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>

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index cf50ce9..ae434db 100644 (file)
--- 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");