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Date: Wed, 1 Apr 2009 22:44:25 +0900
From: Tejun Heo <tj@...nel.org>
To: axboe@...nel.dk, bharrosh@...asas.com,
linux-kernel@...r.kernel.org, fujita.tomonori@....ntt.co.jp
Cc: Tejun Heo <tj@...nel.org>
Subject: [PATCH 10/17] bio: use bio_create_from_sgl() in bio_map_user_iov()
Impact: cleanup
As bio_map_user_iov() is unique in the way it acquires pages to map
from all other three operations (user-copy, kern-map, kern-copy), the
function still needs to get the pages itself but the bio creation can
use bio_create_from_sgl(). Create sgl of mapped pages and use it to
create bio from it. The code will be further simplified with future
changes to bio_create_from_sgl().
Signed-off-by: Tejun Heo <tj@...nel.org>
---
fs/bio.c | 79 ++++++++++++++++++++++++++------------------------------------
1 files changed, 33 insertions(+), 46 deletions(-)
diff --git a/fs/bio.c b/fs/bio.c
index 4540afc..1ca8b16 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1059,13 +1059,13 @@ struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *md,
struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
struct iovec *iov, int count, int rw, gfp_t gfp)
{
- int i, j;
size_t tot_len = 0;
int nr_pages = 0;
+ int nents = 0;
+ struct scatterlist *sgl;
struct page **pages;
struct bio *bio;
- int cur_page = 0;
- int ret, offset;
+ int i, ret;
for (i = 0; i < count; i++) {
unsigned long uaddr = (unsigned long)iov[i].iov_base;
@@ -1088,70 +1088,57 @@ struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
if (!nr_pages || tot_len & q->dma_pad_mask)
return ERR_PTR(-EINVAL);
- bio = bio_kmalloc(gfp, nr_pages);
- if (!bio)
+ sgl = kmalloc(nr_pages * sizeof(sgl[0]), gfp);
+ if (!sgl)
return ERR_PTR(-ENOMEM);
+ sg_init_table(sgl, nr_pages);
ret = -ENOMEM;
- pages = kcalloc(nr_pages, sizeof(struct page *), gfp);
+ pages = kcalloc(nr_pages, sizeof(pages[0]), gfp);
if (!pages)
- goto out;
+ goto err_sgl;
for (i = 0; i < count; i++) {
unsigned long uaddr = (unsigned long)iov[i].iov_base;
unsigned long len = iov[i].iov_len;
- unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
- unsigned long start = uaddr >> PAGE_SHIFT;
- const int local_nr_pages = end - start;
- const int page_limit = cur_page + local_nr_pages;
-
+ unsigned long offset = offset_in_page(uaddr);
+ int local_nr_pages = PFN_UP(uaddr + len) - PFN_DOWN(uaddr);
+
ret = get_user_pages_fast(uaddr, local_nr_pages, rw == READ,
- &pages[cur_page]);
+ &pages[nents]);
if (ret < local_nr_pages) {
ret = -EFAULT;
- goto out_unmap;
+ goto err_pages;
}
- offset = uaddr & ~PAGE_MASK;
- for (j = cur_page; j < page_limit; j++) {
- unsigned int bytes = PAGE_SIZE - offset;
+ while (len) {
+ unsigned int bytes = min(PAGE_SIZE - offset, len);
- if (len <= 0)
- break;
-
- if (bytes > len)
- bytes = len;
-
- /*
- * sorry...
- */
- if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
- bytes)
- break;
+ sg_set_page(&sgl[nents], pages[nents], bytes, offset);
+ nents++;
len -= bytes;
offset = 0;
}
-
- cur_page = j;
- /*
- * release the pages we didn't map into the bio, if any
- */
- while (j < page_limit)
- page_cache_release(pages[j++]);
}
+ BUG_ON(nents != nr_pages);
- kfree(pages);
+ bio = bio_create_from_sgl(q, sgl, nents, nr_pages, rw, gfp);
+ if (IS_ERR(bio)) {
+ ret = PTR_ERR(bio);
+ goto err_pages;
+ }
- /*
- * set data direction, and check if mapped pages need bouncing
- */
- if (rw == WRITE)
- bio->bi_rw |= (1 << BIO_RW);
+ /* release the pages we didn't map into the bio, if any */
+ for (i = bio->bi_vcnt; i < nr_pages; i++)
+ page_cache_release(pages[i]);
bio->bi_bdev = bdev;
bio->bi_flags |= (1 << BIO_USER_MAPPED);
+ kfree(sgl);
+ kfree(pages);
+
/*
* subtle -- if __bio_map_user() ended up bouncing a bio,
* it would normally disappear when its bi_end_io is run.
@@ -1162,15 +1149,15 @@ struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
return bio;
- out_unmap:
+err_pages:
for (i = 0; i < nr_pages; i++) {
- if(!pages[i])
+ if (!pages[i])
break;
page_cache_release(pages[i]);
}
- out:
kfree(pages);
- bio_put(bio);
+err_sgl:
+ kfree(sgl);
return ERR_PTR(ret);
}
--
1.6.0.2
--
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