From: Gao Xiang <hsiangkao@linux.alibaba.com>
Date: Fri, 8 Jul 2022 10:10:01 +0000 (+0800)
Subject: erofs: avoid consecutive detection for Highmem memory
X-Git-Tag: v5.15.73~1598
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1c350a597c2d617291d353ac40f505b396ac8365;p=platform%2Fkernel%2Flinux-rpi.git

erofs: avoid consecutive detection for Highmem memory

[ Upstream commit 448b5a1548d87c246c3d0c3df8480d3c6eb6c11a ]

Currently, vmap()s are avoided if physical addresses are
consecutive for decompressed buffers.

I observed that is very common for 4KiB pclusters since the
numbers of decompressed pages are almost 2 or 3.

However, such detection doesn't work for Highmem pages on
32-bit machines, let's fix it now.

Reported-by: Liu Jinbao <liujinbao1@xiaomi.com>
Fixes: 7fc45dbc938a ("staging: erofs: introduce generic decompression backend")
Link: https://lore.kernel.org/r/20220708101001.21242-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index ad3f313..8193c14 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -93,14 +93,18 @@ static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
 
 		if (page) {
 			__clear_bit(j, bounced);
-			if (kaddr) {
-				if (kaddr + PAGE_SIZE == page_address(page))
+			if (!PageHighMem(page)) {
+				if (!i) {
+					kaddr = page_address(page);
+					continue;
+				}
+				if (kaddr &&
+				    kaddr + PAGE_SIZE == page_address(page)) {
 					kaddr += PAGE_SIZE;
-				else
-					kaddr = NULL;
-			} else if (!i) {
-				kaddr = page_address(page);
+					continue;
+				}
 			}
+			kaddr = NULL;
 			continue;
 		}
 		kaddr = NULL;