linux-kernel - Re: [PATCH] zram: take device and not only bvec offset into account

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Date:   Sat, 5 Aug 2023 16:46:45 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Christoph Hellwig <hch@....de>
Cc:     minchan@...nel.org, senozhatsky@...omium.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dusty Mabe <dusty@...tymabe.com>
Subject: Re: [PATCH] zram: take device and not only bvec offset into account

On (23/08/05 07:55), Christoph Hellwig wrote:
> Commit af8b04c63708 ("zram: simplify bvec iteration in
> __zram_make_request") changed the bio iteration in zram to rely on the
> implicit capping to page boundaries in bio_for_each_segment.  But it
> failed to care for the fact zram not only care about the page alignment
> of the bio payload, but also the page alignment into the device.  For
> buffered I/O and swap those are the same, but for direct I/O or kernel
> internal I/O like XFS log buffer writes they can differ.
> 
> Fix this by open coding bio_for_each_segment and limiting the bvec len
> so that it never crosses over a page alignment boundary in the device
> in addition to the payload boundary already taken care of by
> bio_iter_iovec.
> 
> Fixes: af8b04c63708 ("zram: simplify bvec iteration in __zram_make_request")
> Reported-by: Dusty Mabe <dusty@...tymabe.com>
> Signed-off-by: Christoph Hellwig <hch@....de>

Acked-by: Sergey Senozhatsky <senozhatsky@...omium.org>