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

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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>
(cherry picked from commit 936aa701d82d397c2d1afcd18ce2c739471d978d
    https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git dev)
Bug: 296824280

Change-Id: I279b0fadcfa8c0ff0d638a86c7bb2c6b4d07f194
Signed-off-by: sunshijie <sunshijie@xiaomi.corp-partner.google.com>
Signed-off-by: sunshijie <sunshijie@xiaomi.com>
This commit is contained in:
sunshijie 2023-08-21 21:00:15 +08:00 committed by Sandeep Dhavale
parent 2f805fb912
commit 8497f46a87
1 changed files with 1 additions and 1 deletions
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2
fs/erofs/zdata.c
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@ -1691,7 +1691,7 @@ 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;