FAILED: patch "[PATCH] staging: erofs: fix error handling when failed to read" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b6391ac73400eff38377a4a7364bd3df5efb5178 Mon Sep 17 00:00:00 2001
From: Gao Xiang <gaoxiang25@huawei.com>
Date: Mon, 25 Mar 2019 11:40:07 +0800
Subject: [PATCH] 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: 3883a79abd02 ("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>

diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index c7b3b21123c1..31eef8395774 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) {
@@ -1198,6 +1212,7 @@ 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