From: Nicholas Bellinger <n...@linux-iscsi.org>
This patch adds ANY_LAYOUT prerequisites logic for accepting a set of
protection + data payloads via iovec + offset. Also includes helpers
for calcuating SGLs + invoking vhost_scsi_map_to_sgl() with a known
number of iovecs.
Required by ANY_LAYOUT processing when struct iovec may be offset into
the first outgoing virtio-scsi request header.
v2 changes:
- Clear ->tvc_sgl_count for vhost_scsi_mapal failure
- Make vhost_scsi_mapal + vhost_scsi_calc_sgls accept max_niov
- Minor cleanups
Cc: Michael S. Tsirkin <m...@redhat.com>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Nicholas Bellinger <n...@linux-iscsi.org>
---
drivers/vhost/scsi.c | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 115 insertions(+)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 049e603..ecbd567 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -909,6 +909,121 @@ vhost_scsi_map_iov_to_prot(struct tcm_vhost_cmd *cmd,
return 0;
}
+static int
+vhost_scsi_calc_sgls(struct iovec *iov, size_t off, size_t bytes,
+ int *niov, int max_niov, int max_sgls)
+{
+ size_t tmp = 0;
+ int sgl_count = 0;
+
+ *niov = 0;
+
+ while (tmp < bytes) {
+ void __user *base = iov[*niov].iov_base + off;
+ size_t len = iov[(*niov)++].iov_len - off;
+
+ if (*niov > max_niov) {
+ pr_err("%s: current *niov %d exceeds max_niov: %d\n",
+ __func__, *niov, max_niov);
+ return -EINVAL;
+ }
+ sgl_count += iov_num_pages(base, len);
+ tmp += min(len, bytes);
+ off = 0;
+ }
+ if (sgl_count > max_sgls) {
+ pr_err("%s: requested sgl_count: %d exceeds pre-allocated"
+ " max_sgls: %d\n", __func__, sgl_count, max_sgls);
+ return -ENOBUFS;
+ }
+ return sgl_count;
+}
+
+static int
+vhost_scsi_iov_to_sgl(struct tcm_vhost_cmd *cmd, bool write,
+ struct iovec *iov, size_t iov_off, int niov,
+ struct scatterlist *sg, int sg_count)
+{
+ int i, ret;
+
+ for (i = 0; i < niov; i++) {
+ void __user *base = iov[i].iov_base + iov_off;
+ size_t len = iov[i].iov_len - iov_off;
+
+ ret = vhost_scsi_map_to_sgl(cmd, base, len, sg, write);
+ if (ret < 0) {
+ for (i = 0; i < sg_count; i++) {
+ struct page *page = sg_page(&sg[i]);
+ if (page)
+ put_page(page);
+ }
+ return ret;
+ }
+ sg += ret;
+ iov_off = 0;
+ }
+ return 0;
+}
+
+static int
+vhost_scsi_mapal(struct tcm_vhost_cmd *cmd, int max_niov,
+ size_t prot_bytes, struct iovec *prot_iov, size_t prot_off,
+ size_t data_bytes, struct iovec *data_iov, size_t data_off)
+{
+ int sgl_count = 0, niov, ret;
+ bool write = (cmd->tvc_data_direction == DMA_FROM_DEVICE);
+
+ if (prot_bytes) {
+ if (!prot_iov) {
+ pr_err("%s: prot_iov is NULL, but prot_bytes: %zu"
+ "present\n", __func__, prot_bytes);
+ return -EINVAL;
+ }
+ sgl_count = vhost_scsi_calc_sgls(prot_iov, prot_off, prot_bytes,
+ &niov, max_niov,
+ TCM_VHOST_PREALLOC_PROT_SGLS);
+ if (sgl_count < 0)
+ return sgl_count;
+
+ sg_init_table(cmd->tvc_prot_sgl, sgl_count);
+ cmd->tvc_prot_sgl_count = sgl_count;
+ pr_debug("%s prot_sg %p prot_sgl_count %u\n", __func__,
+ cmd->tvc_prot_sgl, cmd->tvc_prot_sgl_count);
+
+ ret = vhost_scsi_iov_to_sgl(cmd, write, prot_iov, prot_off,
+ niov, cmd->tvc_prot_sgl,
+ cmd->tvc_prot_sgl_count);
+ if (ret < 0) {
+ cmd->tvc_prot_sgl_count = 0;
+ return ret;
+ }
+ max_niov -= niov;
+ }
+ if (!data_iov) {
+ pr_err("%s: data_iov is NULL, but data_bytes: %zu present\n",
+ __func__, data_bytes);
+ return -EINVAL;
+ }
+ sgl_count = vhost_scsi_calc_sgls(data_iov, data_off, data_bytes,
+ &niov, max_niov,
+ TCM_VHOST_PREALLOC_SGLS);
+ if (sgl_count < 0)
+ return sgl_count;
+
+ sg_init_table(cmd->tvc_sgl, sgl_count);
+ cmd->tvc_sgl_count = sgl_count;
+ pr_debug("%s data_sg %p data_sgl_count %u\n", __func__,
+ cmd->tvc_sgl, cmd->tvc_sgl_count);
+
+ ret = vhost_scsi_iov_to_sgl(cmd, write, data_iov, data_off, niov,
+ cmd->tvc_sgl, cmd->tvc_sgl_count);
+ if (ret < 0) {
+ cmd->tvc_sgl_count = 0;
+ return ret;
+ }
+ return 0;
+}
+
static void tcm_vhost_submission_work(struct work_struct *work)
{
struct tcm_vhost_cmd *cmd =
--
1.9.1
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