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Subject[PATCH 1/3] staging: erofs: fix error handling when failed to read compresssed data
Date
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
--
2.12.2
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