linux-kernel - Re: [PATCH] io_uring: fix manual setup of iov

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Message-ID: <ab327769-f18d-61d4-1c71-fb7ad60bb53d@kernel.dk>
Date:   Thu, 15 Aug 2019 11:22:09 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Aleix Roca Nonell <aleix.rocanonell@....es>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] io_uring: fix manual setup of iov_iter for fixed buffers

On 8/15/19 6:03 AM, Aleix Roca Nonell wrote:
> Commit bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed
> buffers") introduced an optimization to avoid using the slow
> iov_iter_advance by manually populating the iov_iter iterator in some
> cases.
> 
> However, the computation of the iterator count field was erroneous: The
> first bvec was always accounted for an extent of page size even if the
> bvec length was smaller.
> 
> In consequence, some I/O operations on fixed buffers were unable to
> operate on the full extent of the buffer, consistently skipping some
> bytes at the end of it.

Applied, thanks.

-- 
Jens Axboe