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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 17/29] iov_iter: Split iov_iter_revert() From: David Howells To: Pavel Begunkov , Matthew Wilcox , Jens Axboe , Alexander Viro Cc: dhowells@redhat.com, Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Date: Sat, 21 Nov 2020 14:15:34 +0000 Message-ID: <160596813488.154728.6654456287509529880.stgit@warthog.procyon.org.uk> In-Reply-To: <160596800145.154728.7192318545120181269.stgit@warthog.procyon.org.uk> References: <160596800145.154728.7192318545120181269.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Split iov_iter_revert() by type. Signed-off-by: David Howells --- lib/iov_iter.c | 132 ++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 79 insertions(+), 53 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 9859b4b8a116..b8e3da20547e 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1319,71 +1319,97 @@ static void discard_advance(struct iov_iter *i, size_t size) i->count -= size; } -static void xxx_revert(struct iov_iter *i, size_t unroll) +static void iovec_kvec_revert(struct iov_iter *i, size_t unroll) { + const struct iovec *iov = i->iov; if (!unroll) return; if (WARN_ON(unroll > MAX_RW_COUNT)) return; i->count += unroll; - if (unlikely(iov_iter_is_pipe(i))) { - struct pipe_inode_info *pipe = i->pipe; - unsigned int p_mask = pipe->ring_size - 1; - unsigned int i_head = i->head; - size_t off = i->iov_offset; - while (1) { - struct pipe_buffer *b = &pipe->bufs[i_head & p_mask]; - size_t n = off - b->offset; - if (unroll < n) { - off -= unroll; - break; - } - unroll -= n; - if (!unroll && i_head == i->start_head) { - off = 0; - break; - } - i_head--; - b = &pipe->bufs[i_head & p_mask]; - off = b->offset + b->len; - } - i->iov_offset = off; - i->head = i_head; - pipe_truncate(i); + if (unroll <= i->iov_offset) { + i->iov_offset -= unroll; return; } - if (unlikely(iov_iter_is_discard(i))) + unroll -= i->iov_offset; + while (1) { + size_t n = (--iov)->iov_len; + i->nr_segs++; + if (unroll <= n) { + i->iov = iov; + i->iov_offset = n - unroll; + return; + } + unroll -= n; + } +} + +static void bvec_revert(struct iov_iter *i, size_t unroll) +{ + const struct bio_vec *bvec = i->bvec; + + if (!unroll) return; + if (WARN_ON(unroll > MAX_RW_COUNT)) + return; + i->count += unroll; if (unroll <= i->iov_offset) { i->iov_offset -= unroll; return; } unroll -= i->iov_offset; - if (iov_iter_is_bvec(i)) { - const struct bio_vec *bvec = i->bvec; - while (1) { - size_t n = (--bvec)->bv_len; - i->nr_segs++; - if (unroll <= n) { - i->bvec = bvec; - i->iov_offset = n - unroll; - return; - } - unroll -= n; + while (1) { + size_t n = (--bvec)->bv_len; + i->nr_segs++; + if (unroll <= n) { + i->bvec = bvec; + i->iov_offset = n - unroll; + return; } - } else { /* same logics for iovec and kvec */ - const struct iovec *iov = i->iov; - while (1) { - size_t n = (--iov)->iov_len; - i->nr_segs++; - if (unroll <= n) { - i->iov = iov; - i->iov_offset = n - unroll; - return; - } - unroll -= n; + unroll -= n; + } +} + +static void pipe_revert(struct iov_iter *i, size_t unroll) +{ + struct pipe_inode_info *pipe = i->pipe; + unsigned int p_mask = pipe->ring_size - 1; + unsigned int i_head = i->head; + size_t off = i->iov_offset; + + if (!unroll) + return; + if (WARN_ON(unroll > MAX_RW_COUNT)) + return; + + while (1) { + struct pipe_buffer *b = &pipe->bufs[i_head & p_mask]; + size_t n = off - b->offset; + if (unroll < n) { + off -= unroll; + break; + } + unroll -= n; + if (!unroll && i_head == i->start_head) { + off = 0; + break; } + i_head--; + b = &pipe->bufs[i_head & p_mask]; + off = b->offset + b->len; } + i->iov_offset = off; + i->head = i_head; + pipe_truncate(i); +} + +static void discard_revert(struct iov_iter *i, size_t unroll) +{ + if (!unroll) + return; + if (WARN_ON(unroll > MAX_RW_COUNT)) + return; + i->count += unroll; } /* @@ -2082,7 +2108,7 @@ static const struct iov_iter_ops iovec_iter_ops = { .type = ITER_IOVEC, .copy_from_user_atomic = iovec_copy_from_user_atomic, .advance = iovec_advance, - .revert = xxx_revert, + .revert = iovec_kvec_revert, .fault_in_readable = iovec_fault_in_readable, .single_seg_count = xxx_single_seg_count, .copy_page_to_iter = iovec_copy_page_to_iter, @@ -2116,7 +2142,7 @@ static const struct iov_iter_ops kvec_iter_ops = { .type = ITER_KVEC, .copy_from_user_atomic = kvec_copy_from_user_atomic, .advance = kvec_advance, - .revert = xxx_revert, + .revert = iovec_kvec_revert, .fault_in_readable = no_fault_in_readable, .single_seg_count = xxx_single_seg_count, .copy_page_to_iter = bkvec_copy_page_to_iter, @@ -2150,7 +2176,7 @@ static const struct iov_iter_ops bvec_iter_ops = { .type = ITER_BVEC, .copy_from_user_atomic = bvec_copy_from_user_atomic, .advance = bvec_iov_advance, - .revert = xxx_revert, + .revert = bvec_revert, .fault_in_readable = no_fault_in_readable, .single_seg_count = xxx_single_seg_count, .copy_page_to_iter = bkvec_copy_page_to_iter, @@ -2184,7 +2210,7 @@ static const struct iov_iter_ops pipe_iter_ops = { .type = ITER_PIPE, .copy_from_user_atomic = no_copy_from_user_atomic, .advance = pipe_advance, - .revert = xxx_revert, + .revert = pipe_revert, .fault_in_readable = no_fault_in_readable, .single_seg_count = xxx_single_seg_count, .copy_page_to_iter = pipe_copy_page_to_iter, @@ -2218,7 +2244,7 @@ static const struct iov_iter_ops discard_iter_ops = { .type = ITER_DISCARD, .copy_from_user_atomic = no_copy_from_user_atomic, .advance = discard_advance, - .revert = xxx_revert, + .revert = discard_revert, .fault_in_readable = no_fault_in_readable, .single_seg_count = xxx_single_seg_count, .copy_page_to_iter = discard_copy_page_to_iter,