block: introduce struct rq_map_data to use reserved pages
This patch introduces struct rq_map_data to enable bio_copy_use_iov()
use reserved pages.
Currently, bio_copy_user_iov allocates bounce pages but
drivers/scsi/sg.c wants to allocate pages by itself and use
them. struct rq_map_data can be used to pass allocated pages to
bio_copy_user_iov.
The current users of bio_copy_user_iov simply passes NULL (they don't
want to use pre-allocated pages).
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Douglas Gilbert <dougg@torque.net>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/bio.c b/fs/bio.c
index 3d2e9ad..a2f0726 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -439,16 +439,19 @@
struct bio_map_data {
struct bio_vec *iovecs;
- int nr_sgvecs;
struct sg_iovec *sgvecs;
+ int nr_sgvecs;
+ int is_our_pages;
};
static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
- struct sg_iovec *iov, int iov_count)
+ struct sg_iovec *iov, int iov_count,
+ int is_our_pages)
{
memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
bmd->nr_sgvecs = iov_count;
+ bmd->is_our_pages = is_our_pages;
bio->bi_private = bmd;
}
@@ -483,7 +486,8 @@
}
static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
- struct sg_iovec *iov, int iov_count, int uncopy)
+ struct sg_iovec *iov, int iov_count, int uncopy,
+ int do_free_page)
{
int ret = 0, i;
struct bio_vec *bvec;
@@ -526,7 +530,7 @@
}
}
- if (uncopy)
+ if (do_free_page)
__free_page(bvec->bv_page);
}
@@ -545,7 +549,8 @@
struct bio_map_data *bmd = bio->bi_private;
int ret;
- ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs, bmd->nr_sgvecs, 1);
+ ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs, bmd->nr_sgvecs, 1,
+ bmd->is_our_pages);
bio_free_map_data(bmd);
bio_put(bio);
@@ -555,6 +560,7 @@
/**
* bio_copy_user_iov - copy user data to bio
* @q: destination block queue
+ * @map_data: pointer to the rq_map_data holding pages (if necessary)
* @iov: the iovec.
* @iov_count: number of elements in the iovec
* @write_to_vm: bool indicating writing to pages or not
@@ -564,8 +570,10 @@
* to/from kernel pages as necessary. Must be paired with
* call bio_uncopy_user() on io completion.
*/
-struct bio *bio_copy_user_iov(struct request_queue *q, struct sg_iovec *iov,
- int iov_count, int write_to_vm, gfp_t gfp_mask)
+struct bio *bio_copy_user_iov(struct request_queue *q,
+ struct rq_map_data *map_data,
+ struct sg_iovec *iov, int iov_count,
+ int write_to_vm, gfp_t gfp_mask)
{
struct bio_map_data *bmd;
struct bio_vec *bvec;
@@ -600,13 +608,26 @@
bio->bi_rw |= (!write_to_vm << BIO_RW);
ret = 0;
+ i = 0;
while (len) {
- unsigned int bytes = PAGE_SIZE;
+ unsigned int bytes;
+
+ if (map_data)
+ bytes = 1U << (PAGE_SHIFT + map_data->page_order);
+ else
+ bytes = PAGE_SIZE;
if (bytes > len)
bytes = len;
- page = alloc_page(q->bounce_gfp | gfp_mask);
+ if (map_data) {
+ if (i == map_data->nr_entries) {
+ ret = -ENOMEM;
+ break;
+ }
+ page = map_data->pages[i++];
+ } else
+ page = alloc_page(q->bounce_gfp | gfp_mask);
if (!page) {
ret = -ENOMEM;
break;
@@ -625,16 +646,17 @@
* success
*/
if (!write_to_vm) {
- ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0);
+ ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
if (ret)
goto cleanup;
}
- bio_set_map_data(bmd, bio, iov, iov_count);
+ bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
return bio;
cleanup:
- bio_for_each_segment(bvec, bio, i)
- __free_page(bvec->bv_page);
+ if (!map_data)
+ bio_for_each_segment(bvec, bio, i)
+ __free_page(bvec->bv_page);
bio_put(bio);
out_bmd:
@@ -645,6 +667,7 @@
/**
* bio_copy_user - copy user data to bio
* @q: destination block queue
+ * @map_data: pointer to the rq_map_data holding pages (if necessary)
* @uaddr: start of user address
* @len: length in bytes
* @write_to_vm: bool indicating writing to pages or not
@@ -654,15 +677,16 @@
* to/from kernel pages as necessary. Must be paired with
* call bio_uncopy_user() on io completion.
*/
-struct bio *bio_copy_user(struct request_queue *q, unsigned long uaddr,
- unsigned int len, int write_to_vm, gfp_t gfp_mask)
+struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
+ unsigned long uaddr, unsigned int len,
+ int write_to_vm, gfp_t gfp_mask)
{
struct sg_iovec iov;
iov.iov_base = (void __user *)uaddr;
iov.iov_len = len;
- return bio_copy_user_iov(q, &iov, 1, write_to_vm, gfp_mask);
+ return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
}
static struct bio *__bio_map_user_iov(struct request_queue *q,
@@ -1028,7 +1052,7 @@
bio->bi_private = bmd;
bio->bi_end_io = bio_copy_kern_endio;
- bio_set_map_data(bmd, bio, &iov, 1);
+ bio_set_map_data(bmd, bio, &iov, 1, 1);
return bio;
cleanup:
bio_for_each_segment(bvec, bio, i)