From 936aa701d82d397c2d1afcd18ce2c739471d978d Mon Sep 17 00:00:00 2001
From: Chunhai Guo <guochunhai@vivo.com>
Date: Mon, 10 Jul 2023 12:25:31 +0800
Subject: [PATCH] erofs: avoid useless loops in z_erofs_pcluster_readmore()
when reading beyond EOF
z_erofs_pcluster_readmore() may take a long time to loop when the page
offset is large enough, which is unnecessary should be prevented.
For example, when the following case is encountered, it will loop 4691368
times, taking about 27 seconds:
- offset = 19217289215
- inode_size = 1442672
Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Fixes: 386292919c25 ("erofs: introduce readmore decompression strategy")
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230710042531.28761-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
fs/erofs/zdata.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 5f1890e309c6e..d9a0763f45957 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1841,7 +1841,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
}
cur = map->m_la + map->m_llen - 1;
- while (cur >= end) {
+ while ((cur >= end) && (cur < i_size_read(inode))) {
pgoff_t index = cur >> PAGE_SHIFT;
struct page *page;
--
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