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RDS: Copy rds_iovecs into kernel memory instead of rereading from userspace 

Change rds_rdma_pages to take a passed-in rds_iovec array instead
of doing copy_from_user itself.

Change rds_cmsg_rdma_args to copy rds_iovec array once only. This
eliminates the possibility of userspace changing it after our
sanity checks.

Implement stack-based storage for small numbers of iovecs, based
on net/socket.c, to save an alloc in the extremely common case.

Although this patch reduces iovec copies in cmsg_rdma_args to 1,
we still do another one in rds_rdma_extra_size. Getting rid of
that one will be trickier, so it'll be a separate patch.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Andy Grover 2010-10-28 15:40:58 +00:00 committed by David S. Miller
parent f4a3fc03c1
commit fc8162e3c0
1 changed files with 65 additions and 39 deletions
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104
net/rds/rdma.c
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@ -479,13 +479,38 @@ void rds_atomic_free_op(struct rm_atomic_op *ao)
/*
* Count the number of pages needed to describe an incoming iovec.
* Count the number of pages needed to describe an incoming iovec array.
*/
static int rds_rdma_pages(struct rds_rdma_args *args)
static int rds_rdma_pages(struct rds_iovec iov[], int nr_iovecs)
{
int tot_pages = 0;
unsigned int nr_pages;
unsigned int i;
/* figure out the number of pages in the vector */
for (i = 0; i < nr_iovecs; i++) {
nr_pages = rds_pages_in_vec(&iov[i]);
if (nr_pages == 0)
return -EINVAL;
tot_pages += nr_pages;
/*
* nr_pages for one entry is limited to (UINT_MAX>>PAGE_SHIFT)+1,
* so tot_pages cannot overflow without first going negative.
*/
if (tot_pages < 0)
return -EINVAL;
}
return tot_pages;
}
int rds_rdma_extra_size(struct rds_rdma_args *args)
{
struct rds_iovec vec;
struct rds_iovec __user *local_vec;
unsigned int tot_pages = 0;
int tot_pages = 0;
unsigned int nr_pages;
unsigned int i;
@ -507,16 +532,11 @@ static int rds_rdma_pages(struct rds_rdma_args *args)
* nr_pages for one entry is limited to (UINT_MAX>>PAGE_SHIFT)+1,
* so tot_pages cannot overflow without first going negative.
*/
if ((int)tot_pages < 0)
if (tot_pages < 0)
return -EINVAL;
}
return tot_pages;
}
int rds_rdma_extra_size(struct rds_rdma_args *args)
{
return rds_rdma_pages(args) * sizeof(struct scatterlist);
return tot_pages * sizeof(struct scatterlist);
}
/*
@ -527,13 +547,12 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
struct cmsghdr *cmsg)
{
struct rds_rdma_args *args;
struct rds_iovec vec;
struct rm_rdma_op *op = &rm->rdma;
int nr_pages;
unsigned int nr_bytes;
struct page **pages = NULL;
struct rds_iovec __user *local_vec;
unsigned int nr;
struct rds_iovec iovstack[UIO_FASTIOV], *iovs = iovstack;
int iov_size;
unsigned int i, j;
int ret = 0;
@ -553,7 +572,22 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
goto out;
}
nr_pages = rds_rdma_pages(args);
/* Check whether to allocate the iovec area */
iov_size = args->nr_local * sizeof(struct rds_iovec);
if (args->nr_local > UIO_FASTIOV) {
iovs = sock_kmalloc(rds_rs_to_sk(rs), iov_size, GFP_KERNEL);
if (!iovs) {
ret = -ENOMEM;
goto out;
}
}
if (copy_from_user(iovs, (struct rds_iovec __user *)(unsigned long) args->local_vec_addr, iov_size)) {
ret = -EFAULT;
goto out;
}
nr_pages = rds_rdma_pages(iovs, args->nr_local);
if (nr_pages < 0) {
ret = -EINVAL;
goto out;
@ -606,50 +640,40 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
(unsigned long long)args->remote_vec.addr,
op->op_rkey);
local_vec = (struct rds_iovec __user *)(unsigned long) args->local_vec_addr;
for (i = 0; i < args->nr_local; i++) {
if (copy_from_user(&vec, &local_vec[i],
sizeof(struct rds_iovec))) {
ret = -EFAULT;
goto out;
}
struct rds_iovec *iov = &iovs[i];
/* don't need to check, rds_rdma_pages() verified nr will be +nonzero */
unsigned int nr = rds_pages_in_vec(iov);
nr = rds_pages_in_vec(&vec);
if (nr == 0) {
ret = -EINVAL;
goto out;
}
rs->rs_user_addr = vec.addr;
rs->rs_user_bytes = vec.bytes;
rs->rs_user_addr = iov->addr;
rs->rs_user_bytes = iov->bytes;
/* If it's a WRITE operation, we want to pin the pages for reading.
* If it's a READ operation, we need to pin the pages for writing.
*/
ret = rds_pin_pages(vec.addr, nr, pages, !op->op_write);
ret = rds_pin_pages(iov->addr, nr, pages, !op->op_write);
if (ret < 0)
goto out;
rdsdebug("RDS: nr_bytes %u nr %u vec.bytes %llu vec.addr %llx\n",
nr_bytes, nr, vec.bytes, vec.addr);
rdsdebug("RDS: nr_bytes %u nr %u iov->bytes %llu iov->addr %llx\n",
nr_bytes, nr, iov->bytes, iov->addr);
nr_bytes += vec.bytes;
nr_bytes += iov->bytes;
for (j = 0; j < nr; j++) {
unsigned int offset = vec.addr & ~PAGE_MASK;
unsigned int offset = iov->addr & ~PAGE_MASK;
struct scatterlist *sg;
sg = &op->op_sg[op->op_nents + j];
sg_set_page(sg, pages[j],
min_t(unsigned int, vec.bytes, PAGE_SIZE - offset),
min_t(unsigned int, iov->bytes, PAGE_SIZE - offset),
offset);
rdsdebug("RDS: sg->offset %x sg->len %x vec.addr %llx vec.bytes %llu\n",
sg->offset, sg->length, vec.addr, vec.bytes);
rdsdebug("RDS: sg->offset %x sg->len %x iov->addr %llx iov->bytes %llu\n",
sg->offset, sg->length, iov->addr, iov->bytes);
vec.addr += sg->length;
vec.bytes -= sg->length;
iov->addr += sg->length;
iov->bytes -= sg->length;
}
op->op_nents += nr;
@ -665,6 +689,8 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
op->op_bytes = nr_bytes;
out:
if (iovs != iovstack)
sock_kfree_s(rds_rs_to_sk(rs), iovs, iov_size);
kfree(pages);
if (ret)
rds_rdma_free_op(op);