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Date: Mon, 12 Jan 2015 12:43:59 +0100
From: Dongsu Park <dongsu.park@...fitbricks.com>
To: linux-kernel@...r.kernel.org
Cc: Christoph Hellwig <hch@...radead.org>,
Kent Overstreet <kmo@...erainc.com>,
Jens Axboe <axboe@...nel.dk>,
Dongsu Park <dongsu.park@...fitbricks.com>,
Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH v2 2/7] block: rewrite __bio_copy_iov()
Rewrite __bio_copy_iov() so that it can call either _read() or _write()
variant, which is determined by direction to_iov, given as either READ
or WRITE. Moreover, make __bio_copy_iov() take its parameter iov_iter
by value, to avoid awkward situations like ref-/dereferencing pointer
and value repeatedly.
This commit should contain only literal replacements, without
functional changes.
Suggested-by: Christoph Hellwig <hch@...radead.org>
Cc: Kent Overstreet <kmo@...erainc.com>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Dongsu Park <dongsu.park@...fitbricks.com>
---
block/bio.c | 113 ++++++++++++++++++++++++++++++++++++++++--------------------
1 file changed, 75 insertions(+), 38 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 8267676..7b1aed3 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1046,46 +1046,84 @@ static struct bio_map_data *bio_alloc_map_data(unsigned int iov_count,
sizeof(struct sg_iovec) * iov_count, gfp_mask);
}
-static int __bio_copy_iov(struct bio *bio, const struct iov_iter *iter,
- int to_user, int from_user, int do_free_page)
+/**
+ * __bio_copy_iov_read - copy all pages from iov_iter to bio
+ * @bio: The &struct bio which describes the I/O as destination
+ * @iter: iov_iter as source
+ *
+ * Copy all pages from iov_iter to bio.
+ * Returns 0 on success, or error on failure.
+ */
+static int __bio_copy_iov_read(struct bio *bio, struct iov_iter iter)
{
- int ret = 0, i;
+ int i;
struct bio_vec *bvec;
- struct iov_iter iov_iter = *iter;
bio_for_each_segment_all(bvec, bio, i) {
- char *bv_addr = page_address(bvec->bv_page);
- unsigned int bv_len = bvec->bv_len;
-
- while (bv_len && iov_iter.count) {
- struct iovec iov = iov_iter_iovec(&iov_iter);
- unsigned int bytes = min_t(unsigned int, bv_len,
- iov.iov_len);
-
- if (!ret) {
- if (to_user)
- ret = copy_to_user(iov.iov_base,
- bv_addr, bytes);
-
- if (from_user)
- ret = copy_from_user(bv_addr,
- iov.iov_base,
- bytes);
-
- if (ret)
- ret = -EFAULT;
- }
+ ssize_t ret;
- bv_len -= bytes;
- bv_addr += bytes;
- iov_iter_advance(&iov_iter, bytes);
- }
+ ret = copy_page_from_iter(bvec->bv_page,
+ bvec->bv_offset,
+ bvec->bv_len,
+ &iter);
- if (do_free_page)
- __free_page(bvec->bv_page);
+ if (!iov_iter_count(&iter))
+ break;
+
+ if (ret < bvec->bv_len)
+ return -EFAULT;
}
- return ret;
+ return 0;
+}
+
+/**
+ * __bio_copy_iov_write - copy all pages from bio to iov_iter
+ * @bio: The &struct bio which describes the I/O as source
+ * @iter: iov_iter as destination
+ *
+ * Copy all pages from bio to iov_iter.
+ * Returns 0 on success, or error on failure.
+ */
+static int __bio_copy_iov_write(struct bio *bio, struct iov_iter iter)
+{
+ int i;
+ struct bio_vec *bvec;
+
+ bio_for_each_segment_all(bvec, bio, i) {
+ ssize_t ret;
+
+ ret = copy_page_to_iter(bvec->bv_page,
+ bvec->bv_offset,
+ bvec->bv_len,
+ &iter);
+
+ if (!iov_iter_count(&iter))
+ break;
+
+ if (ret < bvec->bv_len)
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+/**
+ * __bio_copy_iov - copy all pages between bio and iov_iter
+ * @bio: The &struct bio which describes the I/O
+ * @iter: iov_iter either as source or destination
+ * @to_iov: whether to %READ (0) or %WRITE (1)
+ *
+ * Simple wrapper around __bio_copy_iov_{write,read}().
+ * Returns 0 on success, or the error returned as-is on failure.
+ */
+static inline int __bio_copy_iov(struct bio *bio, struct iov_iter iter,
+ int to_iov)
+{
+ if (to_iov == WRITE)
+ return __bio_copy_iov_write(bio, iter);
+ else
+ return __bio_copy_iov_read(bio, iter);
}
/**
@@ -1106,11 +1144,10 @@ int bio_uncopy_user(struct bio *bio)
* if we're in a workqueue, the request is orphaned, so
* don't copy into a random user address space, just free.
*/
- if (current->mm)
- ret = __bio_copy_iov(bio, &bmd->iter,
- bio_data_dir(bio) == READ,
- 0, bmd->is_our_pages);
- else if (bmd->is_our_pages)
+ if (current->mm && bio_data_dir(bio) == READ)
+ ret = __bio_copy_iov(bio, bmd->iter, WRITE);
+
+ if (bmd->is_our_pages)
bio_for_each_segment_all(bvec, bio, i)
__free_page(bvec->bv_page);
}
@@ -1233,7 +1270,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
*/
if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
(map_data && map_data->from_user)) {
- ret = __bio_copy_iov(bio, iter, 0, 1, 0);
+ ret = __bio_copy_iov(bio, *iter, READ);
if (ret)
goto cleanup;
}
--
2.1.0
--
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