From: Jan Kara <jack@suse.cz>
To: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] Possible fs corruption when hole punch races with other ops
Date: Wed, 21 Apr 2021 18:29:53 +0200 [thread overview]
Message-ID: <20210421162953.GA13863@quack2.suse.cz> (raw)
Hello,
I'm unifying protection various filesystems use to protect hole punch
operations from racing with other operations (like readahead, page fault,
writepage etc.). I was looking into OCFS2 and I think it is prone to a
following race which can possibly lead to filesystem corruption. But maybe
I miss something so that's why I'm writing here. The scenario I'm concerned
about is:
CPU1 CPU2
ocfs2_remove_inode_range() ocfs2_writepage()
... block_write_full_page()
ocfs2_remove_btree_range() ocfs2_extent_map_get_blocks()
Now ocfs2_extent_map_get_blocks() runs without protection of ip_alloc_sem
AFAICT and so both these operations can be modifying extent map at the same
time? What am I missing?
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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next reply other threads:[~2021-04-21 16:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 16:29 Jan Kara [this message]
2021-04-22 3:22 ` [Ocfs2-devel] Possible fs corruption when hole punch races with other ops Joseph Qi
2021-04-22 10:44 ` Jan Kara
2021-04-22 15:56 ` Wengang Wang
2021-04-22 16:06 ` Darrick J. Wong
2021-04-22 16:36 ` Wengang Wang
2021-04-22 16:46 ` Darrick J. Wong
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