1 files changed, 323 insertions, 0 deletions
diff --git a/linux/bio.c b/linux/bio.c
new file mode 100644
index 0000000..966f227
--- /dev/null
+++ b/linux/bio.c
@@ -0,0 +1,323 @@
+/*
+ * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public Licens
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
+ *
+ */
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+
+void bio_copy_data_iter(struct bio *dst, struct bvec_iter dst_iter,
+			struct bio *src, struct bvec_iter src_iter)
+{
+	struct bio_vec src_bv, dst_bv;
+	void *src_p, *dst_p;
+	unsigned bytes;
+
+	while (1) {
+		if (!src_iter.bi_size) {
+			src = src->bi_next;
+			if (!src)
+				break;
+
+			src_iter = src->bi_iter;
+		}
+
+		if (!dst_iter.bi_size) {
+			dst = dst->bi_next;
+			if (!dst)
+				break;
+
+			dst_iter = dst->bi_iter;
+		}
+
+		src_bv = bio_iter_iovec(src, src_iter);
+		dst_bv = bio_iter_iovec(dst, dst_iter);
+
+		bytes = min(src_bv.bv_len, dst_bv.bv_len);
+
+		src_p = kmap_atomic(src_bv.bv_page);
+		dst_p = kmap_atomic(dst_bv.bv_page);
+
+		memcpy(dst_p + dst_bv.bv_offset,
+		       src_p + src_bv.bv_offset,
+		       bytes);
+
+		kunmap_atomic(dst_p);
+		kunmap_atomic(src_p);
+
+		bio_advance_iter(src, &src_iter, bytes);
+		bio_advance_iter(dst, &dst_iter, bytes);
+	}
+}
+
+void bio_copy_data(struct bio *dst, struct bio *src)
+{
+	bio_copy_data_iter(dst, dst->bi_iter,
+			   src, src->bi_iter);
+}
+
+void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
+{
+	unsigned long flags;
+	struct bio_vec bv;
+	struct bvec_iter iter;
+
+	__bio_for_each_segment(bv, bio, iter, start) {
+		char *data = bvec_kmap_irq(&bv, &flags);
+		memset(data, 0, bv.bv_len);
+		bvec_kunmap_irq(data, &flags);
+	}
+}
+
+void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
+{
+	/*
+	 * most users will be overriding ->bi_bdev with a new target,
+	 * so we don't set nor calculate new physical/hw segment counts here
+	 */
+	bio->bi_bdev = bio_src->bi_bdev;
+	bio_set_flag(bio, BIO_CLONED);
+	bio->bi_opf = bio_src->bi_opf;
+	bio->bi_iter = bio_src->bi_iter;
+	bio->bi_io_vec = bio_src->bi_io_vec;
+}
+
+struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
+{
+	struct bio *b;
+
+	b = bio_alloc_bioset(gfp_mask, 0, bs);
+	if (!b)
+		return NULL;
+
+	__bio_clone_fast(b, bio);
+	return b;
+}
+
+struct bio *bio_split(struct bio *bio, int sectors,
+		      gfp_t gfp, struct bio_set *bs)
+{
+	struct bio *split = NULL;
+
+	BUG_ON(sectors <= 0);
+	BUG_ON(sectors >= bio_sectors(bio));
+
+	/*
+	 * Discards need a mutable bio_vec to accommodate the payload
+	 * required by the DSM TRIM and UNMAP commands.
+	 */
+	if (bio_op(bio) == REQ_OP_DISCARD || bio_op(bio) == REQ_OP_SECURE_ERASE)
+		split = bio_clone_bioset(bio, gfp, bs);
+	else
+		split = bio_clone_fast(bio, gfp, bs);
+
+	if (!split)
+		return NULL;
+
+	split->bi_iter.bi_size = sectors << 9;
+
+	bio_advance(bio, split->bi_iter.bi_size);
+
+	return split;
+}
+
+int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
+{
+	int i;
+	struct bio_vec *bv;
+
+	bio_for_each_segment_all(bv, bio, i) {
+		bv->bv_page = alloc_page(gfp_mask);
+		if (!bv->bv_page) {
+			while (--bv >= bio->bi_io_vec)
+				__free_page(bv->bv_page);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+void bio_advance(struct bio *bio, unsigned bytes)
+{
+	bio_advance_iter(bio, &bio->bi_iter, bytes);
+}
+
+static void bio_free(struct bio *bio)
+{
+	unsigned front_pad = bio->bi_pool ? bio->bi_pool->front_pad : 0;
+
+	kfree((void *) bio - front_pad);
+}
+
+void bio_put(struct bio *bio)
+{
+	if (!bio_flagged(bio, BIO_REFFED))
+		bio_free(bio);
+	else {
+		BUG_ON(!atomic_read(&bio->__bi_cnt));
+
+		/*
+		 * last put frees it
+		 */
+		if (atomic_dec_and_test(&bio->__bi_cnt))
+			bio_free(bio);
+	}
+}
+
+static inline bool bio_remaining_done(struct bio *bio)
+{
+	/*
+	 * If we're not chaining, then ->__bi_remaining is always 1 and
+	 * we always end io on the first invocation.
