linux-kernel - Re: [PATCH] iomap: Fix the write_count in iomap_add_to

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Message-ID: <20200821133150.GT17456@casper.infradead.org>
Date:   Fri, 21 Aug 2020 14:31:50 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Anju T Sudhakar <anju@...ux.vnet.ibm.com>
Cc:     hch@...radead.org, darrick.wong@...cle.com,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, riteshh@...ux.ibm.com
Subject: Re: [PATCH] iomap: Fix the write_count in iomap_add_to_ioend().

On Wed, Aug 19, 2020 at 03:58:41PM +0530, Anju T Sudhakar wrote:
> __bio_try_merge_page() may return same_page = 1 and merged = 0. 
> This could happen when bio->bi_iter.bi_size + len > UINT_MAX. 
> Handle this case in iomap_add_to_ioend() by incrementing write_count.

One of the patches I have pending ignores same_page by just using the
write_count as a byte count instead of a segment count.  It's currently
mixed into this patch but needs to be separated.

http://git.infradead.org/users/willy/pagecache.git/commitdiff/0186d1dde949a458584c56b706fa8dfd252466ff

(another patch does the same thing to the read count).