[RFC 1/6] vhost/scsi: Move sanity check into vhost_scsi_map_iov_to_sgl

Nicholas A. Bellinger
2014-02-24T05:32:25Z

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>
Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
drivers/vhost/scsi.c | 59 +++++++++++++++++++++-----------------------------
1 file changed, 25 insertions(+), 34 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 0a025b8..31feb47 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 */
@@ -762,35 +762,28 @@ 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_iov_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)
@@ -820,33 +813,32 @@ 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]));
@@ -854,7 +846,6 @@ vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *cmd,
cmd->tvc_sgl_count = 0;
return ret;
}
-
sg += ret;
sgl_count -= ret;
}
@@ -1753,7 +1744,7 @@ 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");
--
1.7.10.4