fix the copy vs. map logics in blk_rq_map_user_iov()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/block/blk-map.c b/block/blk-map.c
index a54f054..b9f88b7 100644 (file)
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -9,24 +9,6 @@
 
 #include "blk.h"
 
-static bool iovec_gap_to_prv(struct request_queue *q,
-                            struct iovec *prv, struct iovec *cur)
-{
-       unsigned long prev_end;
-
-       if (!queue_virt_boundary(q))
-               return false;
-
-       if (prv->iov_base == NULL && prv->iov_len == 0)
-               /* prv is not set - don't check */
-               return false;
-
-       prev_end = (unsigned long)(prv->iov_base + prv->iov_len);
-
-       return (((unsigned long)cur->iov_base & queue_virt_boundary(q)) ||
-               prev_end & queue_virt_boundary(q));
-}
-
 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
                      struct bio *bio)
 {
@@ -125,31 +107,18 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
                        struct rq_map_data *map_data,
                        const struct iov_iter *iter, gfp_t gfp_mask)
 {
-       struct iovec iov, prv = {.iov_base = NULL, .iov_len = 0};
-       bool copy = (q->dma_pad_mask & iter->count) || map_data;
+       bool copy = false;
+       unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
        struct bio *bio = NULL;
        struct iov_iter i;
        int ret;
 
-       if (!iter || !iter->count)
-               return -EINVAL;
-
-       iov_for_each(iov, i, *iter) {
-               unsigned long uaddr = (unsigned long) iov.iov_base;
-
-               if (!iov.iov_len)
-                       return -EINVAL;
-
-               /*
-                * Keep going so we check length of all segments
-                */
-               if ((uaddr & queue_dma_alignment(q)) ||
-                   iovec_gap_to_prv(q, &prv, &iov))
-                       copy = true;
-
-               prv.iov_base = iov.iov_base;
-               prv.iov_len = iov.iov_len;
-       }
+       if (map_data)
+               copy = true;
+       else if (iov_iter_alignment(iter) & align)
+               copy = true;
+       else if (queue_virt_boundary(q))
+               copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
 
        i = *iter;
        do {

diff --git a/include/linux/uio.h b/include/linux/uio.h
index fd9bcfe..1b5d1cd 100644 (file)
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -87,6 +87,7 @@ size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 unsigned long iov_iter_alignment(const struct iov_iter *i);
+unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
                        unsigned long nr_segs, size_t count);
 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 5fecddc..ca5316e 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -569,6 +569,25 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
 }
 EXPORT_SYMBOL(iov_iter_alignment);
 
+unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
+{
+        unsigned long res = 0;
+       size_t size = i->count;
+       if (!size)
+               return 0;
+
+       iterate_all_kinds(i, size, v,
+               (res |= (!res ? 0 : (unsigned long)v.iov_base) |
+                       (size != v.iov_len ? size : 0), 0),
+               (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
+                       (size != v.bv_len ? size : 0)),
+               (res |= (!res ? 0 : (unsigned long)v.iov_base) |
+                       (size != v.iov_len ? size : 0))
+               );
+               return res;
+}
+EXPORT_SYMBOL(iov_iter_gap_alignment);
+
 ssize_t iov_iter_get_pages(struct iov_iter *i,
                   struct page **pages, size_t maxsize, unsigned maxpages,
                   size_t *start)