
> .
>