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

JIRA: https://issues.redhat.com/browse/RHEL-31991
Upstream status: Linus

commit 936aa701d82d397c2d1afcd18ce2c739471d978d
Author: Chunhai Guo <guochunhai@vivo.com>
Date:   Mon Jul 10 12:25:31 2023 +0800

    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>

Signed-off-by: Ian Kent <ikent@redhat.com>
This commit is contained in:
Ian Kent 2024-12-21 06:22:29 +08:00
parent 34bcbb75c4
commit da004034d7
1 changed files with 1 additions and 1 deletions
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2
fs/erofs/zdata.c
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@ -1805,7 +1805,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
} }
cur = map->m_la + map->m_llen - 1; 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; pgoff_t index = cur >> PAGE_SHIFT;
struct page *page; struct page *page;