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([2620:10d:c092:600::1:c8e6]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5f36f5054cfsm9706295a12.55.2025.04.17.02.33.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Apr 2025 02:33:06 -0700 (PDT) Message-ID: Date: Thu, 17 Apr 2025 10:34:23 +0100 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/4] io_uring/rsrc: send exact nr_segs for fixed buffer To: io-uring@vger.kernel.org, Nitesh Shetty References: <7a1a49a8d053bd617c244291d63dbfbc07afde36.1744882081.git.asml.silence@gmail.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <7a1a49a8d053bd617c244291d63dbfbc07afde36.1744882081.git.asml.silence@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/17/25 10:32, Pavel Begunkov wrote: > From: Nitesh Shetty ... > diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c > index 5cf854318b1d..4099b8225670 100644 > --- a/io_uring/rsrc.c > +++ b/io_uring/rsrc.c > @@ -1037,6 +1037,7 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, > u64 buf_addr, size_t len) > { > const struct bio_vec *bvec; > + size_t folio_mask; > unsigned nr_segs; > size_t offset; > int ret; > @@ -1067,6 +1068,7 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, > * 2) all bvecs are the same in size, except potentially the > * first and last bvec > */ > + folio_mask = (1UL << imu->folio_shift) - 1; > bvec = imu->bvec; > if (offset >= bvec->bv_len) { > unsigned long seg_skip; > @@ -1075,10 +1077,10 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, > offset -= bvec->bv_len; > seg_skip = 1 + (offset >> imu->folio_shift); > bvec += seg_skip; > - offset &= (1UL << imu->folio_shift) - 1; > + offset &= folio_mask; > } > > - nr_segs = imu->nr_bvecs - (bvec - imu->bvec); > + nr_segs = (offset + len + folio_mask) >> imu->folio_shift; Nitesh, let me know if you're happy with this version. > iov_iter_bvec(iter, ddir, bvec, nr_segs, len); > iter->iov_offset = offset; > return 0; -- Pavel Begunkov