[PATCH 1/3] staging: erofs: fix error handling when failed to read compresssed data - Linux-stable-mirror

19 Mar 2019

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


    