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

Hi Chao,
could you take some time looking into this series?

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
>

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