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authorPavel Begunkov <asml.silence@gmail.com>2022-06-20 01:25:59 +0100
committerJens Axboe <axboe@kernel.dk>2022-07-24 18:39:15 -0600
commitc059f785840807ed5e1f2810420c1555969b6246 (patch)
tree00096dfd3084ad7fe1f5072e08ceaea12e1d684d /io_uring/rsrc.c
parentf337a84d39527a2c46b1230470748d7bd0672ce0 (diff)
io_uring: move io_import_fixed()
Move io_import_fixed() into rsrc.c where it belongs. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/4d5becb21f332b4fef6a7cedd6a50e65e2371630.1655684496.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring/rsrc.c')
-rw-r--r--io_uring/rsrc.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 68629eba4132..110608955159 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1310,3 +1310,63 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
io_rsrc_node_switch(ctx, NULL);
return ret;
}
+
+int io_import_fixed(int ddir, struct iov_iter *iter,
+ struct io_mapped_ubuf *imu,
+ u64 buf_addr, size_t len)
+{
+ u64 buf_end;
+ size_t offset;
+
+ if (WARN_ON_ONCE(!imu))
+ return -EFAULT;
+ if (unlikely(check_add_overflow(buf_addr, (u64)len, &buf_end)))
+ return -EFAULT;
+ /* not inside the mapped region */
+ if (unlikely(buf_addr < imu->ubuf || buf_end > imu->ubuf_end))
+ return -EFAULT;
+
+ /*
+ * May not be a start of buffer, set size appropriately
+ * and advance us to the beginning.
+ */
+ offset = buf_addr - imu->ubuf;
+ iov_iter_bvec(iter, ddir, imu->bvec, imu->nr_bvecs, offset + len);
+
+ if (offset) {
+ /*
+ * Don't use iov_iter_advance() here, as it's really slow for
+ * using the latter parts of a big fixed buffer - it iterates
+ * over each segment manually. We can cheat a bit here, because
+ * we know that:
+ *
+ * 1) it's a BVEC iter, we set it up
+ * 2) all bvecs are PAGE_SIZE in size, except potentially the
+ * first and last bvec
+ *
+ * So just find our index, and adjust the iterator afterwards.
+ * If the offset is within the first bvec (or the whole first
+ * bvec, just use iov_iter_advance(). This makes it easier
+ * since we can just skip the first segment, which may not
+ * be PAGE_SIZE aligned.
+ */
+ const struct bio_vec *bvec = imu->bvec;
+
+ if (offset <= bvec->bv_len) {
+ iov_iter_advance(iter, offset);
+ } else {
+ unsigned long seg_skip;
+
+ /* skip first vec */
+ offset -= bvec->bv_len;
+ seg_skip = 1 + (offset >> PAGE_SHIFT);
+
+ iter->bvec = bvec + seg_skip;
+ iter->nr_segs -= seg_skip;
+ iter->count -= bvec->bv_len + offset;
+ iter->iov_offset = offset & ~PAGE_MASK;
+ }
+ }
+
+ return 0;
+}