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-rw-r--r--block/bio.c54
1 files changed, 41 insertions, 13 deletions
diff --git a/block/bio.c b/block/bio.c
index 04969b392c72..b12966e415d3 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -828,25 +828,27 @@ int bio_add_page(struct bio *bio, struct page *page,
EXPORT_SYMBOL(bio_add_page);
/**
- * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
+ * __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
* @bio: bio to add pages to
* @iter: iov iterator describing the region to be mapped
*
- * Pins as many pages from *iter and appends them to @bio's bvec array. The
+ * Pins pages from *iter and appends them to @bio's bvec array. The
* pages will have to be released using put_page() when done.
+ * For multi-segment *iter, this function only adds pages from the
+ * the next non-empty segment of the iov iterator.
*/
-int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
+static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
{
- unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
+ unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt, idx;
struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
struct page **pages = (struct page **)bv;
- size_t offset, diff;
+ size_t offset;
ssize_t size;
size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
if (unlikely(size <= 0))
return size ? size : -EFAULT;
- nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE;
+ idx = nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE;
/*
* Deep magic below: We need to walk the pinned pages backwards
@@ -859,21 +861,46 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
bio->bi_iter.bi_size += size;
bio->bi_vcnt += nr_pages;
- diff = (nr_pages * PAGE_SIZE - offset) - size;
- while (nr_pages--) {
- bv[nr_pages].bv_page = pages[nr_pages];
- bv[nr_pages].bv_len = PAGE_SIZE;
- bv[nr_pages].bv_offset = 0;
+ while (idx--) {
+ bv[idx].bv_page = pages[idx];
+ bv[idx].bv_len = PAGE_SIZE;
+ bv[idx].bv_offset = 0;
}
bv[0].bv_offset += offset;
bv[0].bv_len -= offset;
- if (diff)
- bv[bio->bi_vcnt - 1].bv_len -= diff;
+ bv[nr_pages - 1].bv_len -= nr_pages * PAGE_SIZE - offset - size;
iov_iter_advance(iter, size);
return 0;
}
+
+/**
+ * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
+ * @bio: bio to add pages to
+ * @iter: iov iterator describing the region to be mapped
+ *
+ * Pins pages from *iter and appends them to @bio's bvec array. The
+ * pages will have to be released using put_page() when done.
+ * The function tries, but does not guarantee, to pin as many pages as
+ * fit into the bio, or are requested in *iter, whatever is smaller.
+ * If MM encounters an error pinning the requested pages, it stops.
+ * Error is returned only if 0 pages could be pinned.
+ */
+int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
+{
+ unsigned short orig_vcnt = bio->bi_vcnt;
+
+ do {
+ int ret = __bio_iov_iter_get_pages(bio, iter);
+
+ if (unlikely(ret))
+ return bio->bi_vcnt > orig_vcnt ? 0 : ret;
+
+ } while (iov_iter_count(iter) && !bio_full(bio));
+
+ return 0;
+}
EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
static void submit_bio_wait_endio(struct bio *bio)
@@ -1780,6 +1807,7 @@ struct bio *bio_split(struct bio *bio, int sectors,
bio_integrity_trim(split);
bio_advance(bio, split->bi_iter.bi_size);
+ bio->bi_iter.bi_done = 0;
if (bio_flagged(bio, BIO_TRACE_COMPLETION))
bio_set_flag(split, BIO_TRACE_COMPLETION);