+	 */
+	if (!bio_flagged(bio, BIO_CHAIN))
+		return true;
+
+	BUG_ON(atomic_read(&bio->__bi_remaining) <= 0);
+
+	if (atomic_dec_and_test(&bio->__bi_remaining)) {
+		bio_clear_flag(bio, BIO_CHAIN);
+		return true;
+	}
+
+	return false;
+}
+
+static struct bio *__bio_chain_endio(struct bio *bio)
+{
+	struct bio *parent = bio->bi_private;
+
+	if (!parent->bi_error)
+		parent->bi_error = bio->bi_error;
+	bio_put(bio);
+	return parent;
+}
+
+static void bio_chain_endio(struct bio *bio)
+{
+	bio_endio(__bio_chain_endio(bio));
+}
+
+void bio_endio(struct bio *bio)
+{
+again:
+	if (!bio_remaining_done(bio))
+		return;
+
+	/*
+	 * Need to have a real endio function for chained bios, otherwise
+	 * various corner cases will break (like stacking block devices that
+	 * save/restore bi_end_io) - however, we want to avoid unbounded
+	 * recursion and blowing the stack. Tail call optimization would
+	 * handle this, but compiling with frame pointers also disables
+	 * gcc's sibling call optimization.
+	 */
+	if (bio->bi_end_io == bio_chain_endio) {
+		bio = __bio_chain_endio(bio);
+		goto again;
+	}
+
+	if (bio->bi_end_io)
+		bio->bi_end_io(bio);
+}
+
+void bio_endio_nodec(struct bio *bio)
+{
+	goto nodec;
+
+	while (bio) {
+		if (unlikely(!bio_remaining_done(bio)))
+			break;
+nodec:
+		if (bio->bi_end_io == bio_chain_endio) {
+			struct bio *parent = bio->bi_private;
+			parent->bi_error = bio->bi_error;
+			bio_put(bio);
+			bio = parent;
+		} else {
+			if (bio->bi_end_io)
+				bio->bi_end_io(bio);
+			bio = NULL;
+		}
+	}
+}
+
+void bio_reset(struct bio *bio)
+{
+	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
+
+	memset(bio, 0, BIO_RESET_BYTES);
+	bio->bi_flags = flags;
+	atomic_set(&bio->__bi_remaining, 1);
+}
+
+struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
+{
+	unsigned front_pad = bs ? bs->front_pad : 0;
+	struct bio *bio;
+	void *p;
+
+	p = kmalloc(front_pad +
+		    sizeof(struct bio) +
+		    nr_iovecs * sizeof(struct bio_vec),
+		    gfp_mask);
+
+	if (unlikely(!p))
+		return NULL;
+
+	bio = p + front_pad;
+	bio_init(bio);
+	bio->bi_pool		= bs;
+	bio->bi_max_vecs	= nr_iovecs;
+	bio->bi_io_vec		= bio->bi_inline_vecs;
+
+	return bio;
+}
+
+struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
+			     struct bio_set *bs)
+{
+	struct bvec_iter iter;
+	struct bio_vec bv;
+	struct bio *bio;
+
+	bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
+	if (!bio)
+		return NULL;
+
+	bio->bi_bdev		= bio_src->bi_bdev;
+	bio->bi_opf		= bio_src->bi_opf;
+	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
+	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;
+
+	switch (bio_op(bio)) {
+	case REQ_OP_DISCARD:
+	case REQ_OP_SECURE_ERASE:
+		break;
+	case REQ_OP_WRITE_SAME:
+		bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
+		break;
+	default:
+		bio_for_each_segment(bv, bio_src, iter)
+			bio->bi_io_vec[bio->bi_vcnt++] = bv;
+		break;
+	}
+
+	return bio;
+}