From: Andrew Morton <akpm@linux-foundation.org>
To: Jan Kara <jack@suse.cz>
Cc: <linux-fsdevel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH] fs: gracefully handle ->get_block not mapping bh in __mpage_writepage
Date: Thu, 26 Jan 2023 11:54:55 -0800 [thread overview]
Message-ID: <20230126115455.296681b67273410e729309b0@linux-foundation.org> (raw)
In-Reply-To: <20230126085155.26395-1-jack@suse.cz>
On Thu, 26 Jan 2023 09:51:55 +0100 Jan Kara <jack@suse.cz> wrote:
> When filesystem's ->get_block function does not map the buffer head when
> called from __mpage_writepage(), the function will happily go and pass
"the function" being __mpage_writepage(), not ->get_block()...
> bogus bdev and block number to bio allocation routines which leads to
> crashes sooner or later.
Crashes are unwelcome. How is this bug triggered? Should we backport
the fix? I assume this is a longstanding thing and that any Fixes:
target would be ancient? If ancient, why did it take so long to
discover?
> E.g. UDF can do this because it doesn't want to
> allocate blocks from ->writepages callbacks. It allocates blocks on
> write or page fault but writeback can still spot dirty buffers without
> underlying blocks allocated e.g. if blocksize < pagesize, the tail page
> is dirtied (which means all its buffers are dirtied), and truncate
> extends the file so that some buffer starts to be within i_size.
>
> ...
next prev parent reply other threads:[~2023-01-26 19:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-26 8:51 [PATCH] fs: gracefully handle ->get_block not mapping bh in __mpage_writepage Jan Kara
2023-01-26 15:15 ` Christoph Hellwig
2023-01-26 19:54 ` Andrew Morton [this message]
2023-01-27 13:32 ` Jan Kara
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