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erofs: avoid useless loops in z_erofs_pcluster_readmore() when reading beyond EOF

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[ Upstream commit 936aa701d82d397c2d1afcd18ce2c739471d978d ]

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: 386292919c ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Chunhai Guo 2023-07-10 12:25:31 +08:00 committed by Greg Kroah-Hartman
parent 27272795a7
commit 83879f72e0
1 changed files with 1 additions and 1 deletions
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2
fs/erofs/zdata.c
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@ -1660,7 +1660,7 @@ 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;