vhost/scsi: Move sanity check into vhost_scsi_map_iov_to_sgl

Move the overflow check for sgl_count > TCM_VHOST_PREALLOC_SGLS into
vhost_scsi_map_iov_to_sgl() so that it's based on the total number
of SGLs for all IOVs, instead of single IOVs.

Also, rename TCM_VHOST_PREALLOC_PAGES -> TCM_VHOST_PREALLOC_UPAGES
to better describe pointers to user-space pages.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 25 insertions, 34 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index cf50ce93975b..ae434db2d384 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -57,7 +57,7 @@
 #define TCM_VHOST_MAX_CDB_SIZE 32
 #define TCM_VHOST_DEFAULT_TAGS 256
 #define TCM_VHOST_PREALLOC_SGLS 2048
-#define TCM_VHOST_PREALLOC_PAGES 2048
+#define TCM_VHOST_PREALLOC_UPAGES 2048
 
 struct vhost_scsi_inflight {
         /* Wait for the flush operation to finish */
@@ -767,35 +767,28 @@ vhost_scsi_map_to_sgl(struct tcm_vhost_cmd *tv_cmd,
                       struct scatterlist *sgl,
                       unsigned int sgl_count,
                       struct iovec *iov,
-                      int write)
+                      struct page **pages,
+                      bool write)
 {
         unsigned int npages = 0, pages_nr, offset, nbytes;
         struct scatterlist *sg = sgl;
         void __user *ptr = iov->iov_base;
         size_t len = iov->iov_len;
-        struct page **pages;
         int ret, i;
 
-        if (sgl_count > TCM_VHOST_PREALLOC_SGLS) {
-                pr_err("vhost_scsi_map_to_sgl() psgl_count: %u greater than"
-                       " preallocated TCM_VHOST_PREALLOC_SGLS: %u\n",
-                        sgl_count, TCM_VHOST_PREALLOC_SGLS);
-                return -ENOBUFS;
-        }
-
         pages_nr = iov_num_pages(iov);
-        if (pages_nr > sgl_count)
+        if (pages_nr > sgl_count) {
+                pr_err("vhost_scsi_map_to_sgl() pages_nr: %u greater than"
+                       " sgl_count: %u\n", pages_nr, sgl_count);
                 return -ENOBUFS;
-
-        if (pages_nr > TCM_VHOST_PREALLOC_PAGES) {
+        }
+        if (pages_nr > TCM_VHOST_PREALLOC_UPAGES) {
                 pr_err("vhost_scsi_map_to_sgl() pages_nr: %u greater than"
-                       " preallocated TCM_VHOST_PREALLOC_PAGES: %u\n",
-                        pages_nr, TCM_VHOST_PREALLOC_PAGES);
+                       " preallocated TCM_VHOST_PREALLOC_UPAGES: %u\n",
+                        pages_nr, TCM_VHOST_PREALLOC_UPAGES);
                 return -ENOBUFS;
         }
 
-        pages = tv_cmd->tvc_upages;
-
         ret = get_user_pages_fast((unsigned long)ptr, pages_nr, write, pages);
         /* No pages were pinned */
         if (ret < 0)
@@ -825,33 +818,32 @@ out:
 static int
 vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *cmd,
                           struct iovec *iov,
-                          unsigned int niov,
-                          int write)
+                          int niov,
+                          bool write)
 {
-        int ret;
-        unsigned int i;
-        u32 sgl_count;
-        struct scatterlist *sg;
+        struct scatterlist *sg = cmd->tvc_sgl;
+        unsigned int sgl_count = 0;
+        int ret, i;
 
-        /*
-         * Find out how long sglist needs to be
-         */
-        sgl_count = 0;
         for (i = 0; i < niov; i++)
                 sgl_count += iov_num_pages(&iov[i]);
 
-        /* TODO overflow checking */
+        if (sgl_count > TCM_VHOST_PREALLOC_SGLS) {
+                pr_err("vhost_scsi_map_iov_to_sgl() sgl_count: %u greater than"
+                        " preallocated TCM_VHOST_PREALLOC_SGLS: %u\n",
+                        sgl_count, TCM_VHOST_PREALLOC_SGLS);
+                return -ENOBUFS;
+        }
 
-        sg = cmd->tvc_sgl;
         pr_debug("%s sg %p sgl_count %u\n", __func__, sg, sgl_count);
         sg_init_table(sg, sgl_count);
-
         cmd->tvc_sgl_count = sgl_count;
 
-        pr_debug("Mapping %u iovecs for %u pages\n", niov, sgl_count);
+        pr_debug("Mapping iovec %p for %u pages\n", &iov[0], sgl_count);
+
         for (i = 0; i < niov; i++) {
                 ret = vhost_scsi_map_to_sgl(cmd, sg, sgl_count, &iov[i],
-                                            write);
+                                            cmd->tvc_upages, write);
                 if (ret < 0) {
                         for (i = 0; i < cmd->tvc_sgl_count; i++)
                                 put_page(sg_page(&cmd->tvc_sgl[i]));
@@ -859,7 +851,6 @@ vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *cmd,
                         cmd->tvc_sgl_count = 0;
                         return ret;
                 }
-
                 sg += ret;
                 sgl_count -= ret;
         }
@@ -1765,7 +1756,7 @@ static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tpg,
                 }
 
                 tv_cmd->tvc_upages = kzalloc(sizeof(struct page *) *
-                                        TCM_VHOST_PREALLOC_PAGES, GFP_KERNEL);
+                                        TCM_VHOST_PREALLOC_UPAGES, GFP_KERNEL);
                 if (!tv_cmd->tvc_upages) {
                         mutex_unlock(&tpg->tv_tpg_mutex);
                         pr_err("Unable to allocate tv_cmd->tvc_upages\n");