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

From: Chao Yu
Date: Sun Mar 24 2019 - 22:04:45 EST


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@xxxxxxxxxxxxxxx> # 4.19+
>> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
>> ---
>>
>> 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
>>
> .
>