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Date: Wed, 18 Sep 2019 09:47:24 +0800 From: yangerkun <yangerkun@...wei.com> To: "Theodore Y. Ts'o" <tytso@....edu> CC: <jack@...e.cz>, <linux-ext4@...r.kernel.org>, <yi.zhang@...wei.com>, <houtao1@...wei.com> Subject: Re: [PATCH] ext4: fix a bug in ext4_wait_for_tail_page_commit On 2019/9/17 23:31, Theodore Y. Ts'o wrote: > On Tue, Sep 17, 2019 at 04:48:14PM +0800, yangerkun wrote: >> No need to wait when offset equals to 0. And it will trigger a bug since >> the latter __ext4_journalled_invalidatepage can free the buffers but leave >> page still dirty. > That's only true if the block size == the page size, no? If the > offset is zero and the block size is 1k, we still need to wait. > Shouldn't the better fix be: > >> - if (offset > PAGE_SIZE - i_blocksize(inode)) >> + if (offset >= PAGE_SIZE - i_blocksize(inode)) It can trigger free buffers in __ext4_journalled_invalidatepage(offset==0,blocksize=1k), and we will see the bug again. For some other case, like offset==3k blocksize=1k, actually we should wait the commit, but now we will return directly. Thanks. > - Ted > > . >
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