pw@xxxxxxx wrote on Mon, 19 Mar 2007 14:07 -0400:
> Here is the patch to use sg_iovec, with its userspace void * and
> size_t, and the CONFIG_COMPAT code to fixup 32-bit userspace. I'm
> not fond of having __u64 for non-iovec buffer representations, and
> void * for iovec buffer representations, but it saves having to
> build an sg_iovec just to call into the existing blk_rq_map_user_iov.
Just for comparison, a cleaned up version of the earlier patch that
does not require compat conversion. Instead, use a new struct
sg_v4_iovec with explicit u64/u32 representation for user pointer
and length.
Perhaps later we might change blk_rq_map_user_iov to take
sg_v4_iovec and let sgv3 convert its sg_iovec into that.
-- Pete
Support vectored IO as in SGv3. The iovec structure uses explicit
sizes to avoid the need for compat conversion.
Signed-off-by: Pete Wyckoff <pw@xxxxxxx>
---
block/bsg.c | 95 ++++++++++++++++++++++++++++++++++++++------------
include/linux/bsg.h | 14 +++++++
2 files changed, 86 insertions(+), 23 deletions(-)
diff --git a/block/bsg.c b/block/bsg.c
index f1ea258..e334f75 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -280,6 +280,56 @@ bsg_validate_sgv4_hdr(request_queue_t *q, struct sg_io_v4 *hdr, int *rw)
}
/*
+ * Map either the in or out bufs. Convert sg_v4_iovec to sg_iovec
+ * to use existing blk_rq_map infrastructure. We could do a copy-in-place
+ * conversion on 64-bit kernels, just by zeroing the top half of sg_iovec's
+ * iov_len, but do not, for simplicity.
+ */
+static int bsg_map_data(struct request_queue *q, struct request *rq,
+ __u64 uaddr, __u32 tot_len, __u32 numiov,
+ enum dma_data_direction dir)
+{
+ int i, ret;
+ void __user *ubuf = (void __user *) (unsigned long) uaddr;
+ struct sg_iovec fastiov[8], *iov = fastiov;
+ struct sg_v4_iovec v4_fastiov[8], *v4_iov = v4_fastiov;
+
+ if (numiov == 0) {
+ ret = blk_rq_map_user(q, rq, ubuf, tot_len);
+ goto out;
+ }
+
+ if (numiov >= ARRAY_SIZE(fastiov)) {
+ iov = kmalloc(numiov * (sizeof(*iov) + sizeof(*v4_iov)),
+ GFP_KERNEL);
+ if (iov == NULL) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ v4_iov = (void *) &iov[numiov];
+ }
+
+ if (copy_from_user(v4_iov, ubuf, numiov * sizeof(*v4_iov))) {
+ ret = -EFAULT;
+ goto outfree;
+ }
+
+ for (i=0; i<numiov; i++) {
+ iov[i].iov_base = (void *)(unsigned long) v4_iov[i].iov_base;
+ iov[i].iov_len = v4_iov[i].iov_len;
+ }
+
+ ret = blk_rq_map_user_iov(q, rq, iov, numiov, tot_len);
+
+outfree:
+ if (iov != fastiov)
+ kfree(iov);
+
+out:
+ return ret;
+}
+
+/*
* map sg_io_v4 to a request.
*/
static struct request *
@@ -288,12 +338,12 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
request_queue_t *q = bd->queue;
struct request *rq;
int ret, rw = 0; /* shut up gcc */
- unsigned int dxfer_len;
- void *dxferp = NULL;
- dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
- hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
- hdr->din_xfer_len);
+ dprintk("map hdr %llx/%u/%u %llx/%u/%u\n",
+ (unsigned long long) hdr->dout_xferp, hdr->dout_xfer_len,
+ hdr->dout_iovec_count,
+ (unsigned long long) hdr->din_xferp, hdr->din_xfer_len,
+ hdr->din_iovec_count);
ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
if (ret)
@@ -305,29 +355,28 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
rq = blk_get_request(q, rw, GFP_KERNEL);
ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, test_bit(BSG_F_WRITE_PERM,
&bd->flags));
- if (ret) {
- blk_put_request(rq);
- return ERR_PTR(ret);
- }
+ if (ret)
+ goto errout;
if (hdr->dout_xfer_len) {
- dxfer_len = hdr->dout_xfer_len;
- dxferp = (void*)(unsigned long)hdr->dout_xferp;
+ ret = bsg_map_data(q, rq, hdr->dout_xferp, hdr->dout_xfer_len,
+ hdr->dout_iovec_count, DMA_TO_DEVICE);
+ if (ret)
+ goto errout;
} else if (hdr->din_xfer_len) {
- dxfer_len = hdr->din_xfer_len;
- dxferp = (void*)(unsigned long)hdr->din_xferp;
- } else
- dxfer_len = 0;
-
- if (dxfer_len) {
- ret = blk_rq_map_user(q, rq, dxferp, dxfer_len);
- if (ret) {
- dprintk("failed map at %d\n", ret);
- blk_put_request(rq);
- rq = ERR_PTR(ret);
- }
+ ret = bsg_map_data(q, rq, hdr->din_xferp, hdr->din_xfer_len,
+ hdr->din_iovec_count, DMA_FROM_DEVICE);
+ if (ret)
+ goto errout;
}
+ goto out;
+
+errout:
+ blk_put_request(rq);
+ rq = ERR_PTR(ret);
+
+out:
return rq;
}
diff --git a/include/linux/bsg.h b/include/linux/bsg.h
index 51152cb..7c11e67 100644
--- a/include/linux/bsg.h
+++ b/include/linux/bsg.h
@@ -16,6 +16,8 @@ struct sg_io_v4 {
__u64 response; /* [i], [*o] {SCSI: (auto)sense data} */
/* "din_" for data in (from device); "dout_" for data out (to device) */
+ __u32 dout_iovec_count; /* [i] =0 -> "flat" data transfer */
+ __u32 din_iovec_count; /* [i] >0 -> dxfer is struct sg_v4_iovec * */
__u32 dout_xfer_len; /* [i] bytes to be transferred to device */
__u32 din_xfer_len; /* [i] bytes to be transferred from device */
__u64 dout_xferp; /* [i], [*i] */
@@ -40,6 +42,18 @@ struct sg_io_v4 {
__u32 padding;
};
+/*
+ * Vector of address/length pairs, used when dout_iovec_count (or din_)
+ * is non-zero. In that case, dout_xferp is a list of struct sg_v4_iovec
+ * and dout_iovec_count is the number of entries in that list. dout_xfer_len
+ * is the total length of the list.
+ */
+struct sg_v4_iovec {
+ __u64 iov_base;
+ __u32 iov_len;
+ __u32 __pad1;
+};
+
#ifdef __KERNEL__
#if defined(CONFIG_BLK_DEV_BSG)
--
1.5.0.3
-
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