staging: erofs: fix error handling when failed to read compresssed data

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: 3883a79a ("staging: erofs: introduce VLE decompression support")
Cc: <stable@vger.kernel.org> # 4.19+
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/unzip_vle.c

@@ -973,6 +973,7 @@ 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;
 
@@ -982,16 +983,19 @@ 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));
+				if (unlikely(!PageUptodate(page)))
+					err = -EIO;
 				continue;
 			}
 #endif
 
-		/* only non-head page could be reused as a compressed page */
+			/*
+			 * only if non-head page can be selected
+			 * for inplace decompression
+			 */
 			pagenr = z_erofs_onlinepage_index(page);
 
 			DBG_BUGON(pagenr >= nr_pages);
@@ -1002,6 +1006,16 @@ static int z_erofs_vle_unzip(struct super_block *sb,
 			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) {
@@ -1195,6 +1209,7 @@ 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